Luteinizing Hormone-releasing Hormone Stimulation Research Articles

The Effects of Aging on the Secretion of the Common Alpha‐Subunit of the Glycoprotein Hormones in Men

To investigate the effects of aging on the secretion of the common alpha-subunit of the glycoprotein hormones, we measured basal levels of luteinizing hormone (LH), testosterone (T) and alpha-subunit in 176 normal men aged 19 to 89 years. In addition, in two groups of young (less than 65 years; n = 25) and old (greater than 65 years; n = 15) subjects, the effects of luteinizing hormone-releasing hormone (LHRH) on LH and alpha-subunit secretion were determined. Age-related increases in serum alpha-subunit and LH were noted only in the oldest men while T levels decreased progressively with advancing age. LHRH stimulation resulted in significantly greater secretion of alpha-subunit in the old subjects while no difference in LH release between young and old men was observed. Moreover, there was a delay to peak LH and alpha-subunit levels after LHRH in the old subjects. These data suggest that the aging process in males involves deficits in both testicular and gonadotroph functions as demonstrated by (1) the relative hypogonadotropic hypogonadism seen until the ninth decade; (2) the hypergonadotropic hypogonadism apparent in men greater than 80 years; (3) the delay in the timing of peak responses of LH and alpha-subunit after LHRH administration; and (4) the disproportionate increase in the secretion of alpha subunit relative to intact LH.

Prolactin and pituitary gonadotropin values and responses to acute luteinizing hormone-releasing hormone (LHRH) challenge in patients having long-term treatment with a depot lhrh analogue

Sixty patients with advanced prostatic carcinoma were treated with monthly subcutaneous injections of a depot formulation of goserelin, a luteinizing hormone-releasing hormone (LHRH) analogue (Zoladex, ICI Pharma, Destelbergen, Belgium). All patients were regularly evaluated with measurements of luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone (T), and prolactin (PRL) levels. In 15 patients among them who could be treated for more than 42 months, an LHRH stimulation test was performed at the end of each 28-day period and before the next administration of the depot formulation. A complete and maintained suppression of both T and LH levels was seen. FSH levels also decreased, but to a lesser extent than LH levels, and showed a small escape after reaching a minimum value after 1 month of therapy. The LHRH challenge after 42 months of therapy elicited no significant responses of LH and FSH levels. The PRL values showed a small decrease.

Melatonin inhibitory effect on luteinizing hormone release is potentiated after long pretreatment with the indole

The effect of melatonin on luteinizing-hormone releasing-hormone stimulation of cyclic AMP accumulation and luteinizing hormone (LH) release from neonatal rat hemipituitaries was studied in vitro. Melatonin inhibited LH-release from pituitaries of animals kept previously on long but not on short photoperiods; cyclic AMP accumulation was, however, inhibited on both photoperiods. There were no daily changes in the melatonin effect. Inhibition of LH-release was strongly potentiated after 6 h preincubation with melatonin as compared with 20 min preincubation; cyclic AMP was not significantly affected by the length of preincubation.

Progesterone modulation of gonadotropin secretion by dispersed rat pituitary cells in culture. I. Basal and gonadotropin-releasing hormone-stimulated luteinizing hormone release

Dispersed, estradiol-treated, rat pituitary cells were cultured to characterize the influences of a physiologic concentration of progesterone (P, 10 −7 M) on gonadotroph responsiveness to gonadotropin-releasing hormone (GnRH). Acute ( $ ̌ 6 h) P treatment enhanced and chronic ( $ ̆ 12 h) treatment suppressed both basal and GnRH-stimulated luteinizing hormone (LH) release. This modulation took place without any change in intracellular LH stores, indicating that the secretory changes are not attributable to changes in LH synthesis, and were not accompanied by similar alterations in basal or thyrotropin-releasing hormone-stimulated prolactin secretion. Moreover, the timing of these responses was fixed since a 10-fold lower P concentration produced only smaller and briefer alterations in LH release. Analyses of the temporal characteristics of effective P stimuli indicated that a brief 6 h exposure to P inhibited GnRH-stimulated LH secretion 18 h later. In contrast, P's acute actions rapidly dissipated following removal of the steroid from the culture medium. Finally, P-induced enhancement and suppression of GnRH-stimulated LH release could be blocked by appropriately timed treatments with protein synthesis inhibitors. Our findings are consistent with the hypothesis that P influences gonadotroph secretory function via the production of specific proteins.

