Acute effects of unilateral sectioning the superior ovarian nerve of rats with unilateral ovariectomy on ovarian hormones (progesterone,testosterone and estradiol) levels vary during the estrous cycle

The present study analyzed the participation of the left and right superior ovarian nerves (SON) in regulating progesterone, testosterone, and estradiol serum levels in unilaterally ovariectomized rats on each day of the estrous cycle. For this purpose, ovarian hormone concentrations in serum were measured in animals with either sham-surgery, unilateral ovariectomy (ULO), unilateral sectioning of the SON, or sectioning of the SON innervation of the in situ ovary in rats with ULO.     

The effects of superior ovarian nerve sectioning on ovulation in the guinea pig

The effects on spontaneous ovulation associated with the unilateral or bilateral sectioning of the superior ovarian nerves (SON) were analyzed in guinea pigs at different time intervals of the estrous cycle. Day 1 of the estrous cycle was defined as the day when the animal presents complete loss of the vaginal membrane (open vagina). Subsequent phases of the cycle were determined by counting the days after Day 1. All animals were autopsied on the fifth day of the estrous cycle after surgery. Sectioning the right, left, or both SONs on day 5 (early luteal phase) resulted in a significant increase in the number of fresh corpora lutea. Ovulation increased significantly when the left SON (L-SON) was sectioned during late follicular phase (day 1) and medium luteal phase (day 8). When surgery was performed on days 1 or 8, neither sectioning the right SON (R-SON) nor sectioning the SON bilaterally had an apparent effect on ovulation rates. Similarly, ovulation rates were not affected when unilateral (right or left) or bilateral sectioning of the SON was performed during late luteal phase two (day 12). Unilateral or bilateral sectioning of the SON performed during the early luteal phase (day 5) was associated with a significant decrease in uterine weight. A comparable effect was observed when the L-SON was sectioned during late follicular phase (day 1), or medium luteal phase (day 8). No effects on uterine weight were observed when unilateral or bilateral sectioning of the SON was performed during late luteal phase. Our results suggest that in the guinea pig the SON modulates ovulation, and that the degree of modulation varies along the estrous cycle. The strongest influence of the SONs on ovulation occurs during early luteal phase, and decrease thereafter, being absent by late luteal phase. In addition, sectioning the left or the right SON caused different responses by the ovaries of adult guinea pigs. This paper discusses the mechanisms by which ovulation increased when the SON was surgically cut.     

Changes in serum and ovarian steroids during reproductive development in the female guinea pig

This study was designed to measure ovarian hormones prior to and during the first estrous cycle in guinea pigs. Blood was obtained from 12 animals throughout the first estrous cycle. Ovaries and peripheral serum were obtained from 25 additional animals at various stages of development prior to and after first ovulation. Estradiol, progesterone, androstenedione, and testosterone were measured in all sera and half of the ovaries. The remaining ovaries were fixed for histology. Serum estradiol was nondetectable until a few days before first ovulation, but was present in the ovary throughout development. Serum progesterone was nondetectable until the day of ovulation, but the luteal phase pattern was similar to that observed in adults. Serum androgens were detectable throughout development, with androstenedione higher than testosterone. The immature ovary contained more testosterone than androstenedione, but this pattern was reversed after ovulation. These results indicate that the immature ovary in the guinea pig contains minimal amounts of estradiol and progesterone, the first estrous cycle is similar to that in adults, and that the pattern of ovarian androgen content changes during the peripubertal period.     

