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J K Findlay

Publications and source records attributed to J K Findlay.

At least 109 records · Page 6Linked to original sources
PubMed1990

Oxytocin and progesterone secretion by bovine granulosa cells of individual preovulatory follicles cultured in serum-free medium.

To examine the secretion of oxytocin (OT) and progesterone (P) from a homogeneous population of cells during luteinization, we developed a serum-free culture technique for granulosa cells, obtained from individual preovulatory bovine follicles. Granulosa cells from earlier stages of the follicle development did not have the capability to secrete OT under the in vitro conditions used. For optimal stimulation of the cells the medium (a 1:1 mixture of Dulbecco's modified Eagle's medium and Ham's F-12) was supplemented with bovine serum albumin (BSA) and insulin. OT was detectable from day 1 of culture reaching a maximum level between days 2 and 4 and then declined towards day 5. In the absence of insulin OT declined from day 1 onwards and was undetectable from day 4. When cells were cocultured with theca tissue or theca-conditioned medium (TCM), there was an enhancement in OT secretion, but not in P secretion. Other tissues including liver, kidney, aorta, muscle and adrenal incubated with the cells induced a similar increase in OT production. In the presence of insulin progesterone secretion was increased and was correlated with OT production, but did not show a consistent pattern among follicles. We conclude that (a) culture of granulosa cells from an individual follicle in a serum-free medium can be used to study the secretion of OT and P from bovine granulosa cells, (b) insulin is essential for the optimal production of OT and P by these cells, and (c) the addition of theca or other tissues enhanced OT secretion by a mechanism not understood.

Animals↗
PubMed1990

Secretion and gene expression of inhibin, oxytocin and steroid hormones during the in vitro differentiation of bovine granulosa cells.

Bovine granulosa cells were cultured under defined conditions to examine (1) their secretion of immunoreactive inhibin, oxytocin, progesterone and oestradiol during differentiation in vitro; (2) their expression, by Northern analysis, of specific mRNAs for inhibin and oxytocin as compared with uncultured cells; (3) possible interrelationships between the four secreted hormones; and (4) the hypothesis that androgens and steroidogenesis influence the secretion of inhibin. The secretion of inhibin and oestradiol fell rapidly over the first few days of culture but remained at detectable levels for at least 7 days. Conversely, the secretion of oxytocin and progesterone rose steadily as culture progressed. These changes occurred spontaneously (i.e. without gonadotrophin treatment) and were not dependent on the addition of serum to the culture medium. Messenger RNAs for the inhibin alpha- and beta A-subunits were present in uncultured cells but barely detectable or undetectable in cells cultured for 4 days. Conversely, the mRNA for oxytocin, which was not detectable in uncultured cells, was present in cultured cells and increased in quantity as culture progressed. Treatment of cells with testosterone (5 nM-5 microM), in the presence or absence of serum (10% FCS), had no effect on the secretion of inhibin but stimulated the declining oestradiol secretion. Treatment with ascorbic acid (0.5 mM) increased the secretion of oxytocin and progesterone, as previously described, but not that of inhibin. Treatment with aminoglutethimide (0.5 mM), an inhibitor of steroidogenesis, substantially inhibited progesterone secretion and the response of oestradiol secretion to testosterone, but had no effect on the secretion of either inhibin or oxytocin. We conclude that bovine granulosa cells differentiate spontaneously in defined culture in a manner that, as defined by the secretion of steroid and peptide hormones, closely resembles their luteinization in vivo. The switch in protein hormone secretion from inhibin to oxytocin is accompanied by a corresponding change in mRNA expression. The changes in steroid and peptide hormone secretions that take place in culture appear to occur independently of one another although their absolute cause remains to be determined. In contrast to previous studies, we could find no evidence for the regulation of inhibin secretion by either androgens or steroidogenesis.

Animals↗
PubMed1990

Immunocytochemical localization of prostaglandin synthase in the ovine uterus during the oestrous cycle and in early pregnancy.

