Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 86
Filtrar
Más filtros

Tipo del documento
Intervalo de año de publicación
1.
Adv Exp Med Biol ; 1383: 141-156, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36587154

RESUMEN

Autism spectrum disorder (ASD; autism) is a prevalent neurodevelopmental disorder associated with changes in gut-brain axis communication. Gastrointestinal (GI) symptoms are experienced by a large proportion of individuals diagnosed with autism. Several mutations associated with autism modify cellular communication via neuronal synapses. It has been suggested that modifications to the enteric nervous system, an intrinsic nervous system of the GI tract, could contribute to GI dysfunction. Changes in gut motility, permeability, and the mucosal barrier as well as shifts in the large population of microbes inhabiting the GI tract could contribute to GI symptoms. Preclinical research has demonstrated that mice expressing the well-studied R451C missense mutation in Nlgn3 gene, which encodes cell adhesion protein neuroligin-3 at neuronal synapses, exhibit GI dysfunction. Specifically, NL3R451C mice show altered colonic motility and faster small intestinal transit. As well as dysmotility, macrophages located within the gut-associated lymphoid tissue of the NL3R451C mouse caecum show altered morphology, suggesting that neuro-inflammation pathways are modified in this model. Interestingly, NL3R451C mice maintained in a shared environment demonstrate fecal microbial dysbiosis indicating a role for the nervous system in regulating gut microbial populations. To better understand host-microbe interactions, further clarification and comparison of clinical and animal model profiles of dysbiosis should be obtained, which in turn will provide better insights into the efforts taken to design personalized microbial therapies. In addition to changes in neurophysiological measures, the mucosal component of the GI barrier may contribute to GI dysfunction more broadly in individuals diagnosed with a wide range of neurological disorders. As the study of GI dysfunction advances to encompass multiple components of the gut-brain-microbiota axis, findings will help understand future directions such as microbiome engineering and optimisation of the mucosal barrier for health.


Asunto(s)
Trastorno del Espectro Autista , Enfermedades Gastrointestinales , Microbiota , Ratones , Animales , Trastorno del Espectro Autista/genética , Eje Cerebro-Intestino , Disbiosis/metabolismo , Enfermedades Gastrointestinales/genética , Enfermedades Gastrointestinales/tratamiento farmacológico , Encéfalo/metabolismo
2.
Phys Rev Lett ; 121(2): 022502, 2018 Jul 13.
Artículo en Inglés | MEDLINE | ID: mdl-30085703

RESUMEN

Lifetimes of the first excited 2^{+} and 4^{+} states in the extremely neutron-deficient nuclide ^{172}Pt have been measured for the first time using the recoil-distance Doppler shift and recoil-decay tagging techniques. An unusually low value of the ratio B(E2:4_{1}^{+}→2_{1}^{+})/B(E2:2_{1}^{+}→0_{gs}^{+})=0.55(19) was found, similar to a handful of other such anomalous cases observed in the entire Segré chart. The observation adds to a cluster of a few extremely neutron-deficient nuclides of the heavy transition metals with neutron numbers N≈90-94 featuring the effect. No theoretical model calculations reported to date have been able to explain the anomalously low B(E2:4_{1}^{+}→2_{1}^{+})/B(E2:2_{1}^{+}→0_{gs}^{+}) ratios observed in these cases. Such low values cannot, e.g., be explained within the framework of the geometrical collective model or by algebraic approaches within the interacting boson model framework. It is proposed that the group of B(E2:4_{1}^{+}→2_{1}^{+})/B(E2:2_{1}^{+}→0_{gs}^{+}) ratios in the extremely neutron-deficient even-even W, Os, and Pt nuclei around neutron numbers N≈90-94 reveal a quantum phase transition from a seniority-conserving structure to a collective regime as a function of neutron number. Although a system governed by seniority symmetry is the only theoretical framework for which such an effect may naturally occur, the phenomenon is highly unexpected for these nuclei that are not situated near closed shells.

