Somatostatin tonically inhibits growth hormone secretion in domestic fowl

1986 ◽  
Vol 111 (1) ◽  
pp. 91-97 ◽  
Author(s):  
S. Harvey ◽  
S.-K. Lam ◽  
T. R. Hall
Keyword(s):  
Growth Hormone ◽  
Domestic Fowl ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Passive Immunization ◽  
Inhibitory Effect ◽  
Gh Secretion ◽  
Basal Plasma ◽  
Plasma Gh

ABSTRACT Passive immunization of immature chickens with sheep somatostatin (SRIF) antiserum promptly increased the basal plasma GH concentration and augmented TRH-induced GH secretion. Although exogenous SRIF had no inhibitory effect on the basal GH concentration in untreated birds or birds pretreated with non-immune sheep serum, it suppressed the stimulatory effect of SRIF immunoneutralization on GH secretion. These results suggest that SRIF is physiologically involved in the control of GH secretion in birds, in which it appears to inhibit GH release tonically. J. Endocr. (1986) 111, 91–97

Stimulation of in-vivo growth hormone secretion in young chickens by rat hypothalamic growth hormone-releasing factor and synthetic analogues

1986 ◽  
Vol 108 (3) ◽  
pp. 413-416 ◽  
Author(s):  
C. G. Scanes ◽  
S. Harvey ◽  
J. Rivier ◽  
W. Vale
Keyword(s):  
Growth Hormone ◽  
Domestic Fowl ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Gh Secretion ◽  
Structure Activity ◽  
In Vivo Growth ◽  
Plasma Gh ◽  
Stimulation Of

ABSTRACT Rat hypothalamic GH-releasing factor (rhGRF), at doses between 0·1 and 10 μg/kg, increased plasma GH concentrations in immature domestic fowl 5–10 min after i.v. injection. Sodium pentobarbitone anaesthesia blunted the GH responses to rhGRF, although in both conscious and anaesthetized chicks the maximal responses were induced by a dose of 1 μg rhGRF/kg. The stimulatory effect of rhGRF on in-vivo GH secretion was less than that provoked by corresponding doses of human pancreatic GRF, but greater than that elicited by two rhGRF analogues, (Nle27)-rhGRF(1–32) and (Nle27)-rhGRF(1–29). These results demonstrate that the chicken pituitary is responsive to mammalian GRF and provide evidence of structure-activity relationships of GRF in the domestic fowl. J. Endocr. (1986) 108, 413–416

Thyroid hormones inhibit growth hormone secretion in domestic fowl (Gallus domesticus)

1983 ◽  
Vol 96 (2) ◽  
pp. 329-334 ◽  
Author(s):  
S. Harvey
Keyword(s):  
Domestic Fowl ◽  
Single Injection ◽  
Mammalian Species ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Similar Reduction ◽  
Thyrotrophin Releasing Hormone ◽  
Gh Secretion ◽  
Basal Plasma ◽  
Plasma Gh

The influence of thyroxine (T4) and tri-iodothyronine (T3) on the secretion of GH in immature fowl was investigated. In birds pretreated with i.m. injections of T4 (100 μg/day for 10 days or 250 μg/kg for 7 days) or T3 (250 μg/kg for 7 days) the basal plasma GH level was markedly reduced. A similar reduction in the basal plasma GH level was also observed 60 min after a single injection or T3 (25 and 250 μg/kg) or T4 (250 μg/kg). In control birds the concentration of plasma GH was greatly increased (> 450 μg/l) within 10 min of an i.v. injection of thyrotrophin releasing hormone (TRH; 10 μg/kg). In birds pretreated with T3 or T4 the increase in GH concentration after TRH treatment was significantly less than that in the controls. In birds pretreated for 60 min with T3 or T4 the GH response to TRH was inversely dose-related and lowest in T3-treated birds. These results demonstrate that T3 and T4 inhibit GH secretion in birds, which is an effect not observed in mammalian species.

