Radiographic and ultrasonographic findings of seminal vesiculitis with nonmineral stones in a guinea pig: Case report.

This case report refers to a 1-year-old Guinea pig showing signs of anorexia and antipain posture. On abdominal radiography, five rounded mineral opaque structures were evident in the mid-caudal abdomen. On ultrasound, a right seminal vesicle with a reduction in diameter was observed, containing less echogenic material than the contralateral one, with five oval structures with a hyperechogenic contour and a central hypoechogenic area, forming acoustic shadowing. The left seminal vesicle presented with the usual characteristics. After bilateral vesiculectomy, the patient recovered well, with no further symptoms. The histopathological result was a suppurative/abscessive inflammatory process with an accumulation of proteinaceous material.

Immune-mediated impairment of tonic immobility defensive behavior in an experimental model of colonic inflammation.

Ulcerative colitis has been associated with psychological distress and an aberrant immune response. The immunomodulatory role of systemic cytokines produced during experimental intestinal inflammation in tonic immobility (TI) defensive behavior remains unknown. The present study characterized the TI defensive behavior of guinea pigs subjected to colitis induction at the acute stage and after recovery from intestinal mucosa injury. Moreover, we investigated whether inflammatory mediators (tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, IL-8, IL-10, and prostaglandins) act on the mesencephalic nucleus, periaqueductal gray matter (PAG). Colitis was induced in guinea pigs by intrarectal administration of acetic acid. The TI defensive behavior, histology, cytokine production, and expression of c-FOS, IBA-1, and cyclooxygenase (COX)-2 in PAG were evaluated. Colitis reduced the duration of TI episodes from the first day, persisting throughout the 7-day experimental period. Neuronal c-FOS immunoreactivity was augmented in both columns of the PAG (ventrolateral (vlPAG) and dorsal), but there were no changes in IBA-1 expression. Dexamethasone, infliximab, and parecoxib treatments increased the duration of TI episodes, suggesting a modulatory role of peripheral inflammatory mediators in this behavior. Immunoneutralization of TNF-α, IL-1ß, and IL-8 in the vlPAG reversed all effects produced by colitis. In contrast, IL-10 neutralization further reduced the duration of TI episodes. Our results reveal that peripherally produced inflammatory mediators during colitis may modulate neuronal functioning in mesencephalic structures such as vlPAG.

Translational Perspectives on the Therapeutic Potential of Hyptis Crenata Essential Oil Terpenes in Smooth Muscle Function.

Monoterpenes and sesquiterpenes are classes of organic compounds found in various natural products, such as the essential oil of Hyptis crenata (EOHc). The therapeutic potential of these terpenes present in EOHc is evidenced by their effect on smooth muscle and potential clinical applications. Among the highlighted monoterpenes, such as sabinene, α-pinene, and ß-pinene, a relaxing effect on rat intestinal smooth muscles is observed, attributed to interaction with calcium channels. Furthermore, monoterpenoids like borneol, cineole, and linalool also demonstrate vasorelaxant properties, suggesting potential in the treatment of cardiovascular conditions. Sesquiterpenes, such as caryophyllene and aromadendrenes, exhibit relaxing effects in various smooth muscle tissues, such as rat uterus and guinea pig ileum, indicating pharmacological potential in these areas. The translational exploration of targets, such as calcium channels and G protein-coupled receptors, highlights the importance of these compounds in discovering new therapies based on natural products for treating various medical conditions.

Auditory changes in awake guinea pigs exposed to overcompressed music.