3.
Diabetologia ; 56(7): 1547-56, 2013 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-23595248

RESUMEN

AIMS/HYPOTHESIS: We analysed the genomic organisation of miR-153, a microRNA embedded in genes that encode two of the major type 1 diabetes autoantigens, islet-associated protein (IA)-2 and IA-2ß. We also identified miR-153 target genes that correlated with IA-2ß localisation and function. METHODS: A bioinformatics approach was used to identify miR-153's genomic organisation. To analyse the co-regulation of miR-153 and IA-2ß, quantitative PCR analysis of miR-153 and Ia-2ß (also known as Ptprn2) was performed after a glucose stimulation assay in MIN6B cells and isolated murine pancreatic islets, and also in wild-type Ia-2 (also known as Ptprn), Ia-2ß single knockout and Ia-2/Ia-2ß double knockout mouse brain and pancreatic islets. Bioinformatics identification of miR-153 target genes and validation via luciferase reporter assays, western blotting and quantitative PCR were also carried out. RESULTS: Two copies of miR-153, miR-153-1 and miR-153-2, are localised in intron 19 of Ia-2 and Ia-2ß, respectively. In rodents, only miR-153-2 is conserved. We demonstrated that expression of miR-153-2 and Ia-2ß in rodents is partially co-regulated as demonstrated by a strong reduction of miR-153 expression levels in Ia-2ß knockout and Ia-2/Ia-2ß double knockout mice. miR-153 levels were unaffected in Ia-2 knockout mice. In addition, glucose stimulation, which increases Ia-2 and Ia-2ß expression, also significantly increased expression of miR-153. Several predicted targets of miR-153 were reduced after glucose stimulation in vitro, correlating with the increase in miR-153 levels. CONCLUSIONS/INTERPRETATION: This study suggests the involvement of miR-153, IA-2ß and miR-153 target genes in a regulatory network, which is potentially relevant to insulin and neurotransmitter release.


Asunto(s)
Encéfalo/metabolismo , MicroARNs/genética , Páncreas/metabolismo , Proteínas Tirosina Fosfatasas Clase 8 Similares a Receptores/metabolismo , Animales , Western Blotting , Línea Celular Tumoral , Femenino , Masculino , Ratones , Ratones Noqueados , Proteínas Tirosina Fosfatasas Clase 8 Similares a Receptores/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa
4.
Braz J Biol ; 83: e271425, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37341252

RESUMEN

Medicinal plant species are genetically engineered to obtain higher production of biomass and specific secondary metabolites, which can be used in the pharmaceutical industry. The aim of the present study was to evaluate the effect of Pfaffia glomerata (Spreng.) Pedersen tetraploid hydroalcoholic extract on the liver of adult Swiss mice. The extract was prepared from the plant roots and given to the animals by gavage, for 42 days. The experimental groups were treated with water (control), Pfaffia glomerata tetraploid hydroalcoholic extract (100, 200 and 400 mg/kg) and Pfaffia glomerata tetraploid hydroalcoholic extract discontinuously (200 mg/kg). The last group received the extract every 3 days, for 42 days. The oxidative status, mineral dynamics, and cell viability were analysed. The liver weight and the number of viable hepatocytes were reduced, despite the increased cell's number. Increased levels of malondialdehyde and nitric oxide, and changes in iron, copper, zinc, potassium, manganese and sodium levels were observed. aspartate aminotransferase levels were increased while alanine aminotransferase levels were decreased due to BGEt intake. Our results showed that BGEt induced alterations of oxidative stress biomarkers leading to liver injury, which was associated with a reduction in the number of hepatocytes.


Asunto(s)
Amaranthaceae , Tetraploidía , Animales , Ratones , Hígado , Estrés Oxidativo , Extractos Vegetales/toxicidad
5.
Lett Appl Microbiol ; 55(3): 202-9, 2012 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-22748120

