Rat Polycystic Ovary Research Articles

Altered expression of Bcl-2 and Bax in follicles within dehydroepiandrosterone-induced polycystic ovaries in rats

PCOS (polycystic ovary syndrome) is a heterogeneous disease characterized by hyperandrogenaemia, hirsutism, oligo- or amenorrhea, insulin resistance and anovulation. The aim of the present study was to evaluate if the balance between the ovarian expression of Bax (proapoptotic protein) and Bcl-2 (antiapoptotic protein) is altered in a PCOS model developed in rats by DHEA (dehydroepiandrosterone) administration. In addition, the ovarian morphology and the circulating progesterone levels were evaluated. Histological studies confirmed the presence of follicular cysts, atretic follicles and the absence of corpora lutea in the ovaries from the PCOS group and a significant decrease in circulating progesterone levels. Immunohistochemical studies showed that the expression of Bcl-2 and Bax were mainly localized in granulosa cells of AFs (antral follicles) in both groups. Bax expression was greater in preantral and AFs from PCOS ovarian sections than in the controls. In contrast, intense Bcl-2 immunostaining was observed in the control AFs, while Bcl-2 protein was either absent in PFs (preantral follicles) or weakly expressed in AFs from PCOS rats. These results were partially confirmed by Western studies. Data revealed that the ovarian level of Bcl-2 protein was lower in PCOS than in the control and that there were no differences in Bax ovarian levels between groups. However, Bax/Bcl-2 ratio was significantly higher in PCOS group than in the control group. In conclusion, an increase in ovarian apoptosis through an imbalance among the Bcl-2 family members may be involved in the transformation of growing follicles in cystic follicles in the ovaries from DHEA-induced PCOS rats.

Relationship between Metabolic Disorders and Pituitary Gonadotropins in a Rat Polycystic Ovary Syndrome Model.

Polycystic ovary syndrome (PCOS) is one of the most common endocrine diseases among reproductive women and usually associated with obesity and insulin resistance. However, the etiology of PCOS is still unknown. A rat PCOS model is described for investigating possible pathogenesis. Female prepubertal rats were randomly divided into three experimental groups treated with vehicle (sesame oil, 1ml/kg/day, n=18), testosterone propionate (TP, 10mg/kg/day, subcutaneously, n=17), or dihydrotestosterone (DHT, 10mg/kg/day, subcutaneously, n=16) for 56 days. Vaginal smears of both TP and DHT groups showed continuous diestrus phase rather than normal 4~5-day estrous cycle in vehicle group. DHT treated female rats were significantly heavier and their ratios of parametrial fat weight to total body weight were also higher. Oral glucose tolerance test performed at 12-week-old revealed insulin resistance phenomenon in DHT group but not in the other two groups. Ovarian histology showed polycystic morphology in DHT treated group but not in vehicle and TP-treated groups. There were no significant differences in serum follicle-stimulating hormone (FSH) levels, but in vitro culture of anterior pituitaries demonstrated that DHT group produced significantly more FSH but less luteinizing hormone (LH). Anterior pituitaries of TP group also produced less LH but even more FSH than those in DHT group. Abnormally low LH/FSH ratio might result in estrous cycle disruption, but was not correlated with the severity of metabolic disturbance. This research was supported by a grant (V98B1-008) from Taipei Veterans General Hospital. (poster)

Effects of Bushen Tongmai Recipe (补肾通脉方) on protein kinase Bα expression in polycystic ovary rats with insulin resistance

