The pineal gland and the photoperiodic control of luteinizing hormone secretion in intact and castrated Japanese quail

1983 ◽  
Vol 99 (2) ◽  
pp. 281-287 ◽  
Author(s):  
S. M. Simpson ◽  
H. F. Urbanski ◽  
J. E. Robinson
Keyword(s):  
Pineal Gland ◽  
Japanese Quail ◽  
Prolonged Exposure ◽  
Hormone Secretion ◽  
Quantitative Relationship ◽  
Luteinizing Hormone Secretion ◽  
Photoperiodic Responses ◽  
Induced Changes ◽  
Lh Secretion ◽  
Sexually Mature

The effects of pinealectomy on a range of photoperiodic responses were investigated in male Japanese quail by measuring plasma LH concentrations in intact, sham-operated and pinealectomized birds in the following four experiments: (1) transfer of sexually quiescent birds from a short photoperiod of 8 h light: 16 h darkness (8L: 16D) to a photostimulatory daylength of 16L: 8D; (2) transfer of sexually mature birds from 16L: 8D to 8L: 16D; (3) castration in 16L: 8D and exposure to 13L: 11D; (4) castration in 8L: 16D and exposure to 13L: 11D. There was no evidence of effects of the pineal gland on the photoperiodically induced changes in LH secretion, the quantitative relationship between LH secretion and photoperiod in intact and castrated birds, or the induction of relative photorefractoriness by prolonged exposure to 16L: 8D. This suggests that there is no pineal influence on the photoperiodic clock or its effectors in this bird.

Androgenic and oestrogenic steroid participation in feedback control of luteinizing hormone secretion in male sheep

1983 ◽  
Vol 102 (4) ◽  
pp. 499-504 ◽  
Author(s):  
M. J. D'Occhio ◽  
B. D. Schanbacher ◽  
J. E. Kinder
Keyword(s):  
Luteinizing Hormone ◽  
Pulse Generator ◽  
Hormone Secretion ◽  
Pulse Interval ◽  
Serum Concentrations ◽  
Luteinizing Hormone Secretion ◽  
Lh Release ◽  
Lh Secretion ◽  
Additional Feedback ◽  
Male Sheep

Abstract. The acute castrate ram (wether) was used as an experimental model to investigate the site(s) of feedback on luteinizing hormone (LH) by testosterone, dihydrotestosterone and oestradiol. At the time of castration, wethers were implanted subdermally with Silastic capsules containing either crystalline testosterone (three 30 cm capsules), dihydrotestosterone (five 30 cm capsules) or oestradiol (one 6.5 cm capsule). Blood samples were taken at 10 min intervals for 6 h 2 weeks after implantation to determine serum steroid concentrations and to characterize the patterns of LH secretion. Pituitary LH response to exogenous LRH (5 ng/kg body weight) were also determined at the same time. The steroid implants produced serum concentrations of the respective hormones which were either one-third (testosterone) or two-to-four times (dihydrotestosterone, oestradiol) the levels measured in rams at the time of castration. Non-implanted wethers showed rhythmic pulses of LH (pulse interval 40–60 min) and had elevated LH levels (16.1 ± 1.6 ng/ml; mean ± se) 2 weeks after castration. All three steroids suppressed pulsatile LH release and reduced mean LH levels (to below 3 ng/ml) and pituitary LH responses to LRH. Inhibition of pulsatile LH secretion by all three steroids indicated that testosterone as well as its androgenic and oestrogenic metabolites can inhibit the LRH pulse generator in the hypothalamus. Additional feedback on the pituitary was indicated by the dampened LH responses to exogenous LRH.

