EFFECTS OF TESTOSTERONE ON GONADOTROPHIN RESPONSES TO SYNTHETIC LH AND FSH RELEASING HORMONE (LRH) IN NORMAL MEN

1976 ◽  
Vol 83 (4) ◽  
pp. 692-699 ◽  
Author(s):  
C. Robyn ◽  
M. L'Hermite ◽  
R. Leclercq ◽  
G. Copinschi
Keyword(s):  
Intramuscular Injection ◽  
Serum Prolactin ◽  
Reserve Capacity ◽  
Intravenous Injections ◽  
Adult Men ◽  
Gonadotrophin Secretion ◽  
Normal Men ◽  
Lh Secretion ◽  
Circulating Levels ◽  
Hypothalamic Level

ABSTRACT LRH tests were performed in 6 adult men with intravenous injections of 25 μg, before and one week after an intramuscular injection of 250 mg testosterone oenanthate (Testoviron Depot®). One week after intramuscular injection of Testoviron the tonic secretion of LH was completely suppressed, but the reactivity or the reserve capacity of LH secretion, as tested by LRH, remained unchanged. In contrast, the tonic secretion of FSH and the reactivity of FSH secretion to LRH were both partly suppressed. Three months after the Testoviron injection, the basal levels of LH were still significantly lower than the control values, but the basal levels of FSH were identical to the control values. These data indicate that, in man, the feedback action of testosterone on gonadotrophin secretion could be exerted, at least for LH, at the hypothalamic level rather than at the pituitary level. No significant effects of LRH were noted on the circulating levels of growth hormone and sugar. There was a distinct rise in serum prolactin, which was occasionally significant, within 30 min after LRH injection; this is considered to be without physiological significance.

Suppressive effect of prolactin on oestrogen-induced secretion of LH by sequentially perifused rat hypothalamus-pituitary

1985 ◽  
Vol 108 (2) ◽  
pp. 151-155 ◽  
Author(s):  
Jin-Woo Lee ◽  
Akira Miyake ◽  
Keiichi Tasaka ◽  
Shirou Otsuka ◽  
Toshihiro Aono ◽  
...  
Keyword(s):  
Experimental Period ◽  
Suppressive Effect ◽  
Control Group ◽  
Gonadotrophin Secretion ◽  
Lh Release ◽  
Lh Secretion ◽  
Hypothalamic Level ◽  
Experimental Group ◽  
Perifusion System

Abstract. The effect of prolactin (Prl) on oestrogeninduced gonadotrophin secretion was examined in vitro in a sequential double chamber perifusion system. As control groups, mediobasal hypothalamus (MBH)-pituitary pairs or pituitaries without the MBHs were perifused with Medium 199. As an experimental group, MBH-pituitary pairs were perifused with Medium 199 containing 1 μg/ml of rat Prl. These groups were stimulated with 10−7m oestradiol-17β (E2) for 30 min, and luteinizing hormone (LH) in the serial fractions of effluent was measured. In the control group of MBH-pituitary pairs perifused with medium without Prl, secretion of LH began to rise within 30 min after the beginning of stimulation, reached a peak 30 min after the end of stimulation and then remained at a plateau for the rest of the experimental period, whereas in the control group of pituitaries alone no significant response was observed. In the experimental group perifused with medium containing Prl, LH-secretion showed peaks 20 and 80 min after the end of E2-stimulation, respectively, and the first peak was significantly (P < 0.01) less than the level in the control group. These data demonstrate that Prl at this concentration suppressed the rapid LH release induced by E2. Its site of action is suggested to be at the hypothalamic level, and its possible mechanism of action is discussed.