Adolescent Varicocele: Objective Indications for Treatment

We measured the gonadotropin response pattern to the intravenous injection of luteinizing hormone-releasing hormone in 53 male adolescents 11 to 17 years old (average age 14.2 years) with a grade II to III varicocele. Volume loss of the testis ipsilateral to the varicocele of 2cc or more was noted in 32 patients. Baseline serum levels of follicle-stimulating hormone, luteinizing hormone and testosterone were determined, and measured again at 15, 30 and 60 minutes following intravenous injection of luteinizing hormone-releasing hormone. Of the patients 23 had an exaggerated response pattern following luteinizing hormone-releasing hormone stimulation, including abnormally high post-stimulation levels of luteinizing hormone only in 6, follicle-stimulating hormone only in 4, and follicle-stimulating and luteinizing hormones in 13. No significant difference in mean age, testosterone levels or loss of testicular volume was noted between the abnormal and normal response groups. This study indicates that approximately 45 per cent of adolescents with a varicocele have evidence of testicular injury. The physical examination was of no value in predicting which patient with a varicocele would display evidence of testicular dysfunction. We suggest that the luteinizing hormone-releasing hormone stimulation test become a routine part of the evaluation of an adolescent with a varicocele.

Melatonin and pituitary-gonadal function in disorders of eating behavior.

In order to study the possible relationships between melatonin secretion and pituitary-gonadal function, the circadian rhythm of plasma melatonin, the basal levels of estradiol-17beta and testosterone and the luteinizing hormone (LH) and follicle-stimulating hormone (FSH) response to luteinizing hormone-releasing hormone (LH-RH) stimulation were evaluated in normally cycling healthy women and in two groups of women with menstrual dysfunctions related to eating disorders (19 patients with anorexia nervosa and 16 with primary obesity). The circadian rhythm of plasma melatonin reached statistical significance in anorectic patients but not in obese patients. The mean 24 h melatonin level was significantly higher in anorectic than in obese patients and in control subjects. However, both groups of patients shared some abnormalities of melatonin circadian pattern, such as increased ratio between day and night melatonin levels, abnormal secretory peaks during the light hours and great interindividual variability for timing, amplitude, and duration of melatonin nocturnal peak. A selective impairment of LH secretion was observed in both anorectic and obese patients. By considering together the two groups of patients and controls, a linear inverse correlation between the circadian mesor of plasma melatonin and the basal and LH-RH stimulated LH levels was found. The persistence of a certain melatonin secretion during the light hours in both anorectic and obese patients could play an inhibitory role on the pituitary gonadal function in these subjects.

Steroid receptors and regulation of LH and secretogranin II (GP87) secretion in pituitary cell aggregates

The gonadotrope polypeptide (GP87), a secretogranin II form, has previously been found to be co-released with luteinizing hormone (LH) by rat gonadotrope cells under luteinizing hormone-releasing hormone (LHRH) stimulation. Nothing is hitherto known concerning its function and regulation. In the present paper, the modulatory effects of steroids on GP87 release were investigated using cultures of rat pituitary cell aggregates. As steroid effects are dependent on the presence of receptors, we firstly demonstrated that the steroid receptors are maintained with their typical characteristics in this culture system. In steroid-free medium, the estrogen receptor concentration increased significantly (P < 0.01) within 7 days in culture (646 +/- 122 fmol/mg DNA, n = 3) when compared to the level in freshly dispersed cells (355 +/- 59 fmol/mg DNA, n = 4) suggesting that cells can synthesize the estrogen receptor and that this cell culture system is suitable for studying regulatory effects of steroids. Pituitary cell aggregates from 14 day-old female rats were maintained for 24 h in the absence or presence of 10 nM estradiol (E(2)) or 50 nM 5?-dihydrotestosterone (DHT) and incubated for 2.5 h with [(35)S] methionine. Perifusion was initiated and 4 min pulses of 20 nM LHRH occurred every 1 h. The effects of steroids were investigated on LH, total and labeled GP87. The results indicated that: (1) DHT pretreatment reduced the amplitude of LHRH-stimulated GP87 and LH release responses; (2) by contrast, E(2) pretreatment enhanced the effects of LHRH on total or labeled GP87 release whereas the LH release was not significantly modified; and (3) when E(2) treatment started only 60 min before the first LHRH pulse, no differences between responses of E(2)-treated and control aggregates were observed. The present data show for the first time that sex steroids can modulate the GP87 release through a direct effect on the pituitary. E(2) could either stimulate the GP87 synthesis or increase its intracellular trafficking. That LH and GP87 do not strictly exhibit the same release response further suggests either some heterogeneity of GP87 localization in gonadotrope sub-types or within secretory granules.

