Effects of luteinizing hormone and indomethacin on blood flow and steroidogenesis in the rabbit ovary

Ovarian, uterine, and luteal vascular perfusions during follicular and luteal phases in the adult cyclic female rabbits with special orientation to their histological detection of hormone receptor

Understanding the does reproductive hemodynamic changes during the estrous cycle is crucial for improving reproductive competence and fertility potential in this species. The objective of this study is to investigate the hemodynamic variations in ovarian (OA) and uterine (UA) arteries, histological and morphometric changes in ovarian and uterine tissues throughout the follicular (FP) and luteal (LP) phases in rabbits and determine estrogen (ER), progesterone (PR) receptors, and vascular endothelial growth factor (VEGF) distributions using immunohistochemistry.

Fourteen adults pluriparous New Zealand rabbits were divided into rabbits at the FP (Day − 1; n = 7) and those at the LP (Day 9; n = 7). Animals were subjected to Doppler, hormonal (estrogen [E2], progesterone [P4], insulin-like growth factor [ILGF], and VEGF), histological, and immunohistochemical analyses. In LP, OA Doppler indices were significantly increased, whereas peak systolic velocity (PSV) was decreased compared with that in FP. UA Doppler indices were significantly decreased in the LP, whereas PSV was increased (P < 0.05). E2 levels were increased in the FP, whereas P4 levels were increased in the LP. The morphometric analysis of uterine tissues during the LP revealed an increase in the mean uterine endometrium length, endometrial connective tissue area percentage (%), endometrial glands number, myometrial area (%) and thickness. Furthermore, ovarian follicles and corpus luteum (CL) displayed strong positive immunoreactivity for ER, PR, and VEGF-A during both phases. The ovarian sections displayed a substantial (P < 0.05) increase in the area % of VEGF-A in the ovarian follicles during FP while in the CL during LP. Conversely, area percentage of VEGF-A immunoreactivity in the uterine luminal and glandular epithelia during the FP and LP revealed no differences. However, the number of VEGF-A–stained blood capillaries revealed an increase during LP than FP. In conclusion, this study demonstrated for the first time the changes in both ovarian and uterine arteries during two different phases of the rabbit cycle in relation to the histo-morphometric analysis and distribution of ER, PR, and VEGF-A, which regulate uterine functions that play a role in reproduction.

Cellular and molecular mechanisms of the preovulatory follicle differenciation and ovulation: What do we know in the mare relative to other species

Terminal follicular differentiation and ovulation are essential steps of reproduction. They are induced by the increase in circulating LH, and lead to the expulsion from the ovary of oocytes ready to be fertilized. This review summarizes our current understanding of cellular and molecular pathways that control ovulation using a broad mammalian literature, with a specific focus to the mare, which is unique in some aspects of ovarian function in some cases. Essential steps and key factors are approached. The first part of this review concerns LH, receptors and signaling, addressing the description of the equine gonadotropin and cloning, signaling pathways that are activated following the binding of LH to its receptors, and implication of transcription factors which better known are CCAAT-enhancer-binding proteins (CEBP) and cAMP response element-binding protein (CREB). The second and major part is devoted to the cellular and molecular actors within follicular cells during preovulatory maturation. We relate to 1) molecules involved in vascular permeability and vasoconstriction, 2) involvement of neuropeptides, such as kisspeptin, neurotrophins and neuronal growth factor, neuropeptide Y (NPY), 3) the modification of steroidogenesis, steroids intrafollicular levels and enzymes activity, 4) the local inflammation, with the increase in prostaglandins synthesis, and implication of leukotrienes, cytokines and glucocorticoids, 5) extracellular matrix remodelling with involvement of proteases, antiproteases and inhibitors, as well as relaxin, and finaly 6) the implication of oxytocine, osteopontin, growth factors and reactive oxygen species. The third part describes our current knowledge on molecular aspect of in vivo cumulus-oocyte-complexe maturation, with a specific focus on signaling pathways, paracrine factors, and intracellular regulations that occur in cumulus cells during expansion, and in the oocyte during nuclear and cytoplasmic meiosis resumption. Our aim was to give an overall and comprehensive map of the regulatory mechanisms that intervene within the preovulatory follicle during differentiation and ovulation.

