Destruction Of Ovarian Follicles Research Articles

Exposure to environmentally relevant concentrations of ambient fine particulate matter (PM2.5) depletes the ovarian follicle reserve and causes sex-dependent cardiovascular changes in apolipoprotein E null mice

BackgroundFine particulate matter (PM2.5) exposure accelerates atherosclerosis and contains known ovotoxic chemicals. However, effects of exposure to PM2.5 on the finite ovarian follicle pool have hardly been investigated, nor have interactions between ovarian and cardiovascular effects. We hypothesized that subchronic inhalation exposure to human-relevant concentrations of PM2.5 results in destruction of ovarian follicles via apoptosis induction, as well as accelerated recruitment of primordial follicles into the growing pool. Further, we hypothesized that destruction of ovarian follicles enhances the adverse cardiovascular effects of PM2.5 in females.ResultsHyperlipidemic apolipoprotein E (Apoe) null ovary-intact or ovariectomized female mice and testis-intact male mice were exposed to concentrated ambient PM2.5 or filtered air for 12 weeks, 5 days/week for 4 h/day using a versatile aerosol concentration enrichment system. Primordial, primary, and secondary ovarian follicle numbers were decreased by 45%, 40%, and 17%, respectively, in PM2.5-exposed ovary-intact mice compared to controls (P < 0.05). The percentage of primary follicles with granulosa cells positive for the mitosis marker Ki67 was increased in the ovaries from PM2.5-exposed females versus controls (P < 0.05), consistent with increased recruitment of primordial follicles into the growing pool. Exposure to PM2.5 increased the percentages of primary and secondary follicles with DNA damage, assessed by γH2AX immunostaining (P < 0.05). Exposure to PM2.5 increased the percentages of apoptotic antral follicles, determined by TUNEL and activated caspase 3 immunostaining (P < 0.05). Removal of the ovaries and PM2.5-exposure exacerbated the atherosclerotic effects of hyperlipidemia in females (P < 0.05). While there were statistically significant changes in blood pressure and heart rate variability in PM2.5-compared to Air-exposed gonad-intact males and females and ovariectomized females, the changes were not consistent between exposure years and assessment methods.ConclusionsThese results demonstrate that subchronic PM2.5 exposure depletes the ovarian reserve by increasing recruitment of primordial follicles into the growing pool and increasing apoptosis of growing follicles. Further, PM2.5 exposure and removal of the ovaries each increase atherosclerosis progression in Apoe-/- females. Premature loss of ovarian function is associated with increased risk of osteoporosis, cardiovascular disease and Alzheimer’s disease in women. Our results thus support possible links between PM2.5 exposure and other adverse health outcomes in women.

Sphingosine-1-phosphate and its mimetic FTY720 do not protect against radiation-induced ovarian fibrosis in the nonhuman primate†.

Oocytes are highly radiosensitive, so agents that prevent radiation-induced ovarian follicle destruction are important fertility preservation strategies. A previous study in rhesus macaques demonstrated that ovarian treatment with antiapoptotic agents, sphingosine-1-phosphate (S1P) and FTY720, its long-acting mimetic, preserved follicles following a single dose of 15Gy X-ray radiation, and live offspring were obtained from FTY720-treated animals. However, it is unknown whether these antiapoptotic agents also protected the ovarian stroma from late effects of radiation, including vascular damage and fibrosis. Using ovarian histological sections from this study, we evaluated the vasculature and extracellular matrix in the following cohorts: vehicle + sham irradiation, vehicle + irradiation (OXI), S1P+irradiation (S1P), and FTY720+irradiation (FTY720). One ovary from each animal was harvested prior to radiation whereas the contralateral ovary was harvested 10months post-treatment. We assessed vasculature by immunohistochemistry with a PECAM1 antibody, hyaluronan by a hyaluronan binding protein assay, and collagen by picrosirius red and Masson's trichrome staining. Disorganized vessels were observed in the medulla in the OXI and S1P cohorts relative to the sham, but the vasculature in the FTY720 cohort appeared intact, which may partially explain fertoprotection. There were no differences in the hyaluronan matrix among the cohorts, but there was thickening of the tunica albuginea and fibrosis in the OXI cohort relative to the sham, which was not mitigated by either S1P or FTY720 treatment. Thus, the fertoprotective properties of S1P and FTY720 may be limited given their inability to protect the ovarian stroma against the late effects of radiation-induced fibrosis.