To observe the effects of Bushen Tongmai Recipe (, BSTMR) on mRNA and protein expressions of protein kinase B alpha (PKB alpha) in hepatic, adipose, muscular, and ovarian tissues of polycystic ovary (PCO) rats with insulin resistance (IR) and to explore the possible molecular mechanism of BSTMR in treating IR and ovulation dysfunction. Female 22-day-old SD rats were injected subcutaneously with sodium prasterone sulfate (9 mg.100g(-1).d(-1)) for 20 days and fed with high-fat diet for 80 days to induce PCO rats with IR. Then, the PCO rats were randomly divided into the model group (n=23) and the treated group (n=21). The treated group was administered with BSTMR for 2 weeks. Meanwhile, a group with 15 rats of the same age was used as the control group. The histological changes in the ovaries were examined. Fasting blood glucose (FBG) was determined by the glucose oxidase method. Serum fasting insulin (Fins) was determined by radioimmunoassay (RIA). The mRNA level of PKBalpha was measured by reverse transcription polymerase chain reaction (RT-PCR). Immunohistochemistry staining and Western blot analysis were employed to detect the protein expression in target tissues. Compared with the control group, the ovaries in the model group showed multiple follicular cysts, levels of FBG and Fins in the model group increased markedly (P<0.05 or P<0.01, respectively), and the insulin sensitive index (ISI) decreased obviously (P<0.01). The mRNA and protein expressions of PKBalpha in target tissues in the model group were dramatically lower than those in the control group (P<0.05 or P<0.01). Compared with the model group, the stratum granulosum of the ovarian follicle in the treated group increased markedly, the level of Fins in the treated group decreased obviously (P<0.01), ISI in the treated group improved markedly (P<0.01), and the mRNA and protein expressions of PKBalpha in target tissues of the treated rats were elevated significantly (P<0.05 or P<0.01). BSTMR could improve IR and ovulation dysfunction in PCO rats with IR, and its molecular mechanisms might be closely related with the elevation of mRNA and protein expressions of PKBalpha in target tissues of PCO rats with IR.

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

BackgroundCystic 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.MethodsWe 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.ResultsThe 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.ConclusionThese 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.

Effect of Korean red ginseng extract in a steroid-induced polycystic ovary murine model

Experimental induction of polycystic ovary (PCO) in rodent resembling some aspects of human PCO syndrome was produced using the long-acting compound estradiol valerate (EV). Our previous study on the role of Korean red ginseng total saponins in a steroid-induced PCO rat model demonstrated that electro-acupuncture modulates nerve growth factor (NGF) concentration in the ovaries. In fact, the involvement of a neurogenic component in the pathology of PCO-related ovarian dysfunction is preceded by an increase in sympathetic outflow to the ovaries. In the present study, we tested the hypothesis that Korean red ginseng extract (KRGE) administration modulates sympathetic nerve activity in PCO-induced rats. This was done by analyzing NGF protein and NGF mRNA expression involved in the pathophysiological process underlying steroid-induced PCO. EV injection resulted in significantly higher ovarian NGF protein and NGF mRNA expression in PCO-induced rats compared to control rats, and PCO ovaries were counteracted by KRGE administration with significantly lower expression of NGF protein and NGF mRNA compared to EV treated ovaries. These results indicate that EV modulates the neurotrophic state of the ovaries, which may be a component of the pathological process by which EV induces cyst formation and anovulation in rodents.

Disruption in the expression and immunolocalisation of steroid receptors and steroidogenic enzymes in letrozole-induced polycystic ovaries in rat

The objective of the present study was to characterise the expression and tissue distribution of steroid receptors (oestrogen receptor-alpha and -beta (ERalpha, ERbeta), androgen receptor (AR) and progesterone receptor (PR)) and steroidogenic enzymes (P450 aromatase (P450arom), 3beta-hydroxysteroid dehydrogenase (3beta-HSD) and steroidogenic acute regulatory protein (StAR)) in letrozole-induced polycystic ovaries of rats. Changes in serum hormone levels, protein expression in whole ovaries by western blot analysis and protein localisation by immunohistochemistry were determined in female rats treated with the aromatase inhibitor letrozole and compared with controls in proestrous and diestrous rats. Increases in the serum LH, FSH and testosterone concentrations were observed in letrozole-treated rats whereas serum oestradiol and progesterone levels were reduced. Protein expression as analysed by western immunoblot was consistent with the immunohistochemical data. Letrozole treatment induced an increase in the expression of AR, StAR and 3beta-HSD and a decrease in ERbeta. ERalpha, PR and P450arom showed partial changes in relation to some cycle stages. These results indicate that cystogenesis in this experimental model is characterised by changes in steroid receptors and steroidogenic enzyme expression that may be essential to proper ovarian functioning and are in agreement with similar changes observed in women with PCOS.

