FSH Response Research Articles

Hypothalamic-pituitary-testicular function in end-stage non-alcoholic liver disease before and after liver transplantation.

Gonadal dysfunction is common in chronic liver disease, but most of the previous studies have been restricted to men with alcohol-induced liver disease. We have evaluated hypothalamic-pituitary-testicular function in patients with end-stage non-alcoholic liver disease before and at 6 and 12 months after hepatic transplantation. A prospective study of hypothalamic-pituitary-testicular endocrine function before and after cadaveric hepatic transplantation. Fifty four consecutive patients with end-stage, non-alcoholic liver disease were evaluated before and after liver transplantation. Hypothalamic-pituitary-testicular (HPT) axis function was evaluated under basal conditions by single morning measurements of plasma total and free testosterone, sex hormone-binding globulin and by plasma LH and FSH responses to 100 micrograms i.v. GnRH. Men with chronic non-alcoholic liver disease had reduced levels of total and free testosterone and increased levels of SHBG compared with controls with normal liver function. Total and free testosterone were positively correlated with basal and stimulated LH (but not FSH) concentrations. Gonadotrophin responses to GnRH were preserved but delayed compared with healthy controls consistent with a predominantly hypothalamic defect in regulation of pituitary-testicular function. Increasing severity of underlying liver disease was associated with declining total and free testosterone as well as peak GnRH-stimulated LH concentrations. Spironolactone treatment was associated with decreased circulating testosterone levels only in men with liver disease of intermediate severity (Child-Pugh class B). Following hepatic transplantation, total and free testosterone and SHBG concentrations returned progressively towards eugonadal control levels over the first 12 months but total and free testosterone levels remained subnormal. Hypothalamic-pituitary regulation of testicular function is impaired in end-stage non-alcoholic liver disease in proportion to the severity of underlying liver disease. Spironolactone reduces circulating testosterone but only among men with Child-Pugh B liver cirrhosis. Gonadal function improves, but is not normalized, over the first year following successful liver transplantation.

Alterations in hypophysial responsiveness to synthetic GnRH at different postpartum intervals in Murrah buffalo ( [formula omitted

The objective of this study was to investigate the hypophysial responsiveness to GnRH at different intervals post partum in Murrah buffalo. Plasma LH and FSH levels were measured at 1 h before and upto 6 h subsequent to the administration of GnRH (1 ug/kg body weight) or saline on Days 2, 20 and 35 post partum in 2 groups of buffalo (n=4 each). Plasma progesterone levels were measured in samples collected once daily from Day 3 to Day 46 post partum. Pretreatment basal LH levels exhibited a progressive increase from Day 2 through Day 35 post partum, while the basal FSH levels increased only until Day 20 post partum. Following a highly subdued LH response to GnRH on Day 2 post partum, a 408% increase (P < 0.01) was observed in the total LH released in response to GnRH on Day 20 post partum, followed by a 20% reduction (non-significant) over Days 20 to 35 post partum. The interval from parturition was highly correlated with total LH released (r = 0.711, P < 0.01). Unlike LH, a substantial amount of FSH was released following GnRH treatment on Day 2 post partum, which was not significantly different from the FSH response on Days 20 and 35 post partum. The LH and FSH response to GnRH was not significantly different between animals in which luteal activity resumed and in those which showed no luteal activity post partum. While pointing to a dramatic enhancement in the hypophysial responsiveness to GnRH between Days 2 and 20 post partum, these results suggest that pituitary responsiveness to GnRH does not appear to be the limiting factor for resumption of estrous cycles by Day 35 post partum in Murrah buffalo.

Effect of haemoglobin and endogenous erythropoietin on hypothalamic-pituitary thyroidal and gonadal secretion: an analysis of anaemic (high EPO) and polycythaemic (low EPO) patients.