Psychosocial stress and ovarian function in adolescent and young adult cancer survivors.

Is psychosocial stress associated with ovarian function in reproductive-aged survivors of cancer diagnosed as adolescents and young adults (AYA survivors)? We observed no association between self-reported and biomarkers of psychosocial stress and ovarian function in AYA survivors. Psychosocial stress suppresses hypothalamic-pituitary-ovarian axis, resulting in ovulatory dysfunction, decreased sex steroidogenesis and lower fertility in reproductive-aged women. Many cancer survivors experience high psychosocial stress and hypothalamic-pituitary-adrenal axis dysregulation. The menstrual pattern disturbances and infertility they experience have been attributed to ovarian follicle destruction, but the contribution of psychosocial stress to these phenotypes is unknown. A cross-sectional study was conducted estimating the association between perceived stress, measured by self-report and saliva cortisol, and ovarian function, measured by bleeding pattern, dried blood spot (DBS) FSH and LH, and saliva estradiol. We included 377 AYA survivor participants. AYA survivor participants were ages 15-35 at cancer diagnosis and ages 18-40 at study enrollment, had completed primary cancer treatment, had a uterus and at least one ovary, did not have uncontrolled endocrinopathy and were not on hormone therapy. Recruited from cancer registries, physician referrals and cancer advocacy groups, participants provided self-reported information on psychosocial stress (Perceived Stress Scale-10 (PSS-10)) and on cancer and reproductive (fertility, contraception, menstrual pattern) characteristics. DBS samples were collected timed to the early follicular phase (cycle Days 3-7) for menstruating individuals and on a random day for amenorrheic individuals; saliva samples were collected three time points within 1 day. FSH and LH were measured by DBS ELISAs, cortisol was measured by ELISA and estradiol was measured by liquid chromatography tandem mass spectrometry. The median age of participants was 34.0 years (range 19-41) at a median of 6.0 years since cancer diagnosis. The most common cancer was breast (32.1%). Median PSS-10 score was 15 (range 0-36), with 5.3% scoring ≥26, the cut point suggestive of severe stress. Cortisol levels followed a diurnal pattern and cortisol AUC was negatively correlated with PSS-10 scores (P = 0.03). Neither PSS-10 scores nor cortisol AUC were associated with FSH, LH, estradiol levels or menstrual pattern. Waking and evening cortisol and the cortisol awakening response also were not related to ovarian function measures. Our analysis is limited by its cross-sectional nature, heterogeneity of cancer diagnosis and treatments and low prevalence of severe stress. The lack of association between psychosocial stress and a variety of ovarian function measures in female AYA cancer survivors suggests that psychosocial stress does not have a significant impact on the reproductive axis of AYA survivors. This finding is important in counseling this population on their menstrual pattern and family building plans. NIH HD080952, South Korea Health Industry Development Institute HI18C1837 (JK). Dr A.D. works for Bluebird Bio, Inc., Dr D.Z. works for ZRT Labs and Dr P.M.S. works for Ansh Labs, which did not sponsor, support or have oversight of this research. Other authors report no competing interests. N/A.

Molecular Mechanisms of Laparoscopic Ovarian Drilling and Its Therapeutic Effects in Polycystic Ovary Syndrome.