Prostaglandin (PG) synthase has been localized by immunocytochemistry within the ovine uterus throughout the oestrous cycle and in early pregnancy. On Day 4 of the cycle, PG synthase was located primarily in the stromal cells in caruncular and intercaruncular tissue with little staining in the epithelium. On Days 14 through to 16, the most intense staining was in the luminal epithelial cells (caruncular and intercaruncular) and in epithelial cells of glands close to the uterine lumen. PG synthase was also located in the intercaruncular stromal cells, particularly close to the myometrium. Staining for the enzyme on Day 10 was intermediate between that of Day 4 and Day 14. On Day 15 of pregnancy, the pattern of staining was identical to that on Day 15 of the cycle, with no detectable difference in intensity. When endometrial cells (cycle, Day 14) were cultured with and without ovine trophoblast protein-1 (3 ng mL-1) in vitro, release of PGE and PGF2 alpha was attenuated (54% and 47% of control respectively) but no differences were observed in the intensity of staining for PG synthase in the cells. These results demonstrate marked cyclical changes in the endometrial cell types producing PGs, suggesting differential regulation of PG synthase. In addition, it appears that conceptus-induced changes in PGF2 alpha release do not occur via changes in the concentration or cellular localization of PG synthase, but rather that the activity of the enzyme is modified.

Animals↗
PubMed1990

Regulation of endometrial prostaglandins during the menstrual cycle and in early pregnancy.

Prostaglandins are important regulators of endometrial function. In turn, their secretion is controlled by endocrine and paracrine mediators. Cyclical effects of ovarian oestrogen and progesterone throughout the menstrual or oestrous cycle result in overall higher levels of prostaglandin release during the secretory or luteal phase of the cycle than during the proliferative phase. Potential paracrine regulators of endometrial origin include cytokines, growth factors and histamine, some of which may arise from infiltrating cells. Embryo-derived factors can regulate endometrial prostaglandin release in early pregnancy. Both platelet-activating factor and ovine trophoblast protein-1 (an embryonic interferon) modify prostaglandin release from primary cultures of endometrial cells of human and ovine origin respectively. Manipulation of such mediators may provide new means for fertility control.

Animals↗
PubMed1990

Separation and culture of ovine endometrial epithelial and stromal cells: evidence of morphological and functional polarity.

Epithelial and stromal cells from endometria of ovariectomized estradiol-treated Corriedale ewes were separated and purified after collagenase digestion. The separation method utilized differences in the speed and ease of detachment of cultured epithelial and stromal cells attached to plastic in response to brief trypsin exposure. Cells were characterized according to morphological, growth, and histochemical criteria. Contamination of each cell type with the other was less than 1%. Separated cells were grown on plastic or on Matrigel-coated Millicell inserts with nitrocellulose membranes. Transmission and scanning electron microscope analyses demonstrated the existence of tight junctions and prominent microvilli in the epithelial cultures on inserts but not on plastic. Asymmetrical secretion of prostaglandin F2 alpha (PGF2 alpha) and prostaglandin E (PGE) by epithelial cells provided further evidence of polarization. Epithelial cell secretion of PGF2 alpha was greater than that by stromal cells whereas PGE secretion by stromal cells was greater than that by epithelial cells. Epithelial secretion in the basal direction was approximately 4 and 3 times that of apical secretion for PGF2 alpha and PGE, respectively. The separation protocol provides pure populations of ovine endometrial epithelial and stromal cells and the cultured epithelial cells exhibit characteristics of in vivo morphology and polarized function.

Animals↗
PubMed1990

Inhibin concentrations in ovarian and jugular venous plasma and the relationship of inhibin with follicle-stimulating hormone and luteinizing hormone during the ovine estrous cycle.