Correction of anaemia with recombinant human erythropoietin (rHu-EPO) improves the responsiveness of thyroidal and gonadal axes to exogenous TRH and GnRH in chronic haemodialysis patients, but the mechanisms remain to be fully elucidated. In order to assess the influences of endogenous erythropoietin on the hypothalamo-hypophyseal thyroidal and gonadal axes, we studied the response of polycythaemic and anaemic patients, in comparison to normal controls, after the administration of exogenous TRH and GnRH. Exogenous hypothalamic factors, 500 micrograms TRH and 100 micrograms GnRH, were administered as a bolus and blood samples were obtained over a 3-hour period at 30, 60, 90, 120 and 180 minutes. Five male polycythaemic patients (low EPO), three male anaemic patients (high EPO) and six normal age and sex matched controls were studied. Blood samples were centrifuged immediately and the serum was stored at -20 degrees C until assayed for total T4, free T4, free T3, TSH, prolactin, growth hormone (TRH test), and FSH, LH, testosterone (GnRH test). Haematological parameters and biochemical profiles were also measured. After TRH administration, both patient groups showed a normal TSH response; however, their free T4 and free T3 secretion was blunted compared to controls. Normal basal PRL levels increased in an exaggerated fashion, whereas, when compared to chronic renal failure patients on chronic haemodialysis, we did not see a paradoxical GH response or a basal GH increase in these 5 patients. GnRH administration in the study groups elicited a normalization in the LH response without an increase in testosterone levels; however, an exaggerated FSH response was found in the polycythaemic patients (low EPO). Thus by investigating the role of low endogenous EPO levels in non-anaemic and anaemic patients with high EPO levels, our study suggests that the underlying chronic disease state may be the major contributing factor in the regulation of the hypothalamo-hypophyseal thyroid and gonadal axes, rather than the EPO levels.

Effect of retinol palmitate on ovulation rate and embryo quality in superovulated cattle

We evaluated the influence of administration of retinol palmitate (Vitamin A) on ovulation rate and embryo quality in 48 beef cows superovulated with 2 different doses of FSH. Synchronization of estrus was accomplished by giving 2 injections of prostaglandin F 2α (PGF) 11 d apart. Multiple ovulation was induced by giving a total of either 32.5 mg or 27 mg of FSH over 4 d beginning on the 8th to 10th d post estrus. Within FSH dose, cows received either 1 million IU of Vitamin A (im) in corn oil or an equivalent volume of corn oil alone on the 1st d of FSH injections. Embryos were recovered nonsurgically and evaluated 7 d post estrus. Ovulation rate was estimated on the day of embryo recovery by use of transrectal ultrasonography and actual counts of corpora lutea were made on ovaries taken at slaughter following embryo recovery. The FSH response rate (percentage of cows with multiple ovulations) for all cows was 65.9% and was not affected by FSH dose or Vitamin A. Cows with less than 20 ovulations had a higher percentage of total embryos recovered (59.6 vs 35.8%; P = 0.002), and more of those embryos were transferable (36.2 vs 14.3%; P = 0.005) compared to cows with more than 20 ovulations. The dose of FSH did not affect embryo quality or the total number of embryos recovered, but the lower dosage resulted in more ovulations per cow (26.7 vs 18.0; P = 0.03). Vitamin A did not affect ovulation rate or total embryos recovered, but it increased the mean number of high quality (Grades 1 and 2; 4.25 vs 1.86; P = 0.01) and total transferable embryos (Grades 1, 2 and 3; 5.87 vs 3.13; P = 0.04). The mean number of blastocysts was greater for Vitamin A-treated cows (2.25 vs .73; P = 0.02). Means for nontransferable embryos were not different between FSH dose or Vitamin A treatment groups. These findings suggest that 1) ovulation rates above 20 per cow do not yield gains in total or transferable embryos, and 2) Vitamin A may improve embryo quality without affecting ovulation rate in superovulated cattle.

A simplified gonadotrophin‐releasing hormone test for precocious puberty

The gonadotrophin-releasing hormone (GnRH) test is important for the evaluation of children with disorders of puberty. Traditionally, the test determines the peak LH and the peak FSH responses from 5 to 8 blood samples, which makes it cumbersome and costly. We suspected that the test could be simplified to require fewer hormonal measurements. A retrospective clinical study. Subjects were 44 girls and 7 boys with signs of precocious puberty, of whom 39 were diagnosed as definite central precocious puberty. Fifty-five diagnostic tests and 39 tests for suppression during GnRH-analogue treatment were reviewed. LH and FSH were measured in serum samples obtained during a standard GnRH test. LH and FSH responses and the LH:FSH ratio at 30, 45 and 60 minutes, and the respective peak levels. For each parameter, the sensitivities and specificities were estimated and the receiver operating characteristic curve was constructed. The receiver operating characteristic curves for the LH responses at 30, 45 and 60 minutes and peak, were similar and showed high specificities and sensitivities for the diagnosis of central precocious puberty. A single LH cut-off (15 IU/I) had diagnostic sensitivity > 90% and specificity > 80% for LH concentrations at 30, 45 or 60 minutes and peak, and sensitivity > 90% to detect suppression. Calculations of the LH:FSH ratio did not improve the diagnostic accuracy of the GnRH test achieved by LH alone. A single LH determination 30 minutes after GnRH administration is as useful as the peak LH; FSH measurements are unnecessary for the differential diagnosis of central precocious puberty. We propose that for the diagnosis of central precocious puberty and for treatment monitoring, the GnRH test to be simplified to LH measurement in a single blood sample at 30 minutes.