Polycystic ovary syndrome (PCOS) is a common endocrinopathy, characterized by chronic anovulation, hyperandrogenism, and multiple small subcapsular cystic follicles in the ovary during ultrasonography, and affects 5–10% of women of reproductive age. PCOS is frequently associated with insulin resistance (IR) accompanied by compensatory hyperinsulinemia and, therefore, presents an increased risk of type 2 diabetes mellitus (DM). The pathophysiology of PCOS is unclear, and many hypotheses have been proposed. Among these hypotheses, IR and hyperandrogenism may be the two key factors. The first line of treatment in PCOS includes lifestyle changes and body weight reduction. Achieving a 5–15% body weight reduction may improve IR and PCOS-associated hormonal abnormalities. For women who desire pregnancy, clomiphene citrate (CC) is the front-line treatment for ovulation induction. Twenty five percent of women may fail to ovulate spontaneously after three cycles of CC treatment, which is called CC-resistant PCOS. For CC-resistant PCOS women, there are many strategies to improve ovulation rate, including medical treatment and surgical approaches. Among the various surgical approaches, one particular surgical method, called laparoscopic ovarian drilling (LOD), has been proposed as an alternative treatment. LOD results in an overall spontaneous ovulation rate of 30–90% and final pregnancy rates of 13–88%. These benefits are more significant for women with CC-resistant PCOS. Although the intra- and post-operative complications and sequelae are always important, we believe that a better understanding of the pathophysiological changes and/or molecular mechanisms after LOD may provide a rationale for this procedure. LOD, mediated mainly by thermal effects, produces a series of morphological and biochemical changes. These changes include the formation of artificial holes in the very thick cortical wall, loosening of the dense and hard cortical wall, destruction of ovarian follicles with a subsequently decreased amount of theca and/or granulosa cells, destruction of ovarian stromal tissue with the subsequent development of transient but purulent and acute inflammatory reactions to initiate the immune response, and the continuing leakage or drainage of “toxic” follicular fluid in these immature and growth-ceased pre-antral follicles. All these factors contribute to decreasing local and systemic androgen levels, the following apoptosis process with these pre-antral follicles to atresia; the re-starting of normal follicular recruitment, development, and maturation, and finally, the normalization of the “hypothalamus–pituitary–ovary” axis and subsequent spontaneous ovulation. The detailed local and systematic changes in PCOS women after LOD are comprehensively reviewed in the current article.

Immune-mediated destruction of ovarian follicles associated with the presence of HSP90 antibodies.

We previously established that the presence of autoantibodies to heat-shock protein 90 (HSP90) is one common causes of female infertility, and demonstrated that its presence leads to detrimental effects on ovarian and reproductive function in mice. The pathophysiological mechanism and alteration in the immune physiology, however, remain unknown. We therefore carried out detailed analysis of various immune cells in the spleen and ovary following immunization of C57BL/6 female mice to generate antibodies to HSP90 in the general circulation. We observed a significant increase in levels of CD45- cells; CD4+ T cells; Ly6G6C+ cells; and CD11b+ Ly6G+ cells in the spleen of these mice, which correlate with the increased anti-HSP90 antibody production. Ovarian- and granulosa-cell populations also showed increased infiltration of CD45+ leukocytes and neutrophil and monocyte populations, which may have led to the observed ovarian follicular degeneration that predominantly manifested as empty follicles. A decrease in the number of functional ovarian follicles was also associated with a decrease in the level of Gdf9 gene expression. Thus, changes in the immune physiology of the spleen and ovary that leads to the generation of antibodies to HSP90 can also bring about the destruction of ovarian follicles.

Does ovarian autoimmunity play a role in the pathophysiology of premature ovarian insufficiency?

Premature Ovarian Failure (POF) is an important cause of amenorrhoea and infertility. However some women may spontaneously ovulate and conceive. Primary ovarian insufficiency (POI) is thus the preferred term. POF / POI is multifactorial in etiology. Autoimmunity is an important mechanism for accelerated destruction of ovarian follicles. The present review focuses on the role of autoimmunity in the pathophysiology of POI. Antibodies to multiple ovarian antigens have been proposed as markers of ovarian autoimmunity. However, there has been lack of clinically proven sensitive and specific serum tests to confirm autoimmune involvement in POI. The review details recently developed specific test for antiovarian antibodies (AOA) that has enabeled identification of different molecular antigenic targets in the ovary. The application of this specific test for AOA has brought to light the need for screening for autoimmunity prior to patients undergoing IVF technique.