Exposure to loud sound during leisure time is identified as a significant risk factor for hearing by health authorities worldwide. The current standard that defines unsafe exposure rests on the equal-energy hypothesis, according to which the maximum recommended exposure is a tradeoff between level and daily exposure duration, a satisfactory recipe except for strongly non-Gaussian intense sounds such as gunshots. Nowadays, sound broadcast by music and videoconference streaming services makes extensive use of numerical dynamic range compression. By filling in millisecond-long valleys in the signal to prevent competing noise from masking, it pulls sound-level statistics away from a Gaussian distribution, the framework where the equal-energy hypothesis emerged. Auditory effects of a single 4 hour exposure to the same music were compared in two samples of guinea pigs exposed either to its original or overcompressed version played at the same average level of 102 dBA allowed by French regulations. Apart from a temporary shift of otoacoustic emissions at the lowest two frequencies 2 and 3 kHz, music exposure had no detectable cochlear effect, as monitored at 1, 2 and 7 days post-exposure. Conversely, middle-ear muscle strength behaved differentially as the group exposed to original music had fully recovered one day after exposure whereas the group exposed to overcompressed music remained stuck to about 50% of baseline even after 7 days. Subsamples were then re-exposed to the same music as the first time and sacrificed for density measurements of inner-hair-cell synapses. No difference in synaptic density was found compared to unexposed controls with either type of music. The present results show that the same music piece, harmless when played in its original version, induces a protracted deficit of one auditory neural pathway when overcompressed at the same level. The induced disorder does not seem to involve inner-hair cell synapses.

Cull guinea pigs: carcass and non-carcass traits in males and females compared to their fattening counterparts.

Culling of guinea pigs can provide a large number of animals per year for meat production, but little information is available in the scientific literature on the carcass characteristics and non-carcass components of these animals. The objective of this study was to evaluate the carcass and non-carcass characteristics of cull guinea pigs in comparison to their fattening counterparts. Forty-eight fattening (3 months-age, 24 females and 24 males) and forty-eight cull (14 months-age, 24 females and 24 males) guinea pigs were slaughtered and carcass yield, linear measurements, tissular composition, and non-carcass components were evaluated. In general, cull guinea pigs had higher carcass, tissue, and non-carcass component weights. Cull male and both female guinea pig groups had similar carcass yields. Cull animals had higher carcass and hind leg lengths, lumbar and thoracic circumferences, and carcass compactness than their young counterparts. However, a sex effect was found for leg compactness depending on whether they were fattened or cull. Tissue percentages values were similar between fattening and culling animals of the same sex. However, females had a higher percentage of fat tissue than males. Fattening females had the best muscle to bone ratio, followed by cull males. The non-carcass elements were more represented in fattening animals than in culls, probably due to an allometric growth of the viscera in relation to the rest of the body. In commercial and cooking terms, this information is valuable for producers and researchers who need to understand the factors that influence carcass characteristics of guinea pigs.

Molecular detection of Toxoplasma gondii in domestic and wild guinea pigs (Cavia spp.) from the Marangani district in Cuzco, Peru.

Toxoplasmosis is a foodborne disease caused by the protozoan Toxoplasma gondii, and transmitted to humans by eating raw or undercooked meat, mainly. Poultry, beef, and pork are the main meats consumed in Peru; despite this, guinea pig meat is also widely consumed. For this reason, the objective of this study was to molecularly detect T. gondii in domestic and wild guinea pigs from the Marangani district in Cuzco, Peru, and identify some risk factors associated with this pathogen. DNA was extracted from the brain tissue samples of guinea pigs (30 domestic and 30 wild), and PCR protocols were used to amplify the internal transcribed spacer (ITS-1) region and a 529 bp fragment from the T. gondii genome. T. gondii DNA was detected in 14 (23.3%) guinea pigs. T. gondii frequency was 33.3% in domestic guinea pigs and 13.3% in wild guinea pigs. Our results demonstrated that guinea pigs represent an important source for T. gondii infection in human populations in this locality.

[Primary immune thrombocytopenia linked to the ingestion of guinea pigs (Cavia porcellus) causality or coincidence?] / Trombocitopenia inmune primaria vinculada a la ingesta de cuy (Cavia porcellus). ¿casualidad o coincidencia?