Gonadotrophin and gonadal steroid response to a single dose of a long‐acting agonist of gonadotrophin‐releasing hormone in ovulatory and anovulatory women with polycystic ovary syndrome

A previously published study has identified that anovulatory women with PCOS have an increased response of 17 alpha-hydroxyprogesterone (17OHP) and androstenedione to a GnRH analogue suggesting dysregulation of cytochrome P450c17 alpha. The object of this study was to compare the responses of the pituitary-ovarian axis to a single dose of a long-acting GnRH agonist (GnRHa) in both ovulatory and anovulatory women with PCOS with those in normal subjects. Comparative study of responses of LH, FSH and ovarian steroids to buserelin and the adrenal steroid response to synthetic ACTH in two groups of women with hyperandrogenaemia and polycystic ovaries: those with anovulatory menses or amenorrhoea and those with equally elevated serum testosterone concentrations but regular menses. Results in both groups of women with PCO were compared with those in normal subjects. Twenty-four women with hyperandrogenism and PCO (14 had oligo or amenorrhoea, 10 regular cycles) and 12 weight matched controls with normal ovaries, regular cycles and neither clinical nor biochemical evidence of hyperandrogenism. Subjects were given synthetic ACTH (Synacthen) 250 micrograms i.v. on day 1 of the study and blood collected at 30 and 60 minutes thereafter. On the evening of day 1, dexamethasone treatment was commenced to suppress adrenal androgens. GnRHa 100 micrograms s.c. was given on day 2 and blood samples collected at 30-minute intervals for 4 hours and once more at 24 hours after the injection. The acute responses of both immunoactive and bioactive LH to GnRHa were significantly greater in the ovulatory PCO group (ovPCO) than controls but the response was greater in anovulatory women with polycystic ovaries (anovPCO) than in either ovPCO or controls, throughout the 24-hour study period. Despite the discrepancy in LH concentrations, basal serum concentrations of androstenedione were equally elevated in anovulatory and ovulatory women with PCO, compared with controls. There was a small but significant increase in androstenedione following GnRHa in both PCO groups at 24 hours but not in controls. A similar pattern was observed in the response of 17OHP to GnRHa although the response was significantly higher than controls in anovPCO women only. By contrast, the responses of both androstenedione and 17OHP to 250 micrograms synthetic ACTH were similar in PCO women to those in controls. These data provide evidence for ovarian hypersecretion of androgens in ovulatory, as well as anovulatory women with PCO, supporting the concept of abnormal regulation of 17-hydroxylase and (17,20-lyase activity in the ovary. The finding of an equal degree of hyperandrogenaemia in ovPCO and anovPCO groups, even though LH levels were much higher in the latter, suggests that hypersecretion of LH is not the primary cause of ovarian hyperandrogenism. Hyperandrogenism in PCOs may therefore represent an intrinsic abnormality of ovarian theca-interstitial cell function.

Protein kinase C inhibition of in vitro FSH-induced differentiation in pig granulosa cells

In granulosa cells, growth factor IGF I plays a major role in both growth and differentiation, acting through an autocrine/paracrine mechanism, and its production is regulated by FSH, via cyclic AMP (cAMP). As protein kinase C is also involved in granulosa cell function, we investigated the possibility that its activation could balance the positive effects of FSH. Using pig granulosa cells cultured in vitro, we studied the effects of protein kinase C activation by tetradecanoylphorbol acetate (TPA) on IGF I mRNA level. We also checked morphological modifications, cAMP production and steroidogenesis at the P450 side chain cleavage mRNA and progesterone levels. Our data demonstrate that protein kinase C activation antagonizes the in vitro FSH-induced diferentiation, particularly morphological modifications and accumulation of IGF I mRNA. These inhibitory effects on FSH responses suggest that there could be a balance between protein kinase A and protein kinase C pathways in regulating differentiation in pig granulosa cells.