154. EFFECT OF KOREAN RED GINSENG EXTRACT IN STEROID-INDUCED POLYCYSTIC OVARY MURINE MODEL

Experimental induction of polycystic ovary (PCO) resembling some aspects of human PCO syndrome was produced using the long-acting compound estradiol valerate (EV). Our previous study on the role of Korean red ginseng total saponins in a steroid-induced PCO rat model demonstrated that electro-acupuncture modulates nerve growth factor (NGF) concentration in the ovaries. In fact, the involvement of a neurogenic component in the pathology of PCO-related ovarian dysfunction is preceded by an increase in sympathetic outflow to the ovaries. In the present study, we tested the hypothesis that Korean red ginseng extract (KRGE) administration modulates sympathetic nerve activity in rats with PCO. This was done by analysing NGF protein and NGF mRNA expression involved in the pathophysiological process underlying steroid-induced PCO. EV injection resulted in significantly higher ovarian NGF protein and NGF mRNA expression in PCO rats compared to control rats, and PCO ovaries were counteracted by KRGE administration with significantly lower expression of NGF protein and NGF mRNA compared to EV treated ovaries. These results indicate that EV modulates the neurotrophic state of the ovaries, which may be a component of the pathological process by which EV induces cyst formation and anovulation in rodents.

Locus Coeruleus Mediates Cold Stress-Induced Polycystic Ovary in Rats

Previous reports about the rat ovary have shown that cold stress promotes ovarian morphological alterations related to a polycystic ovary (PCO) condition through activation of the ovarian sympathetic nerves. Because the noradrenergic nucleus locus coeruleus (LC) is activated by cold stress and synaptically connected to the preganglionic cell bodies of the ovarian sympathetic pathway, this study aimed to evaluate the LC's role in cold stress-induced PCO in rats. Ovarian morphology and endocrine and sympathetic functions were evaluated after 8 wk of chronic intermittent cold stress (4 C, 3 h/d) in rats with or without LC lesion. The effect of acute and chronic cold stress upon the LC neuron activity was confirmed by Fos protein expression in tyrosine hydroxylase-immunoreactive neurons. Cold stress induced the formation of follicular cysts, type III follicles, and follicles with hyperthecosis alongside increased plasma estradiol and testosterone levels, irregular estrous cyclicity, and reduced ovulation. Considering estradiol release in vitro, cold stress potentiated the ovarian response to human chorionic gonadotropin. Ovarian norepinephrine (NE) was not altered after 8 wk of stress. However, LC lesion reduced NE activity in the ovary of cold-stressed rats, but not in controls, and prevented all the cold stress effects evaluated. Cold stress increased the number of Fos/tyrosine hydroxylase-immunoreactive neurons in the LC, but this effect was more pronounced for acute stress as compared with chronic stress. These results show that cold stress promotes PCO in rats, which apparently depends on ovarian NE activity that, under this condition, is regulated by the noradrenergic nucleus LC.

Testosterone Environment of Splenocytes Modifies the Steroidogenesis of Polycystic Ovary in Rats

The functional relationship between the ovary and immune cells is well known. The modulation of ovarian steroidogenesis in adult rats with polycystic ovary (PCO) by secretions of cultured splenocytes treated with 10 (-6) M testosterone or 10 (-6) M testosterone plus 10 (-4) M flutamide, an androgen receptor antagonist, was investigated. Polycystic ovary was induced by estradiol valerate (2 mg/rat). Polycystic ovary splenocyte secretions decreased the release of androstenedione from PCO ovaries in contrast to the effect of non-PCO splenocyte secretions. This decrease was associated with a significant decrease in androgen receptor and IL-12 mRNA expression in PCO splenocytes. When splenocytes were treated with testosterone, their conditioned media further decreased androstenedione release from the ovary and had a greater inhibitory effect on PCO ovary compared with non-PCO ovary. This effect was reversed by flutamide. Polycystic ovary splenocytes showed a decrease in IL-1 beta mRNA expression. Their secretions scarcely affected progesterone release from non-PCO ovaries but significantly stimulated progesterone release from PCO ovary by an androgen-independent mechanism. The differential steroidogenic ability of splenocyte secretions from PCO rats is associated with the IN VITRO testosterone environment. Polycystic ovary splenocytes might exert a protective action against PCO effects through their secretions by inducing a low androstenedione response from the ovary.