Ipsilateral vagotomy to unilaterally ovariectomized pre-pubertal rats modifies compensatory ovarian responses

The present study evaluates the participation of the vagus nerve in pre-pubertal rats with unilateral ovariectomy on puberty onset, and on progesterone, testosterone and estradiol serum levels, and the compensatory responses of the ovary. Unilateral vagotomy did not modify the onset of puberty in unilaterally ovariectomized rats. Ovulation rates of animals with the left vagus nerve sectioned and the left ovary in-situ was lower than in rats with only unilateral ovariectomy. Sectioning the left vagus to 32-day old rats with the left ovary in-situ resulted in lower compensatory ovarian hypertrophy than in rats with right unilateral ovariectomy. Twenty-eight or 32-day old animals with sectioning of the right vagus nerve and the right ovary in situ showed higher compensatory ovulation. Twenty-eight -day old rats with the right ovary in situ had higher progesterone and testosterone levels than animals of the same age with the left ovary in-situ. Compared to animals with the right ovary in situ, animals treated at 32-days of age, sectioning the ipsi-lateral vagus nerve resulted in higher progesterone levels. Higher progesterone levels were observed in 28- and 32 days old rats with the left ovary in situ and left vagus nerve sectioned. Thirty-two day old animals with the right ovary in situ and right vagus nerve sectioned had higher progesterone levels than rats of the same age with the left ovary in situ and left vagus nerve sectioned. Left vagotomy to 28-day old rats with the left ovary in situ resulted in higher testosterone levels, a reverse response to that observed in animals with sectioning of the right vagus and the right ovary in situ. Thirty-two day old rats with the left ovary in situ and left vagus nerve sectioned showed lower testosterone levels than animals without vagotomy and with the left ovary in situ.     

The acute effects of bilateral ovariectomy or adrenalectomy on progesterone, testosterone and estradiol serum levels depend on the surgical approach and the day of the estrous cycle when they are performed

Bilateral ovariectomy or adrenalectomy are experimental tools used to understand the mechanisms regulating the hypothalamus-pituitary-ovarian and the hypothalamus-pituitary-adrenal axis. There is evidence that acute unilateral perforation of the dorsal peritoneum in rats results in significant changes in progesterone, testosterone and estradiol serum concentrations. Because different surgical approaches for unilateral or bilateral ovariectomy or adrenalectomy, sectioning the superior ovarian nerve or the vagus nerve are used, we compare the acute effects on hormone serum concentrations resulting from the unilateral or bilateral dorsal approach to performing bilateral ovariectomy or adrenalectomy with those obtained when an unilateral incision is performed in the ventral abdomen. In general, the progesterone, testosterone and estradiol serum concentrations were higher in animals with ventral approach than in those with dorsal surgery, the effects varying depending on the day of the estrous cycle when surgery was performed. The results suggest that the neural signals arising from different zones of the peritoneum and/or the abdominal wall play different roles in the mechanisms regulating steroid hormones concentrations.     

Pituitary and ovarian responses to luteinizing hormone releasing hormone in a rat with polycystic ovaries

Female rats injected with a single dose of 2 mg estradiol valerate (EV) develop anovulatory acyclicity characterized by persistent vaginal cornification and the formation of multiple large cystic follicles on the ovaries. In order to determine if these effects of EV are accompanied by changes in ovarian and/or pituitary function, the following studies were conducted. Ovarian androgen production was determined by the measurement at 4, 5 and 6 weeks after EV treatment of circulating dehydroepiandrosterone, androstenedione and testosterone. The capacity of the polycystic ovary to ovulate in response to luteinizing hormone releasing hormone (LHRH) stimulus was assessed. Ovarian histology was examined at the termination of the study (9 weeks after EV treatment). Pituitary function was assessed 9 weeks after the EV treatment by examining the acute changes in plasma luteinizing hormone (LH) concentration in response to a double pulse of LHRH. Plasma concentrations of the androgens were unchanged over the 3-week sampling period and were similar to those found in sesame-oil-treated normal cycling control rats. The ovaries from EV-treated animals were smaller than those of controls and the cystic follicles exhibited marked thecal hypertrophy and attenuation of the granulosa cell layer. The basal plasma LH concentration at 9 weeks after EV treatment were significantly lower than in proestrus controls and plasma concentrations of LH elicited by LHRH pulses was significantly lower than in controls. The relative increase in plasma LH following the LHRH stimulus was, however, greater in the EV-treated animals than in controls. In spite of the diminished LH surge elicited in response to LHRH, the EV-treated animals ovulated as indicated by the presence of fresh corpora lutea on the ovaries. These results indicate that androgens are not responsible for the polycystic ovarian condition in this system and that the polycystic ovary is capable of ovulatory function when appropriately stimulated.     