9 PSEDOPRECOCIOUS PUBERTY IN A BOY WITH PEUTZ-JEGHERS SYNDROME (PJS) AND FEMINIZING SEXCORD TUMOR (SCT). EFFECTS OF TREATMENT WITH KETOCONAZOLE (KTZ)

The association of PJS and SCT is rare. Gynecomastia and advanced bone age in the affected individuals depends of estradiol secretion. KTZ inhibit p450-cythochrome dependent enzyme 17,20 - 1 lyase and hence testosterone synthesis. We report a case of a 6,5 y old white boy with gynecomastia. Height 90th and weight 25th centiles; melanotic spots in nose and lips; breasts Tanner stage III at right and II at left; no pubic hair; penile length was at 50th centile: testes 4 ml with no palpable masses. BA was 9,5 y. Brain CT and ultrassonograpy (US) and CT of the abdomen were normal; US of the gonadas showed multiple areas of hyperechogenicity. GI RY series with polips in stomach and duodenum. Alpha-fetoprotein and carcinoembrionic antigen were negative.17KS: 11,4 umol,and 17 OHCS: 21,8 umol; undetectable b-HCG;normal prolactin; two LH-RH tests without response of both FSH and LH; random E2 serum concentrations were normal in one occasion (42.2 pmol/L) and elevated in another (205.6 pmol/L); basal and post-HCG serum testosterone were 0.4 and 17.3 nmol/L respectively, Bilateral testicular biopsy revealed a SCT. The father, father's brother and sister, and a 9 old sib have PJS. Started on KTZ until reaching 600 mg/day (for 19 months). Liver function not affected. Gynecomastia waned completely at left and has been stage II (soft) at right. Testes are 6ml; BA (11 y) advanced 1.5 years in the last 2.1 years, though the treatment started 6 months after the first BA evaluation. PAH was 170 cm before therapy, and is currently 1.75 cm., KTZ appears to be an promising therapeutical approach

Preoperative octreotide treatment of growth hormone-secreting and clinically nonfunctioning pituitary macroadenomas: effect on tumor volume and lack of correlation with immunohistochemistry and somatostatin receptor scintigraphy.

The factors that determine the hormone and volume responses of pituitary adenomas to the somatostatin analog octreotide are poorly understood. We, therefore, studied the correlation between 111indium-pentetreotide somatostatin receptor scintigraphy (SRS) and the clinical and immunohistochemical classification of pituitary adenomas, on the one hand, and hormone and volume responses, on the other hand. Ten patients with GH-secreting (6 females and 4 males; age, 31-67 yr) and 14 patients with clinically nonfunctioning (NF) macroadenomas (5 females and 9 males; age, 22-79 yr) were preoperatively treated with 300 micrograms/day octreotide, which was increased to 600 and 1500 micrograms/day at weekly intervals and then continued for at least 3 months until surgery. SRS was performed before therapy. A sellar magnetic resonance imaging scan was performed before therapy; 1, 2, and 3 weeks and 3 months after start of therapy; and after surgery. Acromegalics also had an 8-h GH profile, insulin-like growth factor-I determination, and a 100-g oral glucose load at these time points. An attempt was made to identify NF adenomas as gonadotroph adenomas using their LH, FSH, and alpha-subunit responses to TRH. In acromegalic patients, octreotide suppressed mean GH (8-h profile) and insulin-like growth factor-I concentrations from 34.9 +/- 9.7 to 8.1 +/- 3.6 micrograms/L and from 2122 +/- 1025 to 701 +/- 208 micrograms/L, respectively, after 3 months. Significant (26-85% decline) tumor shrinkage occurred in 5 of 10 patients, mainly within the first week. Tumor shrinkage and GH suppression were not correlated. Four of 7 patients had increased pituitary 111indium-pentetreotide uptake, but this did not predict GH suppression or tumor shrinkage. Of the NF adenomas, 2 responded with shrinkage (57% and 96% decline). Four of 12 adenomas had increased 111indium-pentetreotide uptake, but this did not correlate with tumor shrinkage (2 adenomas; 1 gonadotroph and 1 null cell adenoma), immunohistochemistry, or clinical classification. We conclude that preoperative octreotide therapy suppresses GH in most patients and reduces tumor volume in up to 50% of acromegalic patients. It also induces shrinkage in some NF adenomas, although less frequently. SRS does not predict shrinkage of either tumor type. Shrinkage does not correlate with clinical classification or immunohistological characteristics. Further studies are needed to identify the factors that determine the hormone and volume responses of pituitary adenomas to octreotide therapy.