RESUMEN

AIMS: To develop a specific and highly sensitive loop-mediated isothermal amplification (LAMP) technique for the rapid detection of canine parvovirus (CPV) DNA directly in suspected faecal samples of dogs by employing a simple method of template preparation. METHODS AND RESULTS: LAMP reaction was developed by designing two sets of outer and inner primers, which target a total of six distinct regions on VP2 gene of CPV. The template DNA was prepared by a simple boiling and chilling method. Of the 140 faecal samples screened by the developed LAMP and the conventional PCR assays, 104 samples (74·28%) were found positive by LAMP, whereas 81 samples (57·85%) were found positive by PCR. The specificity of the LAMP assay was tested by cross-examination of common pathogens of dogs and further confirmed by sequencing. The detection limit of the LAMP was 0·0001 TCID50 ml⁻¹, whereas the detection limit of the PCR was 1000 TCID50 ml⁻¹. CONCLUSIONS: The developed LAMP assay detects CPV DNA in faecal specimens directly within an hour by following a simple and rapid boiling and chilling method of template preparation. The result also shows that the developed LAMP assay is specific and highly sensitive in detecting CPV. SIGNIFICANCE AND IMPACT OF THE STUDY: The result indicates the potential usefulness of LAMP which is a simple, rapid, specific, highly sensitive and cost-effective field-based method for direct detection of CPV from the suspected faecal samples of dogs.


Asunto(s)
Enfermedades de los Perros/diagnóstico , Heces/virología , Técnicas de Amplificación de Ácido Nucleico/veterinaria , Infecciones por Parvoviridae/veterinaria , Parvovirus Canino/aislamiento & purificación , Animales , Cartilla de ADN/genética , ADN Viral/aislamiento & purificación , Perros/virología , Límite de Detección , Técnicas de Amplificación de Ácido Nucleico/métodos , Infecciones por Parvoviridae/diagnóstico , Parvovirus Canino/genética , Reacción en Cadena de la Polimerasa/métodos , Reacción en Cadena de la Polimerasa/veterinaria , Sensibilidad y Especificidad
6.
J Calif Dent Assoc ; 40(1): 65-78, 2012 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-22439491

RESUMEN

The objective of the current study was to systematically evaluate the existing evidence in relation to the safety, quality, productivity or cost-benefit, and patient satisfaction of the procedures performed by the different groups of dental providers. Due to the diversity of the procedures performed and the outcomes measured, it was not possible to create pooled estimates in a meaningful manner. Therefore, summary results of individual studies are presented and critically evaluated.


Asunto(s)
Atención a la Salud , Auxiliares Dentales , Atención Odontológica , Seguridad del Paciente , Calidad de la Atención de Salud , Análisis Costo-Beneficio , Atención a la Salud/economía , Atención a la Salud/organización & administración , Atención a la Salud/normas , Auxiliares Dentales/economía , Auxiliares Dentales/organización & administración , Auxiliares Dentales/normas , Atención Odontológica/economía , Atención Odontológica/organización & administración , Atención Odontológica/normas , Eficiencia Organizacional , Humanos , Satisfacción del Paciente , Calidad de la Atención de Salud/economía , Calidad de la Atención de Salud/organización & administración , Calidad de la Atención de Salud/normas
7.
Indian J Tuberc ; 69 Suppl 2: S202-S204, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36400509

RESUMEN

The article deals with challenges faced by the geriatric populations while on MDR treatment. Risk factors like tobacco use, low socio-economic status, previous disease, longer delays in seeking treatment and reduced mobility are some of the challenges while initiating MDR treatment. Other issues like drug-related adverse events and increased co-morbidity pose a major challenge while treating patients. Susceptibility among the geriatric age group includes various anatomical and physiological changes including nutritional deficiencies and co morbidities.


Asunto(s)
Desnutrición , Tuberculosis Resistente a Múltiples Medicamentos , Humanos , Anciano , Tuberculosis Resistente a Múltiples Medicamentos/tratamiento farmacológico , Tuberculosis Resistente a Múltiples Medicamentos/epidemiología , Desnutrición/epidemiología , Comorbilidad , Factores de Riesgo
8.
Cell Mol Bioeng ; 15(1): 67-86, 2022 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-34777597