The guinea pig in Ecuador is synonymous with our ancestral gastronomy and cultural tradition, but because of the diet rich in L-canavanine (alfalfa) that they receive; could limit its consumption in patients with primary immune thrombocytopenia (ITP). Ingestion of alfalfa in humans can cause kidney failure and lupus-like syndrome. The John Hopkins Lupus Center recommends avoiding it in the diet of patients with Systemic Lupus Erythematosus (SLE), as it aggravates inflammation by stimulating immune activity (flares). We present two cases of patients with ITP linked to guinea pig ingestion. It is probable

El cuy en el Ecuador es sinónimo de nuestra gastronomía ancestral y de tradición cultural, pero por la alimentación rica en L-canavanina (alfalfa) que reciben; podría limitar su consumo en pacientes con trombocitopenia inmune primaria (PTI). La ingesta de alfalfa en humanos puede propiciar insuficiencia renal y síndrome lupus-like.  El centro de Lupus John Hopkins recomiendan evitarla en la dieta de los pacientes con Lupus Eritematoso Sistémico (LES), al agravar la inflamación por estimulación de la actividad inmune (flares). Presentamos dos casos de pacientes con PTI vinculados con la ingesta de cuy.  ¿Es probable?

miRNA Expression Profiles in Isolated Ventricular Cardiomyocytes: Insights into Doxorubicin-Induced Cardiotoxicity.

Doxorubicin (DOX), widely used as a chemotherapeutic agent for various cancers, is limited in its clinical utility by its cardiotoxic effects. Despite its widespread use, the precise mechanisms underlying DOX-induced cardiotoxicity at the cellular and molecular levels remain unclear, hindering the development of preventive and early detection strategies. To characterize the cytotoxic effects of DOX on isolated ventricular cardiomyocytes, focusing on the expression of specific microRNAs (miRNAs) and their molecular targets associated with endogenous cardioprotective mechanisms such as the ATP-sensitive potassium channel (KATP), Sirtuin 1 (SIRT1), FOXO1, and GSK3ß. We isolated Guinea pig ventricular cardiomyocytes by retrograde perfusion and enzymatic dissociation. We assessed cell morphology, Reactive Oxygen Species (ROS) levels, intracellular calcium, and mitochondrial membrane potential using light microscopy and specific probes. We determined the miRNA expression profile using small RNAseq and validated it using stem-loop qRT-PCR. We quantified mRNA levels of some predicted and validated molecular targets using qRT-PCR and analyzed protein expression using Western blot. Exposure to 10 µM DOX resulted in cardiomyocyte shortening, increased ROS and intracellular calcium levels, mitochondrial membrane potential depolarization, and changes in specific miRNA expression. Additionally, we observed the differential expression of KATP subunits (ABCC9, KCNJ8, and KCNJ11), FOXO1, SIRT1, and GSK3ß molecules associated with endogenous cardioprotective mechanisms. Supported by miRNA gene regulatory networks and functional enrichment analysis, these findings suggest that DOX-induced cardiotoxicity disrupts biological processes associated with cardioprotective mechanisms. Further research must clarify their specific molecular changes in DOX-induced cardiac dysfunction and investigate their diagnostic biomarkers and therapeutic potential.

Testosterone Enhances KV Currents and Airway Smooth Muscle Relaxation Induced by ATP and UTP through P2Y4 Receptors and Adenylyl Cyclase Pathway.

