THE EFFECT OF INTRAVENOUS L-DOPA ON GROWTH HORMONE AND LUTEINIZING HORMONE LEVELS IN MAN

1973 ◽  
Vol 73 (2) ◽  
pp. 259-265 ◽  
Author(s):  
Athanasius Souvatzoglou ◽  
Klaus von Werder ◽  
Peter Bottermann
Keyword(s):  
Growth Hormone ◽  
Luteinizing Hormone ◽  
Normal Subjects ◽  
Serum Levels ◽  
Hormone Release ◽  
Growth Hormone Release ◽  
Serum Growth Hormone ◽  
Provocative Test ◽  
Hormone Levels ◽  
Serum Lh

ABSTRACT The effect of various intravenous doses of L-dopa on growth hormone and LH-serum levels in 25 normal subjects was investigated. Growth hormone increased 30–40 minutes following the injection of 25 mg and 100 mg L-dopa whereas doses of less than 25 mg had no significant effect on the serum growth hormone levels. The serum LH-level was not significantly altered by the intravenous administration of various doses (1 to 100 mg) of L-dopa. These findings, which are in agreement with the results obtained with L-dopa given orally, suggest that the intravenous injection of 25 mg L-dopa may be useful as a short provocative test for growth hormone release in man.

scholarly journals The inhibitory effects of (gamma)-aminobutyric acid (GABA) on growth hormone secretion in the goldfish are modulated by sex steroids

2000 ◽  
Vol 203 (9) ◽  
pp. 1477-1485
Author(s):  
V.L. Trudeau ◽  
O. Kah ◽  
J.P. Chang ◽  
B.D. Sloley ◽  
P. Dubourg ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Aminobutyric Acid ◽  
Electron Microscopic Level ◽  
Hormone Release ◽  
Growth Hormone Release ◽  
Gamma Aminobutyric Acid ◽  
Inhibitory Effects ◽  
Serum Growth Hormone ◽  
Hormone Levels

Double-labelling studies at the electron microscopic level demonstrated that gamma-aminobutyric acid (GABA)-immunoreactive nerve endings are associated with growth-hormone-secreting cells in the proximal pars distalis of the goldfish pituitary gland, suggesting that GABA may be important for the control of growth hormone release in this species. An in vitro assay for GABA-transaminase activity demonstrated that the pituitary is a site for the metabolism of GABA to succinic acid. In vitro, GABA or the GABA antagonists bicuculline and saclofen did not affect the rate of growth hormone release from dispersed pituitary cells in static incubation. In contrast, intracerebroventricular injection of GABA reduced serum growth hormone levels within 30 min. During the seasonal gonadal cycle, intraperitoneal injection of GABA was without effect in sexually regressed goldfish, but caused a significant decrease in serum growth hormone levels in sexually recrudescent animals. Intraperitoneal implantation of solid silastic pellets containing oestradiol increased serum GH levels fivefold in sexually regressed and recrudescent goldfish; in both groups, GABA suppressed the oestradiol-stimulated increase in circulating growth hormone levels. The effect of oestradiol on basal serum growth hormone levels was specific since progesterone and testosterone were without effect. However, in recrudescent animals treated with progesterone and testosterone, the inhibitory effects of GABA on serum growth hormone levels were absent, indicating a differential role for these steroids in growth hormone release. Taken together, these results demonstrate that GABA has an inhibitory effect on growth hormone release in goldfish.

Reliability of Estimates of Pulsatile Characteristics of Luteinizing Hormone and Growth Hormone Release in Women*

1990 ◽  
Vol 71 (6) ◽  
pp. 1646-1652 ◽  
Author(s):  
J. Y. WELTMAN ◽  
J. D. VELDHUIS ◽  
A. WELTMAN ◽  
J. R. KERRIGAN ◽  
W. S. EVANS ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Luteinizing Hormone ◽  
Hormone Release ◽  
Growth Hormone Release

EFFECT OF SYNTHETIC LUTEINIZING HORMONE-AND FOLLICLE STIMULATING HORMONE-RELEASING HORMONE (LH/FSH-RH) ON SERUM LEVELS OF LH, FSH, THYROTROPHIN (TSH) AND GROWTH HORMONE (HGH) IN NORMAL MALE SUBJECTS

1973 ◽  
Vol 73 (3) ◽  
pp. 465-474 ◽  
Author(s):  
Egil Haug ◽  
Peter Torjesen
Keyword(s):  
Growth Hormone ◽  
Luteinizing Hormone ◽  
Follicle Stimulating Hormone ◽  
Normal Male ◽  
Serum Growth Hormone ◽  
Maximum Serum ◽  
Releasing Hormone ◽  
Serum Lh ◽  
Male Subjects ◽  
Stimulating Hormone

ABSTRACT Four normal male subjects received iv injections of synthetic luteinizing hormone- and follicle stimulating hormone-releasing hormone (LH/FSH-RH) in doses of 12.5, 25, 100, 200 and 400 μg, respectively. A dose of 12.5 μg of LH/FSH-RH caused a significant increase in serum FSH, and 25 μg significantly increased the serum LH. The peak responses occurred 15 to 30 min after the LH/FSH-RH injections in most of the experiments. The increase in the mean maximum serum LH and FSH levels was 2 to 4 fold. There was great variation in response between the subjects, but when tested repeatedly with the same dose of LH/FSH-RH a given individual responded in a consistent manner. The log dose-response curve between LH/FSH-RH and serum LH, and between LH/FSH-RH and serum FSH was approximately linear. A small but significant (P < 0.05) rise in serum thyrotrophin (TSH) was found after LH/FSH-RH in doses ranging from 25 to 400 μg. There was no significant rise in serum growth hormone (HGH). On the basis of the present study a standard 100 μg iv LH/FSH-RH test is suggested.

Somatostatin reduces plasma growth hormone levels during seawater adaptation in coho salmon, Oncorhynchus kisutch

1986 ◽  
Vol 64 (9) ◽  
pp. 2062-2063 ◽  
Author(s):  
R. M. Sweeting ◽  
B. A. McKeown
Keyword(s):  
Growth Hormone ◽  
Inhibitory Action ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Hormone Release ◽  
Growth Hormone Release ◽  
Plasma Growth Hormone ◽  
Seawater Adaptation ◽  
Hormone Levels ◽  
Potent Growth

Plasma growth hormone levels were measured in coho salmon exposed to seawater to examine whether somatostatin has growth hormone release inhibitory action in salmon. Somatostatin (2 μg/10 g body weight) was injected prior to exposure to seawater and samples were taken 6 and 12 h postexposure. The results indicate that somatostatin does have potent growth hormone release inhibitory action in salmon, as it does in other teleosts.

The effect of d-fenfluramine on anterior pituitary hormone release in the rat: in vivo and in vitro studies

1987 ◽  
Vol 65 (12) ◽  
pp. 2449-2453 ◽  
Author(s):  
O. Serri ◽  
E. Rasio
Keyword(s):  
Growth Hormone ◽  
Male Rats ◽  
Serum Prolactin ◽  
Pituitary Hormone ◽  
Pituitary Cells ◽  
Hormone Release ◽  
Growth Hormone Release ◽  
Serum Growth Hormone

Administration of d-fenfluramine, a serotonin-releasing drug, to male rats induced a dose-dependent increase in both serum prolactin and corticosterone concentrations. Serum growth hormone levels increased, but not significantly, at a dose of 1.25 mg/kg i.p. and decreased significantly at higher doses. When rats were pretreated with the serotonin uptake inhibitor fluoxetine (10 mg/kg i.p.) 30 min prior to injection of d-fenfluramine (5 mg/kg i.p.), the serum prolactin response to d-fenfluramine was partially inhibited, whereas the growth hormone response was not significantly modified. Fluoxetine pretreatment increased the serum corticosterone to the same level as did d-fenfluramine. d-Fenfluramine's effect on prolactin and growth hormone release was further tested in a hypothalamic–pituitary in vitro system. The addition of d-fenfluramine (5–500 ng/mL) for 30 min to rat hypothalami resulted in an enhancement of prolactin and growth hormone-releasing activities. These were expressed as the ability of the media in which the hypothalami had been incubated to stimulate prolactin and growth hormone release by cultured pituitary cells. The data suggest that the effect of d-fenfluramine on prolactin secretion is exerted through the hypothalamus and is probably mediated, at least partially, by a serotoninergic mechanism. The mechanism of d-fenfluramine's effect on corticosterone and growth hormone release needs further evaluation.

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