RESUMEN

Introduction: Since the outbreak began in January 2020, Covid-19 has affected more than 161 million people worldwide and resulted in about 3.3 million deaths. Despite efforts to detect human infection with the virus as early as possible, the confirmatory test still requires the analysis of sputum or blood with estimated results available within approximately 30 minutes; this may potentially be followed by clinical referral if the patient shows signs of aggravated pneumonia. This work aims to implement a soft collar as a sound device dedicated to the objective evaluation of the pathophysiological state resulting from dysphonia of laryngeal origin or respiratory failure of inflammatory origin, in particular caused by Covid-19. Methods: In this study, we exploit the vibrations of waves generated by the vocal and respiratory system of 30 people. A biocompatible acoustic sensor embedded in a soft collar around the neck collects these waves. The collar is also equipped with thermal sensors and a cross-data analysis module in both the temporal and frequency domains (STFT). The optimal coupling conditions and the electrical and dimensional characteristics of the sensors were defined based on a mathematical approach using a matrix formalism. Results: The characteristics of the signals in the time domain combined with the quantities obtained from the STFT offer multidimensional information and a decision support tool for determining a pathophysiological state representative of the symptoms explored. The device, tested on 30 people, was able to differentiate patients with mild symptoms from those who had developed acute signs of respiratory failure on a severity scale of 1 to 10. Conclusion: With the health constraints imposed by the effects of Covid-19, the heavy organization to be implemented resulting from the flow of diagnostics, tests and clinical management, it was urgent to develop innovative and safe biomedical technologies. This passive listening technique will contribute to the non-invasive assessment and dynamic observation of lesions. Moreover, it merits further examination to provide support for medical operators to improve clinical management. Supplementary Information: The online version contains supplementary material available at 10.1007/s12195-021-00712-w.

9.
Ann Nutr Metab ; 57(1): 23-34, 2010.
Artículo en Inglés | MEDLINE | ID: mdl-20664255

RESUMEN

Although the effects of trans fatty acids (TFA) from industrially produced sources (IP-TFA), such as partially hydrogenated vegetable oil, are reported, their implications on metabolism and growth are still not fully disclosed. In this study, female Wistar rats were assigned to control diet (AIN-93G) or Trans diet groups (5% IP-TFA) after gestation. The male offspring were classified and grouped as infant, weanling, and young adult (YA) rats (n = 10), and received the same control or Trans diets throughout their life span. Samples of abdominal adipose tissue, liver and plasma were collected to determine fatty acid profile and fasting glycemia. Morphometric analysis of the liver and hepatosomatic index determination were conducted. Deposition of TFA was observed in the liver, adipose tissue and plasma of IP-TFA-fed rats. Fasting glycemia concentration was higher in Trans YA rats than in the control YA group (p = 0.004). A higher accumulation of fat was observed in the liver of the Trans group than in the control group during the three phases. Hepatosomatic index was higher in the YA Trans group than in the YA control group (p < 0.05). Dietary TFA was deposited in the tissues and plasma and raised fasting glucose in growing rats.


Asunto(s)
Fenómenos Fisiológicos Nutricionales de los Animales , Grasas de la Dieta/farmacología , Resistencia a la Insulina/fisiología , Ácidos Grasos trans/farmacología , Tejido Adiposo/metabolismo , Tejido Adiposo/patología , Animales , Femenino , Insulina/sangre , Insulina/farmacología , Metabolismo de los Lípidos , Hígado/metabolismo , Hígado/fisiología , Masculino , Ratas , Ratas Wistar
10.
Histol Histopathol ; 35(10): 1135-1149, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-32735026

RESUMEN

Properties attributed to the Panax ginseng are also attributed to the Brazilian ginseng, such as adaptogenic and aphrodisiac effects. There are studies demonstrating that the Brazilian ginseng (BGE) possibly increases the serum levels of testosterone and nitric oxide in mice and rats. The present study aimed to evaluate the effects of its extract on male fertility and sperm quality. Male Swiss mice (n = 60) were divided into six groups. The control animals were provided 0.5 mL of water, and 0.5 mL of water containing 7 mg/kg per day (d) sildenafil citrate. Other animals were treated with BGE at 100 mg/kg/d, 200 mg/kg/d, and 400 mg/kg/d by gavage for 42 days. Finally, animals from the last group received 200 mg/kg BGE every 3 days (3-3d) by gavage for 42 days. The results showed a reduction in the number of resistant spermatids in the testis and damage to daily sperm production, culminating in a reduction in the number of epididymal spermatozoa. Although the sperm quality decreased in all experimental animals, only males treated with BGE 100 mg/kg/d showed pre and post implantation embryo losses. We concluded that BGE alters sperm viability compromising the embryonic development after implantation.