Gonadotropin secretion in ovariectomized Chinese Meishan and hybrid large white gilts; responses to challenges with estradiol benzoate, gonadotropin-releasing hormone, or porcine follicular fluid.

Castrated Meishan (MS) and hybrid Large White (hLW) gilts were used in a series of challenge experiments to establish differences in the control of gonadotropin secretion. Acutely ovariectomized gilts (72 h) were injected i.m. with 10 micrograms/kg estradiol benzoate (EB) and serially bled for evaluation of estradiol clearance from the blood and patterns of LH and FSH release. Estradiol was more rapidly metabolized from the circulatory system of the acutely ovariectomized MS gilts than from the hLW gilts; as a consequence, hLW gilts had higher concentrations of estradiol than MS gilts at 24-32 h (p < 0.05) and 48-60 h (p < 0.01) post-EB treatment. The hLW but not the MS gilts exhibited a classic negative/positive LH response to EB; MS gilts responded with a random release of large episodes of LH. Plasma FSH concentrations were consistently greater (p < 0.05) in acutely ovariectomized MS gilts than in hLW gilts. Both breeds demonstrated a slight negative FSH response to EB and then exhibited increased variability in plasma FSH with time after treatment. Mean plasma LH was immediately elevated in chronically ovariectomized (> 14 days) hLW and MS gilts given 1 microgram/kg of GnRH i.m., but the magnitude of the LH response was greater (p < 0.01) in the hLW gilts. Comparable differences (p < 0.01) in FSH secretion were also observed, indicating the presence of greater pools of releasable FSH and LH in the hLW gilts, or a greater sensitivity to GnRH.(ABSTRACT TRUNCATED AT 250 WORDS)

Potential for fertility with replacement of hypothalamic gonadotropin-releasing hormone in long term female survivors of cranial tumors.

Dysfunction of the hypothalamic-pituitary axis presenting as hypogonadotropic amenorrhea is a common sequelae of treatment for cranial tumors with surgery and/or radiation. We hypothesized that the site of the defect in this condition is hypothalamic, rather than pituitary, in the majority of patients. Nine women with acquired hypogonadotropic hypogonadism after treatment with transphenoidal pituitary surgery (n = 3), transphenoidal surgery plus conventional radiotherapy (XRT; n = 1), hypothalamic surgery plus XRT (n = 2), or XRT with or without noncentral nervous system surgery (n = 3) underwent assessment of endogenous pulsatile LH secretion and a standard GnRH test followed by iv administration of a physiological replacement regimen of exogenous GnRH. A total of 25 cycles were completed at doses of 75 or 100 ng/kg.bolus. Ovulation occurred in 78% of patients, with all ovulatory patients who desired fertility becoming pregnant. The hormonal responses in these cycles did not differ from the patterns of sex steroids and gonadotropins in normal women. The response to pulsatile GnRH was not influenced by GH deficiency or PRL abnormalities. Of the two patients who failed to ovulate, there was no evidence of folliculogenesis in one, whereas the second consistently developed follicles, but proved incapable of mounting a LH surge despite adequate preovulatory estradiol levels. Both patients had a history of pituitary radiation and surgery. There was no consistent relationship between the results of GnRH testing and the pattern of pulsatile LH secretion. However, the only patient who failed to achieve folliculogenesis was the only patient without a FSH response to GnRH testing and an apulsatile baseline study. Hypothalamic GnRH deficiency is the etiology of hypogonadism in the majority of patients after treatment with hypothalamic or pituitary surgery or cranial irradiation. Therefore, exogenous pulsatile GnRH represents a physiological replacement therapy that completely restores normal gonadotropin dynamics, resulting in ovulation and fertility.

