High fat diet- induced obesity decreases ErbB receptors expression in liver and adipose tissue in C57BL/6 mice

Neuregulins (NRGs) are a family of signaling proteins that bind to receptor tyrosine kinases of the ErbB family (ErbB2 to ErbB4), which can homo- or heterodimerize depending on their structural features and cell type. Many studies have proposed that decreased NRG levels are a common characteristic of obesity. In liver and adipose tissue, the increase in NRG expression has protective effects against obesity. However, it is still unknown whether ErbBs expression is altered in this pathology. We hypothesized that high fat diet-induced obesity downregulates ErbB receptors expression in obese mice compared to normal weight mice. Males C57BL/6 mice (n=6-7 for each group) were fed for 12 weeks and divided into: (i) control diet (CD; 10%-kcal fat, 20%-kcal protein, 70%-kcal carbohydrates), and (ii) high fat diet (HFD; 60%-kcal fat, 20%-kcal protein, 20%-kcal carbohydrates). General parameters and ErbBs expression (qPCR, immunohistochemistry and Western blot) were evaluated. We observed a significant increase in final body weight (47%), adipose tissue to body weight ratio (244%) and HOMA-IR (69%), among other parameters, in obese mice. In HFD group significantly decreased ErbB2 (48%) and ErbB3 (66%) mRNA levels in liver (no change in ErbB4), and ErbB2 (43%), ErbB3 (76%) and ErbB4 (35%) in adipose tissue, compared to CD. Furthermore, ErbB2 and ErbB3 protein levels decreased significantly in HFD group compared to the CD in liver. Therefore, our results suggest that HFD-induced obesity significantly decreases ErbBs expression in liver and adipose tissue in this murine model, that may be associated with alterations in the NRG pathway in obese mice.

Las neuregulinas (NRGs) son una familia de proteínas de señalización que se unen a receptores tirosina quinasas de la familia ErbB (ErbB2 a ErbB4), que pueden homo- o heterodimerizar dependiendo de sus características estructurales y del tipo celular. Estudios han propuesto que la disminución de los niveles de NRG es una característica común de la obesidad. En el hígado y el tejido adiposo (TA), el aumento de la expresión de NRG tiene efectos protectores contra la obesidad. Sin embargo, aún se desconoce si la expresión de ErbBs está alterada en esta patología. Nuestra hipótesis es que la obesidad inducida por una dieta alta en grasas (DAG) disminuye la expresión de los ErbB en ratones obesos. Ratones machos C57BL/6 (n=6-7 para c/grupo) fueron alimentados durante 12 semanas y divididos en: (i) dieta control (DC; 10%-kcal grasa, 20%-kcal proteína, 70%-kcal carbohidratos), y (ii) DAG (60%-kcal grasa, 20%-kcal proteína, 20%-kcal carbohidratos). Se evaluaron los parámetros generales y la expresión de ErbBs (qPCR, inmunohistoquímica y Western blot). Observamos un aumento significativo del peso corporal final (47%), de la relación tejido adiposo/peso corporal (244%) y del HOMA-IR (69%), entre otros parámetros, en ratones obesos. En este grupo disminuyó significativamente los niveles de ARNm de ErbB2 (48%) y ErbB3 (66%) en el hígado (sin cambios en ErbB4), y de ErbB2 (43%), ErbB3 (76%) y ErbB4 (35%) en el TA. Además, los niveles de proteína ErbB2 y ErbB3 disminuyeron significativamente, en comparación con el grupo DC en el hígado. Nuestros resultados sugieren que la obesidad inducida por DAG disminuye significativamente la expresión de ErbBs en el hígado y el TA, que puede estar asociado con alteraciones en la vía NRG en ratones obesos.

Histomorphological, Histochemical and Ultrastructural Studies on the Healthy Liver of Yemen Veiled Chameleon (Chamaeleo calyptratus) in Southern Saudi Arabia / Estudios Histomorfológicos, Histoquímicos y Ultraestructurales en el Hígado Sano del Camaleón Velado de Yemen (Chamaeleo calyptratus) en el Sur de Arabia Saudita

SUMMARY: The livers of reptiles are being studied as a model for the link between the environment and hepatic tissue. There have been few investigations on the histology of reptile livers, and very few or no studies have examined the histology of liver of veiled chameleon (Chamaeleo calyptratus). This paper describes the histomorphological, histochemical and ultrastructural characterization of the liver of veiled chameleons in southern Saudi Arabia. Seven Chamaeleo calyptratus were captured in the summer season in Abha City, Aseer region, southern Saudi Arabia. Chamaeleon liver samples were processed for histomorphology, histochemistry and ultrastructure analyses. Morphologically liver of Chamaeleo calyptratus was observed as a large dark brown organ with lighter speckles, which represent melanin deposits. It located at the ventral part of abdominal cavity forward of the stomach. Its dimensions approximately were 3.7 x 2 cm. The liver was a bilobed organ divided into two lobes, right and left lobes. The right one was bigger than the others. The gallbladder was well developed and had an elongated shape, situated between the two lobes and contained the bile for the digestion. Microscopically, the liver was found to be covered by a thick layer of connective tissue, which formed the hepatic capsule. Hepatic parenchyma probably appeared in cross sections as hepatic glandular-like alveoli "acini" or follicular structures with various diameters, each acinus contains approximately four to six hepatocytes, surrounded by sinusoidal capillaries filled with abundant melanomacrophages, which are absent in birds and mammals. Melanomacrophages are common in the hepatic parenchyma's perisinusoidal areas, particularly near portal spaces. Hepatocytes are polyhedral or pyramidal with and mostly contained large, rounded nuclei mostly peripherally located, with prominent dark oval nucleoli. Some of nuclei are eccentric or central position. The cytoplasm appeared spongy or vacuolated and more eosinophilic when stained by hematoxylin-eosin and strongly reactive to PAS staining technique, indicating abundant glycogen content. The reticular fibers that surround hepatocytes, blood arteries, and sinusoids supported the hepatic parenchyma. The blood sinusoids are seen interspersed among hepatocytes of varying sizes. The sinusoidal lumen was bordered by flattened endothelial cells and includes elliptical nucleated erythrocytes and liver macrophages as phagocytes, which are also known as Kupffer cells. Branches of the portal vein, hepatic artery, small bile duct, and lymph vessels were detected in the hepatic portal area "tract" or triad which made up of connective. Hematopoietic tissue was observed in subcapsular region and portal triads. Ultrastructurally, the hepatocyte appeared polyhedric containing a single large rounded basal or eccentric vesicular nucleus with prominent nucleolus. Extensive network of rough endoplasmic reticulum (RER) often arranged in an array parallel to the nuclear membrane with many mitochondria, and Golgi apparatus were described. The cytoplasm contained glycogen granules, vesicles or vacuoles scattered throughout the cytoplasm especially at the apical region were reported. The bile canaliculi and the hepatic "Kupffer" cells were also discussed. This is the first study on the histological characterization of the healthy liver of Yemen veiled chameleon in southern Saudi Arabia. The findings reported here should be used as a reference to compare with the pathological abnormalities of the liver in this animal.