ALG2 inhibits the epithelial-to-mesenchymal transition and stemness of ovarian granulosa cells through the Wnt/β-catenin signaling pathway in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is an endocrine disorder that affects fertility in women of reproductive age, and a leading cause of anovulatory infertility. Ovarian granulosa cells are a major functional cell type in the ovary that undergo epithelial-to-mesenchymal transition (EMT) to initiate ovulation. Protein glycosylation, catalyzed by specific glycosyltransferases, has been implicated in reproductive events, such as embryo implantation, endometrial receptivity, and decidualization, etc. However, the relationship between glycosylation and EMT-mediated ovulation in PCOS is not well understood. To clarify the role of cobalt chloride (CoCl₂) and α-1,3/1,6-mannosyltransferase (ALG2) in PCOS, transwell assay, Real-time PCR, Western blot, immunofluorescence, and sphere formation assay were applied to assess cell migration, invasion, EMT, and stemness of ovarian granulosa cells. Enzyme-linked immunosorbent assay (ELISA) was performed to measure the serum level of ALG2 in PCOS patients. We found that CoCl₂ promoted the migration, invasion, EMT, and stemness of ovarian granulosa cells by downregulating the expression of ALG2. Upregulation of ALG2 rescued the effects of CoCl₂ partially, and inhibited the EMT and stemness of ovarian granulosa cells by inactivating the Wnt/β-catenin signaling pathway. Moreover, the serum level of ALG2 was increased in patients with PCOS. Elevated ALG2, in combination with testosterone, represented better diagnostic value for PCOS as a multimarker than ALG2 or testosterone alone as a single marker. Thus, ALG2, downregulated by CoCl₂, was increased in PCOS patients which inhibited the EMT and stemness of ovarian granulosa cells by deactivating the Wnt/β-catenin signaling pathway. The combination of ALG2 and testosterone might thus act as a novel but promising biomarker for PCOS detection.     

A neuroimmune regulation at peripheral level on the steroidogenesis of polycystic ovary in rats.

It is known that noradrenergic sympathetic nerve fibers connect the ovary and the spleen from the celiac ganglion. The modulation of the ovarian steroidogenesis in rats with polycystic ovary (PCO) by secretions of culture splenocytes from control (non PCO), PCO and PCO rats with superior ovarian nerve transection (PCO+SON-t) is investigated. Splenocytes from PCO rats increased progesterone (P) and decreasing estradiol (E) and androstenedione (A) release, a steroidogenic response different from that obtained with splenocytes of control rats. PCO also decreased the number of splenocyte beta-adrenergic receptors (betaR). SON transection reverted the effect of PCO on splenocytes betaR numbers and secretions of these splenocytes also reverted the stimulatory effect of PCO on P release, while norepinephrine (NE) treatment to PCO+SON-t splenocytes decreased their betaR number and their secretions restored the stimulation on progesterone release. Inversely, PCO+SON-t splenocyte secretions intensified the inhibition in estradiol with no effect on A. Treatment of PCO+SON-t splenocytes with NE or neuropeptide Y partially reverted the effects of PCO and SON-t The P and E-A response of PCO ovary might be differentially regulated by the splenocyte secretions through the neural connection involving ovary, SON, celiac ganglion and spleen and the neurotransmitter NE.     