In vivo release of beta human chorionic gonadotropin by luteinizing hormone releasing hormone stimulation and its clinical application as a remission criterion in patients with gestational trophoblastic disease

In vivo responses of trophoblasts to luteinizing hormone releasing hormone (LHRH) stimulation in 48 gestational trophoblastic disease patients were observed. Serum beta human chorionic gonadotropin (β-hCG) levels after LHRH injection were significantly increased in patients with hCG values between 5 and 20 mIU/ml (minimal resistance group) but not in patients whose hCG levels were less than 5 mIU/ml (possible remission group). The sensitivity, specificity and the predictive values of LHRH stimulation test were 75.0, 91.3 and 95.5% in the possible remission group and 87.5, 20.0 and 77.8% in the minimal resistance group.

Response of human chorionic gonadotrophin to luteinizing hormone-releasing hormone stimulation in the culture media of normal human placenta, choriocarcinoma cell lines, and in the serum of patients with gestational trophoblastic disease

International Journal of Gynecology & ObstetricsVolume 26, Issue 3 p. 474-474 Citations from the literature endocrinology Response of human chorionic gonadotrophin to luteinizing hormone-releasing hormone stimulation in the culture media of normal human placenta, choriocarcinoma cell lines, and in the serum of patients with gestational trophoblastic disease S.J. Kim, S.J. KimSearch for more papers by this authorS.E. Namkoong, S.E. NamkoongSearch for more papers by this authorJ.W. Lee, J.W. LeeSearch for more papers by this author S.J. Kim, S.J. KimSearch for more papers by this authorS.E. Namkoong, S.E. NamkoongSearch for more papers by this authorJ.W. Lee, J.W. LeeSearch for more papers by this author First published: June 1988 https://doi.org/10.1016/0020-7292(88)90381-5AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume26, Issue3June 1988Pages 474-474 RelatedInformation

Modulation of luteinizing hormone pulse amplitude by the frequency of luteinizing hormone-releasing hormone stimulation and by testosterone in castrated, hypothalamic-lesioned male rats.

The frequency of spontaneous luteinizing hormone (LH) pulses is thought to be a direct result of the frequency of luteinizing hormone-releasing hormone (LHRH) pulses from the hypothalamus. By contrast, the amplitude of spontaneous LH pulses may be controlled by several factors other than the amplitude of LHRH pulses. We tested two hypotheses: 1) that LH pulse amplitude is determined in part by the frequency of LHRH pulses of constant magnitude, and 2) that testosterone (T) exerts a direct feedback effect on the pituitary gland to regulate LH pulse amplitude. Gonadal feedback was eliminated by castrating adult male rats (n = 20). Endogenous LHRH secretion was eliminated by lesioning the medial basal hypothalamus. Serum LH levels (0.19 +/- 0.04 ng/ml RP-2, mean +/- SEM) and T levels (0.15 +/- 0.02 ng/ml), measured several weeks after hypothalamic lesioning, confirmed the hypogonadotropic hypogonadal state of the animals. During a 8-h period, unanesthetized, unrestrained animals were injected with 40-ng pulses of LHRH via catheters into the jugular vein, and blood samples for LH measurement were drawn at 10-min intervals. The LHRH pulse interval was 20 min during the first 4 h in all animals. The pulse interval was doubled to 40 min in half of the animals (n = 10) during the next 4 hours; in the other 10 animals, the pulse interval was maintained constant at 20 min throughout the study. Within both of these groups, one-half of the animals (n = 5) were infused with T to achieve a physiological level of T in serum (2.46 +/- 0.36 ng/ml at 4 h), while the other half received vehicle.(ABSTRACT TRUNCATED AT 250 WORDS)