Stimulation of LH, FSH, and luteal blood flow by GnRH during the luteal phase in mares

A study was performed on the effect of a single dose per mare of 0 (n = 9), 100 (n = 8), or 300 (n = 9) of GnRH on Day 10 (Day 0 = ovulation) on concentrations of LH, FSH, and progesterone (P4) and blood flow to the CL ovary. Hormone concentration and blood flow measurements were performed at hours 0 (hour of treatment), 0.25, 0.5, 1, 2, 3, 4, and 6. Blood flow was assessed by spectral Doppler ultrasonography for resistance to blood flow in an ovarian artery before entry into the CL ovary. The percentage of the CL with color Doppler signals of blood flow was estimated from videotapes of real-time color Doppler imaging by an operator who was unaware of mare identity, hour, or treatment dose. Concentrations of LH and FSH increased (P < 0.05) at hour 0.25 and decreased (P < 0.05) over hours 1 to 6; P4 concentration was not altered by treatment. Blood flow resistance decreased between hours 0 and 1, but the decrease was greater (P < 0.05) for the 100-μg dose than for the 300-μg dose. The percentage of CL with blood flow signals increased (P < 0.05) between hours 0 and 1 with no significant difference between the 100- and 300-μg doses. The results supported the hypothesis that GnRH increases LH concentration, vascular perfusion of the CL ovary, and CL blood flow during the luteal phase; however, P4 concentration was not affected.

Circulating nitric oxide metabolites during luteolysis and the effect of luteinizing hormone on circulating nitric oxide metabolites in heifers

Temporal relationships among circulating concentrations of nitric oxide metabolites (NOM), progesterone (P4), and luteinizing hormone (LH) within the hours of a PGFM pulse were studied during luteolysis in heifers. The peak of a PGFM pulse was designated Hour 0. All of the following increases and decreases were significant. Within a spontaneous PGFM pulse (experiment 1; n = 7), concentrations of P4 and LH decreased between Hours -1 and 0 and increased between Hours 0 and 1; NOM increased between Hours -1 and 2. In experiment 2, PGFM pulses were simulated by intrauterine infusion of PGF2α (PGF group, n = 6), and another group was also treated with acyline to inhibit LH secretion (acyline-PGF group, n = 6). Averaged over the two groups, concentration of P4 decreased between Hours -2 and 0, increased (rebounded) between Hours 0 and 1, and decreased after Hour 2. In the PGF group, concentration of LH decreased between Hours -2 and -0.5 and increased between Hour 0 and Hour 1.5 to a maximum at Hour 1.5; NOM decreased between Hours -2 and -1.5 and increased between Hours 0 and 1.5. In the acyline-PGF group, the effect of hour was not significant for concentrations of LH and NOM. The absence of an increase in NOM concentration when LH was inhibited is a novel finding. The hypotheses were supported that concentrations of LH and NOM are temporally related, and LH has a role in the increase in NOM within the hours of a PGFM pulse.

Expression of Angiopoietin (ANPT)-1, ANPT-2 and their Receptors in Dominant Follicles during Periovulatory Period in GnRH-Treated Cow

Ovarian follicular vasculature is involved in follicular development and ovulation. Angiopoietin (ANPT)-Tie system is important for vascularization of the tissue surrounding the developing follicles and corpus luteum (CL). To determine how the expression of ANPT-1, ANPT-2 and their receptors in the follicles would be associated with the ovulatory process, the present study was conducted to examine mRNA expressions of ANPT-1, ANPT-2 and their receptors during the periovulatory phase in gonadotrophin-releasing hormone (GnRH)-treated cows. The ovaries were collected by transvaginal ovariectomy (n = 5, cows/group) and the follicles (n = 5, one follicle/cow) were classified into following groups: before GnRH administration [before luteinizing hormone (LH) surge]; 3-5 h after GnRH (during LH surge); 10 h after GnRH; 20 h after GnRH; 25 h after GnRH (peri-ovulation); and early CL (days 2-3). The mRNA expression was analysed by quantitative real-time PCR (rotor-gene 3000). Angiopoietin-1 expression rapidly decreased at 3-5 h and kept low level at 10 h after GnRH treatment compared with that before GnRH, and returned to the level before LH surge in the follicles >20 h after GnRH treatment. The levels of ANPT-2 mRNA decreased at 10 and 25 h after treatment compared with other periods. The ratio of ANPT-2/ANPT-1 (an index for destabilization of blood vessels) increased in the follicles at 3-5 h after GnRH treatment only. Both of Tie-1 and Tie-2 receptor expressions decreased in the follicles at 25 h after GnRH treatment. The results of the present study indicated that mRNA expressions of ANPT-1, ANPT-2 and their receptors changed in the bovine follicles during periovulatory period. These results suggest that angiopoietin-Tie system is associated with the initiation of vasculature of follicle that grows towards ovulation.