EFFECT OF METHYLERGOBASINE MALEATE ON SERUM GONADOTROPHIN AND PROLACTIN IN HUMANS

1975 ◽  
Vol 79 (4) ◽  
pp. 644-657 ◽  
Author(s):  
F. R. Perez-Lopez ◽  
P. Delvoye ◽  
P. Denayer ◽  
M. L'Hermite ◽  
M. C. Roncero ◽  
...  
Keyword(s):  
Intramuscular Injection ◽  
Post Partum ◽  
Prolactin Secretion ◽  
Serum Prolactin ◽  
Pituitary Cells ◽  
Adult Men ◽  
Specific Effects ◽  
Serum Lh ◽  
Menstruating Women

ABSTRACT Intramuscular injection of 0.2 mg methylergobasine maleate3) (Methergin®, Sandoz) in women on day 3 post-partum, in regularly menstruating women and in adult men, is followed within 30 to 75 min by a 50 % decrease in serum prolactin concentration: the levels remain low until 180 min and increase between 180 and 240 min. The amplitude of the decrease is the same when prolactin is measured in terms of the same serum prolactin standard by a homologous ovine assay and by a homologous human assay. However, in the case of regularly menstruating women and of men serum prolactin concentration is some three times higher when estimated by the ovine assay than when estimated by the human assay. This difference between assay results obtained by the two radioimmunoassay methods could be due to heterogeneity of serum prolactin. However, non-specific effects of serum are not excluded. In regularly menstruating women and in men, intramuscular injection of 0.2 mg methylergobasine maleate is followed within 45 to 75 min by a 50% decrease in immunoreactive serum LH concentration without concomtant change in immunoreactive FSH. The depression of LH secretion lasts for 1 to 2 h. The circulating levels of HCG in post-partum women are not modified after intramuscular injection of Methergin. In humans as in animals and in in vitro studies, inhibition of prolactin and LH release induced by ergot drugs are likely due to both an indirect effect via the hypothalamus and to a direct effect on the pituitary cells. Finally, these data suggest that, because of its interference with prolactin secretion, intensive treatment with ergot drugs during the post-partum period may impair lactation.

scholarly journals Time-dependent effects of starvation on pituitary, hypothalamic and serum prolactin levels in rats: Comparison to the galanin expression pattern

2016 ◽  
Vol 68 (1) ◽  
pp. 117-123
Author(s):  
Predrag Vujovic ◽  
Iva Lakic ◽  
Nebojsa Jasnic ◽  
Tanja Jevdjovic ◽  
Sinisa Ðurasevic ◽  
...  
Keyword(s):  
Energy Homeostasis ◽  
Metabolic Response ◽  
Expression Patterns ◽  
Male Rats ◽  
Serum Prolactin ◽  
Dark Phase ◽  
Ad Libitum ◽  
Pituitary Prolactin ◽  
Circulating Levels ◽  
Hypothalamic Level

Given that both prolactin and galanin take part in the regulation of energy homeostasis and that galanin is localized within lactotrophs, this study was aimed at comparing the pituitary expression patterns of prolactin and galanin during different phases of metabolic response to starvation in adult Wistar male rats. Food was removed at the onset of the dark phase (6:00 pm) and the animals were deprived for 6, 12, 24 and 48 h. Each of the starved groups (n=6) was killed simultaneously with a group of ad libitum-fed rats (n=6), and the intrapituitary levels of prolactin and galanin were examined. Galanin expression in the hypothalamus and the circulating levels of prolactin were also assessed. Starvation induced a rise in the intrapituitary prolactin level (p<0.001), whereas the opposite trend was detected in the serum (p<0.05). The galanin pituitary level was initially increased (6, 12 h) (p<0.05), but as starvation progressed, it first reached (at 24 h) and ultimately fell below the level recorded in the ad libitum rats (at 48 h) (p<0.05). Both prolactin and galanin were elevated in the hypothalamus after 24- and 48-h starvation. The results show that the starvation-induced increase in the pituitary prolactin expression did not lead to the rise in prolactin circulating levels, but rather resulted in the elevation of the prolactin hypothalamic content. Furthermore, the results suggest that under the circumstances of disturbed energy homeostasis, galanin might be responsible for the augmented prolactin production, initially at the pituitary and subsequently at the hypothalamic level.