Rudimentary Testes Syndrome Revisited

Sixteen children who were one day to 9 years of age underwent clinical, anatomic, and hormonal study because of extreme hypoplasia of the phallus and small testes associated with normal 46XY male karyotype. Two of them were first cousins. All patients had Leydig cell deficiency. Among 15 patients who received luteinizing hormone-releasing hormone stimulation during childhood, 11 had an exaggerated response of either one or both gonadotropins. Bilateral biopsy, performed in eight patients, showed a clearly testicular structure with either scant or incompletely differentiated tubules. These characteristics allow clear differentiation from chromosomal abnormalities and malformation syndromes. It is more difficult to differentiate between rudimentary testes and primary gonadotropic deficiencies and may not be possible until the child has reached adolescence. The syndrome of rudimentary testes may be a manifestation of XY primary gonadal dysplasia, along with pure XY gonadal dysgenesis, XY hermaphroditism, XY mixed gonadal dysgenesis, and congenital anorchia, probably resulting from fetal regression of the testes. The observed familial occurrence of the syndrome of rudimentary testes, as well as of XY gonadal dysgenesis, leads to speculation about the possibility of X-linked transmission.

Tamoxifen Citrate Therapy in Male Infertility

A prospective, randomized, double-blind study with crossover, using tamoxifen (TAM) (Nolvadex, ici Pharma, Missisauga, Canada) 20 mg/day and placebo (p) for 6 months each, was conducted in 16 infertile men with idiopathic oligozoospermia. Baseline sperm count was 17.092 +/- 3.09 (10(6)/ml). Hormonal profile was performed and included follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2), testosterone (T), prolactin (PRL), thyroid-stimulating hormone (TSH), and luteinizing hormone-releasing hormone (LH-RH) stimulation tests. The sperm analysis and hormonal profile were repeated at 6 and 12 months of the study. A sperm penetration assay (SPA) was performed on zona-free hamster egg. Compared with the placebo group, the TAM group showed a significant increase in plasma FSH, LH, E2, and T levels (P less than 0.001), but not in PRL and TSH levels. However, LH-RH stimulation tests and SPA were found to be comparable in the two treatment groups, and there was no significant effect on sperm analysis. Tamoxifen appeared to be no more effective than the placebo in the treatment of idiopathic oligozoospermia.

Pulsatile nature of luteinizing hormone release is maintained during luteinizing hormone-releasing hormone stimulation in normal male rats.

The plasma LH concentration is believed to be reasonably steady in normal male rats. We found that LH is released in a regular pulsatile fashion. The overall mean concentration of plasma LH in normal male rats was 46.6 +/- 4.4 (mean +/- SEM) ng/ml. The normal male rats showed periodic LH pulses: the mean pulse amplitude was 144.4 +/- 25.5 ng/ml and the inter-peak interval was 22.5 +/- 2.0 min. Each pulse lasted 9.7 +/- 0.8 min. When LH-RH (1 microgram/kg) was injected as a bolus, the peak concentration was attained in 10-30 min reaching a peak concentration of 279.4 +/- 39.6 ng/ml. Distinct pulsatile bursts of plasma LH were discernible during the period of elevated plasma LH concentration. When a higher dose of LH-RH (5 micrograms/kg) was administered, the LH concentration slowly increased to a peak concentration of 400.2 +/- 38.7 ng/ml in 20-40 min. The pulsatile nature of the LH concentration was recognizable with distinct bursts. We have observed that: (a) normal male rats release LH in a pulsatile fashion with an approximate 20-min inter-peak interval; (b) mean LH pulses last less than 10 min, and (c) the LH pulses are visible even with elevated LH and LH-RH concentrations in the general circulation.