Changes of mRNA expression of vascular endothelial growth factor, angiopoietins and their receptors during the periovulatory period in eCG/hCG-treated immature female rats

Angiogenic factors can induce the perifollicular capillary network in the theca interna that shows marked changes in and around the preovulatory luteinizing hormone (LH) surge. To get more information on their functional crosstalk, the aim of the present study was to investigate the manner of mRNA expression of vascular endothelial growth factors (VEGFs) 120, 164, angiopoietin (Ang)-1, Ang-2 and their specific receptors during the periovulatory phase. We used an established equine and human chorionic gonadotropins (eCG/hCG)-derived experimental model capable of stimulating naturally occurring follicular maturation, ovulation and corpus luteum (CL) formation. On day 28 postpartum, immature female rats were administrated s.c. with 10 IU of eCG to promote follicular development, followed 48 hr later by i.p. administration of 20 IU of hCG. Ovaries were dissected at 0, 6, 12, 18 and 24 hr after hCG treatment, and were obtained on day 30 in the untreated control. After induction of follicular growth by the eCG treatment, each mRNA expression of VEGF 120, VEGF 164, Neuropilin-1 and Flt-1 significantly increased. The peaks in mRNA expressions of VEGF120 and VEGF164 were both found at 18 hr after hCG treatment. Flk-1 mRNA expression maintained up to 6 hr after hCG treatment, and then decreased at 12, 18 and 24 hr after hCG treatment. Ang-2 mRNA expression increased in the ovaries at 6 and 12 hr after hCG treatment. Tie-2 mRNA expression decreased at 24 hr after the treatment of gonadotropins. Our findings suggest that ovarian vascular formation during the periovulatory period including preovulatory follicles, ovulation and CL formation may develop via crosstalk of the VEGF-Flt-1 and Ang-Tie2 systems.

Adipose Differentiation-Related Protein: A Gonadotropin- and Prostaglandin-Regulated Protein in Primate Periovulatory Follicles1

The midcycle LH surge stimulates a rise in follicular fluid prostaglandin E2 (PGE2), which is necessary for normal ovulation. To examine PGE2-regulated processes in primate follicles, monkey granulosa cells were cultured with hCG alone or with hCG and PGE2, and the resulting total RNA was subjected to microarray analysis. Twenty PGE2-regulated mRNAs were identified, and we selected a lipid droplet protein, adipose differentiation-related protein (ADRP), for further study. To determine whether hCG and PGE2 regulate ADRP expression in vivo, monkeys received gonadotropins to stimulate multiple follicular development. Human chorionic gonadotropin was then administered alone or with the PG synthesis inhibitor celecoxib, and follicular aspirates or whole ovaries were obtained at times that span the 40-h periovulatory interval. Administration of hCG increased granulosa cell ADRP mRNA and protein, with peak levels measured just before the expected time of ovulation. Treatment with hCG and celecoxib decreased granulosa cell ADRP mRNA levels compared with those of animals treated with hCG only. ADRP was detected by immunocytochemistry in many monkey tissues that synthesize prostaglandins but was not consistently expressed by steroidogenic tissues. Granulosa cells of periovulatory follicles immunostained for ADRP after, but not before, hCG administration; ADRP colocalized with large lipid droplets within the granulosa cell cytoplasm. These studies identify ADRP as a novel gonadotropin- and PGE2-regulated protein in the granulosa cells of primate periovulatory follicles. Because ADRP facilitates arachidonic acid uptake in non-ovarian cells, ADRP-associated lipid droplets may enhance arachidonic acid uptake by granulosa cells to provide a precursor for periovulatory prostaglandin production.