Numerous studies suggest the involvement of adenosine-5'-triphosphate (ATP) and similar nucleotides in the pathophysiology of asthma. Androgens, such as testosterone (TES), are proposed to alleviate asthma symptoms in young men. ATP and uridine-5'-triphosphate (UTP) relax the airway smooth muscle (ASM) via purinergic P2Y2 and P2Y4 receptors and K+ channel opening. We previously demonstrated that TES increased the expression of voltage-dependent K+ (KV) channels in ASM. This study investigates how TES may potentiate ASM relaxation induced by ATP and UTP. Tracheal tissues treated with or without TES (control group) from young male guinea pigs were used. In organ baths, tracheas exposed to TES (40 nM for 48 h) showed enhanced ATP- and UTP-evoked relaxation. Tetraethylammonium, a K+ channel blocker, annulled this effect. Patch-clamp experiments in tracheal myocytes showed that TES also increased ATP- and UTP-induced K+ currents, and this effect was abolished with flutamide (an androgen receptor antagonist). KV channels were involved in this phenomenon, which was demonstrated by inhibition with 4-aminopyridine. RB2 (an antagonist of almost all P2Y receptors except for P2Y2), as well as N-ethylmaleimide and SQ 22,536 (inhibitors of G proteins and adenylyl cyclase, respectively), attenuated the enhancement of the K+ currents induced by TES. Immunofluorescence and immunohistochemistry studies revealed that TES did not modify the expression of P2Y4 receptors or COX-1 and COX-2, while we have demonstrated that this androgen augmented the expression of KV1.2 and KV1.5 channels in ASM. Thus, TES leads to the upregulation of P2Y4 signaling and KV channels in guinea pig ASM, enhancing ATP and UTP relaxation responses, which likely limits the severity of bronchospasm in young males.

Chamaecyparis lawsoniana and Its Active Compound Quercetin as Ca2+ Inhibitors in the Contraction of Airway Smooth Muscle.

The Cupressaceae family includes species considered to be medicinal. Their essential oil is used for headaches, colds, cough, and bronchitis. Cedar trees like Chamaecyparis lawsoniana (C. lawsoniana) are commonly found in urban areas. We investigated whether C. lawsoniana exerts some of its effects by modifying airway smooth muscle (ASM) contractility. The leaves of C. lawsoniana (363 g) were pulverized mechanically, and extracts were obtained by successive maceration 1:10 (w:w) with methanol/CHCl3. Guinea pig tracheal rings were contracted with KCl, tetraethylammonium (TEA), histamine (HIS), or carbachol (Cch) in organ baths. In the Cch experiments, tissues were pre-incubated with D-600, an antagonist of L-type voltage-dependent Ca2+ channels (L-VDCC) before the addition of C. lawsoniana. Interestingly, at different concentrations, C. lawsoniana diminished the tracheal contractions induced by KCl, TEA, HIS, and Cch. In ASM cells, C. lawsoniana significantly diminished L-type Ca2+ currents. ASM cells stimulated with Cch produced a transient Ca2+ peak followed by a sustained plateau maintained by L-VDCC and store-operated Ca2+ channels (SOCC). C. lawsoniana almost abolished this last response. These results show that C. lawsoniana, and its active metabolite quercetin, relax the ASM by inhibiting the L-VDCC and SOCC; further studies must be performed to obtain the complete set of metabolites of the extract and study at length their pharmacological properties.

Cloprostenol effect with and without male stimulation on oestrus synchronization in Peru guinea pigs.

Cloprostenol, a synthetic derivative of prostaglandin F2α, effectively triggers functional and morphological regression of the corpus luteum (luteolysis). In rural Peru, the guinea pig (Cavia porcellus) holds significance within the local economy and serves as a valuable protein source. Enhancing reproductive efficiency is crucial to achieve uniformity in weight, age, and litter size across commercial systems. Thus, our study aimed to evaluate the effect of cloprostenol with and without male stimulation on the onset, duration, and intensity of oestrus in Peru guinea pigs. A total of 128 guinea pigs (120 females and eight males) between 8 and 12 months of age, weighing between 800 and 1200 g, were distributed in cages of 15 females per treatment. Cloprostenol sodium (0 [control], 0.20, 0.25, and 0.30 mg/animal) was IM administered to the groups with and without male stimulation. Four isolated males in individual cages, different from the one used for the treatment, were considered to detect oestrus. The oestrus intensity was assessed by observing sexual behaviour signs such as restlessness, moaning, attempts to mount, pelvic elevation, loin stretching, and vulvar inflammation. The oestrus was manifested 2 days after the administration of cloprostenol sodium. At a dose of 0.30 mg/animal and with male stimulation, the earliest oestrus was observed at 46.9 h. There was a reduction in the oestrus duration (p < .05) in guinea pigs that received the three doses of cloprostenol sodium compared to the control group. The highest percentages of frank oestrus intensity (66.7%) were strongly associated with the administered doses of cloprostenol sodium (p < .01). In conclusion, the cloprostenol sodium administration was proper for rapid oestrus induction in Peru guinea pigs.