Endocrine disrupters and ovarian function

Endocrine disrupting chemicals are synthetic and naturally occurring chemicals that cannot be classified by any unique physical or chemical properties, but are characterized by their effects on the endocrine system. Recognition that environmental toxicants can mimic endogenous hormones and act as endocrine toxicants or “endocrine disrupters” has lead to concern that exposure to these compounds is linked to adverse health effects in humans. Although contemporary epidemiological studies fail to support an association between exposure to endocrine disrupters and infertility or decreased fecundity, quantification of endocrine toxicants in human ovarian follicular fluid, together with observed adverse effects in animals and in vitro studies, supports concerns that exposure to endocrine toxicants has the potential to adversely affect human ovarian function. Indeed, evidence that endocrine disrupting chemicals can bind with the estrogen receptor, change steroidogenic enzyme expression and activity, increase steroid hormone turnover, and induce ovarian follicle destruction supports the conclusion that these compounds are ovarian toxicants.

Gonadotropin regulation of glutathione synthesis in the rat ovary

Glutathione (GSH), an antioxidant and conjugator of electrophilic toxicants, prevents toxicant-mediated destruction of ovarian follicles and oocytes. Ovarian GSH has previously been shown to change with estrous cycle stage in rats, suggesting that the gonadotropin hormones may regulate ovarian GSH synthesis. The present studies tested the hypotheses that [1] estrous cycle-related changes in ovarian GSH result from cyclic changes in protein and mRNA expression of the rate-limiting enzyme in GSH synthesis, glutamate cysteine ligase (GCL, also called γ-glutamylcysteine synthetase), and [2] that these changes result from gonadotropin-mediated regulation of GCL subunit expression. In the first experiment, ovaries were harvested from cycling adult female rats on each stage of the estrous cycle. In the second experiment immature female rats were injected with pregnant mare’s serum gonadotropin (PMSG) to stimulate follicular development or with vehicle and killed 8, 24, or 48 h later. In both experiments the ovaries were harvested for [1] total GSH assay, [2] Western analysis for GCL catalytic (GCLc) and regulatory (GCLm) subunit protein levels, or [3] Northern analysis for Gclc and Gclm mRNA levels. Ovarian GSH concentrations and Gclc and Gclm mRNA levels, but not GCL subunit protein levels, varied significantly with estrous cycle stage. PMSG administration significantly increased ovarian GSH concentrations 24 and 48 h later. GCLm protein levels increased significantly at 24h and 48h following PMSG. GCLc protein levels did not increase significantly following PMSG. Gcl subunit mRNA levels were not significantly increased at any time point by the planned ANOVA; however, an increase in Gclc at 48 h was identified by t-testing. These results support the hypothesis that gonadotropins regulate ovarian GSH synthesis by modulating GCL subunit expression.

Influence of estradiol and progesterone withdrawal on the secretion of and the temporal correlation between pulses of oxytocin and prostaglandin F2(alpha) in ewes.

The primary objective was to examine the effects of estradiol and the progesterone receptor antagonist onapristone on the pulsatile secretion of prostaglandin F(2alpha) (PGF(2alpha)) and ovarian and pituitary oxytocin. A 2 x 2 factorial arrangement of estradiol and onapristone treatments was administered to groups of 5 ewes after destruction of ovarian follicles on Day 8 of the cycle. Estradiol treatments consisted of the administration of a silicone elastomer implant, either containing or not containing estradiol, on Day 8 plus 50 microg of estradiol or corn oil on Days 11 and 12. Onapristone (2 mg/kg) or its vehicle were administered on Day 13, immediately preceding the simultaneous collection of blood samples from the carotid artery, jugular vein, and vena cava at 7.5-min intervals for 7 h. Ewes were immediately killed for measurements of uterine oxytocin receptor concentrations and phosphatidylinositide turnover. More oxytocin pulses were detected in the jugular vein than in the carotid artery (p < 0.01), suggesting that the pituitary is a source of oxytocin. A similar number (p > 0.1) of PGF(2alpha) pulses were correlated with oxytocin pulses as were not. The linked PGF(2alpha) pulses were longer in duration (p = 0.01) with a tendency toward a higher amplitude (p = 0.08). The corresponding vena caval oxytocin pulses had a longer duration (p = 0.02) than those not linked to PGF(2alpha). Estradiol increased oxytocin receptor concentrations and the turnover of phosphatidylinositides (p = 0.02) without affecting PGF(2alpha) pulse characteristics. Onapristone increased (p = 0.03) PGF(2alpha) pulse amplitude. Although a lower than expected temporal correlation between oxytocin and PGF(2alpha) pulses was observed, the distinguishing characteristics of linked pulses may be indicative of their physiological significance.