Effects of valproate-induced alteration of the GABAergic system on pulsatile luteinizing hormone secretion in ovariectomized women

1996 ◽  
Vol 135 (3) ◽  
pp. 293-298 ◽  
Author(s):  
Joaquin Lado-Abeal ◽  
Jose L Liz ◽  
Carlos Rey ◽  
Manuel Febrero ◽  
Jose Cabezas-Cerrato
Keyword(s):  
Luteinizing Hormone ◽  
Sodium Valproate ◽  
Pulse Generator ◽  
Hormone Secretion ◽  
Gabaergic System ◽  
Luteinizing Hormone Secretion ◽  
Serum Lh ◽  
Nutrition Service ◽  
Significant Difference ◽  
Lh Secretion

Lado-Abeal J, Liz JL, Rey C, Febrero M, Cabezas-Cerrato J. Effects of valproate-induced alteration of the GABAergic system on pulsatile luteinizing hormone secretion in ovariectomized women. Eur J Endocrinol 1996;135:293–8. ISSN 0804–4643 It is well established that valproate increases hypothalamic concentrations of γ-aminobutyric acid (GABA). Although little research has been done on the role of GABA in the control of pulsatile luteinizing hormone (LH) secretion in humans, our group recently found that administration of valproate had no significant effect on pulsatile LH secretion in late follicular and mid-late luteal phase normal women. However, the results of several studies of rats suggest that GABAergic regulation of LH secretion may depend on steroid levels. The objective of this work was to determine whether regular administration of sodium valproate inhibits pulsatile LH secretion in ovariectomized women. Twelve women who had undergone ovariectomy for causes other than malignant tumors were each studied in two 8 h sessions, in each of which blood samples were taken every 5 min. The first session was the control; for the second, 400 mg of sodium valproate was administered every 8 h during the seven preceding days and at 08.00 h and 14.00 h on the day of the study session. Serum valproate was determined by repolarization fluorescence spectrophotometry, and LH, estradiol and progesterone by radioimmunoassay. The serum LH series were subjected to a deconvolution procedure to reconstruct the pattern of pituitary LH secretion. Luteinizing hormone pulses were identified by the authors' nonparametric method. Control and post-valproate results were compared with regard to number of pulses, pulse duration, the quantity of LH secreted in each pulse, interpulse interval and mean serum LH level. There was no statistically significant difference between control and post-valproate results for any of the variables considered. It is concluded that sustained serum valproate levels do not alter pulsatile secretion of LH in ovariectomized women. This implies that, in humans, GABA is probably not a decisive factor in the regulation of the GnRH pulse generator. J Cabezas-Cerrato, Endocrinology and Nutrition Service, General Hospital of Galicia, c/Galeras s/n 15705, Santiago de Compostela, La Coruña, Spain

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.

scholarly journals Induction of final oocyte maturation in Cyprinidae fish by hypothalamic factors: a review

2009 ◽  
Vol 54 (No. 3) ◽  
pp. 97-110 ◽  
Author(s):  
P. Podhorec ◽  
J. Kouril
Keyword(s):  
Luteinizing Hormone ◽  
Oocyte Maturation ◽  
Hormone Secretion ◽  
Inhibitory Effect ◽  
Gonadotropin Releasing Hormone ◽  
Luteinizing Hormone Secretion ◽  
Releasing Hormone ◽  
Final Oocyte Maturation ◽  
In Captivity ◽  
Lh Secretion

Gonadotropin-releasing hormone in Cyprinidae as in other Vertebrates functions as a brain signal which stimulates the secretion of luteinizing hormone from the pituitary gland. Two forms of gonadotropin-releasing hormone have been identified in cyprinids, chicken gonadotropin-releasing hormone II and salmon gonadotropin-releasing hormone. Hypohysiotropic functions are fulfilled mainly by salmon gonadotropin-releasing hormone. The only known factor having an inhibitory effect on LH secretion in the family Cyprinidae is dopamine. Most cyprinids reared under controlled conditions exhibit signs of reproductive dysfunction, which is manifested in the failure to undergo final oocyte maturation and ovulation. In captivity a disruption of endogenous gonadotropin-releasing hormone stimulation occurs and sequentially that of luteinizing hormone, which is indispensible for the final phases of gametogenesis. In addition to methods based on the application of exogenous gonadotropins, the usage of a method functioning on the basis of hypothalamic control of final oocyte maturation and ovulation has become popular recently. The replacement of natural gonadotropin-releasing hormones with chemically synthesized gonadotropin-releasing hormone analogues characterized by amino acid substitutions at positions sensitive to enzymatic degradation has resulted in a centuple increase in the effectiveness of luteinizing hormone secretion induction. Combining gonadotropin-releasing hormone analogues with Dopamine inhibitory factors have made it possible to develop an extremely effective agent, which is necessary for the successful artificial reproduction of cyprinids.