Asunto(s)
Panax , Extractos Vegetales/farmacología , Reproducción/efectos de los fármacos , Animales , Brasil , Epidídimo/efectos de los fármacos , Masculino , Ratones , Motilidad Espermática/efectos de los fármacos , Espermatogénesis/efectos de los fármacos , Espermatozoides/efectos de los fármacos , Testosterona/metabolismo
11.
BMJ Case Rep ; 20182018 Mar 28.
Artículo en Inglés | MEDLINE | ID: mdl-29592994

RESUMEN

A patient with a cystic artery pseudoaneurysm (CAP) presented to the emergency department with upper abdominal and back pain. The patient also had clinical signs of sepsis. CT revealed gallstones with acute suppurative cholecystitis with a gallbladder perforation. In addition, a CAP was also suspected and subsequently diagnosed on CT angiography. The pseudoaneurysm was treated with embolisation and a cholecystostomy was performed for the gallbladder perforation. Following her acute admission, the patient underwent an elective cholecystectomy and made a good recovery post surgery.


Asunto(s)
Aneurisma Falso/diagnóstico por imagen , Aneurisma Falso/terapia , Colecistitis Aguda/complicaciones , Embolización Terapéutica/métodos , Enfermedades de la Vesícula Biliar/diagnóstico por imagen , Enfermedades de la Vesícula Biliar/terapia , Adulto , Aneurisma Falso/complicaciones , Colecistostomía/métodos , Angiografía por Tomografía Computarizada/métodos , Diagnóstico Diferencial , Femenino , Vesícula Biliar/diagnóstico por imagen , Vesícula Biliar/cirugía , Enfermedades de la Vesícula Biliar/complicaciones , Cálculos Biliares/complicaciones , Cálculos Biliares/diagnóstico por imagen , Cálculos Biliares/terapia , Humanos , Perforación Espontánea/complicaciones , Perforación Espontánea/diagnóstico por imagen , Perforación Espontánea/terapia
12.
Anim Reprod Sci ; 102(3-4): 217-27, 2007 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-17145142

RESUMEN

Nitric oxide (NO) is a highly reactive free radical involved in intra- and intercellular signaling in various stages of reproduction. The objective of the present study was to evaluate the effect of the addition of sodium nitroprusside (SNP), a NO donor, on nuclear and cytoplasmic in vitro maturation of bovine oocytes. Analysis of variance was conducted and the means were compared by t test at a level of 5%. Low (10(-7) and 10(-9)M) and intermediate (10(-5)M) concentrations of SNP had no significant effect on nuclear maturation, however, when a greater concentration of SNP (10(-3)M) was added, oocytes remained in metaphase I (MI) after 24 h culture (P<0.05) and did not show cumulus expansion. To evaluate if this effect was reversible and if a retardation or inhibition had occurred in the progression from MI to MII, oocytes were cultured in presence of 10(-3)M of SNP for 24 h followed by culture for an additional 24 h in medium with or without SNP. After 48 h, the oocytes remained in MI even when the medium was changed at 24 h with or without SNP. The kinetics of nuclear maturation was assessed to evaluate if there had been or not a retardation in the progression of meiosis with the concentration of 10(-3)M SNP. This concentration delayed germinal vesicle breakdown (VGBD) at 8 h of culture (P<0.05), and at 12 h there was no significant difference between the control and the treated group. The concentrations that did not induce alterations in nuclear maturation were evaluated for cytoplasmic maturation. The concentration of 10(-5)M improved the percentage of peripheral cortical granules (P<0.05), and significantly increased the percentage of blastocysts. These results demonstrate that SNP at greater concentrations (10(-3)M) has a cytotoxic effect, but at intermediate (10(-5)M) concentrations it increases blastocyst rates. NO exhibits a dual effect on bovine oocytes, inhibits (10(-3)M of SNP) nuclear and cytoplasmic maturation or stimulates (10(-5)M of SNP) cytoplasmic maturation, depending on concentration in the culture medium.