Effect of ovarian antral follicle cauterization on the interestrus interval of the gilt

The objective of the present study was to determine if destruction of ovarian antral follicles by laser-cauterization affects CL lifespan during the estrous cycle of the gilt. Cyclic gilts were randomly assigned to either SHAM, laser (L) or laser-estradiol (L-E2) treatment groups, with the L-E2 group receiving a 5-mg intramuscular (i.m.) injection of estradiol-17β cypionate at the time of the first surgery. Ovarian antral follicles were laser-cauterized on either Days 12 and 14 (L12) or Days 14 and 17 (L14) of the estrous cycle. In the L12-E2 group, 3 of 4 gilts had extended mean interestrus intervals of more than 22 days compared with 0 of 4, 0 of 6, 0 of 7 and 1 of 5 gilts in the SHAM, L12, L14 and L14-E2 groups, respectively. The L12-E2 gilts had a longer (P<0.05) mean interestrus interval (23.5±1.3 days) than the L12 (20.0±1.1 days), L14 (20.7±1.0 days) and SHAM (20.5±1.3 days). The mean interestrus interval of L14-E2 gilts (21.8±1.2 days) did not differ from those of the L12-E2 group or the L12, L14 and SHAM group gilts. Six additional gilts were injected with 5 mg estradiol cypionate-17β to serve as nonsurgical controls for E2 treatment. Gilts (3 of 3) given an E2 injection on Day 12 had extended mean interestrus interval (26.0±2.6 days), while 2 of 3 gilts injected with E2 on day 14 had extended mean interestrus intervals (27.7±2.1 days). These results indicate that in cyclic gilts destruction of ovarian follicles by laser-cauterization did not affect CL lifespan, and that luteolysis is not dependent on the presence of antral follicles.

Differential Ovotoxicity of 4-Vinylcyclohexene and Its Analog, 4-Phenylcyclohexene

Vinylcyclohexene (VCH) is an industrial byproduct that is known to cause the destruction of ovarian follicles in mice. Its analog, 4-phenylcyclohexene (4PC), is a volatile product from latex-backed carpeting. These studies were undertaken to assess the structure-activity relationships of these compounds and the potential for 4PC to cause ovotoxicity. Female B6C3FI mice were dosed with VCH (6 mmol/kg/day, ip) or 4PC (3 or 6 mmol/kg/day, ip) daily for 30 days. Treatment with VCH caused dramatic reductions in small and growing follicles as compared to those of vehicle controls. No treatment-related ovarian lesions were associated with 4PC administration. Plasma FSH concentrations were unaltered by treatment with either compound. These results indicate that in mice, the substitution of the phenyl for the vinyl group in the 4 position eliminates the ovotoxicity caused by this class of compounds. Presumably, the ability of the vinyl group to form an epoxide (or dihydrodiol) and/or its smaller size accounts for this difference in ovarian toxicity.

Influence of Estradiol on the Secretion of Oxytocin and Prostaglandin F2α during Luteolysis in the Ewe1