Effects of acute unilateral ovariectomy to pre-pubertal rats on steroid hormones secretion and compensatory ovarian responses

In the present study we analyzed the existence of asymmetry in the secretion of steroid hormones in pre-pubertal female rats treated with unilateral ovariectomy (ULO) or unilateral perforation of the abdominal wall (sham-surgery). Treated rats were sacrificed at different times after surgery. Since sham-surgery had an apparent effect on the age of first vaginal estrous (FVE) and serum levels hormone, the results of the sham surgery groups were used to assess the effects of their respective surgery treatment groups. On the day of FVE, compensatory ovulation (CO) and compensatory ovarian hypertrophy (COH) were similar in animals with ULO, regardless of the ovary remaining in situ. In ULO treated animals, progesterone (P4) levels were higher than in animals with sham-surgery one hour after treatment but lower in rats sacrificed at FEV. Left-ULO resulted in lower testosterone (T) concentration 48 and 72 hours after surgery. In rats with Right-ULO lower T concentrations were observed in rats sacrificed one or 72 hours after surgery, and at FVE. ULO (left or right) resulted in lower estradiol (E2) concentrations one or 72 hours after treatment. In rats with Left-ULO, E2 levels were higher 48 hours after surgery and at FVE. Left-ULO resulted in higher levels of follicle stimulating hormone (FSH) five hours after surgery and at FVE. FSH levels were higher in rats with Right-ULO sacrificed on FVE. The present results suggest that in the pre-pubertal rat both ovaries have similar capacities to secrete P4, and that the right ovary has a higher capacity to secrete E2. Taken together, the present results support the idea that the effects of ULO result from the decrease in glandular tissue and changes in the neural information arising from the ovary.     

Unilateral ovariectomy restores ovulatory cyclicity in rats with a polycystic ovarian condition

An acyclic polycystic ovarian condition can be induced in adult rats with a single injection of estradiol valerate (EV). The ovaries are small and contain multiple cystic follicles and no new corpora lutea. In the early stages of the condition, both basal plasma luteinizing hormone (LH) and LH responses to luteinizing hormone-releasing hormone (LHRH) are attenuated. Plasma androgens are indistinguishable from normal controls. The present study examines the effect of unilateral ovariectomy (ULO) on this condition. Removal of one cystic ovary results in almost immediate resumption of vaginal cyclicity that persists for at least 3 wk. At 1 or 3 wk after ULO the remaining ovary contains fresh corpora lutea, appears histologically normal, and is significantly heavier than the cystic ovary removed at ULO, indicative of compensatory hypertrophy. Despite the resumption of apparently normal cyclic function, basal plasma LH concentrations and LH responses to LHRH are not significantly better than those in intact animals with polycystic ovaries. Thus, the previously polycystic ovary is fully capable of normal ovulatory function despite obvious impairments in the hypothalamo-pituitary axis. Since ovulatory function resumes on a background of continued poor pituitary responsiveness, the primary defect, which ULO corrects, is probably at the hypothalamic level. Finally, the cystic ovary clearly contributes to the hypothalamic aberration to which it subsequently responds.     

Neonatal exposure to estradiol valerate programs ovarian sympathetic innervation and follicular development in the adult rat

A single injection of estradiol valerate (EV) to 14-day-old rats (when the ovarian follicle population has been already established) disrupts cyclicity, increases the activity of key enzymes of androgen biosynthesis, and develops polycystic ovary by a causally related increase in ovarian noradrenaline (NA). The current study examined an early window of ovarian development to look for a specific stage of development at which estradiol can induce such changes in sympathetic activity and follicular development. A single dose of EV applied to rats before the first 12 h of life rapidly increases (after 24 h) the ovarian expression of nerve growth factor (Ngfb) and p75 low-affinity neurotrophic receptor (Ngfr) mRNAs. When adults, rats presented early vaginal opening, disrupted cyclicity, appearance of follicular cyst, absence of corpus luteum, and infertility. Total follicles decreased, mainly due to a reduced number of primordial follicles, suggesting that estradiol acts in the first stages of folliculogenesis, when primordial follicles are organizing. These changes paralleled a 6-fold increase in NA concentration. No changes in NA content were found in the celiac ganglia, suggesting a local, non-centrally mediated effect of estradiol. Surgical section of the superior ovarian nerve (the main source of sympathetic nerves to the ovary) to rats neonatally treated with EV decreased intraovarian NA, delayed vaginal opening, and blocked the development of follicular cyst and that of preovulatory follicles. Therefore, we can conclude that early exposure to estradiol permanently modifies ovarian sympathetic activity and causes profound changes in follicular development, leading to the polycystic ovary condition.     

