scholarly journals Melatonin Stimulates the Release of Growth Hormone and Prolactin by a Possible Induction of the Expression of Frog Growth Hormone-Releasing Peptide and Its Related Peptide-2 in the Amphibian Hypothalamus

Endocrinology ◽  
2007 ◽  
Vol 149 (3) ◽  
pp. 962-970 ◽  
Author(s):  
Vishwajit S. Chowdhury ◽  
Kazutoshi Yamamoto ◽  
Izumi Saeki ◽  
Itaru Hasunuma ◽  
Taichi Shimura ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Median Eminence ◽  
Physiological Role ◽  
Receptor Subtype ◽  
Melatonin Receptor ◽  
Melatonin Secretion ◽  
Melatonin Administration ◽  
Plasma Gh ◽  
Precursor Mrna

We recently identified a novel hypothalamic neuropeptide stimulating GH release in bullfrogs and termed it frog GH-releasing peptide (fGRP). The fGRP precursor encodes fGRP and its related peptides (fGRP-RP-1, -RP-2, and -RP-3), and fGRP-RP-2 also stimulates GH and prolactin (PRL) release. Cell bodies and terminals containing these neuropeptides are localized in the suprachiasmatic nucleus (SCN) and median eminence, respectively. To understand the physiological role of fGRP and fGRP-RP-2, we investigated the mechanisms that regulate the expression of these neuropeptides. This study shows that melatonin induces the expression of fGRP and fGRP-RPs in bullfrogs. Orbital enucleation combined with pinealectomy (Ex plus Px) decreased the expression of fGRP precursor mRNA and content of mature fGRP and fGRP-RPs in the diencephalon including the SCN and median eminence. Conversely, melatonin administration to Ex plus Px bullfrogs increased dose-dependently their expressions. The expression of fGRP precursor mRNA was photoperiodically controlled and increased under short-day photoperiods, when the nocturnal duration of melatonin secretion increases. To clarify the mode of melatonin action on the induction of fGRP and fGRP-RPs, we further demonstrated the expression of Mel1b, a melatonin receptor subtype, in SCN neurons expressing fGRP precursor mRNA. Finally, we investigated circulating GH and PRL levels after melatonin manipulation because fGRP and fGRP-RP-2 stimulate the release of GH and GH/PRL, respectively. Ex plus Px decreased plasma GH and PRL concentrations, whereas melatonin administration increased these hormone levels. These results suggest that melatonin induces the expression of fGRP and fGRP-RP-2, thus stimulating the release of GH and PRL in bullfrogs.

Effect of actively immunizing sheep against growth hormone-releasing hormone or somatostatin on spontaneous pulsatile and neostigmine-induced growth hormone secretion

1995 ◽  
Vol 144 (1) ◽  
pp. 83-90 ◽  
Author(s):  
E Magnan ◽  
L Mazzocchi ◽  
M Cataldi ◽  
V Guillaume ◽  
A Dutour ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Body Weight ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Physiological Role ◽  
Gh Secretion ◽  
Igf I ◽  
Plasma Gh ◽  
Hypophysial Portal

Abstract The physiological role of endogenous circulating GHreleasing hormone (GHRH) and somatostatin (SRIH) on spontaneous pulsatile and neostigmine-induced secretion of GH was investigated in adult rams actively immunized against each neuropeptide. All animals developed antibodies at concentrations sufficient for immunoneutralization of GHRH and SRIH levels in hypophysial portal blood. In the anti GHRH group, plasma GH levels were very low; the amplitude of GH pulses was strikingly reduced, although their number was unchanged. No stimulation of GH release was observed after neostigmine administration. The reduction of GH secretion was associated with a decreased body weight and a significant reduction in plasma IGF-I concentration. In the antiSRIH group, no changes in basal and pulsatile GH secretion or the GH response to neostigmine were observed as compared to controls. Body weight was not significantly altered and plasma IGF-I levels were reduced in these animals. These results suggest that in sheep, circulating SRIH (in the systemic and hypophysial portal vasculature) does not play a significant role in pulsatile and neostigmine-induced secretion of GH. The mechanisms of its influence on body weight and production of IGF-I remain to be determined. Journal of Endocrinology (1995) 144, 83–90

Diurnal Variations of Plasma Growth Hormone and Brain Monoamines in Adult Male Rats