Twenty ewes of mixed breeds were randomly assigned in equal numbers to one of four groups in a 2 x 2 factorial design. The factors were x-irradiation to destroy ovarian follicles or sham irradiation and the administration of estradiol-containing or empty (placebo) implants. Surgery for irradiation was performed on Day 8 of the cycle. Blood samples were withdrawn from jugular catheters at 1.5-h intervals from Day 10 to Day 17. Luteolysis was not observed by Day 17 in 4 of 5 placebo-treated ewes after destruction of ovarian follicles. Luteolysis was observed in 4 of 5 ewes of the sham-irradiated, placebo-treated group and in all ewes that received estradiol whether or not ovarian follicles had been destroyed. The longest (p less than 0.07) interval between peaks of 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) was observed in the x-irradiated, placebo-treated group, whereas the administration of estradiol reduced (p less than 0.01) the interval between PGFM peaks. These findings indicate that a short interpulse interval in the secretion of prostaglandin F2 alpha (PGF2 alpha) is associated with luteolysis. It is possible that the reduced interpulse interval was either an effect of estradiol that caused luteolysis or a secondary event resulting from luteolysis. The administration of estradiol decreased (p less than 0.05) the number of episodes of oxytocin secretion during luteolysis and increased (p less than 0.01) the interval between episodes.(ABSTRACT TRUNCATED AT 250 WORDS)

Destruction of bovine ovarian follicles: effects on the pulsatile release of luteinizing hormone and prostaglandin F2 alpha-induced luteal regression.

Destruction of ovarian follicles during diestrus prolongs the lifespan of corpora lutea in cows, but the site(s) of action is unclear. Thus, ovarian follicles were destroyed in 10 beifers (X-IRRAD) on Day 9 postestrus, while 10 additional beifers (SHAM) served as a control group. To investigate changes in luteotropic support resulting from destruction of ovarian follicles, pulses of luteinizing hormone (LH) were characterized on Days 8, 13, and 15 postestrus. To study the interaction between products from ovarian follicles and prostaglandin F2 alpha (PGF2 alpha) in luteolysis, changes in serum concentrations of progesterone were monitored after an injection of saline or PGF2 alpha on Day 14 postestrus. Frequency and amplitude of pulses of LH increased by Day 13 in X-IRRAD beifers. An increase of similar magnitude in amplitude but not frequency of pulses of LH occurred between Day 13 and Day 15 postestrus in SHAM beifers. Exogenous PGF2 alpha was significantly less efficacious in causing luteolysis in X-IRRAD animals. We suggest that increased luteotropic support may be involved in but is not the only cause for lengthening the lifespan of corpora lutea following destruction of ovarian follicles. Additionally, we suggest that regression of bovine corpora lutea involves a synergistic action between products from ovarian follicles and PGF2 alpha.

The effect of destruction of ovarian follicles in pregnant rabbits on the maintenance of pregnancy.

Effects of destruction of follicles (by cauterization or puncture) or ovaries (by resection) on maintenance of pregnancy were examined in pregnant rabbits which received unilateral ovariectomy (ULO) on day 23 of pregnancy.Normal delivery was produced after ULO in 2 of 3 pregnant does. Pregnant does which received ULO aborted completely after destruction of all visible follicles (≥ 1.0 mm in diameter) in residual ovaries by cauterization or puncture. Fewer than 2 corpora lutea or 10 large follicles (≥ 1.5 mm in diameter) in residual ovaries of pregnant does which received ULO could not maintain pregnancy. Resection of more than one-third of the residual ovary also resulted in abortion.Plasma progesterone levels in pregnant does which received ULO decreased after follicular or ovarian destruction. The levels after treatment in does with normal delivery were significantly higher than those in does which aborted. Minimal concen-tration of progesterone for maintenance of pregnancy seemed to be about 5 ng/ml in peripheral plasma on day 23 of pregnancy.

Luteal function in cows following destruction of ovarian follicles at midcycle

Luteal function was studied in the absence of non-ovulatory ovarian follicles to determine if these follicles are involved in luteal regression in cattle. After at least one estrous cycle, cows were assigned randomly to treatment (n=5) or control (n=5). All cows were laparotomized on day 10 postestrus (Estrus = day 0). During laparotomy of treated cows, all visible follicles on both ovaries were destroyed by electrocautery, and follicular growth was prevented by ovarian x-irradiation. In controls, laparotomy and ovarian manipulation were as in treated cows but follicles were not destroyed and ovaries were not irradiated. On day 22 postestrus, ovaries of 4 treated cows contained no visible follicles and concentrations of estradiol-17β in jugular plasma (0.4 ± 0.1 pg/ml) were less (P<0.05) than in controls (3.2 ± 0.4 pg/ml). Daily mean concentrations of LH from surgery to day 22 postestrus in treated cows did not differ from controls. On day 22 postestrus, progesterone in jugular plasma and weights of corpora lutea in treated cows were greater (P<0.05) than in controls. Between days 12 and 18 postestrus, concentrations of estradiol-17β and PGF 2α in utero-ovarian venous plasma of controls increased prior to detectable declines in concentrations of progesterone. Therefore, non-ovulatory ovarian follicles present during mid to late diestrus are necessary for luteal regression in non-pregnant cattle.