Follicular Microvasculature and Angiogenic Factors in the Ovaries of Domestic Animals

The genetic and molecular mechanisms that control the development of capillary blood vessels during follicular development are beginning to be elucidated. Ovarian follicles contain and produce angiogenic factors that may act alone or in concert to regulate the process of thecal angiogenesis. These factors are ultimately controlled by endocrine, paracrine and autocrine regulation. A recent study indicated that vascular endothelial growth factor (VEGF) plays an important role in the process of thecal angiogenesis during follicular development. We are developing a novel technology for the induction of follicular development using the technique of in vivo gene administration. Here, we summarize the recent progress of our research.

Glucocorticoids suppress basal (but not interleukin-1-supported) ovarian phospholipase A2 activity: evidence for glucocorticoid receptor-mediated regulation

Ovulation may constitute a cyclic, inflammatory-like process, wherein the increased expression of interleukin (IL)-1 and the biosynthesis of prostaglandins may be established corollaries. In this communication we hypothesize that glucocorticoids, potent anti-inflammatory principles, may exert an antiovulatory effect by interfering with ovarian IL-1-driven prostaglandin biosynthesis. To test this hypothesis, we examined the effect of treatment with dexamethasone on the activity of ovarian phospholipase A2 (PLA2), the event-limiting enzyme in prostaglandin biosynthesis, and on the gene expression pattern of secretory and cytosolic PLA2 (sPLA2 and cPLA2, respectively). Whole ovarian dispersates from immature rats were cultured under serum-free conditions for 48 h in the absence or presence of dexamethasone. At the conclusion of this culture period, PLA2 activity was determined in cell sonicates and conditioned media. Parallel probing for sPLA2 and cPLA2 transcripts was also undertaken using a solution hybridization/RNAse protection assay. Treatment of whole ovarian dispersates with dexamethasone produced a significant (P < 0.005) decrease in basal cellular and extracellular PLA2 activity to 27 and 40% of controls, respectively. A 5-fold decrease in the basal steady state levels of sPLA2 (but not cPLA2) transcripts was also noted. Co-treatment with dexamethasone produced complete inhibition of IL-1-stimulated cPLA2 transcripts but not of IL-1-supported cellular and extracellular PLA2 activity or sPLA2 transcripts. A glucocorticoid receptor antagonist (RU486), blocked the ability of dexamethasone to inhibit basal sPLA2 transcripts and extracellular PLA2 activity. The inhibitory effect of dexamethasone proved glucocorticoid-specific in that aldosterone and 17beta-estradiol were without effect. Taken together, these observations suggest that dexamethasone is capable of inhibiting basal (but not IL-1-supported) ovarian PLA2 activity, a glucocorticoid receptor-mediated effect due, in part, to a decrease in sPLA2 gene expression. Our findings further suggest that sPLA2 and cPLA2 are differentially regulated and that they may well differ in their relative contribution to ovarian prostaglandin biosynthesis in general and to PLA2 activity in particular. To the extent that IL-1 plays a central role in the ovulatory process, these findings argue against the view that the chronic anovulatory state induced by glucocorticoid excess is due, if only in part, to suppression of ovarian IL-1-dependent PLA2 activity.

Different time-course production of peptidic and nonpeptidic leukotrienes and prostaglandins E2 and F2 alpha in the ovary during ovulation in gonadotropin-primed immature rats

Temporal changes in ovarian leukotrienes (LTs) and prostaglandins (PGs) were examined during ovulation to assess roles they may play in this process. Ovulation was induced in immature rats by injection with human chorionic gonadotropin (hCG; 10 IU, s.c.) 2 days after they had been primed with pregnant mare serum gonadotropin (10 IU, s.c.). The ovaries were extirpated at various intervals after hCG administration and assayed for LTB4, and LTC4/D4/E4, as well as PGE2, and PGF2 alpha. Ovarian concentration of LTB4 increased (P < 0.01) rapidly, reaching a peak at 1 hour after hCG administration, then declined (P < 0.05) by 4 hours and remained low thereafter. In contrast, LTC4/D4/E4 peaked (P < 0.01) between 1 and 2 hours, declined (P < 0.05), and then increased (P < 0.01) to achieve a second, larger peak at 10 hours. Prostaglandin E2 increased (P < 0.01) at 6 hours after hCG and did not decrease from the peak value until (P < 0.01) 14 hours after hCG. Concentrations of PGF2 alpha increased (P < 0.01) at 4 hours after hCG, but decreased (P < 0.01) from the peak by 10 hours. Although LTB4, LTC4/D4/E4, PGE2, and PGF2 alpha all increased during ovulation, the time-course differed. This suggests that each eicosanoid may play a distinct role in the process of follicular rupture.