Asunto(s)
Bovinos/fisiología , Donantes de Óxido Nítrico/farmacología , Nitroprusiato/farmacología , Oocitos/efectos de los fármacos , Oocitos/crecimiento & desarrollo , Animales , Blastocisto/efectos de los fármacos , Muerte Celular/efectos de los fármacos , Núcleo Celular/fisiología , Células Cultivadas , Citoplasma/fisiología , Relación Dosis-Respuesta a Droga , Femenino , Fertilización In Vitro/veterinaria , Meiosis/efectos de los fármacos , Nitroprusiato/administración & dosificación , Oocitos/ultraestructura , Folículo Ovárico/fisiología , Factores de Tiempo
13.
Anim Reprod Sci ; 91(1-2): 173-9, 2006 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-16310104

RESUMEN

The aim of the present study was to characterize the intertubule element volume density, individual and total Leydig cells volume, Leydig cell number per testis and per gram of testis, and leydigosomatic index in adult capybaras. Eight capybaras from a commercial abattoir were utilized. The intertubular compartment volume density and the Leydig cells were 45.2 and 31.13%, respectively. The individual and total Leydig cell volumes were 8.51 and 2169.41 x 10(-12) mL, respectively. The Leydig cell number per testis was 3.8 billion and the Leydig cell number per gram of testis was 126 million. The leydigosomatic index was 0.037%. In conclusion, this study shows that capybaras have one of the greatest individual and total Leydig cell volume and Leydig cell volume density, and that the Leydig cell number per gram of testis is at least double the mean for mammals previously investigated in its order.


Asunto(s)
Células Intersticiales del Testículo/citología , Roedores/anatomía & histología , Testículo/anatomía & histología , Testículo/citología , Mataderos , Animales , Recuento de Células/veterinaria , Masculino , Roedores/fisiología , Estaciones del Año
14.
Cell Death Discov ; 2: 16022, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27551515

RESUMEN

Cellular reactive oxygen species (ROS) is a major antibacterial defense mechanism used by macrophages upon activation. Exposure of Mycobacterium tuberculosis (Mtb)-infected macrophages to hypoxia is known to compromise the survival of the pathogen. Here we report that the hypoxia-induced control of intracellular Mtb load in RAW 264.7 macrophages was mediated by regulating the cellular ROS levels. We show that similar to classical activation, hypoxia incubation of macrophages resulted in decreased mitochondrial outer membrane potential (MOMP) and a concomitant increase in the cellular ROS levels. Mitochondrial depolarization and consequently higher ROS could be blocked by knocking down Akt using siRNAs, which acted by inhibiting the switch to glycolytic mode of metabolism, an essential adaptive response upon classical activation or hypoxic incubation of macrophages. Moreover, in the classically activated macrophages or in the macrophages under hypoxia incubation, supplementation with additional glucose had similar effects as Akt knockdown. Interestingly, in both the cases, the reversal of phenotype was linked with the ability of the mitochondrial F0-F1 ATP synthase activity to maintain the MOMP in the absence of oxidative phosphorylation. Both Akt knockdown and glucose supplementation were also able to rescue Mtb survival in these macrophages upon classical activation or hypoxia incubation. These results provide a framework for better understanding of how the interplay between oxygen supply, which is limiting in the human tubercular granulomas, and nutrient availability could together direct the outcome of infections in vivo.