Analysis and 3D Imaging of Morphometric - Mineral Structure Changes in Skulls of Male and Female Guinea Pigs During and After Developmental Period

SUMMARY: Even though morphometric and mineral studies related to the guinea pig (Cavia porcellus) skull have been carried out, this study is the first attempt to evaluate all developmental stages of male and female guinea pigs. This study aims to this study is to create 3D modeling of CT images obtained from the skulls of male and female guinea pigs during the developmental period (prepuberty and the period between puberty and adulthood) and following periods (young adulthood and old adulthood), to analyze some biometric bone data such as volume, surface area and length, and to assess the developmental analysis of the mineral matter change in their skulls. The CT-scanned skulls were transferred to 3D Slicer (5.0.2), which is used for 3D modeling. The surface area and volume were calculated by measuring the measurement points on the models. In addition, the XRF device was used to show elemental ratio changes during different developmental stages. According to metric measurements, a gradual increase was observed during the life period. The metric measurements of the skull bone had a higher measurement value in male guinea pigs than in their female counterparts. While Ca/P ratio increased up to the third group and partially decreased in the fourth group in males, it gradually increased from the first group to the fourth group in females. This study revealed that puberty, adulthood and sex were effective in the physical and chemical characterization of skull bone structure in guinea pigs.

Aunque se han realizado estudios morfométricos y de minerales relacionados con el cráneo del cobayo (Cavia porcellus), esta investigación es el primer intento de evaluar las etapas de desarrollo de cobayos machos y hembras. El objetivo de este estudio fue crear un modelado 3D de imágenes de tomografía computarizada obtenidas de los cráneos de cobayos machos y hembras durante el período de desarrollo (prepubertad y el período entre la pubertad y la edad adulta) y los períodos siguientes (edad adulta joven y edad adulta mayor), para analizar algunos datos biométricos de los huesos, como el volumen, la superficie y la longitud, y además, analizar el cambio de materia mineral en sus cráneos durante el desarrollo. Los cráneos escaneados se transfirieron a 3D Slicer (5.0.2), que se utiliza para el modelado 3D. El área de superficie y el volumen se calcularon midiendo los puntos de medición en los modelos. Además, se utilizó el dispositivo XRF para mostrar los cambios en las proporciones elementales durante diferentes etapas de desarrollo. Según mediciones métricas, se observó un aumento gradual durante el período de vida. Las medidas métricas del hueso del cráneo tuvieron un valor de medición más alto en los cobayos machos que en las hembras. Mientras que la relación Ca/P aumentó hasta el tercer grupo y disminuyó parcialmente en el cuarto grupo en los machos y aumentó gradualmente del primer grupo al cuarto grupo en las hembras. Este estudio reveló que la pubertad, la edad adulta y el sexo fueron efectivos en la caracterización física y química de la estructura ósea del cráneo en cobayos.

Genomic characterization and probiotic potential of lactic acid bacteria isolated from feces of guinea pig (Cavia porcellus).