scholarly journals Neural Determinants of Pulsatile Luteinizing Hormone Secretion in Male Mice

Endocrinology ◽  
2020 ◽  
Vol 161 (2) ◽  
Author(s):  
Su Young Han ◽  
Isaiah Cheong ◽  
Tim McLennan ◽  
Allan E Herbison
Keyword(s):  
Luteinizing Hormone ◽  
High Frequency ◽  
Pulse Generator ◽  
Hormone Secretion ◽  
Pulse Frequency ◽  
Male Mice ◽  
Intact Male ◽  
Luteinizing Hormone Secretion ◽  
Pulse Profile ◽  
Lh Secretion

Abstract The gonadotrophin-releasing hormone (GnRH) pulse generator drives pulsatile luteinizing hormone (LH) secretion essential for fertility. However, the constraints within which the pulse generator operates to drive efficient LH pulsatility remain unclear. We used optogenetic activation of the arcuate nucleus kisspeptin neurons, recently identified as the GnRH pulse generator, to assess the efficiency of different pulse generator frequencies in driving pulsatile LH secretion in intact freely behaving male mice. Activating the pulse generator at 45-minute intervals generated LH pulses similar to those observed in intact male mice while 9-minute interval stimulation generated LH profiles indistinguishable from gonadectomized (GDX) male mice. However, more frequent activation of the pulse generator resulted in disordered LH secretion. Optogenetic experiments directly activating the distal projections of the GnRH neuron gave the exact same results, indicating the pituitary to be the locus of the high frequency decoding. To evaluate the state-dependent behavior of the pulse generator, the effects of high-frequency activation of the arcuate kisspeptin neurons were compared in GDX and intact mice. The same stimulus resulted in an overall inhibition of LH release in GDX mice but stimulation in intact males. These studies demonstrate that the GnRH pulse generator is the primary determinant of LH pulse profile and that a nonlinear relationship exists between pulse generator frequency and LH pulse frequency. This may underlie the ability of stimulatory inputs to the pulse generator to have opposite effects on LH secretion in intact and GDX animals.

scholarly journals Alcohol Alters Luteinizing Hormone Secretion in Immature Female Rhesus Monkeys by a Hypothalamic Action

Endocrinology ◽  
2004 ◽  
Vol 145 (10) ◽  
pp. 4558-4564 ◽  
Author(s):  
Gregory A. Dissen ◽  
Robert K. Dearth ◽  
H. Morgan Scott ◽  
Sergio R. Ojeda ◽  
W. Les Dees
Keyword(s):  
Rhesus Monkeys ◽  
Sucrose Solution ◽  
Hormone Secretion ◽  
Luteinizing Hormone Secretion ◽  
Immature Female ◽  
Blood Samples ◽  
Female Rhesus ◽  
Lh Release ◽  
Lh Releasing Hormone ◽  
Lh Secretion