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Efecto del extracto hidroalcohólico de la planta Lampaya medicinalis Phil . sobre marcadores inflamación inducidos por ácidos grasos en hepatocitos humanos HepG2

RESUMEN Introducción: la enfermedad de hígado graso no alcohólico (EHGNA) se caracteriza por la acumulación de gotas lipídicas (GL) y sobre expresión de la proteína de GL Perilipina 1 (PLIN1) en los hepatocitos. En su patogénesis y progresión participan NF-ĸB, caspasa-1 y citoquinas proinflamatorias como IL-1β. La medicina popular del norte de Chile utiliza la planta Lampaya medicinalis Phil. (Verbenaceae) contra enfermedades. Objetivo: evaluar el efecto de un extracto hidroalcohólico de lampaya (EHL) sobre la expresión de marcadores inflamatorios y proteínas asociadas a las GL en hepatocitos tratados con ácidos grasos. Métodos: se incubó hepatocitos HepG2 con 0,66 mM de ácido oleico (AO) y 0,33 mM de ácido palmítico (AP) por 24 o 48 horas en presencia o no de EHL. Se evaluó la expresión proteica de NF-ĸB, PLIN1 y caspasa-1 por Western blot y la expresión de ARNm de IL-1β por qPCR. Resultados: los hepatocitos tratados por 48 h con AO/AP mostraron un aumento en la expresión de IL-1β que fue revertido por la co-incubación con EHL. Conclusión: estos antecedentes aportan nueva evidencia respecto a la actividad biológica del EHL en un modelo de alteraciones metabólicas e inflamatorias, asociadas a la EHGNA, inducidas por AO/AP en hepatocitos humanos.

ABSTRACT Introduction: Nonalcoholic fatty liver disease (NAFLD) is characterized by the accumulation of lipid droplets (LD) and overexpression of the LD-associated protein Perilipin 1 (PLIN1). NF-ĸB, caspase-1 and proinflammatory cytokine such as IL-1β participate in the pathogenesis and progression of NAFLD. Traditional medicine in northern Chile uses the plant Lampaya medicinalis Phil. (Verbenaceae) against diseases. Objective: To evaluate the effect of a hydroalcoholic extract of lampaya (HEL) on the expression of inflammatory markers and LD-associated proteins in hepatocytes treated with fatty acids. Methods: HepG2 hepatocytes were incubated with 0.66 mM oleic acid (OA) and 0.33 mM palmitic acid (PA) for 24 or 48 h in the presence or not of HEL. The protein expression of NF-ĸB, PLIN1 and caspase-1 was evaluated by Western blot while the mRNA expression of IL-1β was assessed by qPCR. Results: hepatocytes treated for 48 h with OA/AP showed an increase in IL-1β expression that was reversed by co-incubation with HEL. Conclusion: These antecedents provide new evidence regarding the biological activity of HEL in a model of metabolic and inflammatory alterations, associated with NAFLD, induced by OA/PA in human hepatocytes.

Factor de crecimiento de hepatocitos séricos como herramienta diagnóstica en pacientes con dolor torácico agudo / Serum hepatocyte growth factor as diagnostic tool in patients with acute chest pain

Resumen Objetivo Determinar si los niveles plasmáticos de factor de crecimiento de hepatocitos podrían ayudar a realizar el diagnóstico diferencial en pacientes con dolor torácico prolongado y elevación de la troponina cardiaca, y evaluar su valor pronóstico de mortalidad al año en estos pacientes. Método: Estudio prospectivo observacional. Se incluyeron pacientes mayores de 18 años que acudieron a urgencias con dolor torácico agudo de más de 20 minutos y elevación de la troponina cardiaca, con seguimiento al año. Resultados Se incluyeron 303 pacientes, 103 (34%) con infarto de miocardio y 200 (66%) con otras enfermedades. Los niveles plasmáticos del factor de crecimiento de hepatocitos fueron superiores en el grupo sin infarto de miocardio: 329 pg/ml (rango intercuartílico [IQR]: 66-558) vs. 476 pg/ml (IQR: 264-908; p < 0.001). La mortalidad al año fue del 30.7%, superior en el grupo sin infarto de miocardio (36.5% vs. 19.4%; p = 0.002). Se encontró una fuerte asociación entre la mortalidad y los niveles elevados de factor de crecimiento de hepatocitos (650 pg/ml [344-1159] vs. 339 pg/ml [205-607]; p < 0.001). En el análisis multivariado se halló que los niveles de factor de crecimiento de hepatocitos, la edad y la escala GRACE son factores independientes de mortalidad al año en estos pacientes. Conclusiones En los pacientes con dolor torácico agudo prolongado y elevación de la troponina cardiaca, la determinación de los niveles del factor de crecimiento de hepatocitos no permite confirmar ni descartar la presencia de infarto agudo de miocardio. No obstante, podría ser un marcador pronóstico de mortalidad en estos pacientes, junto con la edad y la escala GRACE.

Abstract Objective To determine if plasma levels of hepatocyte growth factor could help in the differential diagnosis of patients with prolonged chest pain and elevated cardiac troponin; and to evaluate its prognostic value for one-year mortality in these patients. Method A prospective observational study. Patients over the age of 18 who were seen in the emergency room for acute chest pain lasting longer than 20 minutes and elevated cardiac troponin were included, with follow up after one year. Results We included 303 patients, 103 (34%) with myocardial infarction and 200 (66%) with other diseases. Plasma levels of hepatocyte growth factor were higher in the group without myocardial infarction: 329 pg/ml (IQR: 166-558) vs. 476 pg/ml (IQR: 264-908; p < 0.001). One-year mortality was 30.7%, higher in the group without myocardial infarction (36.5% vs. 19.4%; p = 0.002). We found a strong association between mortality and elevated levels of hepatocyte growth factor (650 pg/ml [344-1,159] vs. 339 pg/ml [205-607]; p < 0.001). Multivariate analysis showed that levels of hepatocyte growth factor, age and the GRACE scale are independent factors for one-year mortality in these patients. Conclusions In patients with prolonged acute chest pain and elevated cardiac troponin, hepatocyte growth factor levels do not confirm or rule out acute myocardial infarction, although they may be a prognostic marker for mortality in these patients, along with age and the GRACE scale.

Hígado y SARS-CoV-2: aspectos claves de la literatura / Liver and SARS-CoV-2: Literature key aspects

Resumen El nuevo coronavirus del síndrome respiratorio agudo grave de tipo 2 (SARS-CoV-2), virus que se ha expandido por todo el mundo, produce una infección respiratoria aguda capaz de producir la muerte; sin embargo, el daño en otros órganos también es frecuente. Diversos estudios han evidenciado alteraciones en pruebas de lesión hepáticas, las cuales se han asociado con enfermedad grave y mayor estancia hospitalaria; así mismo, en la infección por el virus en pacientes con enfermedad hepática preexistente se observó una elevación significativa de las aminotransferasas durante el curso de la enfermedad y mayor riesgo de enfermedad grave. La explicación fisiopatológica de la afectación hepática en estos pacientes abarca el efecto citopático directo producido por la unión del virus a la enzima convertidora de la angiotensina II (ECA-II) a los hepatocitos y colangiocitos, una respuesta inmunitaria desproporcionada y, en algunos casos, la hepatotoxicidad por medicamentos.