Plasma concentrations of FSH, LH, thyroid-stimulating hormone and growth hormone after exogenous stimulation with GnRH, TRH and GHRH in Booroola ewes that are homozygous carriers or non-carriers of the FecB gene

The aim of the present study in Booroola ewes, either homozygous (BB) or non-carriers (++) of the FecB gene, was to test the specificity of the pituitary responses to exogenous hypothalamic releasing hormones by examining the plasma concentrations of FSH, LH, thyroid-stimulating hormone (TSH) and growth hormone (GH) after injecting the animals with different doses of GnRH, thyroid-releasing hormone (TRH) or growth-hormone-releasing hormone, (GHRH) which were administered on separate occasions. The animals (n = 8 per dose) received 0, 3.1 or 12.5 micrograms of thyroid-releasing hormone and GnRH (i.v.), whereas they (n = 9-13 per dose) received 0, 6.0 or 16.0 micrograms GHRH (i.v.). For each experiment there were no differences between the genotypes in bodymass or age. Gene-specific differences in the mean pretreatment concentrations of plasma FSH (BB > ++; P < 0.05) but not of LH, TSH or GH were noted. After treatment with GnRH, TRH or GHRH, significant effects of dose were noted for all the hormones; however, a gene-specific effect was observed only for FSH in response to GnRH (BB > ++; P < 0.01) with no genotype x dose interaction (ANOVA). For LH, the effects of genotype and the genotype x dose interaction almost reached significance at the 5% level (genotype, P = 0.055; genotype x dose, P = 0.067). For TSH and GH the respective genotype x dose interactions were not significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Nutritional manipulation of growth and metabolic and reproductive status in prepubertal gilts.

Reproductive status, metabolic state, and carcass composition were compared in prepubertal littermate gilts of 85 kg BW and identical ages after allocation to one of two feeding regimens at 75 kg, either twice-daily feeding to appetite up to 85 kg and then maintenance feeding until slaughter (Group 85AR) or an initial period of maintenance feeding at 75 kg and then feeding to appetite to reach 85 kg (Group 85RA). Other littermates were studied at the start of treatment (Group 75C) and after the initial period of feeding to appetite (Group 85A) or maintenance feeding (Group 75R). In the absence of differences in backfat depth or longissimus muscle area, Group 85RA gilts showed increased follicular development (P < .001) compared with their feed-restricted Group 85AR littermates. Plasma LH (P < .001) and FSH (P < .02) responses to an LHRH challenge differed between these same groups. Feed restriction reduced preprandial glucose, postprandial cortisol, and insulin (P < .05), total plasma IGF-I, and basal and postprandial free triiodothyronine (T3; all P < .001) at all stages of the experiment. Postprandial insulin, pre- (P < .001) and postprandial free T3, and plasma IGF-I (P < .001) increased in response to refeeding (Group 75R vs 85RA). These data indicate that changes in metabolic status can mediate short-term nutritional effects on reproductive function, in the absence of changes in age, weight, and widely used indices of body composition, and also establish the short-term, feed-restricted, prepubertal gilt as an effective model for studying the mechanisms mediating nutrition-reproduction interactions.

Maturation of the normal pituitary-testicular axis, as assessed by gonadotropin-releasing hormone agonist challenge.

Pilot studies in boys with abnormalities of puberty have suggested that both gonadotropin and sex steroid responses to GnRH agonist undergo characteristic maturational changes. However, it is not known how the pattern of hormonal secretory responses to GnRH agonist changes during normal puberty. Therefore, we have assessed the responses of normal boys at various stages of pubertal development to a single dose of the GnRH agonist nafarelin. Baseline LH, FSH, testosterone (T), estradiol (E2), and steroid intermediates, including 17-hydroxyprogesterone, increased during puberty. LH responses peaked at 3 h in prepubertal (P1; n = 8) and midpubertal (P2; n = 4) boys, at 12 h in late pubertal (P3; n = 8) boys, but earlier (0.5-1 h) in adults (P4; n = 10). LH levels remained high for 24 h in P3-P4. Indexes of both the readily releasable and reserve pools of pituitary LH increased significantly with advancing pubertal stage (P < 0.003). FSH responses differed among groups only at 24 h. Nafarelin stimulated T significantly in groups P2 < P3 < P4. The maximal responses of T were 0.54 +/- 0.25 (+/- SEM), 8.7 +/- 2.9, 18.5 +/- 1.0, and 15.3 +/- 1.4 nmol/L in these respective groups (by analysis of variance, F = 40.5; P < 0.001). However, nafarelin did not stimulate E2 significantly until late puberty; the maximal E2 responses to nafarelin treatment were 17.9 +/- 5.9, 26.7 +/- 8.7, 318 +/- 71.3, and 329 +/- 17.4 pmol/L in P1, P2, P3, and P4 (F = 18.3; P < 0.001). In contrast to E2, most intermediate steroids measured increased significantly in response to nafarelin in stages P2-P4. We conclude that a single dose of the GnRH agonist nafarelin stimulates gonadotropin secretion in normal prepubertal and pubertal males; it also stimulates gonadal steroid production in pubertal males. Pubertal maturation of gonadotrope function appears to involve mainly increases in both the readily releasable and reserve pools of LH. The findings that late pubertal boys had LH responses similar to those of men, but greater T and lesser 17-hydroxyprogesterone outputs are compatible with their pituitary-testicular axis operating at a less down-regulated state than that of adults. The apparently isolated failure of E2 to increase in response to nafarelin in early puberty suggests that maturation of aromatase activity normally does not become appreciable until late puberty. These findings suggest that a single dose of GnRH agonist may provide a simple means of assessing the maturation of the neuroendocrine-testicular axis.