Clobazam increases pulsatile luteinizing hormone secretion in normal men

1989 ◽  
Vol 120 (4) ◽  
pp. 485-489 ◽  
Author(s):  
G. Thomas ◽  
J. C. Thalabard ◽  
M. Duet ◽  
C. Girre ◽  
P. E. Fournier
Keyword(s):  
Luteinizing Hormone ◽  
Oral Administration ◽  
Hormone Secretion ◽  
Pulse Frequency ◽  
Healthy Male ◽  
Luteinizing Hormone Secretion ◽  
Gnrh Release ◽  
Normal Men ◽  
Lh Secretion ◽  
Hypothalamic Level

Abstract. To investigate the effects of the 1,5-benzodiazepine, clobazam, on LH secretion in normal men, LH pulsatile secretion was defined after oral administration of 40 mg of clobazam or a placebo to 6 healthy male volunteers, according to a randomized cross-over design. LH pulse frequency increased significantly from a mean of 3.8 (range 3–5 pulses/8 h after placebo, to a mean of 5 (range 4–7) pulses/8 h (P< 0.05), after clobazam. Mean LH concentrations and peak amplitudes did not change significantly. These results suggest that clobazam mediates its effects on LH secretion at the hypothalamic level by increasing the frequency of episodic GnRH release.

GABA-ergic and dopaminergic mechanisms in gonadotrophin secretion in males – effects of baclofen and metoclopramide

1983 ◽  
Vol 103 (4) ◽  
pp. 451-456 ◽  
Author(s):  
Alan N. Elias ◽  
Agnes V. Szekeres ◽  
Sergio Stone ◽  
Lubomir J. Valenta ◽  
Tarek Haw ◽  
...  
Keyword(s):  
Normal Male ◽  
Dopamine Antagonist ◽  
Control Phase ◽  
Serum Lh ◽  
Gonadotrophin Secretion ◽  
Dopaminergic Mechanisms ◽  
Lh Release ◽  
Normal Men ◽  
Opposing Effects ◽  
Lh Secretion

Abstract. The GABA analogue, baclofen, and the dopamine antagonist, metoclopramide, were studied with respect to their effects on basal and LRH-induced LH and FSH release in 6 normal male volunteers. Basal gonadotrophin secretion was unchanged following the administration of baclofen or metoclopramide given alone or in combination. LRH-stimulated LH release was significantly blunted after metoclopramide administration in the baclofen pre-treated volunteers. Serum LH concentration (mean ± sd) in the control phase was 30.1 ± 17.2 mIU/ml and was 19.4 ± 9.6 mIU/ml after baclofen plus metoclopramide (P < 0.02). LRH-stimulated values, however, were unaffected by baclofen or metoclopramide when the drugs were given alone. LRH-stimulated FSH release was not significantly influenced by baclofen or metoclopramide given alone or in combination. Basal Prl secretion increased significantly when baclofen and metoclopramide were given separately and in combination. Basal Prl concentration (mean ± sd) increased from 14 ± 2 ng/ml to 18.7 ± 4.8 ng/ml after baclofen and to 111.5 ± 31.9 ng/ml after metoclopramide (P<0.01). The rise in serum Prl concentration, however, was not significantly different when measured after metoclopramide alone (111 ± 31.9 ng/ml) or after metoclopramide and baclofen (112 ± 33.3 ng/ml). It is proposed that GABA and dopamine exert opposing effects on LH secretion in normal men.

Changes in gonadotrophin secretion during childhood and puberty

1994 ◽  
Vol 141 (1) ◽  
pp. 169-176 ◽  
Author(s):  
N A Bridges ◽  
D R Matthews ◽  
P C Hindmarsh ◽  
C G D Brook
Keyword(s):  
Spectral Power ◽  
Pulse Frequency ◽  
Clinical Findings ◽  
Early Puberty ◽  
Pubertal Stage ◽  
Adult Men ◽  
Gonadotrophin Secretion ◽  
Lh Secretion ◽  
Mean Concentration ◽  
End Of Puberty