A heterologous RIA for ovine inhibin was developed which was sufficiently sensitive and specific to describe the peripheral concentrations of immunoreactive inhibin (iINH) during the estrous cycle of the ewe and to examine the effects of cautery of ovarian follicles on concentrations of iINH in ovarian and jugular venous plasma. Parallel logit-log dose-response lines were observed among ovine follicular fluid, ewe plasma, and pure native ovine (31 kDa) and bovine (31 kDa) inhibin. iINH could not be detected in ovariectomized ewe plasma, and there was no apparent cross-reactivity with a variety of structurally related and unrelated hormones and peptides, except a monomeric form of the alpha-subunit of INH, iINH in follicular fluid was 10(4)-fold higher than that in ovarian venous plasma, which was 3-fold higher than that in peripheral plasma. Cautery of the follicles resulted in a 35% reduction in iINH and an 81% reduction in estrogen concentrations in the ovarian vein within 10 min. During the estrous cycle, iINH and FSH were inversely related in samples taken over 30 h in the luteal phase (r = -0.69; P less than 0.001) and in the pre- and postovulatory phases (r = -0.45; P less than 0.001). iINH and LH were not related in the luteal phase, but were weakly positively correlated in the follicular phase (r = 0.31; P less than 0.01). iINH and estrogen concentrations in the follicular phase were also weakly correlated (r = 0.30; P less than 0.001). Furthermore, iINH concentrations rose in the follicular phase and decreased within 3-6 h of the preovulatory surges of LH and FSH, reaching a nadir around the time of the second rise in FSH 24-48 h later. It is concluded that 1) large antral follicles are a major source of peripheral iINH during the ovine estrous cycle; 2) iINH levels increase in the follicular phase with the growth of the dominant follicle and may be inhibited by the preovulatory surge of gonadotropin; 3) the fall in inhibin after the LH surge may be responsible for the second rise in FSH; and 4) the inverse relationship between FSH and iINH is consistent with the hypothesis that inhibin is involved in the feedback regulation of FSH.

Animals↗
PubMed1990

Activin-A inhibits oxytocin and progesterone production by preovulatory bovine granulosa cells in vitro.

The aim was to examine the effect of activin on luteinization of preovulatory bovine granulosa cells in vitro. Bovine activin-A was found to inhibit the production of oxytocin (OT) and progesterone by bovine granulosa cells from individual preovulatory follicles cultured in serum-free medium. The minimal response on OT production (25% inhibition) occurred with 0.1-1 ng/ml activin-A, and the maximal inhibition (83%) occurred with 10 ng/ml activin-A after 2-3 days in culture. Progesterone showed a similar response (30% inhibition for 0.1-1 ng/ml and 74% for 10 ng/ml). Inhibin production was not consistently effected by activin-A. Inhibin (75 U/ml) had no detectable effect upon OT or progesterone production. When activin-A was withdrawn from the cell culture after 72 h and the incubation continued for a further 72 h, a recovery in OT was seen on day 4 and 5 after activin-A doses of 0.1-1 ng/ml, but not after higher doses (3 and 10 ng/ml). Progesterone did not show a recovery, but the levels remained constant for 3 days (0.1 and 0.3 ng/ml activin-A) or for 1 day (1-10 ng/ml activin-A) and then fell to control levels by day 6 of culture. We conclude that bovine activin-A has an autocrine action on bovine granulosa cells in vitro, to inhibit basal production of OT and progesterone, consistent with the role of activin-A in delaying the process of luteinization.

Activins↗
PubMed1990

Effect of inhibin on activators of protein kinase-C and calcium-mobilizing agents which stimulate secretion of gonadotropins in vitro: implication of a postgonadotropin-releasing hormone receptor effect of inhibin on gonadotropin release.