Failure of prostaglandin F2 alpha to cause luteal regression in ewes after destruction of ovarian follicles by x-irradiation.

The hypothesis that estradiol-17..beta.. may play a role in prostaglandin F/sub 2/..cap alpha.. (PGF/sub 2/..cap alpha..)-induced luteolysis was tested in ewes following selective destruction of ovarian follicles by x-irradiation. The effects of two injections of (1) 7 mg PGF/sub 2/..cap alpha.., (2) 750 ..mu..g estradiol benzoate (E/sub 2/B) and (3) 7 mg PGF/sub 2/..cap alpha.. + 750 ..mu..g E/sub 2/B were compared in sham and x-irradiated ewes. Treatment of sham-irradiated ewes with PGF/sub 2/..cap alpha.. resulted in luteolysis in all 5 treated ewes, as judged by a fall in the plasma progesterone concentration to non-detectable levels (less than 0.2 ng/ml) by 54 h after the first injection. In contrast, luteolysis was not observed in 4 of 5 x-irradiated ewes following treatment with PGF/sub 2/..cap alpha.., as indicated by plasma progesterone levels greater than 1.60 ng/ml 96 h after the first injection and corpus luteum weights in excess of 535 mg. Luteolysis was observed in the fifth animal of this group, ewe No. 20, in which plasma progesterone fell to non-detectable levels and a corpus luteum of 203 mg was observed at autopsy. The mean plasma estradiol concentration ranged between 4 and 9 pg/ml in sham-irradiated, PGF/sub 2/..cap alpha..-treated ewes, butmore » fell to non-detectable levels before treatment with PGF/sub 2/..cap alpha.. in all x-irradiated ewes except No. 20 in which levels as high as 11.6 pg/ml were observed. A large luteinized, cystic follicle was observed at autopsy in ewe No. 20. These observations suggest that destruction of ovarian follicles to remove the primary source of estradiol reduced the effectiveness of PGF/sub 2/..cap alpha.. as a luteolytic agent.« less

The Regulation of Ovum Implantation in the Rat by Endogenous and Exogenous FSH and Prolactin: Possible Role of Ovarian Follicles1, 2

rat. Serum LH, FSH, and prolactin were measured during the first 8 days (a) of normal pregnancy and (b) lactating pregnancy with “short” and “long” delays in implantation. Of interest was the considerably lower average FSH secretion (506 ng/mI) and high prolactin (PL) (158 ng/ml) during the 8-day experimental period in animals with d.3lay of implantation when compared to the normal pregnant group (FSH = 876 ng/ml; PL = 32 ng/ml). LH concentrations were low throughout the experimental period and there were no significant differences in LH levels among the groups of animals studied. Utilizing highly sensitive methods for the production and detection of short periods of implantational delay, it was demonstrated that FSH and prolactin levels varied inversely with the delay of implantation. Administration of rat FSH (20 �cg NIH-FSH-B-1), rat PL (200 �cg NIH-PL-RP-1), or 20 �cg FSH + 200 ,tg PL on Day 3 of pregnancy to rats with both “short” and “long” delays in implantation confirmed the ability of FSH to stimulate implantation and PL to antagonize the FSH effect. Destruction of ovarian follicles by X-irradiation eliminated the stimulatory activity of FSH in Overcoming implantational delay. The results suggest that (a) FSH is required for induction of itoplantation, (b) the effectiveness of endogenous and exogenous FSH is dependent upon low serum PL concentrations, (c) the activity of FSH is mediated by the ovarian follicles, possibly due to enhanced estrogen secretion.