Abstract The new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a virus that has spread around the world, causes an acute respiratory infection and it may also cause death. The damage that can cause in other organs is frequent. Many studies had also shown alterations in liver function tests, that are then related to serious illness and with hospitalization requirements. Moreover, in patients infected with the virus that had underlying liver disease, a significant increase in the level of aminotransferases was observed in the course of the disease. A greater risk of serious illness was also detected. The pathophysiological explanation of liver injury in those patients covers the direct cytopathic effect produced by binding the virus, the angiotensin-converting enzyme (ACE2) to the hepatocytes and the cholangiocytes, excessive immune response, and in some cases, drug-induced hepatotoxicity.

Efecto del extracto hidroalcohólico de la planta Lampaya medicinalis Phil. (Verbenaceae) sobre la esteatosis inducida in vitro en hepatocitos humanos / Effect of the hydroalcoholic extract of the plant Lampaya medicinalis Phil. (Verbenaceae) on in vitro-induced steatosis in human hepatocytes

INTRODUCCIÓN: La enfermedad del hígado graso no alcohólico (EHGNA) es la forma más común de enfermedad hepática. A nivel celular se caracteriza por la acumulación de triglicéridos (TG) en forma de gotas lipídicas (GL) dando lugar a esteatosis e inflamación. Entre los factores relevantes para la síntesis de TG se encuentran las enzimas DGAT1/2 que catalizan la etapa final de la síntesis de TG, y la proteína FABP4 que transporta lípidos intracelulares y se expresa en modelos de enfermedad hepática dependiente de obesidad. Por otra parte, TNF-α es una reconocida citoquina involucrada en el proceso inflamatorio en la EHGNA. La medicina popular del norte de Chile ha utilizado la planta Lampaya medicinalis Phil. (Verbenaceae) para el tratamiento de algunas enfermedades inflamatorias. OBJETIVO: Evaluar el efecto de un extracto hidroalcóholico de lampaya (EHL) sobre la esteatosis y expresión de marcadores de inflamación en hepatocitos tratados con ácidos grasos. Diseño experimental: Estudio in vitro en cultivos de la línea celular humana HepG2 tratadas con ácido oleico (AO) y ácido palmítico (AP). MÉTODOS: Se incubó hepatocitos HepG2 con AO/AP por 24 horas en presencia o no de EHL. Se evaluó la presencia de GL y el contenido de TG intracelulares por Oil Red O y Nile Red, respectivamente. La expresión de DGAT1/2, FABP4 y TNF-α fue evaluada por qPCR. RESULTADOS: Los hepatocitos tratados con AO/AP mostraron un aumento en las GL y TG, así como una mayor expresión de DGAT2 en comparación al control. El cotratamiento con EHL revirtió los efectos inducidos por AO/AP. CONCLUSIONES: EHL revierte el incremento en las GL, TG y en la expresión de DGAT2 inducido por AO/AP en células HepG2. Estos hallazgos sugieren un efecto hepatoprotector de la Lampaya contra la esteatosis, y apoyarían su uso complementario en el tratamiento de patologías con componente inflamatorio como la EHGNA.

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease. At the cellular level, it is characterized by the accumulation of triglycerides (TG) in the form of lipid droplets (LD), which leads to steatosis and inflammation. Among relevant factors for TG synthesis are the enzymes DGAT1/2 catalyzing the final stage of TG synthesis, and the protein FABP4 which transports intracellular lipids and is expressed in cell models of obesity-dependent liver disease. Additionally, TNF-α is a cytokine involved in the inflammatory process associated to NAFDL. Lampaya medicinalis Phil. (Verbenaceae) is a plant used in folk medicine in northern Chile to treat some inflammatory diseases. OBJECTIVE: To evaluate the effect of the hydroalcoholic extract of lampaya (HEL) on steatosis and the expression of inflammatory markers in hepatocytes treated with fatty acids. Study design: In vitro study in cultures of the human HepG2 cell line treated with oleic acid (OA) and palmitic acid (PA). METHODS: HepG2 hepatocytes were incubated with OA/PA for 24 hours in the presence and absence of HEL. The formation of LD and the accumulation of intracellular TG were assessed by Oil Red O and Nile Red, respectively. The expression of DGAT1/2, FABP4 and TNF-α was assessed by qPCR. RESULTS: The treatment with OA/PA increased the levels of LD and TG as well as the expression of DGAT2 in HepG2 hepatocytes compared to control cells. HEL cotreatment counteracted OA/PA-induced effects. CONCLUSIONS: HEL prevents the increase in LD and TG levels and DGAT2 expression induced by OA/PA in HepG2 cells. These findings suggest that lampaya may have a protective effect against hepatic steatosis, which would support its complementary use in the treatment of pathologies associated with inflammation, such as NAFLD.

Vitamin C administration attenuated artemether induced hepatic injury in rats / La aAdministración de vitamina C atenúa la lesión hepática inducida por artemeter en ratas

This research was designed to investigate the potential protective effect of vitamin C supplementation against hepatocyte ultrastructural alterations induced by artemether (antimalarial drug) administration. Twenty-four adult male albino rats were used in this study and were divided into four groups (n=6). Group I served as a control and rats in group II administrated artemether (4 mg/kg B.W) orally for three consecutive days. Group III administered artemether plus a low dose of vitamin C (2.86 mg/kg/l water) while group IV received artemether plusa high dose of vitamin C (8.56 mg/kg). At the end of the experimental period (14 days), the harvested liver tissues were examined by transmission electron microscopy (TEM), and blood samples were assayed for biomarkers of liver injury and oxidative stress. Artemether significantly (p<0.05) augmented biomarkers of liver injury such as alanine aminotransferase (ALT), aspartate aminotransferase (AST), and oxidative stress such as superoxide dismutase (SOD), Glutathione Peroxidase (GPX), and caused degeneration and damage of the rough endoplasmic reticulum and disrupted mitochondria. The blood sinusoids were also damaged with distortion of their canaliculi. Administration of vitamin C showed improvement of liver biomarkers, and liver parenchyma, especially in a high dose of vitamin C.We concludes that vitamin C is a partial protective agent against artemether-induced liver injury.

Esta investigación fue diseñada para investigar el posible efecto protector de la vitamina C contra las alteraciones ultraestructurales de los hepatocitos, inducidas por la administración de arteméter (medicamento antipalúdico). En el estudio se utilizaron 24 ratas albinas macho adultas y se dividieron en cuatro grupos (n = 6). El grupo I fue designado como control y las ratas en el grupo II se adminstró Arteméter (4 mg / kg de peso corporal) por vía oral durante tres días consecutivos. En el grupo III se administró arteméter, además de una dosis baja de vitamina C (2,86 mg / kg / l de agua) mientras que el grupo IV recibió arteméter más una dosis alta de vitamina C (8,56 mg / kg). Al final del período experimental (14 días), los tejidos hepáticos recolectados se examinaron por microscopía electrónica de transmisión (MET), y las muestras de sangre se analizaron en busca de biomarcadores de daño hepático y estrés oxidativo. El arteméter aumentó significativamente (p <0,05) los biomarcadores de daño hepático como alanina aminotransferasa (ALT), aspartato aminotransferasa (AST) y estrés oxidativo como superóxido dismutasa (SOD), glutatión peroxidasa (GPX) y causó degeneración y daño de la retículo endoplásmico rugoso y mitocondrias alteradas. Los sinusoides sanguíneos también fueron dañados con la distorsión de sus canalículos. La administración de vitamina C mostró una mejoría de los biomarcadores hepáticos y el parénquima hepático, especialmente en una dosis alta de vitamina C. Concluimos que la vitamina C es un agente protector parcial contra la lesión hepática inducida por arteméter.

Quantificação de mastócitos em lesões reversíveis e irreversíveis do fígado humano / Quantification of mast cells in reversible and irreversible human liver lesions

Os mastócitos são células distribuídas pela maior parte do corpo e são reguladores importantes da resposta inflamatória. Nesse estudo o objetivo foi quantificar os mastócitos presentes em fígado humano normal, com esteatose e com cirrose. Foram utilizadas peças de fígado humano do Laboratório de Patologia Geral da Universidade Federal do Triângulo Mineiro, onde selecionaram 16 peças anatômicas, dividindo-se em três grupos: fígado normal (controle), com esteatose e com cirrose. Realizou-se a confecção de 32 lâminas, as quais foram submetidas à duas colorações, sendo HE para análise histopatológica, e Azul de Toluidina para quantificação de mastócitos. Realizou-se análise estatística e a confecção de gráfico, composto pelo número de mastócitos por campo em cada grupo. Observou-se que o aumento da quantidade de mastócitos presentes é diretamente proporcional ao agravo da doença, sendo que a maior população foi encontrada no processo crônico de cirrose hepática. Portanto, subentende-se que exista uma relação intrínseca entre a presença dos mastócitos e, consequente, agravo do processo fibrótico em humanos, de tal modo que uma célula influencie no funcionamento da outra. Torna-se necessário a realização de mais estudos para esclarecerem de forma detalhada tal interação.

Mast cells are distributed in most tissues of the human body and are key regulators of the inflammatory response. The aim of the study was to quantify the presence of mast cells in healthy human livers and diseased human livers presenting steatosis and cirrhosis. Human liver samples were obtained from the General Pathology Laboratory at the Federal University of Triângulo Mineiro. Sixteen samples were divided into three groups: normal liver (control), steatosis, and cirrhosis. A total of 32 slides were prepared, which were submitted to two stainings, the hematoxylin and eosin (HE) for histopathological analysis, and Toluidine Blue (TB) for mast cell quantification. Statistical analysis and a graph composition were performed, presenting the number of mast cells per field in each group. It was observed that the increase of mast cells is directly proportional to the disease burden, and the greatest increase was found in the population with chronic liver cirrhosis. Therefore, it is understood that there is an intrinsic relationship between the presence of mast cells and the consequent aggravation of the fibrotic process in humans, in such way that one cell influences the functioning of the other. Further studies area necessary in order to clarify such interaction.

Modelos celulares hepáticos para el estudio del metabolismo de los lípidos. Revisión de literatura / Liver cell models for studying lipid metabolism. Literature review

Resumen Introducción. El hígado juega un papel importante en la homeostasis lipídica, especialmente en la síntesis de ácidos grasos y triglicéridos. Una amplia variedad de modelos celulares ha sido utilizada para investigar el metabolismo lipídico hepático y para elucidar detalles específicos de los mecanismos bioquímicos del desarrollo y progresión de enfermedades relacionadas, brindando información para tratamientos que reduzcan su impacto. Los modelos celulares hepáticos poseen un alto potencial en la investigación del metabolismo de lípidos y de agentes farmacológicos o principios activos que permiten la reducción de la acumulación de lípidos. Objetivo. Comparar algunos modelos celulares hepáticos utilizados para el estudio del metabolismo lipídico, sus características y los resultados más relevantes de investigación en ellos. Materiales y métodos. Se realizó una búsqueda sistemática en bases de datos sobre los modelos celulares hepáticos de mayor uso para el estudio del metabolismo de lípidos. Resultados. Se exponen los cinco modelos celulares más utilizados para este tipo de investigaciones, destacando su origen, aplicación, ventajas y desventajas al momento de estimular el metabolismo lipídico. Conclusión. Para seleccionar el modelo celular, el investigador debe tener en cuenta cuáles son los requerimientos y el proceso que desea evidenciar, sin olvidar que los resultados obtenidos solo serán aproximaciones de lo que en realidad podría suceder a nivel del hígado como órgano.

Abstract Introduction: The liver plays an important role in lipid homeostasis, especially in the synthesis of fatty acids and triglycerides. A wide variety of cell models have been used to investigate liver lipid metabolism and to elucidate specific details of the biochemical mechanisms involved in the development and progression of related diseases, providing information for treatments that reduce their impact. Liver cell models have a high potential for the investigation of lipid metabolism, as well as pharmacological agents or active principles that allow the reduction of lipid accumulation. Objective: To compare some liver cell models used for studying lipid metabolism, their characteristics and the most relevant research results. Materials and methods: A systematic search of databases was performed on the most commonly used liver cell models for the study of lipid metabolism. Results: The five most commonly used cell models for this type of research are presented in this paper, highlighting their origin, application, advantages and disadvantages when stimulating lipid metabolism. Conclusion: In order to select a cell model, researchers should take into account the requirements and the process they wish to demonstrate, without forgetting that the results obtained will only be approximations of what could actually happen in the liver as an organ.

Vitamin E protects against hepatocyte ultrastructural damage induced by high fat diet in a rat model of pre-diabetes / La vitamina E protege contra el daño ultraestructural de los hepatocitos inducido por la dieta alta en grasas en un modelo de pre-diabetes en ratas

SUMMARY: We sought to investigate the potential protective effect of Vitamin E supplementation against hepatocyte ultrastructural alterations induced by high fat diet (HFD) in a rat model of pre-diabetes. Therefore, rats were either fed with HFD (model group) or a standard laboratory chow (control group) for 12 weeks before being sacrificed. The protective group fed on a HFD and started the treatment with vitamin E (100 mg/kg/day, i.p) from day 1 until being sacrificed at week 12. The harvested liver tissues were examined using transmission electron microscopy (TEM) and blood samples were assayed for biomarkers of liver injury and prediabetes. TEM images showed that HFD induced profound pathological changes to the hepatocyte ultrastructure as demonstrated by degenerated hepatocytes with damaged cytoplasm that have mitochondrial swelling, dilation of endoplasmic reticulum, blebbing of plasma membranes, and cytoplasmic accumulations of lipid droplets and vacuoles, which were substantially but not completely protected with vitamin E. In addition, HFD significantly (p<0.05) augmented biomarkers of liver injury and pre-diabetes such as alanine aminotransferase (ALT), aspartate aminotransferase (AST), tumor necrosis factor-alpha (TNF-α), malondialdehyde (MDA), total cholesterol (TC), triglycerides (TG), and low density lipoprotein cholesterol (LDL-C), which were significantly (p<0.05) reduced with vitamin E except TNF-α and TC. Furthermore, none of these biomarkers were reduced to the control level by vitamin E. We conclude that vitamin E is a partial protective agent against HFD-induced liver injury and pre-diabetes.