Inequality in function of the right and left ovaries and uterine horns of the mouse

Inequality in function of the left and right ovaries and uterine horns of mice was evaluated in three separate experiments. In Exp. 1, the effect of position in the reproductive tract on various reproductive characteristics was evaluated in 158 pregnant hybrid mice. Ovulation rate, number of fetuses, total fetal weight and total placental weight were higher (P less than 0.05) on the right than the left on Day 18 of pregnancy (vaginal plug = Day 1). In Exp. 2, the effect of previous sham or unilateral ovariectomy (right or left) in mated Swiss-Webster mice was compared with unoperated mated controls (N = 17-24/treatment). In control mice, ovulation rate, total fetal weight and ovarian weight were higher (P less than 0.05) on the right than left side. Surgery (sham or unilateral, ovariectomy) decreased (P less than 0.005) ovulation rates, number of fetuses, ovarian weights, total fetal weight and total placental weight on Day 18 of pregnancy. Unilateral ovariectomy decreased (P less than 0.05) ovulation rates and ovarian weights more than did sham operation. Ovulation rates were higher (P less than 0.01) when the left ovary was manipulated or removed rather than the right ovary. For Exp. 3, pairs of 8 hybrid mouse embryos each (morulae and blastocysts) were surgically transferred to the left and right uterine horns of the same (bilateral, N = 15) or different (unilateral, N = 28) Swiss-Webster recipients. In almost all incidences, embryo survival (to Day 18 of pregnancy) was twice as high (P less than 0.05) in right than left uterine horns. We conclude that the left and right ovaries and uterine horns are not equal in function in Swiss-Webster and a hybrid strain of mice.     

Dehydroepiandrosterone stimulates inflammation and impairs ovarian functions of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is one of the most common causes of infertility in child-bearing-age women. It is characterized by ovulation dysfunction, polycystic ovaries, and hyperandrogenism. Inflammation is likely to be a crucial contributor to the pathogenesis of PCOS. However, the association between the inflammatory cytokines and the development of PCOS has not been reported. To explore the relationship between the inflammatory cytokines and PCOS, alterations of serum proteins in dehydroepiandrosterone (DHEA)-induced PCOS rats were screened by protein array, and the concentration of IFN-γ was further measured by using enzyme-linked immunosorbent assay (ELISA). DHEA-induced PCOS rats had a decreased level of IFN-γ compared with the control rats, which was restored partly in flutamide (an androgen receptor antagonist)-treated rats. Moreover, the level of IFN-γ in serum of patients with PCOS was also lower than that in healthy women. Using the ovarian granulosa cells (KGN), we demonstrated that DHEA downregulated the expression and secretion of IFN-γ in dose- and time-dependent manners, which could be restored to some extent by treating with flutamide. Furthermore, flutamide ameliorated the inhibitory effect on cell proliferation and promotive effect on cell apoptosis by DHEA. The results also revealed that IFN-γ promoted the proliferation but inhibited the apoptosis of KGN cells, which was suppressed by DHEA via activating the downstream PI3K/AKT signaling pathway. Taken together, these results showed that DHEA inhibited the proliferation and promoted the apoptosis of ovarian granulosa cells through downregulating the expression of IFN-γ which could be restored by flutamide, and IFN-γ may serve as a potential inflammatory biomarker for PCOS detection.     