To further characterize the subcellular mechanisms by which inhibin suppresses GnRH-stimulated gonadotropin release, anterior pituitary cells from adult male Sprague-Dawley rats were treated on day 2 of culture with or without purified 31-kDa bovine inhibin (1-300 pM) for a further 3 days. On day 5, the pretreated cells were washed and incubated in the absence or presence of various secretagogues for 4 h. At the end of the stimulation, the media were saved, and cells were lysed for measurement of both extracellular and intracellular FSH and LH by specific RIAs. Released hormone was expressed as the proportion of total (released plus intracellular) hormone that was available for release in each case. This manipulation of the data corrects for the differential effect of the inhibin pretreatments to suppress intracellular FSH before the stimulation period. Pretreatment for 3 days with inhibin suppressed the proportions of FSH and LH released during 4 h in response to 1) phorbol 12-myristate 13-acetate (100 nM), an activator of protein kinase-C, by maxima of 48% and 53% with inhibin median inhibitory concentrations (IC50) of 17 and 18 pM, respectively; 2) mezerein (100 nM), another type of activator of protein kinase-C, by maxima of 49% and 50% with inhibin IC50 of 19 and 20 pM, respectively; 3) high extracellular K+ (60 mM) by 42% (P less than 0.01) and 38% (P less than 0.01), respectively, with 130 pM inhibin; 4) the calcium ionophore, A23187 (100 microM) by maxima of 54% and 56% with IC50 of 18 and 17 pM, respectively; and 5) GnRH (10 nM) by maxima of 52% and 53% with IC50 of 18 and 19 pM, respectively. However, inhibin had no effect on the proportional release of gonadotropin induced by melittin, an activator of phospholipase-A2. Finally, inhibin had no effect on ACTH release either under basal conditions or in response to CRF (10 nM), phorbol 12-myristate 13-acetate (100 nM), or A23187 (100 microM). We conclude that inhibin suppresses the stimulated release of hormones from gonadotrophs in part by a mechanism common to both gonadotropins that is independent of the previously described inhibitory effect of inhibin on the GnRH receptor. The results are consistent with an action at a site(s) beyond the GnRH receptor, such as protein kinase-C and calmodulin.

Adrenocorticotropic Hormone↗
PubMed1990

Chronic inhibitory effect of follicle-stimulating hormone (FSH)-suppressing protein (FSP) or follistatin on activin- and gonadotropin-releasing hormone-stimulated FSH synthesis and secretion in cultured rat anterior pituitary cells.

The effects of bovine FSH-suppressing protein (FSP) or follistatin on activin- and GnRH-stimulated FSH synthesis and secretion have been studied using cultured pituitary cells from adult male Sprague-Dawley rats. Exposure to FSP (0.001-10 nM) for 3 days dose-dependently suppressed basal FSH secretion (IC50 = 146 +/- 21 pM., mean +/- SE), cellular content (IC50 = 269 +/- 8 pM) and total FSH (IC50 = 181 +/- 25 pM), with no effect on LH. Activin (0.3 nM) increased FSH secretion 2.1-fold, cellular content 1.3-fold, and total FSH 1.9-fold during a 3-day incubation, but these increases were dose-dependently inhibited by concomitant treatment with 35-kDa bovine FSP (0.1-3 nM), with complete inhibition occurring at concentrations between 1 and 3 nM. The 31- and 39-kDa forms of bovine FSP also antagonized the actions of activin. GnRH (1 nM) increased FSH secretion 1.8-fold and total FSH 1.6-fold during a 3-day incubation, effects that were dose-dependently inhibited by concomitant treatment with 35-kDa bovine FSP. The highest tested concentration of FSP (3 nM) suppressed GnRH-stimulated FSH secretion and total FSH to 59 and 57%, respectively, of the levels found in untreated cultures. All three forms of bovine FSP produced a significant inhibition of FSH secretion and total FSH stimulated by GnRH. FSP also suppressed FSH secretion and total FSH in response to activators of protein kinase C including 100 nM phorbol 12-myristate 13-acetate (43 and 59%, respectively) and 100 nM mezerein (40 and 60%, respectively). Finally, treatment of cultured pituitary cells with 35-kDa FSP at 1 and 3 nM for 3 days resulted in 21 and 24% decreases in GnRH binding sites, respectively. It is concluded that (i) FSP inhibits not only the secretion but also the synthesis of FSH induced by activin and GnRH in long-term culture, and (ii) FSP may cause its inhibitory effects on GnRH by suppression of the protein kinase C system, and possibly by reduction of GnRH binding sites.

Activins↗
PubMed1990

Role of inhibin-related peptides as intragonadal regulators.

Evidence for intragonadal roles of the inhibin-related peptides, activin, inhibin, alpha N peptide of inhibin (alpha N) and follicle-stimulating hormone suppressing protein (FSP) or follistatin, is reviewed. It is proposed that activin, FSP and alpha N act as intragonadal regulators to influence folliculogenesis, ovulation and luteinization, and that inhibin primarily influences folliculogenesis by its peripheral effects on the secretion of FSH and LH by the pituitary gland, with few, if any, effects directly within the ovarian follicle. We propose that activin promotes follicular differentiation and delays the onset of premature luteinization, whereas FSP promotes atresia of non-dominant follicles and luteinization of dominant follicles, and is therefore antagonistic to activin. We hypothesize that alpha N, a post-translational processing product of the alpha subunit of inhibin, acts locally in the follicle to facilitate ovulation.

Activins↗
PubMed1989

Ovine trophoblast protein-1 and human interferon alpha reduce prostaglandin synthesis by ovine endometrial cells.

Ovine trophoblast protein-1 (oTP-1), a protein secreted by the sheep conceptus immediately prior to implantation has sequence homology with alpha interferon. We have previously shown that, in parallel with human alpha interferon (IFN), oTP-1 reduces the release of prostaglandins (PG) E and F2 alpha from cultured ovine endometrial cells. Here we have examined the time and dose dependence of these actions and the possible site of action of the peptides. The concentrations of oTP-1 and IFN required for 50% inhibition of PGE release were 92 pg/ml and 0.88 pg/ml and for PGF2 alpha release, 165 pg/ml and 1.12 pg/ml respectively. Significant effects on PG release were not measured before 12 h after addition of peptide to culture dishes. Following removal of the peptides, the cells released less PGs for a further 18 h but then recovered. A large increase in PG synthesis and release occurred from cells cultured with added serum or arachidonic acid (AA) and an interactive effect was demonstrated between them, AA having a greater stimulatory effect on PG released in the presence of serum. However, in all cases oTP-1 and IFN continued to attenuate prostaglandin release. We conclude that the IFNs act directly or indirectly on the prostaglandin synthase enzyme.

Animals↗
PubMed1989

Inhibin mRNAs in ovine and bovine ovarian follicles and corpora lutea throughout the estrous cycle and gestation.

Follicles and corpora lutea were dissected from ovine and bovine ovaries and the RNA extracted and subjected to Northern blot analyses for alpha- and beta A-inhibin mRNAs, using bovine cDNA and cRNA probes. A cDNA probe detecting mRNA for cholesterol side-chain cleavage cytochrome P-450 (P-450scc) was used as a positive control. In cattle, alpha- and beta A-inhibin mRNAs were not detected in ovarian stroma, which could potentially have contained follicles up to 0.5 mm in diameter. Inhibin-alpha and -beta A mRNAs were detected in bovine antral follicles but after ovulation, the relative levels of alpha- and beta A-inhibin mRNAs declined and were undetectable in mature fully developed cyclic corpora lutea and in pregnancy corpora lutea from early to late gestation of the cow. In sheep, alpha- and beta A-inhibin mRNAs were detected in a pool of antral follicles but not in cyclic or pregnancy corpora lutea, which did contain P-450scc mRNA. It is concluded that in cattle and sheep, follicles and not mature corpora lutea are the ovarian source of inhibin.

Animals↗
PubMed1989

Sex-hormone-binding globulin in human follicular fluid and serum at the time of oocyte recovery.

Androgen binding activity, indistinguishable from sex-hormone-binding globulin (SHBG) in serum, has been identified in human follicular fluid by binding analyses (saturation and Scatchard analyses and binding specificity), immunoradiometric assay and Con-A Sepharose chromatography. Follicular fluid was obtained at the time of oocyte recovery from either individual follicles (range 2-7) from seven patients, or as a pool obtained from follicles of several patients who had received a Clomid-human menopausal gonadotrophin treatment to stimulate follicular growth as part of an in vitro fertilization program. Concentrations of SHBG in follicular fluid varied between individual follicles (750 +/- 202 fmol mg-1 protein; mean +/- s.d.; n = 14) and ranged above and below concentrations of SHBG in serum (948 +/- 171 fmol mg-1 protein; n = 5) taken 4 h before oocyte recovery and harvest of follicular fluid. There were strong correlations (r = 0.7-0.9) between the steroid and SHBG contents in individual follicular fluids of two patients. However, the concentration of SHBG in follicular fluid was generally 100-fold lower than that of oestradiol or progesterone, suggesting that SHBG may play some role other than determining the concentration of unbound steroid in the follicle.

Androgen-Binding Protein↗
PubMed1989

Increase in ovulation rate in Merino ewes after active immunization with inhibin preparations obtained by immunoaffinity chromatography.

Ewes were immunized with four inhibin preparations of increasing purity obtained from bovine follicular fluid by affinity chromatography. The two purest immunogens, which had 69 and 174 ng inhibin micrograms-1 protein (expressed in terms of 32 kDa ovine inhibin), increased ovulation rate by 240 and 320% respectively following two injections, and gave a transient increase in plasma FSH concentration at the same time. Plasma antibodies recognizing native 125I-31 kDa bovine inhibin appeared at the same time, and, together with the increased ovulation rate, persisted after the injections ceased. Ovulation rate and antibody titres were raised by the less pure immunogens, but to a smaller extent, and the increases did not persist. It was concluded that the increased ovulation rate was due to induced inhibin antibodies, acting at least in part through the consequent rise in plasma FSH concentration.

Analysis of Variance↗
PubMed1989

Inhibitory effect of pure 31-kilodalton bovine inhibin on gonadotropin-releasing hormone (GnRH)-induced up-regulation of GnRH binding sites in cultured rat anterior pituitary cells.

Primary cultures of enzymatically dispersed rat anterior pituitary cells were used to examine the effect of pure 31 kilodalton bovine inhibin on GnRH-induced up-regulation of GnRH binding sites. After 2 days in culture, the cells were exposed to stimuli with or without test substances for 10 h, followed by evaluation of GnRH binding sites using iodinated GnRH-A (Buserelin) as tracer. Inhibin suppressed GnRH-induced up-regulation of GnRH binding sites in a dose-dependent manner with an IC50 of 0.13 U/ml (5.5 pM). The inhibin-related peptides transforming growth factor-beta, and Müllerian inhibitory substance had no detectable effect (stimulatory or inhibitory), suggesting that the action is specific to inhibin. In addition, inhibin inhibited the calcium ionophore A23187-induced up-regulation of GnRH binding sites, indicating that this effect of inhibin can occur, at least in part, at a stage subsequent to Ca2+ mobilization. Inhibin did not compete with iodinated GnRH-A for GnRH binding sites. In conclusion, pure 31 kilodalton bovine inhibin suppressed GnRH-induced up-regulation of GnRH binding sites in cultured rat anterior pituitary cells, providing direct evidence that inhibin modulates delayed actions of GnRH.

Animals↗
PubMed1989

Immunisation against the amino-terminal peptide (alpha N) of the alpha 43 subunit of inhibin impairs fertility in sheep.