RESUMEN: El objetivo de este estudio fue investigar el posible efecto protector de la administración de suplementos de vitamina E contra las alteraciones ultraestructurales de los hepatocitos inducidas por una dieta rica en grasas (DRG) en un modelo de prediabetes en ratas. Antes de ser sacrificadas las ratas fueron alimentadas con DRG (grupo modelo) o un alimento estándar de laboratorio (grupo control) durante 12 semanas. El grupo protector se alimentó con una DRG y comenzó el tratamiento con vitamina E (100 mg/kg/día, i.p) desde el día 1 hasta sacrificarlo en la semana 12. Los tejidos hepáticos recolectados se examinaron mediante microscopía electrónica de transmisión (MET) y se tomaron muestras de sangre y se analizaron los biomarcadores de daño hepático y prediabetes. Las imágenes de MET mostraron que el DRG indujo cambios patológicos profundos en la ultraestructura de los hepatocitos, como lo demuestran los hepatocitos degenerados con citoplasma dañado e hinchazón mitocondrial, dilatación del retículo endoplasmático, formación de ampollas en las membranas plasmáticas y acumulaciones citoplásmicas de gotas de lípidos y vacuolas, los que fueron sustancialmente protegidas con vitamina E. Además, DRG aumentó significativamente (p <0,05) los biomarcadores de daño hepático y prediabetes como alanina aminotransferasa (ALT), aspartato aminotransferasa (AST), factor de necrosis tumoral alfa (TNF-α), malondialdehído (MDA), colesterol total (CT), triglicéridos (TG) y lipoproteína de colesterol de baja densidad (LDL-C), la cual se redujo significativamente (p <0,05) con vitamina E, excepto TNF-α y CT. Ninguno de estos biomarcadores se redujo al nivel de control por la vitamina E. Concluimos que la vitamina E es un agente protector parcial contra la lesión hepática inducida por DRG y la prediabetes.

Comparative histology in the liver and spleen of three species of freshwater teleost

We describe and compare the histology of liver and spleen ofGeophagus brasiliensis (Perciformes), Hypostomus francisci (Siluriformes) and Hoplias aff. malabaricus (Characiformes), tropical freshwater fishes. InG. brasiliensisandH. aff. malabaricusthe hepatocytes were arranged in tubular form whereas in H. franciscithey cord-like. In all species, hepatocytes presented glycogen, but in G. brasiliensis and H. aff. malabaricus they showed strong stained for hemossiderin in the cytoplasm. InG. brasiliensis and H. aff. malabaricus, melanomacrophage centres (MMCs) were associated to hepatic structures and only in G. brasiliensis was observed intrahepatic exocrine pancreas. The spleen, in all species, was characterized by red and white pulp without boundary between the two regions, but only in H. francisci was recorded nodular organization in splenic parenchyma. The G. brasiliensisandH. aff. malabaricuspresented in the white pulp MMCs linked mainly to ellipsoids. Besides, we observed large MMCs in the spleen in relation to liver of G. brasiliensis and H. aff. malabaricus. In liver, highest values of reticular fibers and collagen were observed inG. brasiliensis. In spleen, highest values of reticular fibers and collagen were recorded inH. aff. malabaricusandH. francisci, respectively. Histological differences confirm the hypothesis that the phylogenetic distance is reflected in liver and spleen.(AU)

Nós descrevemos e comparamos a histologia do fígado e do baço de Geophagus brasiliensis (Perciformes), Hypostomus francisci (Siluriformes) e Hoplias aff. malabaricus (Characiformes), peixes neotropicais de água doce. Em G. brasiliensis e H. aff. malabaricus os hepatócitos organizaram-se na forma tubular enquanto que em H. francisci eles apresentaram-se como cordões celulares. Em todas as espécies, os hepatócitos apresentaram glicogênio, mas em G. brasiliensis e H. aff. malabaricus, eles mostraram forte marcação para hemossiderina no citoplasma. Em G. brasiliensis e H. aff. malabaricus, centros melanomacrofágicos (CMMs) foram associados a estruturas hepáticas e somente em G. brasiliensis foi observado pâncreas exócrino intrahepático. O baço, em todas as espécies, foi caracterizado pela polpa vermelha e branca sem limites entre as duas regiões, mas somente em H. francisci foi registrado uma organização nodular no parênquima esplênico. G. brasiliensiseH. aff. malabaricusapresentaram na polpa branca CMMs associados principalmente a elipsoides. Além disso, nós observamos CMMs grandes no baço em relação ao fígado de G. brasiliensis e de H. aff. malabaricus. No fígado, valores altos de fibras reticulares e colágeno foram observado em G. brasiliensis. No baço, valores altos de fibras reticulares e colágeno foram registrados em H. aff. malabaricuseH. francisci, respectivamente. Diferenças histológicas confirmam a hipótese que a distância filogenética está refletida no fígado e no baço.(AU)

Organic-Polymeric Radial Flow Biorreactor for Liver Models / Biorreactor de flujo radial orgánico-polimérico para modelos de hígado

Abstract An artificial liver support system is based on the functional hepatocytes being cultured inside a bioreactor; this technique has being used as an effective therapy for treating chronic liver diseases in recent times. This work evaluates different parameters such as cell viability and metabolic function of the hepatocytes when cultured on a hybrid scaffold. The scaffold was built using a polypyrrole plasma coated polymer layer seeded with endothelial matrix for efficient three-dimensional hepatocyte growth within a radial flow bioreactor. The flow rate inside the bioreactor was 7 ml / min. The parts for the bioreactor where either built using food-grade steel and/or glass or the scaffolds comprise a Poly (L-lactic acid)-coated polypyrrole iodine layer or not for HepG2 culture. The results show that the Poly (L-lactic acid)-coated scaffolds increased cell proliferation by 30%, protein production by 16% and albumin secretion by 40% compared with the non-coated scaffold. All experiments were performed thrice and data was analysed by ANOVA and Tukey statistic models with a p<0.05. The obtained results demonstrated that radial flow bioreactors in conjunction with hybrid scaffolds improve hepatocytes' physiological and functional properties and could be used as an alternative therapy for patients with liver diseases.

Resumen Un sistema de soporte hepático artificial se basa en utilizar hepatocitos funcionales cultivados en un biorreactor; esta técnica ha demostrado que se puede utilizar como una terapia eficaz para el tratamiento de enfermedades crónicas del hígado en los últimos tiempos. Este trabajo evalúa diferentes parámetros tales como la viabilidad celular y la función metabólica de los hepatocitos cuando se cultivan en un andamio híbrido. El andamio fue construido usando una capa de polímero recubierto de polipirrol plasma, se sembró con un cultivo tridimensional de células endoteliales y de hepatocitos dentro de un biorreactor de flujo radial. La velocidad de flujo en el interior del biorreactor fue de 7 ml / min. Las piezas para el biorreactor fueron construidas con acero de calidad alimentaria y / o vidrio. Los andamios control fueron de ácido L-poliláctico y a estos se les agrego un revestimiento de polipirrol-yodo para el cultivo de HepG2. Los resultados muestran que el ácido L-poliláctico recubierto, aumento la proliferación celular en un 30%, la producción de proteínas en un 16% y la secreción de albúmina por 40% en comparación con el andamio no recubierto. Todos los experimentos se llevaron a cabo tres veces y los datos se analizaron mediante modelos estadísticos ANOVA y Tukey con una p <0.05. Los resultados obtenidos demostraron que los biorreactores de flujo radial conjuntamente con andamios híbridos mejoran las propiedades fisiológicas y funcionales hepatocitos y podrían utilizarse como una terapia alternativa para los pacientes con enfermedades hepáticas crónicas.