17.
J Neurosci ; 21(22): 8979-89, 2001 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-11698608

RESUMEN

Norepinephrine (NE) secretion within the hypothalamic paraventricular nucleus (PVN) is pivotal to endocrine and behavioral responses. Activation of NE afferents to PVN also is necessary for the hypothalamo-pituitary-adrenal axis response to passively administered nicotine. The mode of drug delivery is a critical determinant of the dynamics of neurotransmitter secretion, yet the PVN NE response to nicotine self-administration (SA) is unknown. Herein, rats housed in operant chambers had unlimited 23 hr access to self-administered nicotine. In vivo microdialysis of PVN NE was performed, collecting consecutive 7 min samples over 9 hr sessions during three phases of nicotine SA: acquisition (day 1); early maintenance, once stable rates of SA were achieved (day 9.2 +/- 0.6); later maintenance (day 18.6 +/- 0.8). On d1, nicotine animals had an increased percentage of SA episodes (SAEs) in which NE levels were elevated (80 vs 30% with saline; p < 0.01). By early maintenance, a fourfold increase in such episodes was observed in nicotine animals (p < 0.01), and the overall NE level was greater (1.30 +/- 0.24 vs 0.63 +/- 0.07 pg/10 microl in saline; p < 0.05); NE increased during the first, but not the last, SAE. The pattern was similar during later maintenance, although NE responsiveness declined (overall NE level, 0.96 +/- 0.19 in nicotine vs 0.52 +/- 0.08 pg/10 microl in saline; p < 0.05). Therefore, nicotine SAEs were associated with sustained increases in NE secretion during all three phases of SA. However, the reduced NE responsiveness observed both within the dialysis session in each phase and by later versus early maintenance is consistent with progression of partial daily desensitization of PVN NE secretion to nicotine SA. Therefore, in rats chronically self-administering nicotine, the drug stimulates sustained PVN NE secretion that may alter neuroendocrine and behavioral responses mediated by the PVN. Compared with studies of chronic human smokers, our nicotine SA model may reflect the CNS noradrenergic responses that occur during human cigarette smoking.


Asunto(s)
Nicotina/administración & dosificación , Norepinefrina/metabolismo , Núcleo Hipotalámico Paraventricular/efectos de los fármacos , Núcleo Hipotalámico Paraventricular/metabolismo , Abuso de Sustancias por Vía Intravenosa/metabolismo , Animales , Conducta Animal/efectos de los fármacos , Cromatografía Líquida de Alta Presión , Modelos Animales de Enfermedad , Inyecciones Intravenosas , Masculino , Microdiálisis , Ratas , Ratas Endogámicas Lew , Autoadministración
18.
Diabetes ; 30(4): 302-9, 1981 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-6259006

RESUMEN

Young male Holtzman rats injected with nicotinamide and streptozotocin develop grossly visible tumors of pancreatic islet tissue. Using an i.v. glucose tolerance test, some tumor-bearing animals exhibited a vigorous (or fast) response to glucose loading (Diabetic Index = 0.47), whereas others showed a subdiabetic (or slow) response (Diabetic Index = 2.34). In vitro perifusion studies demonstrate that tumor pieces from both groups of rats released immunoreactive insulin (IRI) in response to glucose; tumors from fast responding rats showed a rapid monophasic release of IRI (i.e., rapid transient release with little secondary phase), while tumors from slow responders released IRI in a biphasic pattern resembling that of normal islets. A population of large islet masses (or microscopic tumors), isolated from drug-treated rats by collagenase digestion of the pancreas of tumor-containing rats, exhibited glucose-stimulated IRI release that resembled the pattern of the tumor from the same animal. Isolated islets of Langerhans of ordinary size from the pancreas of tumor-bearing rats, on the other hand, usually exhibited a normal (biphasic) IRI release pattern in response to glucose. Analysis by gel filtration suggests that the predominant form of IRI released from perifused tumor preparations, under either basal or glucose-stimulated conditions, eluted at a rate corresponding to rat insulin.


Asunto(s)
Adenoma/metabolismo , Insulina/metabolismo , Islotes Pancreáticos/metabolismo , Animales , Glucosa/metabolismo , Secreción de Insulina , Masculino , Colagenasa Microbiana , Neoplasias Experimentales/metabolismo , Niacinamida , Ratas , Estreptozocina
19.
Endocrinology ; 132(1): 269-74, 1993 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-8380377