Ovulation as a tissue remodelling process. Proteolysis and cumulus expansion

Ovulation, recurring every midcycle of the mammalian female and triggered by a surge of luteinizing hormone (LH) released from the pituitary, is an essential prerequisite for fertilization and subsequent embryonic development. Here we shall describe two of the biological components of the ovulatory response, cumulus expansion (frequently denoted as cumulus maturation) and the rupture of follicular wall, both crucial for the release of a fertilizable ovum. The role of a proteolytic cascade and its regulation by eicosanoids will be emphasized in relation to follicle rupture. The new data implicating cumulus maturation as an essential step for the release of the ovum and the apparent mediatory role of interleukin-1 in this process will be presented. LH/hCG stimulates, in the preovulatory follicles, a cascade of proteolytic enzymes, including plasminogen activator (PA), plasmin and matrix metalloproteinase 1 (MMP-1). These enzymes bring about the degradation of perifollicular matrix and, most notably, the decomposition of the meshwork of collagen fibers which provides the strength to follicular wall. Furthermore, pharmacological blockage of any of these enzymes resulted in inhibition of follicle rupture. LH/hCG stimulates, in addition, an increase in ovarian production of eicosanoids. These include prostaglandins, obtained from arachidonic acid via the cyclooxygenase pathway and leukotrienes, the products of lipoxygenase. Previous studies from our and other laboratories have demonstrated the ability of inhibitors of cyclooxygenase and of lipoxygenases to suppress ovulation in several mammalian species. MK-886, which inhibits the translocation of 5-lipoxygenase (5-LO) from the cytosol and its binding to the membranal 5-LO activating enzyme, suppressed dose-dependently follicular rupture from the treated ovary. Zymographic analysis of ovarian extracts from PMSG/hCG-stimulated rats revealed a band of collagenolytic activity at 52kD, corresponding to human MMP-1 and at 72kD, corresponding to human MMP-2. Both activities were markedly stimulated by administration of hCG and were significantly inhibited by indomethacin, NDGA or MK-886. Thus, eicosanoids seem to mediate LH stimulation of follicular collagenase. Interleukin-1 (IL-1) has been recently implicated in ovulation. The ability of an IL-1 receptor antagonist (ra) to block ovulation in vivo and in vitro has been demonstrated recently. Morphological examination of the ovulatory follicles failing to ovulate suggests that this effect is exerted by inhibiting cumulus oophorus expansion and detachment from mural granulosa cells. In vitro, IL-1ra attenuated the action of hCG and FSH on cumulus expansion and follicular hyaluronic acid synthesis. Thus, IL-1 seems to mediate and/or facilitate gonadotropin action on cumulus expansion, and hence on ovulation.

New concepts in ovarian regulation: an immune insight

The purpose of the ovary is to produce eggs. In the human, oocyte production occurs cyclically at monthly intervals. The control of egg production is provided by both the endocrine and immune systems. Successful oocyte production is the result of sophisticated communication between the two systems. These interactions allow adaptive processes necessary for continuation of the species.

Involvement of prostaglandins in LH-induced superovulation in the cyclic hamster

Osmotic minipumps containing 400 micrograms ovine LH were inserted subcutaneously (sc) on day 1 (estrus) at 09:00-10:00h of the cycle in the hamster. This treatment induced increased ovarian blood flow by day 3 and superovulation of 30.0 +/- 1.4 ova at the next estrus compared to controls (16.5 +/- 0.8 ova). The continuous infusion of LH throughout the cycle increased prostaglandin F (PGF) and decreased prostaglandin E (PGE) in the growing follicles destined to ovulate and suppressed a day 3 increase in PGF concentrations in the nonluteal ovarian remnant devoid of the larger follicles. Indomethacin, a cyclooxygenase inhibitor, given sc (2 or 4 mg regimens) at 12:00-14:00h on days 1 and 2, at 09:00h and 17:00h on day 3 and at 09:00h on day 4 of the cycle to LH-infused and saline treated animals suppressed ovarian prostaglandin levels, prevented the superovulation and prevented the increased ovarian blood flow. Exogenous PGF2 alpha or PGE2 restored the superovulatory effect of LH infusion in the presence of indomethacin. The results suggest that the superovulation in response to continuous LH infusion may be mediated in part by prostaglandins via altered ovarian blood flow.