1973 ◽  
Vol 51 (12) ◽  
pp. 890-892 ◽  
Author(s):  
R. Collu ◽  
J. C. Jéquier ◽  
J. Letarte ◽  
G. Leboeuf ◽  
J. R. Ducharme
Keyword(s):  
Growth Hormone ◽  
Adult Male ◽  
Physiological Role ◽  
Male Rats ◽  
Male Rat ◽  
Plasma Growth Hormone ◽  
Gh Secretion ◽  
Adult Male Rat ◽  
Plasma Gh

Brain levels of monoamines (MA) in the adult male rat show a diurnal pattern of secretion with noradrenaline (NA) and serotonin (5-HT) reaching a peak at 1300 and 1800, respectively, and dopamine (DA) showing a bimodal pattern with peaks at 0500 and 1800. Plasma growth hormone (GH) values fluctuate widely during the nycthemeral period. Statistically significant correlations between plasma GH and brain MA levels, confirming the existence of a physiological role of MA in the control of GH secretion, could not be demonstrated in the present study.

The growth hormone axis and cognition: empirical results and integrated theory derived from giant transgenic mice

1999 ◽  
Vol 77 (12) ◽  
pp. 1874-1890 ◽  
Author(s):  
C D Rollo ◽  
C V Ko ◽  
JG A Tyerman ◽  
L J Kajiura
Keyword(s):  
Growth Hormone ◽  
Accelerated Aging ◽  
Error Rates ◽  
Transgenic Rat ◽  
Brain Functioning ◽  
Neuroendocrine Mechanisms ◽  
System Functioning ◽  
Plasma Gh ◽  
Enhanced Learning

Sleep is required for the consolidation of memory for complex tasks, and elements of the growth-hormone (GH) axis may regulate sleep. The GH axis also up-regulates protein synthesis, which is required for memory consolidation. Transgenic rat GH mice (TRGHM) express plasma GH at levels 100-300 times normal and sleep 3.4 h longer (30%) than their normal siblings. Consequently, we hypothesized that they might show superior ability to learn a complex task (8-choice radial maze); 47% of the TRGHM learned the task before any normal mice. All 17 TRGHM learned the task, but 33% of the 18 normal mice learned little. TRGHM learned the task significantly faster than normal mice (p < 0.05) and made half as many errors in doing so, even when the normal nonlearners were excluded from the analysis. Whereas normal mice expressed a linear learning curve, TRGHM showed exponentially declining error rates. The contribution of the GH axis to cognition is conspicuously sparse in literature syntheses of knowledge concerning neuroendocrine mechanisms of learning and memory. This paper synthesizes the crucial role of major components of the GH axis in brain functioning into a holistic framework, integrating learning, sleep, free radicals, aging, and neurodegenerative diseases. TRGHM show both enhanced learning in youth and accelerated aging. Thus, they may provide a powerful new probe for use in gaining an understanding of aspects of central nervous system functioning, which is highly relevant to human health.

Physiological role of human placental growth hormone

1998 ◽  
Vol 140 (1-2) ◽  
pp. 121-127 ◽  
Author(s):  
E. Alsat ◽  
J. Guibourdenche ◽  
A. Couturier ◽  
D. Evain-Brion
Keyword(s):  
Growth Hormone ◽  
Physiological Role ◽  
Placental Growth Hormone

scholarly journals Antagonism by Taurine of Morphine Induced Growth Hormone Secretion

1978 ◽  
Vol 5 (1) ◽  
pp. 139-142 ◽  
Author(s):  
R. Collu ◽  
G. Charpenet ◽  
M. J. Clermont
Keyword(s):  
Growth Hormone ◽  
Amino Acid ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Physiological Role ◽  
Pituitary Hormone ◽  
Hormone Release ◽  
Morphine Administration ◽  
Plasma Gh

SUMMARY:The intraperitoneal (IP) or intraventricular (IVT) administration of small amounts of taurine did not modify pentobarbital-induced sleep or pituitary hormone release. However, the drastic increment in plasma GH values induced by morphine administration was completely blocked by the IVT injection of the amino acid. Whether taurine plays a physiological role in the control ofGH secretion is highly speculative.

Physiological role of somatostatin in the control of growth hormone and thyrotropin secretion

1976 ◽  
Vol 68 (1) ◽  
pp. 149-156 ◽  
Author(s):  
Louise Ferland ◽  
Fernand Labrie ◽  
Michel Jobin ◽  
Akira Arimura ◽  
Andrew V. Schally
Keyword(s):  
Growth Hormone ◽  
Physiological Role
Sign in / Sign up

Export Citation Format

Share Document