Abstract We determined whether the effect of alcohol (ALC) to suppress LH secretion in immature female monkeys is due to a hypothalamic or pituitary site of action. Beginning at 20 months of age, four monkeys received a single intragastric dose of ALC (2.4 g/kg), and four monkeys received an equal volume of a saline/sucrose solution daily until they were 36 months old. For the hypothalamic response test, two basal samples (3.5 ml) were collected at 15-min intervals via the saphenous vein, and then N-methyl-d-l-aspartic acid (NMA; 20 mg/kg) was given iv and four more blood samples collected. Three weeks later, this protocol was repeated except LH-releasing hormone (LHRH) (5 μg/kg) was used to test pituitary responsiveness. NMA or LHRH was administered 3 h after the ALC. After the pituitary challenge, each monkey was ovariectomized and 6 wk later, implanted with an indwelling subclavian vein catheter. Blood samples were drawn every 10 min for 8 h to assess effects of ALC on post-ovariectomy LH levels and the profile of LH pulsatile secretion. The hypothalamic challenge showed NMA stimulated LH release in control monkeys, an action that was blocked by ALC. The pituitary challenge revealed that LHRH stimulated LH release equally well in control and ALC-treated monkeys. A post-ovariectomy rise in LH was observed in both groups, but levels were 45% lower in ALC-treated monkeys. This reduction was attributed to an ALC-induced suppression of both baseline and amplitude of pulses. Results demonstrate that the ALC-induced suppression of LH in immature female rhesus monkeys is due to an inhibitory action of the drug at the hypothalamic level.

ELECTRICAL STIMULATION OF THE HYPOTHALAMUS AND LUTEINIZING HORMONE SECRETION IN JAPANESE QUAIL

1975 ◽  
Vol 67 (3) ◽  
pp. 431-438 ◽  
Author(s):  
D. T. DAVIES ◽  
B. K. FOLLETT
Keyword(s):  
Electrical Stimulation ◽  
Hormone Secretion ◽  
Relative Increase ◽  
Significant Rise ◽  
Bipolar Electrode ◽  
Luteinizing Hormone Secretion ◽  
Coturnix Coturnix ◽  
Electrolytic Lesions ◽  
Lh Secretion ◽  
Stimulation Of

SUMMARY Experiments were undertaken to localize those hypothalamic areas in the male quail (Coturnix coturnix japonica) where electrical stimulation would increase LH secretion. The posterior basal hypothalamus was stimulated with rectangular pulses (height 500 μA) through a bipolar electrode for 6 min, blood samples being taken for LH assay 20 min before, and 2, 10, 20 and 30 min after stimulation. The highest plasma concentration was observed in the 2 min sample. Over the next 30 min the LH level decreased to the resting concentration. The relative increase in LH level was greatest in sexually immature quail and least in photostimulated castrated birds, although the highest absolute levels were seen in the castrated quail. There were no statistical differences between the magnitude of the LH increases in sexually immature, mature and castrated quail. Various hypothalamic regions were then stimulated with a smaller current (200 μA) applied for only 2 min. A highly significant rise in LH followed stimulation of either the tuberal hypothalamus (postero-dorsal part of the infundibular nuclear complex, PD-INC), or the preoptic region (POR) while stimulation 0·5–1·5 mm away from these regions did not change LH secretion. Stimulation of the anterior basal hypothalamus, or of the suprachiasmatic area, caused a significant rise in LH concentration although this was less than that seen after stimulation of the POR. Stimulation in the POR or the PD-INC was ineffective if the tuberal hypothalamus had been deafferentated surgically some days previously. The data complement the studies in which destruction of the PD-INC or the POR by electrolytic lesions has been shown to block photoperiodically induced testicular growth and LH secretion.

scholarly journals Galanin Enhancement of Gonadotropin-Releasing Hormone-Stimulated Luteinizing Hormone Secretion in Female Rats Is Estrogen Dependent

Endocrinology ◽  
2003 ◽  
Vol 144 (2) ◽  
pp. 484-490 ◽  
Author(s):  
Cynthia L. Splett ◽  
Joseph R. Scheffen ◽  
Joshua A. Desotelle ◽  
Vicky Plamann ◽  
Angela C. Bauer-Dantoin
Keyword(s):  
Luteinizing Hormone ◽  
Hormone Secretion ◽  
Gonadotropin Releasing Hormone ◽  
Gonadal Steroids ◽  
Female Rats ◽  
Luteinizing Hormone Secretion ◽  
Ovx Rats ◽  
Lh Secretion ◽  
Lines Of Evidence