Hormone secretion by euthyroid and hypothyroid rat ovaries during the early stages of hCG-induced ovarian cyst development

This study was undertaken to examine ovarian steroid production during the early stages of hCG-induced ovarian cyst formation in the hypothyroid rat. Rats were placed into two groups with one group made hypothyroid by adding thiouracil to their diet. After 10 days, each group was divided into two subgroups with one subgroup receiving daily injections of hCG for 2 days and the other subgroup receiving saline. On the morning of Day 13, ovaries were removed and incubated for 2 hr. No significant difference in progesterone secretion was observed. However, ovaries from hypothyroid, hCG-treated rats secreted significantly more testosterone and estradiol than ovaries from vehicle-treated, hypothyroid rats and euthyroid, hCG-treated rats. In a second experiment, ovaries from euthyroid and hypothyroid rats treated with hCG were incubated in medium supplemented with 100 nM androstenedione and 0 or 100 ng FSH/ml. FSH failed to affect progesterone, testosterone, and estradiol secretions by ovaries from euthyroid, hCG-treated rats. In contrast, FSH significantly enhanced testosterone and estradiol secretion by ovaries from hypothyroid, hCG-treated rats. These results support the hypothesis that increased levels of testosterone and estradiol secretion have a central role in the induction of polycystic ovaries by hCG in the hypothyroid rat.     

经阴道卵巢打孔术治疗克罗米酚耐药性多囊卵巢综合征

目的：研究超声引导下经阴遣卵巢打孔术（TOD）治疗克罗米酚（CC）耐药性多囊卵巢综合征（PCOS）不孕患者的排卵和妊娠情况。方法：2003年12月至2005年06月就诊的CC耐药PCOS患者,阴道超声介导下经阴道卵巢打孔。术后常规用CC＋补佳乐促排卵方案,观察排卵率和妊娠情况,并随访1年内妊娠情况。结果：38例患者采用经阴道卵巢打孔术治疗后血清睾酮较初诊时明显下降（p〈0．04）。术后第1周期21人有排卵,排卵率55．26％。另18人仍然无效。第1周期有3例妊娠,1例流产。第1周期后再用促排卵药B超监测有排卵或自然周期BBT双相但未怀孕7例。随访6月内共5例妊娠。结论：对于CC耐药的PCOS患者,采用超声引导下经阴道卵巢打孔技术是继腹腔镜下卵巢打孔术之后一种简便、有效的选择。     

Hormone concentrations in the homogenates of ovarian tissue and blood serum in postmenopausal women not using hormone therapy

Ovaries in postmenopausal women synthesize steroids, mostly androgens. Removal of the ovaries after menopause may be reflected by menopausal symptoms and arterial hypertension observed during postoperative period, along with a significantly increased risk of death due to cardiovascular complications. It is not understood if the clinical consequences of gonad removal at different time points after menopause are similar. The aim of this study was to evaluate ovarian steroidogenesis and consequently to define the role of the ovaries in postmenopausal women depending on the time after menopause. Concentrations of hormones were determined in ovarian homogenates and serum of postmenopausal women. This study included 207 postmenopausal women. They were divided into groups depending on the time after menopause. All participants had laparotomic removal of the ovaries. Concentrations of estradiol, testosterone and androstenedione were measured in ovarian homogenate and serum. The study revealed that ovarian homogenate and serum concentrations of estradiol, testosterone and androstenedione were the highest in women up to 5 years after menopause and since then significantly decreased. This study showed that testosterone, androstenedione and estradiol are synthesized in the postmenopausal ovaries. The peak synthesis of these hormones occurs up to 5 years after menopause and significantly decreases thereafter.     