Altered expression of Fas/Fas ligand/caspase 8 and membrane type 1-matrix metalloproteinase in atretic follicles within dehydroepiandrosterone-induced polycystic ovaries in rats

One of the characteristics of polycystic ovary syndrome (PCOS) is the presence of cystic follicles in various stages of growth and atresia, the latter of which is known to be the result of apoptosis and tissue remodeling. To further investigate the process of follicular atresia, we compared ovarian expression and localization of Fas, Fas ligand (FasL), casapse-8 and membrane-type1 matrix metalloproteinase (MT1-MMP) in rats treated with dehydroepiandrosterone (DHEA) as a model of PCOS, and in control rats. We found that the numbers of TdT-mediated dUTP-biotin nick end-labeling (TUNEL)-positive follicles were significantly higher in ovaries from PCOS rats than in those from control rats (P < 0.05), as were ovarian levels of FasL mRNA and protein, processed caspase-8 protein and MT1-MMP mRNA. Correspondingly, we also observed an increase in the level of MTI-MMP catalytic activity and a decrease in the level of pro-caspase-8 protein. In addition, immunohistochemical analyses showed that MT1-MMP and FasL co-localize with TUNEL-positive apoptotic granulosa cells within atretic follicles of PCOS ovaries. Our results suggest that under the PCOS-like conditions induced by DHEA, the Fas/FasL/Caspase-8 (death receptor dependent) pathway is pivotal for follicular atresia, and that increased levels of MT1-MMP likely play an important role in tissue remodeling during structural luteolysis.

Persistent estrus rat models of polycystic ovary disease: an update

To critically review published articles on polycystic ovary (PCO) disease in rat models, with a focus on delineating its pathophysiology. Review of the English-language literature published from 1966 to March 2005 was performed through PubMed search. Keywords or phrases used were persistent estrus, chronic anovulation, polycystic ovary, polycystic ovary disease, and polycystic ovary syndrome. Articles were also located via bibliographies of published literature. University Health Sciences Center. Articles on persistent estrus and PCO in rats were selected and reviewed regarding the methods for induction of PCO disease. Changes in the reproductive cycle, ovarian morphology, hormonal parameters, and factors associated with the development of PCO disease in rat models were analyzed. Principal methods for inducing PCO in the rat include exposure to constant light, anterior hypothalamic and amygdaloidal lesions, and the use of androgens, estrogens, antiprogestin, and mifepristone. The validated rat PCO models provide useful information on morphologic and hormonal disturbances in the pathogenesis of chronic anovulation in this condition. These studies have aimed to replicate the morphologic and hormonal characteristics observed in the human PCO syndrome. The implications of these studies to human condition are discussed.

Effect of anti-NGF on ovarian expression of α1- and β2-adrenoceptors, TrkA, p75NTR, and tyrosine hydroxylase in rats with steroid-induced polycystic ovaries

Estradiol valerate (EV)-induced polycystic ovaries (PCO) in rats are associated with higher ovarian release and content of norepinephrine, decreased beta2-adrenoceptors (ARs), and dysregulated expression of alpha1-AR subtypes, all preceded by an increase in the production of ovarian NGF. The aim of this study was to further elucidate the role of NGF in the ovaries by blocking the action of NGF during development of EV-induced PCO in rats. Control and EV-injected rats were treated with intraperitoneal injections of IgG (control and PCO groups) or with anti-NGF antibodies (anti-NGF and PCO anti-NGF groups) every third day for 5 wk starting from the day of PCO induction. Rat weight, estrous cyclicity, ovarian morphology, ovarian mRNA, and protein expression of alpha1-AR subtypes, beta2-AR, the NGF receptor tyrosine kinase A (TrkA), p75 neurotrophin receptor (p75NTR), and tyrosine hydroxylase (TH) were analyzed. Ovaries in both PCO and PCO anti-NGF groups decreased in size as well as in number and size of corpora lutea. mRNA expression of alpha1a-AR and TrkA in the ovaries was lower, whereas expression of alpha1b- and alpha1d-AR and TH was higher, in the PCO group than in controls. Protein quantities of alpha1-ARs, TrkA, p75NTR, and TH were higher in the PCO group compared with controls, whereas the protein content of beta2-AR was lower. Anti-NGF treatment in the PCO group restored all changes in mRNA and protein content, except that of alpha1b-AR and TrkA mRNAs, to control levels. The results indicate that the NGF/NGF receptor system plays a role in the pathogenesis of EV-induced PCO in rats.