Background: Presently, there exists a growing interest in mitigating the utilization of antibiotics in response to the challenges emanating from their usage in livestock. A viable alternative strategy encompasses the introduction of live microorganisms recognized as probiotics, exerting advantageous impacts on the immune system and nutritional aspects of the host animals. Native lactic acid bacteria, inherently possessing specific properties and adaptive capabilities tailored to each animal, are deemed optimal contenders for probiotic advancement. Aim: In the current investigation, microorganisms exhibiting probiotic potential were isolated, characterized, and identified from the fecal samples of guinea pigs (Cavia porcellus) belonging to the Peruvian breed. Methods: The lactic acid bacteria isolated on Man, Rogosa, and Sharpe agar underwent Gram staining, catalase testing, proteolytic, amylolytic, and cellulolytic activity assays, low pH tolerance assessment, hemolytic evaluation, antagonism against Salmonella sp., determination of autoaggregation and coaggregation capacity, and genotypic characterization through sequencing of the 16S rRNA gene. Results: A total of 33 lactic acid bacteria were isolated from the feces of 30 guinea pigs, also 10 isolates were selected based on Gram staining and catalase testing. All strains exhibited proteolytic activity, while only one demonstrated amylolytic capability, and none displayed cellulase activity. These bacteria showed higher tolerance to pH 5.0 and, to a lesser extent, to pH 4.0. Furthermore, they exhibited antagonistic activity against Salmonella sp. Only two bacteria demonstrated hemolytic activity, and were subsequently excluded from further evaluations. Subsequent assessments revealed autoaggregation capacities ranging from 4.55% to 23.19%, with a lesser degree of coaggregation with Salmonella sp. ranging from 3.53% to 8.94% for the remaining eight bacterial isolates. Based on these comprehensive tests, five bacteria with notable probiotic potential were identified by molecular assays as Leuconostoc citreum, Enterococcus gallinarum, Exiguobacterium sp., and Lactococcus lactis. Conclusion: The identified bacteria stand out as promising probiotic candidates, deserving further assessment in Peruvian breed guinea pigs. This exploration aims to enhance production outcomes while mitigating the adverse effects induced by pathogenic microorganisms.

Experimental transmission of a novel relapsing fever group Borrelia harbored by Ornithodoros octodontus (Ixodida: Argasidae) in Chile.

Tick-borne relapsing fever spirochetes of genus Borrelia thrive in enzootic cycles involving Ornithodoros spp. (Argasidae) mainly, and rodents. The isolation of these spirochetes usually involves a murine model in which ticks are fed and the spirochetes detected in blood several days later. Such an experiment also demonstrates that a given species of tick is competent in the transmission of the bacteria. Here, soft ticks Ornithodoros octodontus were collected in Northern Chile with the objective to experimentally determine its capacity to transmit a Borrelia sp. detected in a previous study. Two Guinea pigs (Cavia porcellus) were used to feed nymphs and adults of O. octodontus and the spirochetes in blood were inspected by dark-field microscopy and nested PCR. Although spirochetes were not seen in blood, DNA was detected in only one animal 11 days after the ticks were fed. Genetic sequences of Borrelia flaB, clpX, pepX, recG, rplB, and uvrA genes retrieved from DNA extraction of positive blood were employed to construct two phylogenetic analyses. On the one hand, the flaB tree showed the Borrelia sp. transmitted by O. octodontus clustering with Borrelia sp. Alcohuaz, which was previously detected in that same tick species. On the other hand, concatenated clpX-pepX-recG-rplB-uvrA demonstrated that the characterized spirochete branches together with "Candidatus Borrelia caatinga", a recently discovered species from Brazil. Based on the genetic profile presented in this study, the name "Candidatus Borrelia octodonta" is proposed for the species transmitted by O. octodontus. The fact that spirochetes were not observed in blood of guinea pigs, may reflect the occurrence of low spirochetemia, which could be explained because the susceptibility of infection varies depending on the rodent species that is used in experimental models. Although the vertebrate reservoir of "Ca. Borrelia octodonta" is still unknown, Octodon degus, a rodent species that is commonly parasitized by O. octodontus, should be a future target to elucidate this issue.

Presence of Paraspidodera uncinata (Nematoda: Heterakidae) and Gyropus ovalis (Phthiraptera: Amblycera) in a wild specimen of Cavia aperea (Rodentia: Caviidae) from the campus of the Universidad Nacional de Asunción, San Lorenzo, Paraguay.