Magnetic resonance imaging for the study of ovarian follicles in the mouse

Additional tools to analyze follicle development would be highly advantageous because current methods require sacrifice of animals at specific times and time-consuming sectioning of tissues for histologic analysis. Magnetic resonance imaging (MRI) may provide a less involved, faster and more cost-effective method to analyze follicles in whole ovaries. Fixed ovaries were collected at different stages of the estrus cycle and after stimulation with gonadotrophins (24 and 48 h post pregnant mares serum (PMSG), and 10 and 24 h post human chorionic gonadotrophin (hCG)) with or without administration of the contrast agent gadodiamide. The MR images were generated using a vertical-bore, 11.7 Tesla MR system. Analysis of the MR images revealed large antral follicles in fixed ovaries with the oocyte and cumulus mass identifiable within preovulatory follicles. The use of gadodiamide had no impact on the quality of MR images obtained. The fixed ovaries were paraffin embedded, sectioned, and hematoxylin stained. Follicles were counted using the MR images and the histology sections. Preovulatory follicle numbers determined using MR images were comparable to those using histology; however counts of smaller follicles were inconsistent. MRI of gonadotrophin-stimulated ovaries in situ did not reveal discernable ovarian structures. Therefore, MRI is a useful tool for studying whole fixed ovaries leaving the ovary intact for additional analyses or for selection of samples based on morphology. The MRI is also useful for identifying preovulatory follicles, although analysis of smaller follicles is not possible, and thus the potential exists for cyst analysis in mouse models of polycystic ovarian syndrome (PCOS).     

Effects of prolactin on ovarian plasmin generation in the process of ovulation.

The present study was undertaken to assess the effects of prolactin (PRL) on gonadotropin-induced plasmin generation in the in vitro-perfused rabbit ovary. The ovarian plasmin activity was determined by measuring plasmin bound to its major inhibitor, alpha 2-plasmin inhibitor (alpha 2 PI-Plm). In the first experiment, exposure to hCG enhanced ovarian alpha 2 PI-Plm generation from 1.2 +/- 0.3 ng/min/ovary in unstimulated ovaries to 2.9 +/- 0.3 ng within 2 h. The concentration of alpha 2 PI-Plm reached a maximum at 4 h and then declined. A second peak occurred 8 h after hCG administration; however, the ovarian alpha 2 PI-Plm generation without hCG was very low throughout the entire perfusion period. In the subsequent experiment, the addition of PRL(10-10(3) ng/ml) to the perfusate inhibited hCG-induced ovulation in a dose-dependent manner. Exposure to PRL at 10(3) ng/ml significantly (p less than 0.05) inhibited hCG-induced alpha 2 PI-Plm generation in ovaries throughout the entire perfusion period. Furthermore, PRL inhibited hCG-stimulated alpha 2 PI-Plm generation at 4 h after hCG administration in the perfused rabbit ovaries in a dose-dependent manner. In conclusion, PRL directly inhibits hCG-induced ovulation in rabbit ovary, at least in part, by a mechanism depending upon inhibition of the plasmin-generating system in the preovulatory follicles.     

Mating stimulates estradiol production by ovaries of the musk shrew (Suncus murinus).

Asian musk shrews (Suncus murinus) are induced ovulators, but exhibit no cyclic changes in reproductive structures or in sexual behavior. Mating behavior is induced by contact with a male. To determine if mating induces changes in ovarian steroidogenesis, ovaries removed from unmated animals and at 3, 10, 15, and 36 h after mating were cultured for 4 h in the presence or absence of gonadotropins (LH + FSH, 1 microgram/ml). Histological analysis revealed no obvious changes in follicular size or appearance at the end of culture in ovaries cultured at 3 and 10 h post-mating, as compared with ovaries from unmated shrews, and mating did not stimulate any discernable changes in steroid secretion in these two groups. However, at the end of the culture period, ovulation had occurred or was occurring in ovaries from 35% of the animals ovariectomized at 15 h after mating, and corpora lutea (CLs) were present in 39% of ovarian pairs obtained 36 h after mating. At 15 h post-mating, ovaries with ovulations secreted three times more estradiol than did ovaries that showed no evidence of stimulation by mating, but there were no differences in testosterone or progesterone production. In contrast, ovaries isolated 36 h post-mating with CLs secreted dramatically more of all three steroids than ovaries without CLs (23, 13, and 52 times more estradiol, testosterone, and progesterone, respectively). These data are consistent with plasma concentrations of estradiol at the time of ovariectomy, which were twice as high at both 15 and 36 h after mating, in animals whose ovaries showed evidence of ovarian stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)