Ovarian expression of alpha (1)- and beta (2)-adrenoceptors and p75 neurotrophin receptors in rats with steroid-induced polycystic ovaries

Polycystic ovary syndrome (PCOS) is the main cause of infertility in women. Despite extensive research aimed at identifying the pathogenetic mechanism underlying this condition, the aetiology of the disease is still unknown. Evidence from studies on women with PCOS and on an experimental rat polycystic ovary (PCO) model suggests that the sympathetic regulatory drive to the ovary may be unbalanced. The present study was designed to investigate this hypothesis. Accordingly, we used the well-defined rat PCO model, where PCO is induced by a single intramuscular (i.m.) injection of estradiol valerate (EV), and compared the model with oil-injected controls. We studied the ovarian expression of the α 1- and β 2-adrenoceptors (ARs), the neurotrophin receptor p75 (p75 NTR), and the sympathetic marker tyrosine hydroxylase (TH) at two time points: 30 and 60 days after EV injection. Our data demonstrate for the first time that all of the α 1-AR subtypes are expressed in normal rat ovaries at both the mRNA and the protein levels. Furthermore, the expression of the α 1-AR subtypes was differentially modulated in a time- and subtype-dependent manner in rats with EV-induced PCO. The ovaries in rats with steroid-induced PCO are characterised by an early overexpression of these molecules and p75 NTR, while the β 2-AR was downregulated. An increase in the expression of ovarian TH after EV injection was also detected, suggesting a structural and functional remodelling of ovarian sympathetic innervation in PCO rats. Our evidence strongly indicates that the role of the sympathetic nervous system is crucial in the pathogenesis of EV-induced PCO. Overall, our findings suggest that therapeutical approaches aimed at down-regulating the sympathetic tone to the ovary could be useful in the prevention and clinical treatment of PCOS.

Occasional transsynaptic viral labeling in the central nervous system from the polycystic ovary induced by estradiol valerate

Increased density of catecholaminergic nerves in the human polycystic ovary has been observed. The aim of the present study was to investigate the distribution of transsynaptically virus-labeled neurons in the central nervous system from the rat polycystic ovary to see whether is it different or not from that of cycling control rats. To induce a polycystic ovary, a single injection of estradiol valerate was given to adult female rats and 30 days later a neurotropic virus was injected into the right ovary. Rats were sacrificed 72 or 96 hours after viral infection. Weight of the ovaries of the estradiol valerate-treated rats was significantly lower compared to controls, and the histology of the ovaries of the treated rats displayed severely atretic large antral follicles. There was almost no viral labeling in the central nervous system from the ovaries showing precystic morphology, in spite of the fact that such altered organs are rich in nerve fibres. It is assumed that presently unidentified factors in the precystic ovary, presumably related to the link between the immune and the nervous system, might be involved in the infectivity of the virus, and thus be responsible for the lack of viral labeling from such an ovary.

The effect of herbal medicine on nerve growth factor in estradiol valerate-induced polycystic ovaries in rats.