LH and FSH response to submaximal GnRH stimulation in depressed and healthy subjects

LH and FSH response to submaximal GnRH stimulation in depressed and healthy subjects

Extrapituitary actions of gonadotropin-releasing hormone: stimulation of insulin-like growth factor-binding protein-4 and atresia.

To understand how the intrinsic GnRH system functions in the ovary, we tested the effects of GnRH agonist (GnRH-a) on insulin-like growth factor-binding protein-4 (IGFBP-4) production, a novel marker of atresia. We also tested the ability of GnRH-a to stimulate atresia in vivo. When rat granulosa cells were cultured in defined medium for 2 days (controls), relatively large amounts of the 24,000 relative molecular mass IGFBP-4 accumulated in the medium. FSH (100 ng/ml) inhibited control IGFBP-4 protein levels and stimulated IGFBP-4 protease activity. GnRH-a increased (up to 4-fold) IGFBP-4 accumulation in the medium (ED50 = 1 x 10(-10) M), and the effect was blocked by a GnRH antagonist. Neither GnRH-a nor its antagonist had a detectable effect on protease activity. In coincubation experiments, GnRH-a effectively inhibited (ED50 = 3 x 10(-11) M) the FSH responses, and the effect of GnRH-a was blocked by GnRH antagonist. A 6-day time-course experiment showed that IGFBP-4 accumulation in control cultures remained constant for 2 and 4 days, after which it was undetectable. FSH (100 ng/ml) produced no measurable IGFBP-4 over the 6-day time course. The levels of IGFBP-4 increased markedly during the first 2 days of GnRH-a treatment, but were not significantly different from control levels on days 4 and 6. Similar results were obtained when cells were treated with FSH plus GnRH-a. Treating immature hypophysectomized estrogen-primed rats with GnRH-a in vivo caused a rapid and dramatic decrease (average, 60%) in the mitotic index of the granulosa cells of all preantral follicles (healthy and atretic) and increased pyknosis. These results demonstrate that 1) GnRH-a stimulates the expression of IGFBP-4 protein in rat granulosa cells in vitro; 2) GnRH-a abolishes the ability of FSH to inhibit IGFBP-4 expression and induce IGFBP-4 protease activity; and 3) GnRH-a stimulates atresia in preantral follicles in vivo. These results support the hypothesis that autocrine/paracrine secretion of ovarian GnRH might cause atresia by mechanisms involving increased IGFBP-4 synthesis.

Activation of inositol phospholipid turnover and calcium signaling in rat Sertoli cells by P2-purinergic receptors: modulation of follicle-stimulating hormone responses.

To study the role of extracellular nucleotides in the regulation of Sertoli cells, the effects of ATP and its analogs on the Ca(2+)-phospholipid- and cAMP-dependent pathways were tested. Cultured Sertoli cells from immature animals were incubated with ATP or structurally related compounds, and phosphoinositide (PI) turnover or cAMP accumulation was measured. Among the several nucleotide phosphate analogs tested, adenosine 5'-O-(3-thiotriphosphate) was the agonist most potent in stimulating inositol phosphate accumulation. The effects of purine nucleotides on PI turnover were time and concentration dependent. Because nonhydrolizable ATP analogs also stimulated PI turnover, ATP metabolites or metabolic products are not responsible for the observed stimulation. The order of potency of the different ATP analogs [adenosine 5'-O-(3-thiotriphosphate) > ATP approximately equal to UTP > beta, gamma-methyleneadenosine 5'-triphosphate, 2-methylthio-ATP > adenosine] was consistent with the presence of P2U receptors (nucleotide receptors) on the surface of the Sertoli cell. Augmented PI turnover was accompanied by a transient increase in Ca2+ concentration, measured in single Sertoli cells loaded with the intracellular Ca2+ indicator fura-2. When used alone, ATP and its analogs did not have a direct effect on cAMP levels in the Sertoli cell. However, ATP or its analogs inhibited FSH-dependent cAMP accumulation by more than 70%. Purine nucleotides also efficiently blocked the effects of FSH distal to cAMP accumulation, because extracellular ATP completely reversed the changes in Sertoli cell shape induced by FSH. The nucleotide-dependent inhibition of cAMP accumulation was blocked by pertussis toxin to a different degree depending on the purine or pirimidine nucleotide used. This indicated that more than one mechanism contributes to the purine nucleotide-dependent inhibition of cAMP accumulation. These data provide evidence that purine nucleotide receptors coupled to multiple pathways are present on the Sertoli cell in culture, and that extracellular ATP has profound biological effects on the FSH responsiveness of the Sertoli cell.