Diferentes níveis protéicos na dieta de girinos de rã-touro (Lithobates catesbeianus) e seus efeitos sobre o tecido hepático / Different protein levels in the diet of bullfrog tadpoles (Lithobates catesbeianus) and its effects on the liver tissue

Para verificação da ocorrência de alterações morfológicas no fígado, foram coletados dez animais de cada dieta, no 30º dia (1º período experimental) e no 60º dia (2º período experimental), sendo esse, o último dia do período experimental e início do clímax da metamorfose. Os girinos foram distribuídos em delineamento experimental inteiramente casualizado (DIC) com três tratamentos: dieta experimental com 32,68% de proteína bruta e duas dietas comerciais com 37,92% e 57,53% de proteína bruta. Os órgãos coletados foram fixados em solução de Bouin e depois submetidos às práticas da rotina histotecnológica e coradas com hematoxilina - Eosina (HE). Na avaliação microscópica do fígado foram encontradas diversas alterações morfológicas como: Desorganização e vacuolização de hepatócitos, infiltrado inflamatório mononuclear periportal, multifocal e difuso, infiltrado inflamatório eosinofílico, congestão, hemorragia, hemólise e necrose. As alterações hepáticas encontradas neste estudo sugerem que as dietas utilizadas para os girinos de rã-touro, não atenderam suas necessidades dietéticas, afetando a homeostasia dos mesmos, comprometendo assim, sua sanidade.(AU)

To verify the occurrence of liver morphological changes, bullfrog tadpoles were fed three diets: an experimental diet with 32.68% crude protein and two commercial diets with 37.92% and 57.53% crude protein. Tadpoles were distributed into a completely randomized design (CRD) with three treatments and four replications. Liver samples were collected twice, on the 30th and 60th day of the experiment. Tadpole livers were fixed in Bouin's solution, then subjected to routine histotechnology procedures, and stained with hematoxylin - eosin (HE). Microscopic evaluation of liver tissue showed several morphological changes like disorganization and vacuolization of hepatocytes; periportal, multifocal and diffuse mononuclear inflammatory infiltrate, eosinophilic inflammatory infiltration, congestion, hemorrhage, hemolysis and necrosis. The liver changes found in this study suggest that diets used for bullfrog tadpoles, did not meet their dietary needs, what affected their homeostasis, thus compromising their health.(AU)

Can the intermittent training generate alterations on the liver tissue of rats submitted to a hyperlipidic diet? / ¿El entrenamiento intermitente puede generar alteraciones sobre el tejido hepático de ratas sometidas a una dieta alta en grasa?

Studies indicate that increasing physical activity and decreasing levels of fat in the liver help to decrease the risk of morbidity from liver conditions. This study aimed to evaluate the effects of an eight week intermittent training program on the liver tissue of rats subjected to a hyperlipidic diet. The study consisted of 30 male Wistar rats, divided into the following groups: Sedentary Control (SC) Exercise Control (EC) (fed on standard feed and water) Sedentary Obese (SO) and Exercise Obese (EO) (fed on bacon, ham, sausage, biscuits, soda and standard feed), which performed intermittent training through electrically stimulated jumps, with three sets of 12 repetitions, three times per week for eight weeks. At the end of the training period, the animals were euthanized, and their livers removed for histological processing and hematoxylin and eosin staining (HE). Soon afterwards, caryometric analysis of the hepatocyte nuclei was performed. From the presented results it can be seen that the hepatocyte nuclei of the obese animals were smaller in relation to those of the control animals, therefore, exercise combined with an appropriate diet proved to be efficient in not causing alterations in the hepatocyte nuclei, conserving normal cell function and reducing the chances of the appearance of tissue damage. Furthermore, exercise in isolation cannot be considered a protective factor against the alteration of the liver cells.

Estudios indican que el aumento de la actividad física y la disminución de los niveles de grasa en el hígado ayudan a reducir el riesgo de morbilidad por enfermedades hepáticas. El objetivo fue evaluar el efecto de un programa de entrenamiento intermitente de ocho semanas en el tejido hepático de ratas con dieta alta en grasa. Treinta ratas Wistar machos fueron divididas en grupos Control Sedentario (SC), Control Ejercicio (CE) (con fuente de alimentación que consiste en la ración estándar y agua), Obeso Sedentario (OS) y Obeso Ejercicio (OE) (con alimentación compuesta por tocino, mortadela, salchichas, galletas, refrescos y ración estándar), sometidas a un entrenamiento intermitente a través de saltos mediante estimulación eléctrica con tres series de 12 repeticiones, tres veces por semana durante ocho semanas. Al final del período de entrenamiento, los animales fueron sacrificados; se extrajeron sus hígados para el procesamiento histológico y tinción con hematoxilina y eosina (HE). Luego se realizó el análisis cariométrico de los núcleos de los hepatocitos. Se observó que los núcleos de los hepatocitos fueron menores en los animales obesos en comparación con los núcleos de hepatocitos de los animales de control, pues el ejercicio combinado con una dieta adecuada se mostró eficiente para que causar alteraciones en los núcleos de hepatocitos, y esa combinación puede retener la función normal de las células y disminuir las posibilidades de la aparición de daños en los tejidos. Además, el ejercicio aislado no puede ser considerado como un factor de protección contra la alteración las células del hígado.

Ultrastructure of fetal mice hepatocytes exposed in utero to diazepam / Ultraestructura de hepatocitos fetales de ratón expuestos in utero a diazepam

Previous research has shown that fetal mice hepatic cells from females treated with diazepam (Valium) during pregnancy depict cytoplasmic and nuclear modifications when observed with photonic microscope. The purpose of this work is to investigate if diazepam administered subcutaneously (SC) to pregnant mice females induces ultraestructural alterations in the cytoplasmic organelles and nucleus to fetal hepatocytes. Transmission electron microscopy observations of fetal hepatocytes from pregnant females treated with a single daily dose of diazepam 2.7 mg/kg/bw/SC administered from 6th to 15th days of gestation revealed that they frequently presented disorganized and dilated rough endoplasmic reticulum cisterns, membranous elements, abundant Golgi complex and glycogen granules, around large vacuoles. The voluminous nucleus shows atypical distribution of chromatin. These alterations could modify the hepatocyte's physiology and probably persist after birth.

Estudios previos muestran que las células hepáticas de fetos de ratón, de hembras tratadas con diazepam (Valium) durante la gestación, presentan modificaciones citoplásmicas y nucleares que se pueden observar con el microscopio fotónico, por lo que el propósito de este trabajo es determinar si el diazepam administrado por vía subcutánea (SC) a hembras gestantes de ratón, induce alteraciones ultraestructurales de los organelos citoplásmicos y del núcleo de los hepatocitos fetales. En los fetos de ratón del grupo experimental de hembras gestantes, tratadas con dosis únicas diarias de 2,7 mg/kg de peso corporal administradas por vía SC del 6° al 15° día de la gestación, se observó con el microscopio electrónico de transmisión que los hepatocitos fetales presentaban con frecuencia retículo endoplásmico rugoso desorganizado, con cisternas dilatadas; había elementos membranosos y complejo de Golgi abundante, al igual que gránulos de glucógeno que rodeaban a grandes vacuolas. Los núcleos eran voluminosos, con la cromatina distribuida atípicamente. Estas alteraciones podrían modificar la fisiología de los hepatocitos y probablemente persistan después del nacimiento.