An adult specimen of Cavia aperea was transferred to the Wild Animal Practice, in the Department of Wildlife and Natural Environment, Faculty of Veterinary Sciences, National University of Asunción. Fecal samples and necropsy samples revealed the presence of Paraspidodera uncinata in the digestive tract, and Gyropus ovalis. This is the first documented report of the presence of P. uncinata and G. ovalis in a wild specimen of Cavia aperea in Paraguay.

Reciprocal facilitation between ants and small mammals in tidal marshes.

The role of facilitation in shaping natural communities has primarily been studied in the context of plant assemblages, while its relevance for mobile animals remains less understood. Our study investigates whether reciprocal interspecific facilitation may exist between fire ants (Solenopsis richteri) and cavies (Cavia aperea), two mobile animals, in the SW Atlantic coast brackish marshes. Field samples showed a spatial association between ant mounds and cavies, and that ants prefer to use cavy runways for movement within the marsh. Through experiments involving transplanting the dominant plant, cordgrass (Spartina densiflora), and manipulating cavy presence in areas with and without ant mounds, we observed that cavies forage extensively (and defecate more) near ant mounds. The ants actively remove cavy droppings in their mound vicinity. These ant activities and interactions with cavy droppings led to reduced moisture and organic content while increasing nitrate and phosphate levels in marsh sediment. Consequently, this enhanced plant growth, indirectly facilitating the cavies, which preferred consuming vegetation near ant mounds. These cascading indirect effects persisted over time; even four months after cavies left the marshes, transplanted plants near ant mounds remained larger and exhibited more leaf senescence when exposed to cavy herbivory. Therefore, the networks of positive interactions appear to generate simultaneous selection among species (populations), promoting coexistence within the community. Although complex, these reciprocal facilitative effects among mobile animals may be more common than currently believed and should be further studied to gain a better understanding of the underlying mechanisms driving species coexistence in natural communities.

Estudio Histológico en Embriones de Cobayo (Cavia porcellus) y su Utilidad como Modelo para la Comprensión del Desarrollo Embrionario Humano / Histological Study in Guinea Pig Embryos (Cavia porcellus) and its Usefulness as a Model for Understanding Human Embryonic Development

El cobayo es un modelo animal ampliamente utilizado en la investigación biomédica debido a sus similitudes biológicas con los seres humanos. El objetivo de nuestro estudio es proporcionar sustento morfológico para utilizar preparados histológicos de embriones de cobayo como modelo de estudio para comprender los procesos del desarrollo embrionario humano. Nuestros resultados muestran que los embriones de cobayo presentan características morfológicas similares a las observadas en los embriones humanos, lo que sugiere que pueden utilizarse como un modelo efectivo para estudiar el desarrollo embrionario humano. Este hallazgo tiene importantes implicancias para la investigación y la docencia utilizando este modelo animal. Se analizaron preparados histológicos de embriones de cobayo teñidos con hematoxilina eosina, adquiridos por la Universidad Autónoma de Chile. Se tomaron microfotografías de preparados histológicos de cobayo en diferentes estadios del desarrollo y se seleccionaron las mejores imágenes para la descripción de estructuras y establecer estimados de la embriogénesis. Del análisis de los preparados se desprende que órganos como esófago, médula espinal y corazón presentan similitudes anatómicas e histológicas que hacen posible compararlas con el desarrollo embrionario humano y la edad de gestación en etapas tempranas. El uso de preparados de embriones de cobayo y su análisis desde un aspecto histológico resulta ser una estrategia metodológica factible debido a las similitudes en la embriogénesis de los mamíferos y las concordancias morfológicas con el desarrollo de los órganos entre humanos y roedores. Esto permite implementar este modelo animal como una herramienta para comprender el desarrollo embrionario humano.