Suppression of sex steroids by a gonadotrophin‐releasing hormone agonist increases serum growth hormone‐binding protein activity in girls with central idiopathic precocious puberty

The high-affinity growth hormone (GH)-binding protein corresponds to the extracellular domain of GH receptor. The direct role of sex steroids in pubertal bone growth may be an increased GH receptor-coupled GH action. We examine the GH-binding protein (GHBP) activity before and after the suppression of female sex steroids and the relation of GHBP to pubertal growth. We studied six girls with central idiopathic sexual precocity without any prior gonadal suppression therapy. We measured GHBP activity before and 12, 24 and 48 weeks after the treatment with s.c. injection of a GnRH agonist (leuprolide acetate) every 4 weeks. GHBP activity was measured by immunoprecipitation using anti-GH receptor monoclonal antibody. The treatment caused a decrease in the LH and FSH responses to GnRH test and plasma oestradiol, which resulted in decreased urinary GH excretion, plasma IGF-I levels, height velocity and bone age maturation. GHBP activity before the start of the treatment was normal (75 +/- 27% relative to adult pooled serum, mean +/- SD), and it was increased above adult level (122 +/- 29% at 48 weeks, P < 0.01) by the suppression of the pituitary-gonadal axis. There were significant negative correlations between GHBP and oestradiol (r = 0.452, n = 24, P < 0.05) and between GHBP and urine GH excretion (r = -0.462, n = 24, P < 0.05). The high-affinity GHBP is increased by the withdrawal of female sex steroid. The clinical significance of this finding may be interference with the binding of GH to its receptor resulting in a reduced IGF-I level and decreased height velocity. The mechanism warrants further study.

The Impact of a Pure Anti-Androgen (Flutamide) on LH, FSH, Androgens and Clinical Status in Idiopathic Hirsutism

Service d'Endocrinologie et des Maladies de la Reproduction, Hopital Bicêtre, Kremlin Bicêtre, France

Usefulness of thyrotropin-releasing hormone test, SMS 201-995, and bromocriptine in the diagnosis and treatment of gonadotropin-secreting pituitary adenomas.

Five patients with gonadotropin-secreting pituitary adenomas were studied. The utility of gonadotropin response to TRH stimulation in the diagnosis and follow-up of these tumors was evaluated, as well as the effects of somatostatin analogue SMS 201-995 and bromocriptine on gonadotropin release. Three patients had FSH and LH secreting adenomas while the other two tumors secreted FSH and alpha-subunit. Transsphenoidal resection of the pituitary adenomas were performed in all patients. Following preoperative TRH administration (400 micrograms i.v.), marked increases were observed in FSH levels in two cases, in LH levels in three and in alpha-subunit in one. The FSH and LH responses to t.his stimulus persisted in the same patients after surgery. Following acute bromocriptine administration (5 mg orally), FSH was reduced in all cases by 19% to 46%, LH in three cases by 50-67% and alpha-subunit in one by 33%. In patient no. 5, with persistent high FSH levels in the immediate postoperative period, long-term bromocriptine treatment was administered (15 mg/d orally), resulting in normalization of FSH levels 6 months later, although the size of the tumor was not reduced. After acute SMS 201-995 administration (100 micrograms sc) FSH decreased in two cases by 38% and 76%, LH in three by 30-56% and alpha-subunit in one by 20%. We conclude that gonadotropin response to TRH stimulation is useful in the diagnosis and follow-up of patients with gonadotroph adenoma. Bromocriptine and SMS 201-995 may be effective as coadjuvant treatment following surgery and radiotherapy in these patients, although long-term studies will be necessary to confirm these proposals.