Descripción histológica del higado de Hydrochoerus hydrochaeris, Linnaeus, 1966 / Histological description of the liver of the Hydrochoerus hydrochaeris, Linnaeus, 1766

El objetivo de este estudio fue describir la histología del hígado del chigüire (Hydrochoerus hydrochaeris). Para tal fin, se utilizaron 13 hígados de individuos adultos de ambos sexos, con un peso entre 33 y 50 kg de peso, los cuales fueron sacrificados en el Matadero- frigorífico de Pro-Fauna, localizado en el municipio de Iguape, estado de São Paulo y en el campus de la Universidad Federal de Viçosa, en el estado de minas Gerais, Brasil. Las muestras fueron fijadas en líquido de Bouin y en solución de formol al 10% v/v, y se procedió a realizar el procesamiento histológico de rutina. Para la visualización diferencial del tejido conjuntivo y de las fibras colágenas para la descripción general del tejido, se realizaron cortes de tejido de 4 µm, los cuales fueron coloreados posteriormente para su estudio histológico, utilizando las técnicas de coloración de hematoxilina & eosina, P.A.S. y Tricrómico de Gomori. Los resultados del estudio revelaron la presencia de un parénquima hepático y lobulillos, los cuales se encontraban próximos unos a otros, no existiendo delimitación marcada entre ellos. Los hepatocitos se encontraban agrupados en placas o hileras que se anastomosaban entre sí, y se disponían en una capa de células. Desde el punto de vista histológico, el parénquima hepático del Hydrochoerus hydrochaeris puede ser considerado como semejante en diversos aspectos, al de otros mamíferos.

The objective of the present study was to histologically describe the liver of the capybara (Hydrochoerus hydrochaeris). For that purpose, 13 livers of capybaras of both sexes, weighing between 33 and 50 kg, were used. The animals were slaughtered in the Pro-Fauna refrigerated slaughterhouse, located in Iguape, the State of São Paulo and in the campus of the Universidad Federal de Viçosa, the State of Minas Gerais, Brasil. Samples were fixed in Bouin and formalin solution (10% v/v) and a routine histological processing was made. For the differential visualization of the connective tissue and colagen fibers, and for the general description of the tissue, sections of tissues of 4 µm were made. Subsequently, tissue sections were stained with hematoxylin and eosin, P.A.S., and Gomori trichrome. The results of the study revealed the presence of a liver parenchyma and lobules, which were close to one another, without a marked delimitation among them. The hepatocytes were grouped in plates or rows which anastomosed with each other and were arranged in a layer of cells. From the histological standpoint, the liver parenchyma of the Hydrochoerus hydrochaeris can be considered similar in various aspects, to that of other mammals.

Histologia do fígado de tilápia do Nilo (Oreochromis niloticus) alimentados com dietas contendo silagem biológica de pescado / Histology liver in Nile tilapia (Oreochromis niloticus) fed diets with fish silage

Este estudo teve como objetivo avaliar as possíveis alterações histopatológicas hepática de tilápias do Nilo alimentadas com dietas contendo silagem biológica de pescado com diferentes concentrações protéicas. Foram utilizados 180 juvenis alimentados com dietas contendo três níveis de proteína (20, 24 and 28% PB), e duas proporções de silagem biológica (» e ½) durante 75 dias. Os fragementos de fígado foram fixados em Bouin e inclusos em Histosec®. Posteriorente foram cortados em microtomo com espessura de 2 a 5µm. O método utilizado para coloração foi hematoxilina/eosina e PAS. Os cortes histológicos foram analisados em microscopio de luz. O desarranjo na morfologia do fígado dos peixes alimentados com silagem biológica foi influenciado pelos altos níveis protéicos, e pelo aumento ½ de proporções de proteínas de origem animal das dietas. Foi observado que a variação dos hepatócitos está diretamente ligada com o tipo da dieta fornecida para os peixes. Nos peixes alimentados com as dietas contendo 28% PB, o fígado apresentou desarranjo da estrutura cordonal dos hepatócitos, pontos de necrose e deslocamento do núcleo para periferia. Níveis elevados de silagem biológica de pescado provoca alterações deletérias no fígado. O nível de proteína adequado para manter o desenvolvimento associado à saúde do peixe é de 24%PB.(AU)

This study aimed to evaluate possible histopathological liver of tilapia fed diets containing fish silage and level protein. Sample of 180 fed with tilapia fingerlings fed with diets containing three protein levels (20, 24 and 28% CP), and Proportions residue fermented silage of tilapia (» and ½) of were analyzed during 75 days. The tissue fragments were fixed in Bouin and included in Histosec®. After that, between 2 to 5µm slices were done in a rotation microtome. The methods used for tissue analysis were hematoxilin/eosin and PAS. The histological slices were examined under light microscope (Olympus BX-50). The disarray in the morphology of the liver of fish fed biological silage was influenced by high protein levels, and increased proportions of ½ of animal protein diets. It was observed that the variation of hepatocytes is directly related to the type of diet for fish. In fish fed diets containing 28% CP, the liver showed disruption of the structure cordon of hepatocytes, necrosis and shifting points of the core to the periphery. Elevated levels of biological fish silage cause deleterious changes in the liver. The level of protein required to maintain the health of the associated development fish is 24% crude protein.(AU)

Densidad superficial nuclear de hepatocitos de hígados sometidos a un factor estimulante humoral en ratones / Superficial nuclear density of hepatocytes of livers subjected to a humoral stimulating factor in mice

FUNDAMENTO: la regeneración hepática es la respuesta fundamental del hígado frente a los diversos estímulos internos y externos. Es multifactorial inducida, que origina cambios secuenciales en la expresión génica, la estructura y organización de las células hepáticas. OBJETIVOS: analizar el comportamiento de la densidad superficial de los núcleos de los hepatocitos según la posición que ocupan en las zonas del lóbulo hepático medio de ratones sometidos a citosol regenerativo. Método: se estudió la densidad superficial de los núcleos de hepatocitos con el uso de la morfometría en 14 lóbulos medios de hígados de ratones, que fueron sometidos a dosis de citosol de hígado regenerativo al inicio del experimento. Las muestras fueron tomadas cada 12 horas durante ocho días. El corte se dividió en zonas proximal, medial y distal al hilio donde se realizaron las determinaciones. RESULTADOS: los valores promedios y su desviación estándar en la zonas fueron: proximal 701,23 ± 135,83 (μm2.103), medial 707,48 ± 46,87 (μm2.103) y distal 682,48 ± 125,21 (μm2.103). Al comparar los resultados mediante el análisis de varianza se aprecia que no existen diferencias en el comportamiento de los promedios en las tres zonas. Al comparar la fase inicial con la fase final del experimento se aprecia diferencias significativas (p ≤ 0,05) en las mismas zonas, con un predominio de la zona proximal y distal. CONCLUSIONES: en las tres zonas del lóbulo el comportamiento de la densidad superficial de núcleos de hepatocitos ocurre de manera similar, con un sentido al incremento al final del experimento, lo que se corroboró con la aplicación de la prueba de la t de Student. Los incrementos más significativos ocurrieron en la zona proximal y distal, aunque en todas las zonas existen diferencias significativas entre los valores obtenidos en la primera mitad de tiempo del experimento respecto a la parte final.