A type of polycystic ovary resembling some aspects of human polycystic ovarian syndrome (PCOS) can be induced in the rat with a single injection of long-acting estradiol valerate. Among several theories behind the development of polycystic ovaries (PCO), the involvement of the sympathetic nervous system draws much attention, and herbal medicine is known to relieve the abnormal symptoms of PCO. Two herbal formulas, Changbudodam-Tang (cang fu dao tan tang) and Yongdamsagan-Tang (long dan xie gan tang), were used in the present study. The administration of herbal medicine was done every other day for 60 days. The morphological changes of ovaries from herbal medicine treatment were compared to those from an oil-treated control group and an estradiol valerate-injected group. This study also examined the possible hypothesis of neurogenic participation in terms of nerve growth factor (NGF) in the pathology of ovarian dysfunction. The nerve growth factor was analyzed in the central nervous system and ovaries by immunohistochemistry. The main findings of the present study were: (1) PCO were fully developed in rats with a single intramuscular injection of estradiol valerate, (2) PCO resulted in the expression of NGF in the ovaries and the brain tissues, and (3) herbal medicine administration significantly decreased the elevated NGF staining in the ovaries without affecting the brain tissues significantly.

Lysyl oxidase and MMP-2 expression in dehydroepiandrosterone-induced polycystic ovary in rats.

Polycystic ovary syndrome (PCOS) is characterized by cystogenesis; however, the cause of this cystogenesis is unknown. At ovulation, preovulatory collagenolytic activities in the ovarian follicles increase and various proteinases are needed to degrade the tissues surrounding the follicles. To clarify the roles of enzymes in collagen degradation of the follicular wall of polycystic ovary (PCO) in relation to the cystogenesis, we examined expression of lysyl oxidase (LOX), which initiates cross-link formation of the collagen and elastin in the extracellular matrix, and expression of matrix metalloproteinases (MMPs) in ovaries of model rats with PCO induced by dehydroepiandrosterone (DHEA) compared with MMP expression in control rats. DHEA treatment increased LOX mRNA expression to more than three times the control value (P: < 0.01). MMP-2 mRNA expression in control rats was threefold greater than that in the DHEA-induced group (P: < 0.05). Expression of both latent and active forms of MMP-2 in controls was more than twice that in the DHEA-induced group (P: < 0.05) as shown by Western blotting, and expression of the active form of MMP-2 was also twice as high in the controls as in the DHEA-treated group (P: < 0.05) as shown by zymography. Our results suggest that depression of MMP-2 activity and increased LOX expression may be one of the causes of the cystogenesis of PCO.

Stress promotes development of ovarian cysts in rats: the possible role of sympathetic nerve activation.

Activation of the sympathetic innervation precedes the induction of polycystic ovaries in rats given estradiol valerate (EV). The mechanism of induction by EV may thus involve both direct and neurogenic components. We tested this hypothesis using a combined cold and restraint stress to induce an increase in sympathetic tone, including that of the ovarian sympathetic nerves. Three weeks after the start of stress we found: 1. An increase in the content of norepinephrine (NE) in the celiac ganglion. 2. An increase in the release of NE from the ovary. 3. An unchanged NE uptake by the ovary. 4. An unchanged content of NE in the ovary. The ovarian content of neuropeptide Y (NPY) (colocalized with NE) was significantly decreased. These results suggest that NE synthesis and its secretion are increased during this period and correlate with the increase in secretion of androgens and estradiol, the development of precystic follicles, and a decrease in the ovulatory rate. After 11 wk, NE release had returned to control values, whereas the ovarian NE content had risen significantly, suggesting a maintained high rate of NE synthesis. In the ovary, NPY contents, steroid secretion, morphology, and ovulation had returned to the control state. These results suggest the participation of an extraovarian factor that might act locally to control the release of NE from the ovary, and further support the hypothesis that increased sympathetic activity plays a role in the development and maintenance of ovarian cysts.