RESUMEN

To determine whether prostaglandins (PGs) mediate the ACTH response to tumor necrosis factor-alpha (TNF alpha), indomethacin (Indo; 0.1-1.0 mg/kg, iv) was administered before TNF alpha (1 microgram, iv) in freely moving, alert rats. While Indo alone did not affect plasma ACTH levels, it dose-dependently blocked the ACTH response to TNF alpha. The highest dose of Indo abolished the ACTH response to TNF alpha [peak plasma ACTH values (mean +/- SEM): buffer/buffer, 137 +/- 34 pg/ml; Indo/buffer, 115 +/- 31; buffer/TNF alpha, 469 +/- 77; Indo/TNF alpha, 120 +/- 27] without modifying the ACTH response to CRF 1 microgram/kg, iv, demonstrating that pituitary responsiveness was unaffected. Since it has been reported that Indo elevates plasma corticosterone (B) levels, the effect of Indo could reflect rapid negative feedback by B, rather than the involvement of PGs. However, inhibition of ACTH secretion was shown to be dependent on the dose of Indo, whereas plasma B levels were elevated to the same degree, independent of the Indo dose. In addition, Indo failed to block the ACTH response to an unrelated ACTH stimulus, insulin-induced hypoglycemia (area under response curve: insulin alone, 31,131 +/- 2,794 pg/min.ml; Indo/insulin, 32,919 +/- 3,582 pg/min.ml). Finally, in adrenalectomized B-replaced rats, TNF alpha elevated ACTH to levels similar to those seen in sham animals, and Indo inhibited these ACTH responses to the same extent in both groups. Thus, Indo inhibited the ACTH response to TNF alpha by a mechanism independent of B feedback. These results indicate that acute systemic administration of TNF alpha stimulates ACTH secretion through a PG-dependent mechanism.


Asunto(s)
Hormona Adrenocorticotrópica/metabolismo , Prostaglandinas/fisiología , Factor de Necrosis Tumoral alfa/farmacología , Animales , Glucemia/metabolismo , Corticosterona/sangre , Hormona Liberadora de Corticotropina/farmacología , Relación Dosis-Respuesta a Droga , Indometacina/administración & dosificación , Indometacina/farmacología , Insulina/farmacología , Masculino , Ratas
20.
Endocrinology ; 133(1): 11-9, 1993 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-8391419

RESUMEN

The ACTH response to many stimuli depends on the secretion of norepinephrine, which activates neurons in the hypothalamic paraventricular nucleus (PVN). Studies with adrenergic antagonists and inhibitors of catecholamine synthesis indicate that norepinephrine is a mediator of nicotine-induced ACTH secretion. To directly assess the effect of nicotine on PVN norepinephrine secretion, in vivo microdialysis was performed. Nicotine (0.5 mg/kg BW, ip) induced peak norepinephrine levels within 20 min (approximately 2 x basal). The central nicotinic receptor antagonist, mecamylamine, abolished this response, whereas hexamethonium, a peripheral antagonist, was ineffective. The norepinephrine response was dose dependent (ED50, approximately 0.25 mg/kg), and nicotine (0.5 mg/kg BW) induced maximal secretion. Rapid desensitization occurred, as evidenced by a significant reduction (approximately 50%) in the response to a second injection of nicotine (0.5 mg/kg BW). Animals also received four injections of nicotine to determine whether repetitive dosing leads to progressive reduction of the norepinephrine response. The responses to the third and fourth nicotine injections were similar. Thus, desensitization occurred after a single exposure to nicotine and was not progressive. In contrast, nicotine pretreatment did not affect the release of norepinephrine due to yohimbine. These results indicate that basal and nicotine-stimulated levels of norepinephrine can be detected in microdialysates from the PVN; rapid desensitization of the norepinephrine response to nicotine and inhibition by mecamylamine, but not hexamethonium, parallel the findings previously reported for ACTH.


Asunto(s)
Nicotina/farmacología , Norepinefrina/metabolismo , Núcleo Hipotalámico Paraventricular/metabolismo , Hormona Adrenocorticotrópica/sangre , Animales , Diálisis , Relación Dosis-Respuesta a Droga , Cinética , Masculino , Nicotina/administración & dosificación , Nomifensina/farmacología , Núcleo Hipotalámico Paraventricular/efectos de los fármacos , Ratas , Yohimbina/farmacología
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA