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PubMed1975

Effects of testosterone propionate or dihydrotestosterone propionate on plasma FSH and LH levels in neonatal rats and on sexual differentiation of the brain.

The present study tests the hypothesis that the effects of perinatal androgen administration on the development of the brain are brought about indirectly by a suppression of plasma gonadotropin (GTH) titers. Both castrated male and intact female rats were treated neonatally with 5 alpha-dihydrotestosterone propionate (DHTP) or testosterone propionate (TP) throughout the first ten postnatal days of life and the corresponding effects on neonatal plasma FSH and LH levels and the subsequent ability of the adult to exhibit cyclic GTH release and female sex behavior (lordosis) were determined. In males castrated within 24 h of birth, subcutaneous injections of DHTP (60 or 180 mug per 100 g average body weight) or TP (60 mug/100 g) given on day 2, 4, 6, 8 and 10 reduced plasma levels of FSH and LH as determined by radioimmunoassay 48 h following the first and last injections. However, TP but not DHTP masculinized the development of the regulation of GTH release as mesured by luteinization of subcutaneous ovarian grafts, and also suppressed the ability of adult neonatally castrated male primed with estradiol benzoate and progesterone to display lordosis behavior. In intact females, the same neonatal DHTP and TP injection regime lowered FSH and LH plasma levels following the last injection (day 12), while DHTP lowered LH, but not FSH, following the first injection (day 4). All TP treated females had ovaries devoid of CL by 45 days of age and showed prolonged vaginal cornification. However, DHTP failed to masculinize the pattern of GTH release in females since DHTP-treated females, like oil-treated females, possessed CL(days 45 and 100) and exhibited vaginal cycles (days 80-100). Lordosis quotients of females treated neonatally with DHTP were as high as those of oil-treated females and significantly higher than those of TP-treated females. These results demonstrate that the ability of TP to induce maculine differentiation of the neural regulation of GTH release and female sex behavior does not depend on its ability to depress circulating LH and FSH levels in the neonatal male, or LH levels in the neonatal female rat.

Animals↗
PubMed1976

Capacity of immunologically purified FSH to stimulate cyclic AMP accumulation and steroidogenesis in Graafian follicles and to induce ovum maturation and ovulation in the rat.

Reference preparations of ovine follicle-stimulating hormone (NIH-FSH-S8 and S9; 10-50 mug/ml) induced ovum maturation and stimulated cyclic AMP formation, as well as progesterone and 17beta-estradiol secretion, by rat Graafian follicles in vitro. These actions of NIH-FSH were retained after immunoabsorption of any contaminating luteinizing hormone (LH) present in the preparations, by treatment with an antiserum to the beta-subunit of purified ovine LH (anti-betaLH). In contrast, the corresponding biological actions of NIH-LH-S18 (0.5-10 mug/ml) were abolished by treatment with this anti-betaLH serum. A highly purified FSH preparation (64-96 CD, 0.25 mug/ml) also triggered oocytic meiosis and increased follicular progesterone secretion in vitro. Intraperitoneal (ip) administration of anti-betaLH-treated NIH-FSH-S9 (50 mug/rat at 1430 h) consistently induced ovulation in proestrous rats in which the endogenous gonadotropin surge had been blocked by ip injection of either Nembutal (1345 h) or antiserum to the LH-releasing hormone (1200 h). Injection (ip) of anti-betaLH serum on its own into proestrous rats at 1200 h prevented ovum maturation and follicular rupture. We conclude that currently available reference preparations of ovine FSH possess the capacity to stimulate follicular adenylate cyclase, steroidogenesis, and ovum maturation in vitro, as well as ovulation in vivo, in the rat, and that this capacity cannot be attributed to contamination with material immunochemically identical with LH. However, it is inferred that the physiological triggering of ovulation and related events in this species depends principally on LH.

Animals↗
PubMed1976

Selective suppression of FSH by testicular extracts.

Studies were undertaken to determine the effects of intravenous infusions of bovine testicular extracts on plasma levels of FSH and LH in castrate male sheep. Decapsulated bovine testes were homogenized with phosphate buffer, the homogenates centrifuged at 30,000 X g for 30 min, and the supernatants extracted with diethyl ether. The aqueous extracts were filtered using Diaflo XM-100 membranes and the ultra-filtrates lyophilized. The extracts were infused over 24 hours, and plasma FSH and LH were measured prior to, during, and after the infusion. Control studies using infusions of saline and liver extracts demonstrated no decrease in FSH levels in 6 out of 7 controls, while LH levels tended to rise. Following infusions with the testicular extracts, the levels of FSH were selectively decreased to between 42% and 85% of baseline levels, and they subsequently remained suppressed for at least 24 hours. These results suggest that the testis is the site of production of a water-soluble, non-steroidal substance which exerts an inhibitory effect on the production and/or release of FSH.

Animals↗
PubMed1976

Adenylyl cyclase activities in ovarian tissues. II. Regulation of responsiveness to LH, FSH, and PGE1 in the rabbit.

We conducted a study to determine whether a decline in the capacity of preovulatory follicles to accumulate cAMP in response to in vitro LH exposure, reported by Marsh et al. (1), is due to direct desensitization of the LH-hCG-responsive adenylyl cyclase (AC) system. Enzyme activity was determined in the absence and in the presence of 10 mug/ml of LH, FSH, and prostaglandin (PG) E1 in homogenates prepared from Graafian follicles dissected before and at various times after rendering them preovulatory either by mating (endogenous LH release) or by injection of hCG (100 IU/3.5-4.5 g rabbit, iv). Both of these treatments resulted in desensitization of the AC to LH and FSH stimulation, so that by the time of ovulation these responses were absent. hCG-induced desensitization was rapid (50% loss of LH-stimulated activity was obtained within 5 min of injection), was dose-dependent, requiring an ovulatory dose; was selective for LH- and FSH-stimulated activity, being without effect on basal and PGE1 as well as NaF-stimulated activities; and was induced specifically by LH (mating) and hCG-FSH and PRL being without effect. Desensitization of follicular AC does not seem to be mediated by PG, for doses of indomethacin that inhibited ovulation did not interfere with the loss of LH responsiveness. The incubation in vitro of dissected Graafian (estrous) follicles with LH (2 h) also resulted in desensitization to LH stimulation and indicated that this phenomenon was due to a direct effect of LH on the follicles and was not mediated by hormones derived from other endocrine structures. Newly formed corpora lutea (CL) in either pregnancy or pseudopregnancy (PSP) developed a new AC system that was highly responsive to LH and less responsive to FSH and PGE1. This new system persisted for the duration of pregnancy and PSP, and became inactive with regression of CL. The prolongation of PSP by hysterectomy was accompanied by the persistence of an active LH-responsive AC system. The injection of ovulatory doses of hCG into 6-day PSP rabbits produced, within 2 h, a 50% desensitization of the luteal AC systems to LH stimulation. After day 10 of pregnancy, the levels of LH-stimulated AC activity in CL and the levels of progesterone in serum, reported by Challis et al. (2), were found to parallel each other, suggesting that this enzyme activity may be a physiologic regulatory step in progesterone synthesis by the normal CL throughout most of the animal's pregnancy. This finding is discussed in the light of compelling evidence that estrogens are luteotrophic in the rabbit.

Adenylyl Cyclases↗
PubMed1976

Secretion of an FSH-inhibiting factor by cultured Sertoli cells.

Levels of LH and FSH released in vitro by rat anterior pituitary cells which were either co-cultured with isolated rat Sertoli cells or were grown with spent media recovered from the cultured Sertoli cells were measured by radioimmunoassay. The amounts of FSH released by pituitary cells grown for three days with Sertoli cells isolated from 31-36 day old rats or spent media from the cultured Sertoli cells, were significantly (P less than 0.01) lower compared to control pituitary cultures grown with fresh chemically defined medium. In contrast, the levels of LH were similar to the controls. The selective inhibition of FSH release was not observed when pituitary cells were co-cultured with rat spleen or kidney cells or with ruptured Sertoli cells. The FSH-inhibiting Sertoli-cell factor (SCF) was found to be a heat-labile macromolecule. It is suggested that the SCF may be secreted by the Sertoli cells in vivo, and regulate FSH secretion via negative feedback mechanism at the pituitary level.

Animals↗
PubMed1997

The positive feedback action of estrogen mobilizes LH-containing, but not FSH-containing secretory granules in ovine gonadotropes.

It has previously been shown in the ewe that luteinizing hormone (LH)-containing secretory granules become polarized to the side of the gonadotrope nearest to a vascular sinusoid during the preovulatory period. We have used laser scanning confocal microscopy to monitor the migration of LH and follicle stimulating hormone (FSH)-containing secretory granules in the gonadotrope of the ewe. Ovariectomized (OVX) ewes (n = 4/group) were given either 50 micrograms of estradiol benzoate (EB) or oil and were killed 16 h later for collection of the pituitary glands for immunohistochemistry and confocal microscopy. Pituitary sections were simultaneously immunolabelled for LH and FSH and were visualized on the same sections using fluorescent markers. All cells that contained LH also contained FSH and vice versa. The results showed that LH-containing granules were uniformly distributed throughout the cytoplasm in 83% of gonadotropes from controls, while in the remaining 17% the granules were predominantly located adjacent to the plasma membrane. Following EB treatment, LH-containing secretory granules were distributed around the plasma membrane in 84% of immunopositive gonadotropes; FSH remained uniformly distributed throughout the cytoplasm. We conclude that estrogen causes the movement of LH-containing granules to the plasma membrane in gonadotropes but does not influence the distribution of FSH-containing granules. Rather than being polarized to one side of the cell, the LH-containing granules were distributed around the periphery of the cell.

Animals↗
PubMed1998

Interleukin-1beta regulates pituitary follistatin and inhibin/activin betaB mRNA levels and attenuates FSH secretion in response to activin-A.

Activins and follistatins regulate all levels of the reproductive axis, including the pituitary where they stimulate and inhibit FSH production, respectively. Gonadotropes are known to express inhibin/activin betaB and activin-B (betaBbetaB) functions as an autocrine modulator of FSH production. By contrast, the mRNA for the activin-binding protein, follistatin, is present in most pituitary cells and folliculo-stellate cells may be the major source of the protein secreted by the anterior pituitary. Interleukin-1beta (IL-1beta) is one of several cytokines known to also influence the reproductive axis. IL-1beta inhibits the hypothalamo-pituitary-gonadal (HPG) axis by suppressing GnRH and gonadal steroid production. Because several pituitary cell types, including follistatin-producing folliculo-stellate cells, are targets of IL-1beta, cytokine effects on gonadotrope function were evaluated using cultured rat anterior pituitary cells. Activin-A (0.01 to 1 nM; 24h) increased basal FSH secretion approximately 2-fold. IL-1beta (0.005 to 0.5 nM) by itself had no effect on basal FSH secretion. However, IL-1beta attenuated FSH secretion in response to all concentrations of activin-A. These results suggest that the cytokine might stimulate the local production of a factor, such as follistatin, that antagonizes the action of activin-A. RNase protection analysis indicated that IL-1beta (0.005 to 5 nM) stimulated follistatin and inhibin/activin betaB mRNA accumulation in a time-dependent manner. These in vitro effects of IL-1beta were blocked by the specific IL-1 receptor antagonist (IL-lra) and were not mimicked by either rhIL-6 or lipopolysaccharide (LPS). Treatment of intact male rats with LPS (50 microg, i.v.), which increases plasma IL-1beta and induces IL-1beta expression in many tissues, including the pituitary, produced similar time-dependent increases in pituitary follistatin and inhibin/activin subunit mRNA levels. These results suggest that IL-1beta can modulate gonadotrope responses to activins by influencing the local balance of activin-B and follistatin within the pituitary.

Activins↗
PubMed2001

Pituitary follistatin and activin gene expression, and the testicular regulation of FSH in the adult Rhesus monkey (Macaca mulatta).

In rats, FSHbeta gene expression and FSH secretion are increased and decreased, respectively, by pituitary activin and follistatin. Because little information is available on the paracrine control of FSH secretion in the primate, follistatin and activin/inhibin beta(B) messenger RNA (mRNA) levels were measured in pituitaries of adult male rhesus monkeys 6 weeks after castration or sham surgery (n = 5/group). Follistatin mRNA was determined by quantitative RT-PCR assay using oligonucleotide primers designed to span exons 3-5 of the human follistatin gene. Activin/inhibin beta(B) mRNA levels were measured by ribonuclease protection. Orchidectomy resulted in a 100-fold increase in plasma FSH concentrations and a 60-fold rise in those of LH. In castrated monkeys, levels of mRNA encoding FSHbeta, LHbeta, alpha- subunit, and GnRH receptor (GnRH-R) were increased 21-, 2.1-, 1.7-, and 1.7-fold, respectively (P < 0.01). Levels of pituitary follistatin and activin/inhibin beta(B) mRNAs, however, were similar in castrated and intact animals. These data suggest that the paracrine control of FSH secretion in the male differs substantially in primates and rodents. Specifically, the relatively greater postcastration rise in FSHbeta gene expression and FSH secretion in the adult male monkey may result because in this species pituitary follistatin gene expression does not increase after orchidectomy, as it does in the rat.

Activins↗
PubMed1975

Daily variations of FSH, LH and testosterone response to intravenous luteinizing hormone-releasing factor (LRF) in normal men.

The responses of FSH, LH and testosterone to acute stimulation with synthetic LRF were studied in 6 healthy, fertile men aged 33.4 plus or minus 1.6 yr (X plus or minus SE). Fifty mug of LRF were given, iv at 0600 h, 1200 h, 1800 h and 0000 h, at 1-week intervals, to all 6 volunteers simultaneously. Blood samples were collected by venipuncture before (-5 and 0 min) and 8, 16, 32, 64 and 128 min after LRF injection. Plasma levels of FSH, LH and testosterone were determined by double antibody radioimmunoassay techniques. The responses of FSH and LH to LRF injection showed a clear difference at the times studied. Maximal values were obtained at 0600 h and 1800 h while the response at noon was not significant for LH and absent for FSH. Testosterone secretion showed a clear-cut response to LRF in all the subjects. At three of the four studied times (0600 h, 1800 h, 000 h) plasma testosterone was already increased at 8 min reaching its maximum at 16 min and persisted high until the end of the study. The noon response reached its maximum at the end of the test period. The daily variations of FSH and LH responses to acute LRF stimulation should be taken into consideration in clinical practive and the increment in testosterone secretion makes this test a useful indicator for androgenic testicular reserve.

Adult↗
PubMed1975

Serum LH and FSH responses to the repetitive administration of gonadotropin-releasing hormone in patients with idiopathic hypogonadotropic hypogonadism.

The serum follicle-stimulating hormone (FSH) and luteinizing hormone (LH) responses to the repetitive administration of synthetic gonadotropin-releasing hormone (GnRH) were studied in six male patients with idiopathic hypogonadotropic hypogonadism. Each patient received 50 mug of GnRH intravenously every four hours for 43 consecutive doses, i.e., for one week. Five of the six patients had substantially greater maximum serum LH concentrations in response to the 43rd dose than to the first dose. The mean (+/- SE) maximum serum LH concentration of all six patients following the 43rd dose (14.6 +/- 3.0 mIU/ml) was significantly (P less than 0.01) greater than that to the first dose (8.3 +/- 2.6 mIU/ml. These results suggest that the LH response of the human gonadotroph to GnRH depends on the prior exposure of the gonadotroph to GnRH. All six patients had substantially higher basal serum FSH levels prior to the 43rd dose (13.6 +/- 2.6 mIU/ml) than prior to the first dose (2.8 +/- 0.4; P less than 0.01). Four patients had increases in basal FSH level to within the normal adult male range (5-15 mIU/ml), and two had increases to above it. This uniform elevation of the serum FSH level to normal or above normal suggests that GnRH may be the primary FSH-releasing hormone as well as the primary LH-releasing hormone.

Adolescent↗
PubMed1976

The menopausal transition: analysis of LH, FSH, estradiol, and progesterone concentrations during menstrual cycles of older women.

Studies of menstrual cycle length in large populations demonstrated that there is a striking increase in the variability of intermenstrual intervals just before menopause. The changes in serum concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol (E2), and progesterone (P) during menstrual cycles in a group of perimenopausal women were compared with the findings in young normal women. In 8 women, 46-56 years old with regular cycles, cycle length was shorter and the mean E2 concentration was lower than in younger women. There was a striking increase in FSH concentration throughout the cycle while LH remained in the normal range. In 2 women, 14 cycles of variable length were studied during 2 years of the menopausal transition. In some instances, hormonal changes associated with follicular maturation and corpus luteum function occurred in the presence of high, menopausal levels of LH and FSH with a diminished secretion of E2 and P. In others vaginal bleeding occurred during a fall in serum E2 with no associated rise in P. Cycles of variable length during the menopausal transition may be due either to irregular maturation of residual follicles with diminished responsiveness to gonadotropin stimulation, or to anovulatory vaginal bleeding that may follow estrogen withdrawal without evidence of corpus luteum function. The observation of elevated FSH concentrations and normal LH levels in perimenopausal women emphasizes the complexity of the hypothalamic-pituitary-ovarian regulatory system and suggests that LH and FSH are modulated independently at the level of the pituitary.

Adolescent↗
PubMed1977

FSH and LH secreting pituitary adenoma.

A case of FSH and LH secreting pituitary adenoma which was not preceded by hypogonadism is reported. The patient, a 50-year-old man, was admitted to the hospital because of left temporal hemianopsia. No clinical evidence of hypogonadism was demonstrated. Endocrine studies of hypogonadism was demonstrated. Endocrine studies revealed markedly elevated plasma FSH of 295 mIU/ml and slightly elevated LH of 35 mIU/ml (2nd IRP-HMG). Plasma FSH and LH did not respond to the administration of LRF, conjugated equine estrogens and testosterone. Plasma testosterone was 691 ng/dl and rose nromally after pregnant mare's serum gonadotropin. Sperm count was 46 X 10(6)/ml. Transfrontal hypophysectomy was followed by a marked decrease of both FSH (to 19mIU/ml) and LH (to 22 mIU/ml). Histologic examination of the tumor revealed 90% chromophobe cells and 10% slightly eosinophilic cells. Two sizes of secretory granules were demonstrated. Tumor cells in tissue culture secreted both FSH and LH.

Adenoma↗
PubMed1996

Decreased inhibin B secretion is associated with the monotropic FSH rise in older, ovulatory women: a study of serum and follicular fluid levels of dimeric inhibin A and B in spontaneous menstrual cycles.

UNLABELLED: This study sought to compare circulating and follicular fluid (FF) concentrations of dimeric inhibin A and B utilizing specific two-site ELISAs for these hormones in normal older and younger ovulatory women. METHODS. Normally ovulating women age 40-45 (n = 10) and 20-25 (n = 13) were studied throughout the follicular phase with daily blood sampling, transvaginal ultrasound examinations, and dominant follicle aspiration. When the dominant follicle reached a mean diameter of 16 mm or serum estradiol (E2) was > or = 550 pmol/L, 10,000 IU of hCG was administered intramuscularly followed 32 hours later by transvaginal follicle aspiration. Serum and FF samples were analyzed for E2, FSH, and inhibin A and B. Daily hormone levels were compared by ANOVA, and mean results were compared using t-tests. RESULTS: Older women developed a dominant follicle sooner, meeting criteria for hCG cycle day 10.6 +/- 0.4 vs. 14.5 +/- 1.0 p < 0.001. As expected, the older group had higher maximal serum FSH concentrations compared to the younger women (11.4 +/- 0.5 vs. 8.0 +/- 0.4 IU/L, p < 0.001). We compared hormone concentrations from days-1 to 3 (where day 0 = day of maximal FSH concentration). E2 concentration was higher in the older women (p = 0.002), and there was no significant difference in inhibin A secretion (p = 0.61). In contrast, mean inhibin B concentration was significantly lower in the older women (p = 0.04). On the day of aspiration of the dominant follicle, serum inhibin B was decreased in the older subjects (42.6 +/- 6.5 vs. 153.1 +/- 53 pg/ml, p = 0.02), whereas older subjects had higher levels of inhibin A (106 +/- 16 vs. 60.4 +/- 9.4 pg/ml, p = 0.04) and similar E2 levels (665 +/- 35.2 vs. 687 +/- 92 pmol/L, p = 0.83). There were no differences in FF concentrations of inhibin B (164 +/- 31 vs. 174 +/- 37 ng/ml, p = 0.85), inhibin A (317.7 +/- 38 vs. 248 +/- 57 ng/ml, p = 0.16), or E2 (2074 +/- 294 vs. 2474 +/- 338 nmol/L, p = 0.82) in the older and younger women. CONCLUSION. Follicular phase inhibin B secretion is decreased in older ovulatory women who demonstrate a monotropic FSH rise, whereas inhibin A secretion is similar to that in younger women. The dominant follicle in these older women appears to be normal in terms of FF E2 and inhibin content. We speculate that decreased inhibin B secretion most likely reflects a diminished follicular pool in older women and may be an important regulator of the monotropic FSH rise.

Adult↗
PubMed2001

Importance of inhibin B in the regulation of FSH secretion in the human male.

Regulation of FSH secretion in the male involves a complex balance between stimulation by GnRH from the hypothalamus, inhibitory feedback by sex steroids (T and E2) and inhibin B (Inh B) from the gonads, and autocrine/paracrine modulation by activin and follistatin within the pituitary. The aim of the present study was to delineate the feedback control of FSH in the human male with specific reference to the relative roles of sex steroids vs. Inh B. Two experimental human models were used: 1) normal (NL) men subjected to acute sex steroid withdrawal (-T, -E2, + Inh B), and 2) functional castrate males (-T, -E2, -Inh B). Nine NL men (age range, 25-45 yr) and three castrate males (age range, 23-47 yr) were studied. The NL men underwent acute sex steroid suppression using high dose ketoconazole (1-g loading dose, followed by 400 mg, orally, four times daily for 150 h). Gonadotropin secretion was characterized by frequent blood sampling every 10 min for 12 h at baseline and on d 3 and 6 of sex steroid ablation. In the three castrate subjects, blood sampling was performed every 5 min for 24 h 8 wk after discontinuing androgen replacement therapy. In the NL men, treatment with ketoconazole resulted in a decline to castrate levels in T (451 +/- 20 to 38 +/- 7 ng/dl; P < 0.0005) and E2 (39 +/- 4 to 15 +/- 2 pg/ml; P < 0.005) and a modest, but significant, decline in Inh B levels, which remained within the normal range (183 +/- 19 to 136 +/- 13 pg/ml; P < 0.005). This suppression of sex steroids was associated with a more marked increase in mean LH (9.5 +/- 0.9 to 24.9 +/- 2.0 IU/liter; P < 0.0001) than FSH levels (5.1 +/- 0.7 to 10.0 +/- 1.5 IU/liter; P < 0.005), with the latter not exceeding the normal adult male range. The castrate subjects had a mean T level of 66 +/- 8 ng/dl, an E2 level of 20 +/- 1 pg/ml, and undetectable Inh B levels. Despite a similar sex steroid milieu, the mean FSH levels observed in NL men after acute sex steroid ablation were approximately 6-fold lower than those seen in the castrate subjects (10.0 +/- 1.5 vs. 59.5 +/- 17.7 IU/liter; P < 0.0005). In contrast, mean LH levels in the NL men were less than 3-fold lower than those in castrate subjects (24.9 +/- 2.0 vs. 66.8 +/- 20.1 IU/liter; P < 0.005). From this human model of acute sex steroid withdrawal, we conclude that Inh B is likely to be the major feedback regulator of FSH secretion in the human male.

Adult↗
PubMed2006

PKA implicated in the phosphorylation of Cx43 induced by stimulation with FSH in rat granulosa cells.

Connexin 43 (Cx43)-mediated gap junctional communication in granulosa cells is crucial for germ line development and postnatal folliculogenesis. We previously showed that follicle-stimulating hormone (FSH) promoted phosphorylation of Cx43 in rat primary granulosa cells. We further identified Ser365, Ser368, Ser369, and Ser373 in the carboxy-terminal tail as the major sites of phosphorylation by FSH, and found that the phosphorylation of these residues was essential for channel activity. In this study, we investigated the protein kinase(s) responsible for FSH-induced phosphorylation. H89, a cyclic AMP-dependent protein kinase (PKA) inhibitor, inhibited FSH-induced phosphorylation both in vivo and in vitro, whereas PD98059, a mitogen-activated protein kinase kinase (MEK) inhibitor, had little effect on the phosphorylation level. Ca2+-dependent protein kinase (PKC) appeared to negatively regulate phosphorylation. Phosphopeptide mapping with or without H89 treatment indicated that PKA could be responsible for phosphorylation of the four serine residues. In addition, the purified catalytic subunit of PKA could phosphorylate the recombinant C-terminal region of Cx43, but not the variant in which all four serine residues were substituted with alanine. These results suggest that FSH positively regulates Cx43-mediated channel formation and activity through phosphorylation of specific sites by PKA.

Animals↗
PubMed1997

Ovarian response and FSH profile in cows following injection of various doses of inhibin antiserum.

Dose effect of inhibin antiserum on ovarian response and hormonal profiles were investigated. On day 12 of the estrous cycle (day 0 = estrus), 14 of 19 cows were given a single i.v. injection of 25 ml (n = 4), 37.5 ml (n = 5) or 50 ml (n = 5) antiserum against inhibin produced in a castrated male goat. The other 5 animals were given 50 ml castrated male goat serum (control serum). The animals in each group received a single i.m. injection of 0.5 mg prostaglandin F2 alpha analogue (PG) 48 hr following the serum injection. The population of follicles and ovulation rate (estimated by the number of corpora lutea) were examined by ultrasonography. Administration of inhibin antiserum consistently resulted in a significant (p < 0.01) increase in plasma concentrations of follicle-stimulating hormone (FSH) in inhibin-neutralized groups, although the increased FSH levels were sustained longer in 50-ml group than in the 25- and 37.5- ml groups. Levels in the circulating inhibin antibody titer were positively correlated with dosage of inhibin antiserum. A large number of antral follicles (> or = 4 mm in diameter) developed similarly after hypersecretion of FSH in all neutralized groups, coupled with a rise in plasma estradiol levels, while the number of large follicles (> or = 10 mm in diameter) on estrus showed a dose-dependent increase. Multiple ovulation (2 to 4) was recorded in all animals after injection of 50 ml inhibin antiserum, however all cows in the 25-ml group experienced only one ovulation and injection of 37.5 ml resulted in a variable number of ovulations (1 to 5). These results demonstrated that administration of inhibin antiserum on day 12, followed by injection of PG, was able to induce hypersecretion of FSH and subsequently multiple ovulations. The number of large follicles on estrus day and ovulations were affected by dosage of inhibin antiserum and were correlated with persistence of increased FSH levels or circulating antibody levels.

Animals↗
PubMed1997

Ultrasound-guided follicle aspiration and IVF in dairy cows treated with FSH after removal of the dominant follicle at different stages of the estrous cycle [corrected].