Formation of the rupture site in preovulatory hamster follicles: morphological and morphometric analysis of thinning of the granulosa and thecal layers

The wall of hamster ovarian follicles is composed of the following cell layers: granulosa, theca interna, theca externa, and the surface epithelium. To determine the morphological changes occurring in the follicle during formation of the rupture site, we measured: the thickness of each layer, the number of cells in each layer, and size of cells in each layer, at the apex and base of follicles at specific times during the final 13 hr before ovulation. Changes in the wall occur in 3 stages. During stage 1 (T0-T8), which includes the first 8 hr following the surge in luteinizing hormone, the apical and basal walls thin at the same rate and the antrum increases in size. During stage 2 (T9-T12), there is no change in the thickness of the apical and basal follicle wall nor in the size of the antrum. During the third stage (T12-T13), the size of the antrum decreases slightly and there is an increase in the thickness of the basal wall, which is correlated with its constriction caused by the contraction of smooth muscle cells. The apical wall rapidly thins to the point of rupture. The morphology of cells from each layer is described. Theca interna cells form the final tissue preventing escape of the oocyte-cumulus complex. The roles of cell migration, stretching, and death in thinning of the apical wall are described, and the mechanisms involved in follicle rupture are discussed.

Luteinising hormones activate a factor(s) in testicular interstitial fluid which increases testicular vascular permeability

The mechanism by which hCG increases the rat testicular vascular permeability was studied by injecting the testes with hCG (0.1-100 ng) together with testicular interstitial fluid (150 mul) or with the fluid alone (control) and measuring the uptake of i.v. injected [125I]hCG and the interstitial fluid volume in the testes. Both parameters were already increased with 1 ng of hCG and maxima were seen with 2 ng of hCG. The effect of hCG was not inhibited by injection of a 1000-fold excess of deglycosylated hCG together with hCG. No increase was seen after injection of 2 ng of hCG in saline or in rat serum. The response was specific to luteinising hormones since only rLH mimicked the effect of hCG, but deglycosylated hCG, rFSH or rat prolactin did not. Denaturation of the fluid or addition of serine protease inhibitor (p-aminobenzamidine) to the fluid prevented the effect of hCG. Treatment of the hCG-activated fluid with anti-hCG gamma-globulin Sepharose did not abolish the permeability effect of the fluid. This, and the finding that hCG is not catabolised during incubation in the fluid, suggests that hCG itself is not transformed to a vasoactive compound in the fluid. These results strongly suggest that luteinising hormones activate a factor(s) in rat testicular fluid which mediates their permeability effect. The putative factor(s) seems to be heat-sensitive with a molecular weight of over 10 000 Da.

Glycosaminoglycans in follicular fluid from women undergoing in vitro fertilization and their relationship to cumulus expansion, fertilization, and development

The glycosaminoglycans (GAGs) chondroitin sulfate (CS) and heparan sulfate (HS) were assayed in fluid from 178 individual follicles obtained from women after human menopausal gonadotropin ovulation induction for subsequent in vitro fertilization. CS and HS concentrations ranged from 0 to 3.9 and 0 to 18.6 mg/ml, respectively. The percentage of oocytes fertilized was significantly higher when CS concentrations ranged from 0.3 to 0.8 mg/ml (P less than 0.03). As HS levels increased, maturation scores by visual assessment of the egg-corona-cumulus cell complexes increased (P less than 0.05), but the percentage of oocytes fertilized was not affected. Cleavage rates of developing embryos were not related to the concentrations of GAGs.

Formation of cyclic adenosine monophosphate (cAMP) in the preovulatory rabbit follicle: role of prostaglandins and steroids