Processing of the 58 kDa to the 31 kDa form of inhibin (Inh) involves cleavage of the amino-terminal peptide (alpha N) from the alpha 43-subunit. We show that active immunisation of female sheep against a recombinant bovine alpha N impairs their fertility. In Exp 1, 5 treated (Group 1; 300 micrograms alpha N) and 6 control ewes (Group 2; adjuvant only) were immunized (Day 1) and given boosters on Days 22 and 56. In Group 1, mean +/- SEM binding of 125I-31 kDa Inh was less than 0.5% on Days 33 and 44, whereas binding of 125I-58 kDa Inh was 4.9 +/- 0.7 and 6.2 +/- 0.6%, respectively. In Group 2 binding of both tracers was less than 0.5%. The corpora lutea (CL)/ewe in Group 1 on Days 44 and 82 were 1.8 +/- 0.2 and 2.8 +/- 0.9, respectively, and were not different from those in Group 2 (1.7 +/- 0.3 and 1.5 +/- 0.2, respectively). One ewe in Group 1 versus 5/6 ewes in Group 2 were diagnosed pregnant. In Exp 2, 18 treated and 16 controls were immunized as in Exp 1. The binding of 125I-58 kDa Inh in treated ewes (2.4 +/- 0.3%) was greater than in controls (less than 0.5%) on Day 56. The CL/ewe in treated ewes (1.8 +/- 0.2) was similar to that in controls (2.0 +/- 0.1) on Day 76. All 16 control ewes but only 7/17 treated ewes were subsequently diagnosed pregnant. The plasma progesterone concentrations were similar in treated ewes which did (7.6 +/- 1.2 nmol/L) and did not (7.0 +/- 0.7) become pregnant. Neither basal nor GnRH-stimulated concentrations of LH, nor basal concentrations of Inh differed between treated and controls in Exp 2. Similarly, there were no differences in FSH, except that basal concentrations were higher in the luteal phase of treated ewes. We conclude that immunisation of ewes against alpha N results in a significant reduction in fertility.

Animals↗
PubMed1989

Circulating immunoreactive oxytocin during the human menstrual cycle comes from the pituitary and is estradiol dependent.

The aims of this study were to 1) evaluate the relative contributions of hypothalamic and ovarian oxytocin (OT) to peripheral serum concentrations and 2) determine the relationship between serum OT and ovarian steroid concentrations. Four groups of women were studied: 1) women with spontaneous cycles (n = 4) and normal serum estradiol (E2), progesterone, LH, and FSH levels; 2) in vitro fertilization (IVF) patients (n = 8) undergoing ovarian hyperstimulation; 3) agonadal oocyte-recipient patients (n = 6) receiving replacement E2 and P therapy; and 4) postmenopausal women (n = 21). Peripheral serum samples were collected daily during a menstrual cycle from the normal and agonadal women and for 6 days before ovulation in the IVF group. Serum immunoreactive OT was measured by specific RIA after Sep-Pak extraction; the assay sensitivity was 0.6 pmol/L. Serum OT in the women with normal cycles increased during the follicular phase, reaching a peak 1 day after the LH surge, and decreased in the luteal phase [days 7, 16, and 21, 10.7 +/- 3.5 (mean +/- SE), 25.7 +/- 5.7, and 13.2 +/- 2.5 pmol/L, respectively; P less than 0.05]. Serum OT levels were higher in IVF patients before ovulation than in women with spontaneous cycles, but lower than those in the agonadal women, who had a peak value (49.1 +/- 9.6 pmol/L; P less than 0.05) on day 13 of E2/progesterone replacement therapy. Serum OT was positively correlated (r = 0.68, normal women; r = 0.91, oocyte recipients) with serum E2 values during the first part of the cycle (P less than 0.01). A similar positive correlation between serum OT and E2 was found in the postmenopausal women (r = 0.83). We conclude that serum OT before and around the time of ovulation comes mainly from the pituitary, and not from the ovary, and is E2 dependent.

Adult↗