BACKGROUND: hepatic regeneration is the basic answer of the liver to various internal and external stimuli. It is multifactorial and induced and originates sequential changes in the gene expression, the structure and organization of hepatic cells. OBJECTIVE: to analyze the behaviour of the superficial density of the nuclei of the hepatocytes according to the position they have in the areas of the middle hepatic lobes of mice subjected to regenerative cytosol. METHOD: the superficial density of the nuclei of the hepatocytes was studied with the use of morphometry in 14 middle hepatic lobes of mice subjected to a dose of regenerative liver cytosol at the beginning of the experiment. The samples were taken every 12 hours during eight days. The cut was divided into proximal, medial and distal areas to the hilum, where the determinations were made. Results: the average values and their standard deviations in the areas were: proximal 701,23 ± 135,83 (μm2.103), medial 707,48 ± 46,87 (μm2.103) y distal 682,48 ± 125,21 (μm2.103). When comparing the results through the analysis of variance, it could be seen that there are not differences among the averages in the three areas. When comparing the initial stage with the final stage of the experiment major differences (p ≤ 0,05) could be seen in the same areas, predominating the proximal and distal area. CONCLUSIONS: in the three areas of the lobe the behaviour of the superficial density of the nuclei of the hepatocytes is similar, with a tendency to increase at the end of the experiment. This could be corroborated with the application of the Student’s t- test. In spite of the fact that there were major differences between the values obtained in the first part and the final part of the experiment in all the areas, the most significant increases occurred in the proximal and distal areas.

El retículo endoplasmático liso en hepatocitos estimulados con distintas dosis de láser infrarrojo / The smooth endoplasmic reticulum in hepatocytes stimulated with different doses of infrared laser

Veinticuatro ratas hembras Sprague Dawley de 4 meses de vida con peso aproximado de 250 g, fueron divididas en cuatro grupos (A, B, C y D), donde el grupo A (control) no recibió estimulación infrarroja, B se irradió con láser infrarrojo 4 J/cm², C con dosis de 8 J/cm² y D con 16 J/cm². La estimulación infrarroja se realizó diariamente, por 15 días ininterrumpidos. Las ratas fueron sacrificadas y se extrajeron muestras tanto de hígado normal (control) como estimulado con las distintas dosis infrarrojas, las que fueron procesadas para microscopía electrónica de transmisión. De los hepatocitos normales y estimulados, se obtuvieron microfotografías con aumentos finales de hasta 36.500 X, que fueron sometidas a estudios morfométricos para determinar fracciones volumétricas con especial énfasis en el retículo endoplásmico liso (REL) y de los siguientes componentes celulares: retículo endoplasmático rugoso (RER), mitocondrias, glicógeno, eu y heterocromatina. De igual manera se cuantificaron las áreas celulares y nucleares. Del análisis de los resultados entre hepatocitos normales y estimulados con diferentes dosis infrarrojas, se visualiza que existen notables diferencias en todos los componentes celulares cuantificados particularmente el REL. Se concluye que las estimulaciones infrarrojas provocan una drástica transformación en la ultraestructura y morfología de los hepatocitos, lo que provocaría una variación funcional, representando de esta manera el efecto que estas estimulaciones provocan en este tipo celular.

A total of 24 female Sprague-Dawley rats aged 4 months and weighing approximately 250 g, were divided into four groups labeled A, B, C and D. Group A received no infrared stimulation and served as control. Group B was radiated with a dose of 4 J/cm² of infrared laser, Group C with doses of 8 J/cm² and Group D with 16 J/cm². This infrared stimulation was carried out daily for 15 days uninterrupted. The rats were then sacrificed and samples of both normal-control liver and liver stimulated with the different infrared doses were extracted for immediate processing via transmission electron microscopy. Transmission electron microphotographs were obtained at magnifications of 21300X from both normal and stimulated hepatocytes; these were subjected to morphometric studies to determine volumetric fractions with special emphasis on the smooth endoplasmic reticulum (SER) and the following cell components: rough endoplasmic reticulum (RER), mitochondria, glycogen, eu and heterochromatin. Likewise, cell and nuclear areas were quantified. Analysis of the results of normal and stimulated hepatocytes with different infrared doses showed considerable differences in all the quantified cell components and particularly from the SER it is concluded that the effects of these stimulations bring about a drastic transformation in the ultrastructure and morphology of the hepatocytes, which may ultimately translate into a functional variation, thus representing the effect that these stimulations cause in this cell type.

Morphology and histochemistry of the liver of carnivorous fish Hemisorubim platyrhynchos / Morfología e histoquímica del hígado del pez carnívoro Hemisorubim platyrhynchos

The aim of this study was to characterize the normal structure of the liver of Hemisorubim platyrhynchos, a carnivorous freshwater catfish found in Neotropical region, using gross anatomy, histology and histochemistry. Anatomically, the liver presents C-shaped and only two lobes: smaller right and bigger left. The gallbladder is located in right lobe and shows elongated shaped. Histological analysis demonstrated that the hepatic parenchyma is made of two hepatocytes plates surrounded by sinusoids. The hepatocytes are polygonal-shaped cells, with spherical nucleus and a dark prominent nucleolus. The cytoplasm presents large amount of lipids and glycogen deposits PAS positives. There are no hepatic lobules or portal triads. Bile ducts are lined by columnar epithelial cells with apical mucosubstances PAS and AB positive. Furthermore, the liver presents melano-macrophages centers, distributed next to the blood vessels and bile ducts, constituted by cells accumulating pigments, whose presence may be related to the nutritional status of the fish. Moreover pancreatic tissue was observed in visceral portion of liver, formed by exocrine pancreatic tissue and islet organ, constituting an extrahepatic pancreas.

El objetivo de este estudio fue caracterizar la estructura normal del hígado de Hemisorubim platyrhynchos, un bagre carnívoro de agua dulce encontrado en la región neotropical, utilizando anatomía macroscópica, histología e histoquímica de mucosustancias. Anatómicamente, el hígado presenta una forma de C y sólo dos lóbulos de tamaño diferente: menor derecho y mayor izquierdo. La vesícula biliar se encuentra en el lóbulo derecho y presenta forma alargada. El análisis histológico demostró que el parénquima hepático está hecho de dos placas de hepatocitos rodeados por sinusoides. Los hepatocitos son células poligonales con núcleo esférico y un nucléolo oscuro prominente. El citoplasma presenta gran cantidad de lípidos y depósitos de glucógeno PAS positivos. No hay lóbulos hepáticos o triadas portal. Los conductos biliares están revestidos por células columnares epiteliales con mucosustancias apicales PAS y AB positivos. Además, el hígado presenta centros de melanomacrófagos, distribuidos junto a los vasos sanguíneos y conductos biliares, constituidos por células que acumulan pigmentos, cuya presencia puede estar relacionada con el estado nutricional de los peces. Por otra parte, el tejido pancreático se observó en la porción visceral de hígado, formado por tejido pancreático exocrino y órgano islote, que constituye un páncreas extrahepático.