Síndrome do ovário policístico: caracterização termporal do processo de indução e reversão em um modelo experimental

Numerosos modelos experimentais têm sido desenvolvimos para o estudo da síndrome do ovário policístico em ratos. No presente estudo, a síndrome foi inducida por exposição à luz constante. O processo foi avaliado durante sua indução e inclusive durante sua reversão. O ciclo estral foi analisado através de citologia vaginal; parámetros reprodutivos foram avaliados por acasalamento, bem como a morfologia ovariana. Todos animais desenvolveram a síndrome depois de 13 semanas de luz permanente. As características histológicas dos ovários, na semana 15, foram similares àquelas observadas na síndrome do ovário policístico em humanos e outras espécies. Após a regressão da síndrome, não houve diferenta em nenhum dos parámetros reprodutivos avaliados, quando comparados com o grupo controle.Numerous experimental models have been developed for the study of the polycystic ovarian syndrome in the rat. In the present study, the syndrome was induced by exposure to constant light. The process was evaluated during its induction and also during its reversion. The estral cycle was analyzed through the vaginal cytology; reproductive parameters were evaluated by mating, as well as the ovarian morphology. All the animals developed the syndrome after 13 weeks of permanent light. The histologic characteristics of the ovaries, at week 15, were similar to those observed in the polycystic ovarian syndrome in human and other species. After regression of the syndrome, there was not difference in any of the evaluated reproductive parameters, when compared with the control group

Guinea-pig interpubic joint (symphysis pubica) relaxation at parturition: Underlying cellular processes that resemble an inflammatory response

BACKGROUND: At term, cervical ripening in coordination with uterine contractions becomes a prerequisite for a normal vaginal delivery. Currently, cervical ripening is considered to occur independently from uterine contractions. Many evidences suggest that cervical ripening resembles an inflammatory process. Comparatively little attention has been paid to the increased flexibility of the pelvic symphysis that occurs in many species to enable safe delivery. The aim of this study was to investigate whether the guinea-pig interpubic joint relaxation process observed during late pregnancy and parturition resembles an inflammatory process. METHODS: Samples of pubic symphysis were taken from pregnant guinea-pigs sacrificed along gestation, parturition and postpartum. Serial sections of paraffin-embedded tissues were used to measure the interpubic distance on digitalized images, stained with Giemsa to quantify leukocyte infiltration and to describe the vascular area changes, or studied by the picrosirius-polarization method to evaluate collagen remodeling. P4 and E2 serum levels were measured by a sequential immunometric assay. RESULTS: Data showed that the pubic relaxation is associated with an increase in collagen remodeling. In addition, a positive correlation between E2 serum levels and the increase in the interpubic distance was found. On the other hand, a leukocyte infiltration in the interpubic tissue around parturition was described, with the presence of almost all inflammatory cells types. At the same time, histological images show an increase in vascular area (angiogenesis). Eosinophils reached their highest level immediately before parturition; whereas for the neutrophilic and mononuclear infiltration higher values were recorded one day after parturition. Correlation analysis showed that eosinophils and mononuclear cells were positively correlated with E2 levels, but only eosinophilic infiltration was associated with collagen remodeling. Additionally, we observed typical histological images of dissolution of the connective tissue matrix around eosinophils. CONCLUSION: The present study shows that a timely regulated influx of infiltrating leukocytes is associated with an extensive collagen remodeling process that allows the pubic separation for a normal delivery in guinea-pig. Thus, the findings in this study support the hypothesis that the guinea-pig pubic symphyseal relaxation at parturition resembles an inflammatory process

Changes in IGF-1, IGF-2 and IGF-1r expression in canine placentae of different pregnancy age

The IGF system is involved in human placental development. The aim of the work was to evaluate IGF-1, IGF-2 and IGF1R expression in canine early, mature and term placentae (EP, MP, TP, respectively). Placental samples from 7 dogs were obtained by Hysterectomy and processed by indirect immunohistochemistry for the detection of IGF1, IGF2 and IGF1R.Facultad de Ciencias Veterinaria

Changes in IGF-1, IGF-2 and IGF-1r expression in canine placentae of different pregnancy age

The IGF system is involved in human placental development. The aim of the work was to evaluate IGF-1, IGF-2 and IGF1R expression in canine early, mature and term placentae (EP, MP, TP, respectively). Placental samples from 7 dogs were obtained by Hysterectomy and processed by indirect immunohistochemistry for the detection of IGF1, IGF2 and IGF1R.Facultad de Ciencias Veterinaria

Sympathetic nerve activity in normal and cystic follicles from isolated bovine ovary: local effect of beta-adrenergic stimulation on steroid secretion