SUMMARY: The guinea pig is an animal model widely used in biomedical research due to its biological similarities with humans. The objective of our study is to provide morphological support to use histological preparations of guinea pig embryos as a study model to understand the processes of human embryonic development. Our results show that guinea pig embryos present morphological characteristics similar to those observed in human embryos, suggesting that they can be used as an effective model to study human embryonic development. This finding has important implications for research and teaching using this animal model. Histological preparations of guinea pig embryos stained with hematoxylin eosin, acquired by the Autonomous University of Chile, were analyzed. Photomicrographs of histological preparations of guinea pigs at different stages of development were taken and the best images were selected to describe structures and establish estimates of embryogenesis. From the analysis of the preparations it is clear that organs such as the esophagus, spinal cord and heart present anatomical and histological similarities that make it possible to compare them with human embryonic development and gestation age in early stages. The use of guinea pig embryo preparations and their analysis from a histological aspect turns out to be a feasible methodological strategy due to the similarities in mammalian embryogenesis and the morphological concordances with the development of organs between humans and rodents. This allows this animal model to be implemented as a tool to understand human embryonic development.

Steroidogenic activity and morphological characterization of prenatal testes and epididymis of guinea pig (Cavia porcellus).

The present study aims to establish the morphological, morphometric, and immunostaining patterns of the steroidogenic enzymes 17ß-HSD and 5α-reductase and androgen receptors (AR) during the prenatal development of the male gonad and epididymis of Cavia porcellus. Fetuses at 22, 25, 30, 40, 45, 50, and 60 days of gestation (DG) were used. Specimens were dissected and subjected to macroscopic, histological, histomorphometric, and immunohistochemical analyses. Genital and scrotal protrusions were identified in 22 DG embryos. Gonocytes were identified at 25 DG and the formation of primary testicular cords was observed at 30 DG. Through anatomical evaluation, we observed differentiation of the epididymis into the head, body, and tail at 45 DG. During development, there is a progressive decrease in the diameters of the testicular cords and epididymal ducts. 17ß-HSD enzyme immunostaining was observed in Leydig cells at all ages, while 5α-reductase was observed in Leydig cell cytoplasm and gonocytes at 40, 50, and 60 DG. AR shows gonocyte labeling at 30 DG. Thus, from the second trimester of pregnancy, it is possible to observe patterns of anatomical development, such as genital and scrotal prominence (22 DG), the appearance of gonocytes in the testicular cords at 25 DG, and the beginning of the organization of primary testicular cords at 30 DG, suggesting sexual differentiation. The 17ß-HSD, 5α-reductase, and ARs play an essential role in sexual development and differentiation, presenting immunostaining at different reproductive process times.

Influence of risedronate on orthodontic tooth movement in rodents: a systematic review and case report.

INTRODUCTION: Bisphosphonates have an inhibitory impact on osteoclastic activity, reducing bone resorption. However, the influence of risedronate on tooth movement is not well-defined. OBJECTIVE: This systematic review assessed the effect of risedronate intake on orthodontic tooth movement. A case report was also provided. METHODS: Two independent reviewers searched six databases (PubMed, Web of Science, Ovid, Lilacs, Scopus, and Open Grey). The searches were carried out in April/2020, and an update was set in place in June/2023. Therefore, the searches considered a timeline from the databases' inception date until June/2023, with no publication date and/or language restrictions. The clinical question focused on evaluating the orthodontic tooth movement and relapse movement (Outcome) in animals (Population) exposed to risedronate (Exposure), compared to control groups (Comparison). The Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines were applied, and the protocol was registered in PROSPERO (CRD42020168581). The risk of bias was determined using the Systematic Review Centre for Laboratory Animal Experimentation protocol (SYRCLE). RESULTS: Two studies in rats and one in guinea pigs were included in the systematic review. The studies reported a decrease in orthodontic tooth movement, a reduction in the relapse movement, and a reduced number of positive tartrate-resistant acid phosphatase (TRAP) cells, with a significantly reduced number of bone gaps after the administration of risedronate in rats. A case report illustrated the effects of risedronate administration in one patient. CONCLUSION: Based on the systematic review, risedronate seems to impair orthodontic tooth movement and relapse due to a decrease in bone resorption cells.