Abstract The changes in gonadotrophin secretion in childhood and puberty involve changes in the pulsatile pattern as well as mean concentration. We have examined pulsatile secretion using 24-h LH profiles in 78 children aged 4·2–15·6 years and six adult men. The profiles were analysed by a method which gives an estimate of peak and baseline levels and by spectral analysis. Prepubertal children were divided into groups by age and pubertal children by pubertal stage. Baseline LH levels in children aged 4·2–6·9 years were higher than in those aged 7·1–9·8 years. Pulse frequency in both groups was slow (periodicities 140–200 min). In the oldest prepubertal group there was an increase in peak levels with increased spectral power at periodicities of 100–120 min. Pulse frequency did not change in puberty (periodicity 120–160 min). Girls demonstrated an increase in both peak and baseline LH concentrations in early puberty. Boys had an increase in only peak levels in early puberty; there was no increase in baseline concentrations until a testicular volume of 10 ml was attained. In conclusion, these data show that LH levels do not reach a nadir until 8 years of age. We have detected a sex difference in the pattern of LH secretion seen in early puberty, and this mirrors clinical findings. The mature pattern attained by the end of puberty in both sexes is probably important for fertility. Journal of Endocrinology (1994) 141, 169–176

Prolactin and the return of ovulation in breast-feeding women

1985 ◽  
Vol 17 (S9) ◽  
pp. 25-42 ◽  
Author(s):  
Barbara A. Gross ◽  
Creswell J. Eastman
Keyword(s):  
Breast Feeding ◽  
Follicular Development ◽  
Inhibitory Effect ◽  
The Philippines ◽  
Serum Prolactin ◽  
Ovarian Activity ◽  
Cross Sectional ◽  
Gonadotrophin Secretion ◽  
Direct Inhibitory Effect ◽  
Australian Sample

SummaryCross-sectional studies in Australia and the Philippines and a longitudinal prospective study in a selected Australian sample of breast-feeding mothers have shown that basal serum prolactin (PRL) concentrations are elevated during 15–21 months of lactational amenorrhoea.A predictive model of serum PRL levels and return of cyclic ovarian activity during full breast-feeding, partial breast-feeding and weaning has been developed from the results of breast-feeding behaviour and serum PRL, gonadotrophin and oestradiol measurements in 34 mothers breast-feeding on demand for a mean of 67 weeks.Breast-feeding patterns influence serum PRL levels. Important factors during full breast-feeding are the age of the baby, the longest interval between feeds at night and total 24-hr suckling time, and following the introduction of supplements, the mean interval between feeds, together with the total 24-hr suckling time and the number of solid supplements per day.The precise mechanisms whereby breast-feeding regulates cyclic ovarian activity remain unknown. Gonadotrophin secretion appears to be quantitatively normal, but qualitative changes, secondary to altered hypothalamic activity, may be the most important factor. A direct inhibitory effect of PRL on ovarian follicular development and steroidogenesis remains possible.Ovulation with a normal luteal phase is probable for 30% of breast-feeding mothers before the first menses, but is unlikely before 6 months, provided breast-feeding is frequent day and night.Measurement of serum PRL is a sensitive index of the return of menstruation and fertility during lactation in the population studied.

Sleep deprivation reduces LH secretion in men independently of melatonin

1991 ◽  
Vol 124 (6) ◽  
pp. 646-651 ◽  
Author(s):  
RickJ. Strassman ◽  
Clifford R. Qualls ◽  
E.Jonathan Lisansky ◽  
Glenn T. Peake
Keyword(s):  
Sleep Deprivation ◽  
Hormone Secretion ◽  
Area Under The Curve ◽  
Bright Light ◽  
Pulse Frequency ◽  
Blood Levels ◽  
Luteinizing Hormone Secretion ◽  
Normal Man ◽  
Normal Men ◽  
Lh Secretion

Abstract. Melatonin affects gonadal function in nonprimate mammals. Confirmatory data in man are not available. We assessed melatonin's acute effects on luteinizing hormone secretion in 17 normal men. We studied these men in conditions of sleep in the dark, and sleep deprivation in bright light, dim light, and bright light combined with a physiologically relevant infusion of melatonin, while measuring blood levels of immunoreactive LH every 20 min for 7 h. We compared overnight LH secretion, and LH pulse frequency, amplitude, length, interval and area under the curve using a modification of the PULSAR peak identification program, among the four treatments. Areas under the curve for peaks in all three conditions of sleep deprivation were lower than in normal sleep. The presence or absence of melatonin had no additional effect. We conclude that acute suppression of melatonin does not affect LH pulse parameters in normal man, but that sleep deprivation may reduce the amount of LH secreted per pulse.