Cystic ovarian disease (COD) is an important cause of abnormal estrous behavior and infertility in dairy cows. COD is mainly observed in high-yielding dairy cows during the first months post-partum, a period of high stress. We have previously reported that, in lower mammals, stress induces a cystic condition similar to the polycystic ovary syndrome in humans and that stress is a definitive component in the human pathology. To know if COD in cows is also associated with high sympathetic activity, we studied isolated small antral (5mm), preovulatory (10mm) and cystic follicles (25mm). Cystic follicles which present an area 600 fold greater compared with preovulatory follicles has only 10 times less concentration of NE as compared with small antral and preovulatory follicles but they had 10 times more NE in follicular fluid, suggesting a high efflux of neurotransmitter from the cyst wall. This suggestion was reinforced by the high basal release of recently taken-up 3H-NE found in cystic follicles. While lower levels of beta-adrenergic receptor were found in cystic follicles, there was a heightened response to the beta-adrenergic agonist isoproterenol and to hCG, as measured by testosterone secretion. There was however an unexpected capacity of the ovary in vitro to produce cortisol and to secrete it in response to hCG but not to isoproterenol. These data suggest that, during COD, the bovine ovary is under high sympathetic nerve activity that in addition to an increased response to hCG in cortisol secretion could participate in COD development

An imbalance between apoptosis and proliferation contributes to follicular persistence in polycystic ovaries in rats

<p>Abstract</p> <p>Background</p> <p>Cystic ovarian disease is an important cause of infertility that affects bovine, ovine, caprine and porcine species and even human beings. Alterations in the ovarian micro-environment of females with follicular cysts could alter the normal processes of proliferation and programmed cell death in ovarian cells. Thus, our objective was to evaluate apoptosis and proliferation in ovarian cystic follicles in rats in order to investigate the cause of cystic follicle formation and persistence.</p> <p>Methods</p> <p>We compared the number of in situ apoptotic cells by TUNEL assay, expression of active caspase-3 and members of Bcl-2 family by immunohistochemistry; and cell proliferation by the expression of the proliferation markers: PCNA and Ki-67.</p> <p>Results</p> <p>The proliferation index was low in granulosa of tertiary and cystic follicles of light exposed rats when compared with tertiary follicles of control animals, while in theca interna only cystic follicles presented low proliferation index when compared with tertiary follicles (p < 0.05). The granulosa of cysts exhibited a similar cell DNA fragmentation to early atretic follicles. In the granulosa and theca interna, active caspase-3 shown similar immunostaining levels in tertiary and cystic follicles (p < 0.05). The granulosa cells presented high expression of Bcl-2, Bcl-xL and Bcl-w in the tertiary and cystic follicles with diminishing intensity in the atretic follicles, except with Bcl-w where the intensity was maintained in the atretic follicles (p < 0.05). The expression of Bax was weak in the healthy and cystic follicles. In the theca interna, Bcl-2 expression was the same as the pattern found in the granulosa; no differences were found between tertiary and cystic follicles from both groups for Bcl-xL and Bcl-w. The expression of Bax in this layer was higher in the tertiary follicles of the treated animals (p < 0.05) while the values for cystic follicles were similar to those in the tertiary follicles of controls. The theca externa showed low expression of the pro and anti-apoptotic proteins.</p> <p>Conclusion</p> <p>These results show that the combination of weak proliferation indices and low apoptosis observed in follicular cysts, could explain the cause of the slow growth of cystic follicles and the maintenance of a static condition without degeneration, which leads to their persistence. These alterations may be due to structural and functional modifications that take place in these cells and could be related to hormonal changes in animals with this condition.</p

An imbalance between apoptosis and proliferation contributes to follicular persistence in polycystic ovaries in rats

Background: Cystic ovarian disease is an important cause of infertility that affects bovine, ovine, caprine and porcine species and even human beings. Alterations in the ovarian micro-environment of females with follicular cysts could alter the normal processes of proliferation and programmed cell death in ovarian cells. Thus, our objective was to evaluate apoptosis and proliferation in ovarian cystic follicles in rats in order to investigate the cause of cystic follicle formation and persistence. Methods: We compared the number of in situ apoptotic cellsby TUNEL assay, expression of active caspase-3 and members of Bcl-2 family by immunohistochemistry; and cell proliferation by the expression of the proliferation markers: PCNA and Ki-67. Results: The proliferation index was low in granulosa of tertiary and cystic follicles of light exposed rats when compared with tertiary follicles of control animals, while in theca interna only cystic follicles presented low proliferation index when compared with tertiary follicles (p < 0.05). The granulosa of cysts exhibited a similar cell DNA fragmentation to early atretic follicles. In the granulosa and theca interna, active caspase-3 shown similar immunostaining levels in tertiary and cystic follicles (p < 0.05). The granulosa cells presented high expression of Bcl-2, Bcl-xL and Bcl-w in the tertiary and cystic follicles with diminishing intensity in the atretic follicles, except with Bcl-w where the intensity was maintained in the atretic follicles (p < 0.05). The expression of Bax was weak in the healthy and cystic follicles. In the theca interna, Bcl-2 expression was the same as the pattern found in the granulosa; no differences were found between tertiary and cystic follicles from both groups for Bcl-xL and Bcl-w. The expression of Bax in this layer was higher in the tertiary follicles of the treated animals (p < 0.05) while the values for cystic follicles were similar to those in the tertiary follicles of controls. The theca externa showed low expression of the pro and anti-apoptotic proteins. Conclusion: These results show that the combination of weak proliferation indices and low apoptosis observed in follicular cysts, could explain the cause of the slow growth of cystic follicles and the maintenance of a static condition without degeneration, which leads to their persistence. These alterations may be due to structural and functional modifications that take place in these cells and could be related to hormonal changes in animals with this conditionFacultad de Ciencias Veterinaria