Induction of first cycles in primary hypothalamic amenorrhea with pulsatile luteinizing hormone-releasing hormone: a mirror of female pubertal development

During pubertal development in girls, the attainment of regular ovulatory menstrual cycles usually is preceded by cycles that are either anovulatory or show a defective luteal phase. It is not known whether these defective cycles are caused by inadequate luteinizing hormone-releasing hormone (LH-RH) secretion or by an inadequate response of the pituitary-ovarian axis to LH-RH stimulation. To shed new light on this matter, the authors analyzed endocrine data from 12 menstrual cycles induced by pulsatile LH-RH therapy in five women with primary amenorrhea of hypothalamic origin. Anovulatory cycles occurred with and without an increase in estrogen excretion and with and without a luteinizing hormone surge. In addition, ovulatory cycles with and without deficient corpus luteum function were observed. Most of these types of anovulatory and ovulatory menstrual cycles also have been described during normal puberty. Therefore, these observations suggest that, during normal pubertal development, maturation of the pituitary gonadotropes and of the ovary occurs, as well as the increased secretion of LH-RH from the hypothalamus, which the overall process depends upon.

Rudimentary Testes Syndrome Revisited

Sixteen children who were one day to 9 years of age underwent clinical, anatomic, and hormonal study because of extreme hypoplasia of the phallus and small testes associated with normal 46XY male karyotype. Two of them were first cousins. All patients had Leydig cell deficiency. Among 15 patients who received luteinizing hormone-releasing hormone stimulation during childhood, 11 had an exaggerated response of either one or both gonadotropins. Bilateral biopsy, performed in eight patients, showed a clearly testicular structure with either scant or incompletely differentiated tubules. These characteristics allow clear differentiation from chromosomal abnormalities and malformation syndromes. It is more difficult to differentiate between rudimentary testes and primary gonadotropic deficiencies and may not be possible until the child has reached adolescence. The syndrome of rudimentary testes may be a manifestation of XY primary gonadal dysplasia, along with pure XY gonadal dysgenesis, XY hermaphroditism, XY mixed gonadal dysgenesis, and congenital anorchia, probably resulting from fetal regression of the testes. The observed familial occurrence of the syndrome of rudimentary testes, as well as of XY gonadal dysgenesis, leads to speculation about the possibility of X-linked transmission.

Tamoxifen citrate therapy in male infertility

A prospective, randomized, double-blind study with crossover, using tamoxifen (TAM) (Nolvadex, ici Pharma, Missisauga, Canada) 20 mg/day and placebo (p) for 6 months each, was conducted in 16 infertile men with idiopathic oligozoospermia. Baseline sperm count was 17.092 +/- 3.09 (10(6)/ml). Hormonal profile was performed and included follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2), testosterone (T), prolactin (PRL), thyroid-stimulating hormone (TSH), and luteinizing hormone-releasing hormone (LH-RH) stimulation tests. The sperm analysis and hormonal profile were repeated at 6 and 12 months of the study. A sperm penetration assay (SPA) was performed on zona-free hamster egg. Compared with the placebo group, the TAM group showed a significant increase in plasma FSH, LH, E2, and T levels (P less than 0.001), but not in PRL and TSH levels. However, LH-RH stimulation tests and SPA were found to be comparable in the two treatment groups, and there was no significant effect on sperm analysis. Tamoxifen appeared to be no more effective than the placebo in the treatment of idiopathic oligozoospermia.

An intractable, ovary-independent impairment in hypothalamo-pituitary function in the estradiol-valerate-induced polycystic ovarian condition in the rat.