Recently, transvaginal ultrasound-guided follicle aspiration technology has been found to be of great value for in vitro fertilization (IVF) programs, even though the oocyte recovery rate and cleavage rate of transferrable embryos were low. In this study, we investigated the effect of the removal of the dominant follicle at different stages of the estrous cycle on the ovarian response of donor cows. Four experiments (EXPs) were devised. In EXP 1, 3 cows received 20 mg FSH on Day 1, ovulation occurred on Day 0, and on Day 3 follicles were aspirated. In EXP 2, the dominant follicle of the first wave was removed on Day 6 from 3 cows which received 20 mg FSH on Day 7 and on Day 9 follicles were aspirated. In EXP 3, 2 pregnant cows received 20 mg FSH on 70 d of pregnancy and 48 hr later follicles were aspirated a total of 5 times at 5-day intervals. In EXP 4, after ovulation on Day 0, 9 cows received 20 mg FSH on Days 8 to 14 of the estrous cycle and 48 hr after the last injection, follicles were aspirated once. The respective mean +/- SD numbers of aspirated follicles and recovered oocytes were higher (p < 0.01) in EXP 1 (13.4 +/- 1.7 and 8.7 +/- 2.3), EXP 2 (12.1 +/- 1.4 and 7.7 +/- 1.7) and EXP 3 (10.7 +/- 2.1 and 7.0 +/- 2.2) than in EXP 4 (5.8 +/- 2.3 and 3.1 +/- 1.6). The oocyte recovery rates were higher (p < 0.05) in EXP 1, EXP 2 and EXP 3 than in EXP 4. Similarly, the respective numbers of viable oocytes and cleavage rates were higher in EXP 1, EXP 2 and EXP 3 (6.0 +/- 1.3, 5.0 +/- 1.1 and 4.6 +/- 1.5 viable oocytes (p < 0.01); 66, 73 and 65% cleavage rates (p < 0.05)) than in EXP 4 (2.4 +/- 1.1; 46%). The numbers of morulae and blastocysts were higher (p < 0.05) in EXP 1, EXP 2 and EXP 3 than in EXP 4. In conclusion 1) removal of the dominant follicles from lactating and pregnant cows enabled viable oocytes to be recovered constantly and repeatedly by aspiration at different reproductive stages, and that viable blastocysts can be produced after IVF. 2) The presence or absence of a dominant follicle significantly affects the ovarian responses to FSH treatment. 3) This ultrasound-guided procedure proved to be an effective, repeatable and safe method for viable oocyte recovery from valuable pregnant donors.

Animals↗
PubMed1984

[The physiological significance of the hippocampus on the inhibitory effects of corticosterone upon the estradiol-induced LH and FSH surges in rats].

The effects of corticosterone (CS) on the gonadotropin surge induced by estradiol-benzoate (E2) were studied in adrenalectomized and ovariectomized (ADRX-OVEX) rats. The results are as follows. In ADRX-OVEX rats implanted with E2-tablets in the bilateral axillae, LH and FSH surges occurred 4 days after the implantation of E2, peaking at 17:00 h. The levels of these surges were markedly higher than those in OVEX rats similarly treated but were attenuated significantly by the subcutaneous injection of CS (25 micrograms in sesame oil) given at 12:00 h. The CS implantation (0.5 micrograms in 2 microliters sesame oil) into the dorsal hippocampus at 15:00 h significantly inhibited the levels of LH and FSH surges in ADRX-OVEX rats with E2-tablets. The effect of the CS implant in the lateral septal nucleus was also inhibitory but not statistically significant. The CS administration in the ventral part of the midbrain tegmentum did not elicit any change in the surge of LH and FSH. In animals with the dorsal fornix-section at the post-anterior-commissural level, surges of LH and FSH also occurred in the afternoon of the 4th day after the E2-tablets implantation, but the levels of LH and FSH were not significantly altered by an intravenous injection of CS (5 micrograms in saline) at 15:30 h. It was suggested the CS circulating in the blood would induce a rise of hippocampal activity which would exert a suppressive influence on the gonadotropin release.

Adrenalectomy↗