Stress response elements in the ovary and its implication in ovarian pathophysiology in cattle

En respuesta a varios estresores, la hormona adrenocorticotrópica estimula la síntesis y secreción de los glucocorticoides, los cuales pueden afectar la reproducción directamente por acción sobre el eje hipotálamo-hipófisis-ovario. En este sentido, es importante destacar que la ovulación ha sido descripta como un proceso inflamatorio localizado, donde una sucesión de eventos lleva a la degradación proteolítica de un punto específico de la pared folicular para permitir la salida del ovocito. Por lo tanto, el cortisol liberado a causa del estrés podría actuar a nivel del sitio ovulatorio inhibiendo la ovulación al producir efectos antiinflamatorios locales. Si bien no ha sido demostrado que el ovario sea capaz de producir glucocorticoides de novo, la hormona adrenocorticotrópica, a través de su unión a los receptores de melanocortinas en el ovario bovino, es capaz de estimular la secreción de hormonas esteroides tanto in vivo como in vitro, principalmente la secreción de cortisol, y producir cambios en la expresión de las enzimas 11β-hidroxiesteroide deshidrogenasas responsables de la activación/inactivación del cortisol. Nuestros resultados indican que la hormona adrenocorticotrópica puede estar implicada en los mecanismos regulatorios relacionados a la función ovárica asociados con la ovulación, la esteroidogénesis y la fisiopatología de diferentes enfermedades reproductivas en bovinos.In response to stressors, adrenocorticotropic hormone stimulates the synthesis and secretion of glucocorticoids, which can affect reproduction acting on the hypothalamic-pituitary-ovarian axis. In this sense, that ovulation has been described as a localized inflammatory process, where a sequence of events leading to proteolytic degradation of a specific point of the follicular wall to allow the exit of the oocyte. Hence, cortisol released could act in the ovulatory site, inhibiting the ovulation through the production of local anti-inflammatory effects. Although has not been demonstrated that the ovary is able to produce glucocorticoids de novo, adrenocorticotropic hormone, through binding to melanocortin receptors in bovine ovary, it is able to stimulate the secretion of steroid hormones both in vivo and in vitro, mainly cortisol, and produce changes in the expression of 11β-hydroxysteroid dehydrogenase enzymes responsible for the local activation / inactivation of cortisol. Our results indicate that adrenocorticotropic hormone may be involved in regulatory mechanisms related to ovarian function associated with ovulation, ovarian steroidogenesis, luteal function and the pathophysiology of various reproductive diseases in cattle.Sociedad de Ciencias Morfológicas de La Plat

Estrogen receptors α and β and progesterone receptors in normal bovine ovarian follicles and cystic ovarian disease

The purpose of this study was to determine by immunohistochemistry the expression of estrogen and progesterone receptors in ovarian follicular structures from cows with cystic ovarian disease (COD) and to compare these with normal ovarian structures. Secondary, tertiary, atretic, and cystic follicles were evaluated. The follicular cysts of animals with COD presented a significantly higher expression of estrogen receptor a in all follicular layers than secondary, tertiary, and atretic follicles in both groups (P < .05). The intensity of estrogen receptor β in the granulosa cell layer was stronger in tertiary than in secondary and atretic follicles in normal animals (P < .05) and in growing and cystic follicles in animals with COD (P < .05). Theca cells were scarcely stained in the 2 groups. Growing follicles and cysts from COD animals were less stained than tertiary follicles from normal animals (P < .05). Differences did not exist between the 2 groups with regard to the progesterone receptor. Ovaries of animals with COD exhibited altered estrogen receptors expression compared with that in normal animals.Facultad de Ciencias Veterinaria

Estrogen receptors α and β and progesterone receptors in normal bovine ovarian follicles and cystic ovarian disease

The purpose of this study was to determine by immunohistochemistry the expression of estrogen and progesterone receptors in ovarian follicular structures from cows with cystic ovarian disease (COD) and to compare these with normal ovarian structures. Secondary, tertiary, atretic, and cystic follicles were evaluated. The follicular cysts of animals with COD presented a significantly higher expression of estrogen receptor a in all follicular layers than secondary, tertiary, and atretic follicles in both groups (P < .05). The intensity of estrogen receptor β in the granulosa cell layer was stronger in tertiary than in secondary and atretic follicles in normal animals (P < .05) and in growing and cystic follicles in animals with COD (P < .05). Theca cells were scarcely stained in the 2 groups. Growing follicles and cysts from COD animals were less stained than tertiary follicles from normal animals (P < .05). Differences did not exist between the 2 groups with regard to the progesterone receptor. Ovaries of animals with COD exhibited altered estrogen receptors expression compared with that in normal animals.Facultad de Ciencias Veterinaria