The hypothalamic peptide GnRH is the primary neuroendocrine signal regulating pituitary LH in females. The neuropeptide galanin is cosecreted with GnRH from hypothalamic neurons, and in vitro studies have demonstrated that galanin can act at the level of the pituitary to directly stimulate LH secretion and also augment GnRH-stimulated LH secretion. Several lines of evidence have suggested that the hypophysiotropic effects of galanin are important for the generation of preovulatory LH surges. To determine whether the pituitary actions of galanin are enhanced by the preovulatory steroidal milieu, LH responses to galanin administration (with or without GnRH) were examined in: 1) ovariectomized (OVX); 2) OVX, estrogen (E)-primed; and 3) OVX, E- and progesterone-treated female rats. Results from the study indicate that galanin enhances GnRH-stimulated LH secretion only in the presence of E (in OVX, E-primed, or E- and progesterone-treated rats). Galanin alone does not directly stimulate LH secretion under any of the steroid conditions examined. In the absence of gonadal steroids (OVX rats), galanin inhibits GnRH-stimulated LH secretion. These findings suggest that the primary pituitary effect of galanin is to modulate GnRH-stimulated LH secretion, and that the potentiating effects of galanin occur only in the presence of E.

EFFECT OF SYNTHETIC THYROTROPHIN RELEASING FACTOR ON PROLACTIN AND LUTEINIZING HORMONE SECRETION IN MALE AND FEMALE RATS DURING VARIOUS REPRODUCTIVE STATES

1975 ◽  
Vol 67 (3) ◽  
pp. 425-430 ◽  
Author(s):  
R. P. DEIS ◽  
NIA ALONSO
Keyword(s):  
Hormone Secretion ◽  
Female Rats ◽  
Male Rats ◽  
Serum Prolactin ◽  
Serum Prolactin Level ◽  
Luteinizing Hormone Secretion ◽  
Male And Female Rats ◽  
Serum Lh ◽  
The Mean ◽  
Lh Secretion

SUMMARY The effect of synthetic thyrotrophin releasing factor (TRF) on serum prolactin and LH concentrations was determined by radioimmunoassay in male, cyclic and pseudopregnant female rats. A solution of TRF (0·1, 0·25, 0·5 and 1 μg/rat) was injected i.v. at 17.00 h into rats pretreated with sodium pentobarbitone at 13.00 h. A group of male rats was also treated with TRF at 11.00 h after pretreatment with sodium pentobarbitone at 07.00 h. Fifteen minutes after TRF administration, blood samples were obtained by heart puncture. Doses of 0·25, 0·5 and 1 μg TRF significantly increased the serum prolactin concentration in pro-oestrous rats. The mean serum prolactin level after the injection of 0·5 and 1 μg into oestrous rats and 0·5 μg TRF into dioestrous day 2 rats, was significantly greater than the control values. Injection of TRF on day 1 of dioestrus had no effect. Serum LH concentration was not significantly modified by the various doses of TRF administered. On day 3 of pseudopregnancy a significant increase of serum prolactin values was obtained with 0·5 and 1 μg TRF. On day 7 of pseudopregnancy a dose of 0·5 μg produced the same effect, but on day 10 of pseudopregnancy only 1 μg TRF significantly increased serum prolactin levels when compared with the control rats. In male rats serum prolactin concentration was significantly greater than the control values after TRF treatment either in the morning or the afternoon. The response was similar to that obtained in pro-oestrous rats. The results suggest that the ability of synthetic TRF to stimulate prolactin release exists in both female and male rats and that TRF does not affect LH secretion.

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