A single injection of estradiol valerate (EV) produces anovulatory acyclicity and polycystic ovaries (PCO) in the rat. Basal serum luteinizing hormone (LH) concentrations are attenuated whereas serum follicle stimulating-hormone (FSH) concentrations are in the high normal range in these animals. Subsequent unilateral ovariectomy restores ovulatory cycles and normal histology in the remaining ovary without correcting the aberrant basal serum gonadotropin concentrations. This suggests that although the blocked surge mechanism is correctable, a second relatively intractable, ovary-independent impairment compromises basal gonadotropin production. To identify and characterize this second component, we have examined hypothalamic-pituitary function in PCO rats after bilateral ovariectomy. Adult (200-250 g), normal cyclic Wistar rats were injected with 2 mg EV or with vehicle (control). Nine weeks later all animals were ovariectomized and PCO was confirmed in the EV-treated animals. Animals were killed at 0, 2, 7, 14, and 28 days after ovariectomy, and hypothalamic content of luteinizing hormone-releasing hormone (LHRH) and pituitary and serum concentrations of LH and FSH were measured. LH and FSH responses to exogenous LHRH were assessed. Serum progesterone, testosterone, and estradiol concentrations were determined at 28 days. Hypothalamic LHRH decreased significantly in all animals over the 28-day period. Although LHRH values did not differ at Time 0, by 28 days there was significantly less LHRH in the hypothalami of control than in PCO rats. This pattern of depletion was mirrored by corresponding reciprocal patterns of increasing serum gonadotropin concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Response of human chorionic gonadotrophin to luteinizing hormone-releasing hormone stimulation in the culture media of normal human placenta, choriocarcinoma cell lines, and in the serum of patients with gestational trophoblastic disease.

In vitro and in vivo responses to luteinizing hormone-releasing hormone (LHRH) stimulation of human chorionic gonadotrophin (hCG) production were evaluated. We cultured placental tissues of ten weeks and term pregnancy, choriocarcinoma tissues, and monolayers of the BeWo cell line, and added serial dilutions of LHRH (1, 5 and 10 micrograms) to the media for five to seven days. In in vivo experiments, 100 micrograms LHRH was intravenously administered to 20 normally cycling women (control group), 27 women who were 'possible remission', and 21 women with 'minimal resistance' to gestational trophoblastic disease. After injection of LHRH, blood samples were collected at 0, 30, 60, 90 and 120 minutes. The concentrations of immunoreactive beta-hCG in in vitro culture media, and in sera from patients, were measured before and after LHRH stimulation by double-antibody radioimmunoassay. These in vitro and in vivo experiments revealed that normal and malignant trophoblastic cells responded to the LHRH stimulation by producing immunoreactive beta-hCG. Therefore, LHRH stimulation may be useful in detecting residual choriocarcinoma cells in gestational trophoblastic disease patients during their periremission periods.

Male infertility due to congenital adrenal hyperplasia: testicular biopsy findings, hormonal evaluation, and therapeutic results in three patients

Testicular biopsy in three infertile male patients with congenital adrenal hyperplasia showed different grades of germinal epithelium maturation, and no Leydig cells in the interstitium. In two patients with severe germinal cell hypoplasia, very low serum gonadotropins showed no response to luteinizing hormone-releasing hormone stimulation and responded to long-term clomiphene citrate administration. It is hypothesized that an increase of hypothalamic estrogen production because of local androstenedione aromatization might be responsible for the luteinizing hormone-releasing hormone block observed in these patients. All patients were submitted to adrenal suppressive therapy, and in two cases a return of the fertility status was obtained.

A cytogenetic and endocrinologic study of a set of monozygotic isokaryotic 45,X/46,XY twins discordant for phenotypic sex: mosaicism versus chimerism

Newborn monozygotic twins with phenotypic sexual discordance were diagnosed with 45,X/46,XY gonadal dysgenesis. Cytogenetic studies of peripheral blood (serial), skin, and gonad were performed. Serial comparative gonadotropin data and luteinizing hormone-releasing hormone stimulation tests were obtained. A phenotypically normal male twin was found to have a significant number of 45,X cells only in lymphocytes and was considered endocrinologically intact. The sexually ambiguous twin sister demonstrated a significant number of 45,X cell lines in all tissues and was considered endocrinologically agonadal. These data demonstrate the role of the 45,X karyotype on abnormal gonadal formation and function and make possible different etiologies for the 45,X cell line in both twins. While mosaicism is likely for both, chimerism is possible for the normal male.