Hormonal modulation of the vaginal bacterial flora in experimental polycystic ovarian disease

Rats exposed to constant light develop polycystic ovarian (PCO) disease with persistent estrus, representing an estrogen-dominant condition. Herein, we report that fluctuations seen in the vaginal microflora in cyclic rats were not observed in PCO rats with persistent estrus. The vaginal-cervical mucosa of PCO rats showed numerous adherent bacteria by scanning electron microscopy, similar to that seen in proestrus and estrus rats, but unlike the diestrus rats in which fewer organisms adhered to the mucosa. Administration of human chorionic gonadotropin induced ovulation in PCO rats, which was associated with a significant decrease in serum estradiol, an increase in progesterone, and a significant decrease in the estradiol/progesterone ratio compared with baseline values (P < 0.01). This also resulted in an influx of leukocytes in the vagina with a significant decrease in vaginal anaerobic as well as aerobic bacterial flora. These data demonstrate that loss of cyclic ovarian activity in PCO rats with persistent estrus causes increased bacterial colonization of the vaginal-cervical mucosa, and the ovarian hormones appear to modulate the colonization of bacteria in the lower genital tract.

Pituitary gonadotropin-releasing hormone receptor content in rats with polycystic ovaries.

A single injection of estradiol valerate (EV) induces, after a lag period of 4-6 wk, a chronic anovulatory polycystic ovarian (PCO) condition in adult rats. This condition is associated with a selective compromise of luteinizing hormone (LH) release and/or synthesis reflected in low basal serum LH concentrations, decreased pituitary content of LH, and decreased gonadotropin-releasing hormone (GnRH)-stimulated LH secretion. The present study was undertaken to determine to what extent the aberrant LH release in rats with PCO could be related to alterations in pituitary content of GnRH receptors. Pituitary GnRH-receptor content was assessed by the evaluation of saturation binding of a GnRH analog, [125I]-D-Ala6-des-Gly10-GnRH, to pituitary membrane preparations. The receptor content of pituitaries from rats with PCO was compared to that obtained from intact animals at estrus and diestrus. Receptor levels in ovariectomized normal rats and rats with PCO were also assessed. The pituitary GnRH receptor content in PCO rats was similar to that observed in normal controls at estrus and was significantly lower than that for rats at diestrus. Although a twofold increase in pituitary GnRH receptor content was observed at 28 days following the castration of control rats, GnRH receptor content in the pituitaries of PCO rats, at 28 days following ovariectomy, remained unchanged. Although, castration-induced elevations in mean serum LH and follicle-stimulating hormone (FSH) concentrations were observed in both the PCO and control animals, the rise in both gonadotropins was significantly attenuated in the PCO-castrates when compared to the ovariectomized controls. Since GnRH is a major factor in the regulation of pituitary GnRH receptor content, these findings suggest that hypothalamic GnRH release is impaired in rats with PCO and that this impairment is independent of any influences from the polycystic ovaries.

Enhanced ovarian gonadotropin receptors in the testosterone-induced polycystic ovary in rats.

To establish the role of hormone receptors in patients with polycystic ovary (PCO), PCO rats were prepared by treating with testosterone propionate (TP). Five-day old immature female rats were subcutaneously injected with 1.25 mg TP in sesame oil. They were then killed at the age of 12 weeks. The ovarian receptors for LH and FSH as well as serum hormone levels were investigated in PCO rats and also in control rats at the various stages of the estrous cycle. The LH receptor binding in the TP-treated ovaries was elevated almost as high as that of proestrus control, and was observed to be higher than the other control. The FSH receptor binding of PCO rats was elevated to 173% of that of diestrus control, which showed the highest value throughout the cycle. Thus, the gonadotropin receptors in PCO rats appeared to be in an activated state. High levels of the receptor binding were due to an increase in receptor binding sites. Serum LH level was significantly higher than that of diestrus control but still remained lower than that of proestrus control. In contrast, FSH level was as low as that of diestrus control. Prolactin level was markedly elevated and 17- and 2-fold higher than that of diestrus and proestrus control, respectively. Estradiol level was higher than that of diestrus control, increasing to almost the same level during proestrus control. While progesterone level was largely depressed to 23 and 13% of that of diestrus and proestrus control, respectively, testosterone level was almost the same as that of diestrus control. From these results, it was suggested that tonic secretion of LH, low level of FSH, and markedly high levels of prolactin would increase the gonadotropin receptors and result in extremely low production of progesterone in rat ovaries. Clinically, elevated levels of the LH and FSH receptors may be a relevant occurrence in PCO patients.