PHOTOPERIODIC MODULATION OF GONADOTROPHIN SECRETION IN CASTRATED JAPANESE QUAIL

1982 ◽  
Vol 92 (1) ◽  
pp. 73-83 ◽  
Author(s):  
H. F. URBANSKI ◽  
B. K. FOLLETT
Keyword(s):  
Japanese Quail ◽  
Plasma Levels ◽  
Time Course ◽  
Neural Mechanisms ◽  
Gonadal Steroids ◽  
Photoperiodic Control ◽  
Gonadotrophin Secretion ◽  
Lh Secretion ◽  
Sexually Mature ◽  
Short Days

Male Japanese quail were castrated when sexually immature and immediately exposed to one of the following stimulatory lighting regimes for 52 days: 11 h light: 13 h darkness/day (11L : 13D), 12L : 12D, 13L : 11D, 14L : 10D, 15L : 9D, 16L : 8D, 20L : 4D or 23L : 1D. One group was retained on short days (8L : 16D). Clearcut differences in the plasma levels of LH and FSH emerged between the various groups. Levels remained very low in castrated quail on 8L : 16D but were much greater in those on 14L : 10D, 15L : 9D, 16L : 8D, 20L : 4D and 23L : 1D, eventually becoming 15 to 20 times higher. Less pronounced castration responses developed on 13L : 11D, 12L : 12D or 11L : 13D. Alterations in photoperiod after day 52 caused an appropriate rise or fall in LH secretion. Photoperiodically induced suppressions were rapid, being highly significant within 4 days, but increases usually had a slower time course. When sexually mature quail (on 16L : 8D) were castrated and transferred to 8L : 16D they also exhibited a rapid suppression in LH secretion. Thus in quail, unlike some mammals, the photoperiodic control over gonadotrophin secretion is independent of the reproductive status of the animal at the time of castration. The results confirm the view that changes in sensitivity of the hypothalamo-pituitary axis to gonadal steroids are not a primary factor in the neural mechanisms underlying photoperiodism in quail.

The role of oestrogens on gonadotrophin secretion in the testicular feminization syndrome1

1980 ◽  
Vol 95 (3) ◽  
pp. 314-318 ◽  
Author(s):  
Martha Medina ◽  
Alfredo Ulloa-Aguirre ◽  
Maria A. Fernández ◽  
Gregorio Pérez-palacios
Keyword(s):  
Clomiphene Citrate ◽  
Poor Response ◽  
Testicular Feminization ◽  
Normal Response ◽  
Serum Lh ◽  
Gonadotrophin Secretion ◽  
Before And After ◽  
Complete Form ◽  
Lh Secretion

Abstract. The role of oestrogens on gonadotrophin secretion was assessed in three related patients with the complete form of testicular feminization syndrome. Serum LH and FSH levels were measured before and after I.RH stimulation as well as before, during and after chronic clomiphene citrate administration. Moderately elevated LH basal levels with a significant LH rise following I.RH were observed. Normal or even low FSH level with poor response to LRH were found in all subjects. Administration of clomiphene citrate resulted in a significant serum LH increase without any change of FSH. Following castration both LH and FSH rose and a normal response to LRH was observed. These results were interpreted as demonstrating that, while endogenous oestrogens modulate LH secretion in patients with androgen unresponsiveness, it plays no role in regulating FSH secretion and suggested that a factor of testicular origin without androgenic or oestrogenic activity is responsible for FSH regulation.

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