The preovulatory increase in follicular prostaglandins (PG) stimulated by luteinizing hormone (LH) is dependent upon 3'-5'-cyclic adenosine monophosphate (cAMP) and is essential for ovulation. It has been proposed that follicular PG stimulate a second rise in cAMP, independent of LH. This study examined the temporal relationships among PGE2, PGF2 alpha 6-keto-PGF1 alpha, estradiol-17 beta, progesterone, testosterone, androstenedione and the biphasic increases of cAMP in follicles of rabbits. Does received indomethacin (IN, 20 mg/kg, i.v.; n = 30) or phosphate buffer (C; n = 30), 0.5 h before 50 ug of LH. At laparotomy at 0, 0.5, 1, 2, 4 or 8 h after LH, blood was collected from each ovarian vein and two follicles per ovary were aspirated of fluid and excised. Plasma and follicular tissue and fluid were assayed for PG and steroids. Tissue and fluid were assayed for cAMP. In C does, cAMP (pmol/follicle) in tissue increased from 11.3 at 0 h to 14.2 at 0.5 h, decreased at 1 h (5.4) and increased linearly through 8 h to 14.5. In IN-treated does, cAMP remained high from 0.5 (13.2) to 2 h (16.3), decreased at 4 h (7.9) then increased again by 8 h (15.5). Indomethacin decreased all PG in follicular tissue but 6-keto-PGF1 alpha rose after 2 h, whereas PGE2 and PGF2 alpha did not. Estradiol-17 beta, progesterone, and androstenedione did not vary with treatment; testosterone was increased (P less than .05) by IN. PGE2 or PGF2 alpha may terminate the first phase of cAMP production, rather than initiate the second phase.

Clinical, endocrinologic, and intraovarian prostaglandin F responses to H-1 receptor blockade in the ovarian hyperstimulation syndrome: studies in the rabbit model

The effects of chlorpheniramine maleate, an H-1 receptor blocker, on clinical and endocrinologic features and intraovarian prostaglandin F (PGF) content were assessed in the rabbit model of the ovarian hyperstimulation syndrome. H-1 receptor blockade prevented ascites, attenuated ovarian enlargement (2.68 +/- 0.37 gm versus 4.15 +/- 0.056 gm; p less than 0.05), and augmented intraovarian PGF content (8.4 +/- 0.84 versus 3.95 +/- 1.12 pg/mg protein; p less than 0.05). Steroidogenesis was unaffected. In the control group, in which weights remained stable, animals with minimal ascites (scores less than or equal to 2; n = 4) were compared to other control animals with a greater accumulation of fluid (scores greater than or equal to 3; n = 4). The former also exhibited lower ovarian weights (2.94 +/- 0.41 versus 5.35 +/- 0.59 gm; p less than 0.05) and higher PGF ovarian content (6.05 +/- 1.56 versus 1.8 +/- 0.75 pg/mg of protein; p less than 0.05). This triad of minimal ascites, lower ovarian weights, and elevated intraovarian PGF seen both in treated animals and in inherently more resistant control animals did not appear to depend on changes in body weight. The conclusion reached was that H-1 receptor blockade prevented ascites, reduced ovarian enlargement, and augmented PGF content but did not affect steroidogenesis. This protective effect of chlorpheniramine may be mediated at least in part by prostaglandins.

Prostaglandins and preovulatory follicular maturation in mice

Experiments have been carried out in an effort to reverse the indomethacin-induced inhibition of preovulatory follicular development in immature superovulated mice utilizing prostaglandins E2 and F2 alpha. All mice were primed with 5 IU pregnant mare's serum gonadotropin followed 40 h later by 80 IU luteinizing hormone (LH). Animals were sacrificed 10 1/2 or 11 1/2-12 h post-LH, at which time ovaries were fixed and prepared for microscopic observation. Control mice receiving both indomethacin and prostaglandin (PG) vehicles averaged 92% germinal vesicle breakdown, and 82% of maturing oocytes were surrounded by an expanded cumulus oophorus. Ovarian weight increased by 29% and the apical walls of preovulatory follicles demonstrated appreciable thinning following LH administration. In mice receiving indomethacin plus PG vehicle, follicular maturation was suppressed in a dose-dependent manner; in mice receiving 10 mg/kg, less than 50% of the oocytes resumed meiosis and, of these, only 9% were accompanied by cumulus expansion. Ovarian weight gain was also inhibited, and the apical follicle wall exhibited few signs of preovulatory thinning. PGE2 and PGF2 alpha both reversed the inhibition of cumulus and oocyte maturation induced by indomethacin, though PGE2 was more effective. Only PGF2 alpha promoted apical follicular thinning, and neither PG had a significant effect on ovarian weight. We conclude that, in mice, PGs may play an integral role during preovulatory maturation of the oocyte and cumulus, as well as thinning of the apical wall.