Neuroanatomic localization of the inhibitory effect of TRH on growth hormone secretion

1987 ◽  
Vol 253 (4) ◽  
pp. E354-E359
Author(s):  
K. Ishikawa ◽  
H. Katakami ◽  
L. A. Frohman
Keyword(s):  
Growth Hormone ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Inhibitory Effect ◽  
Releasing Hormone ◽  
Hypothalamic Deafferentation ◽  
Electrolytic Lesions ◽  
Plasma Gh ◽  
The Right ◽  
Lateral Cerebral Ventricle

The inhibitory effect of centrally administered thyrotropin-releasing hormone (TRH) on the plasma growth hormone (GH) response to GH-releasing hormone (GHRH) in the rat was studied in relation to the anatomic loci involved. Experiments were performed in animals with bilateral electrolytic lesions in the medial preoptic (MPO) area or with anterolateral hypothalamic deafferentation and in sham-operated controls. Blood samples were obtained every 10 to 20 min from and drugs were injected into freely moving animals with indwelling cannulas in the right atrium and lateral cerebral ventricle. In control animals, the plasma GH response to GHRH, 1 microgram iv, was almost completely inhibited by TRH, 1 microgram icv, injected 5 min previously. In animals with either MPO lesions or anterolateral hypothalamic deafferentation in which median eminence somatostatin immunochemical staining was almost completely eliminated, the GH response to GHRH was enhanced and TRH did not exhibit any inhibitory effect. These results, together with the previous observation that the inhibitory effect of TRH is blocked by prior treatment with anti-somatostatin serum, suggest that the effect of TRH is mediated by stimulation of somatostatin-containing neurons in the periventricular nucleus of the MPO area.

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

Glucocorticoid modulation of growth hormone secretion in vitro. Evidence for a biphasic effect on GH-releasing hormone mediated release

1987 ◽  
Vol 114 (4) ◽  
pp. 465-469 ◽  
Author(s):  
Gian Paolo Ceda ◽  
Robert G. Davis ◽  
Andrew R. Hoffman
Keyword(s):  
Growth Hormone ◽  
Prolonged Exposure ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Inhibitory Effect ◽  
Pituitary Cells ◽  
Gh Secretion ◽  
Glucocorticoid Action

Abstract. Glucocorticoids have been shown to have both stimulatory and suppressive effects on GH secretion in vitro and in vivo. In order to study the kinetics of glucocorticoid action on the somatotrope, cultured rat pituitary cells were exposed to dexamethasone for varying periods of time. During short-term incubations (≤ 4 h), dexamethasone inhibited GHRH and forskolin-elicited GH secretion, but during longer incubation periods, the glucocorticoid enhanced both basal and GHRH-stimulated GH release. The inhibitory effect of brief dexamethasone exposure was also seen in cells which previously had been exposed to dexamethasone. In addition, growth hormone secretion from cultured rat and human somatotropinoma cells was inhibited by a brief exposure to dexamethasone. Thus, the nature of glucocorticoid action on the isolated cultured somatotrope is biphasic, with brief exposure inhibiting, and more prolonged exposure stimulating GH secretion.

Neuropeptide Y directly inhibits growth hormone secretion by human pituitary somatotropic tumours

1987 ◽  
Vol 115 (1) ◽  
pp. 149-154 ◽  
Author(s):  
Eric F. Adams ◽  
Maria S. Venetikou ◽  
Christine A. Woods ◽  
S. Lacoumenta ◽  
J. M. Burrin
Keyword(s):  
Growth Hormone ◽  
Neuropeptide Y ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Inhibitory Effect ◽  
Pituitary Cells ◽  
Maximal Effect ◽  
Human Pituitary ◽  
Amino Acid Peptide ◽  
Gh Secretion

Abstract. Neuropeptide Y (NPY) is a 36 amino acid peptide, widely distributed throughout the brain and is found in hypothalamic neurones. This latter finding suggests that NPY may possess a hypophysiotropic function. A number of studies have demonstrated effects of NPY on LH and GH secretion by rat pituitary cells. We report here the results of experiments investigating the effects of NPY on GH secretion by tumorous human somatotropic pituitary cells in culture. NPY (0.25–25 nmol/l) inhibited GH secretion by 20–53%, the maximal effect depending upon the tumour studied. The potency of NPY was less than that of somatostatin (SRIH). The stimulatory effects of growth hormone releasing factor (GHRH) and theophylline were reduced by NPY, but NPY did not modify the inhibitory effect of SRIH on GH secretion. It is concluded that NPY may be involved in the control of GH secretion, at least by tumorous human pituitary somatotropes.

Effect of synthetic thyrotrophin-releasing hormone and its analogues on growth hormone secretion in the domestic fowl (Gallus Domesticus)

1981 ◽  
Vol 97 (4) ◽  
pp. 448-453 ◽  
Author(s):  
C. G. Scanes ◽  
S. Harvey ◽  
B. A. Morgan ◽  
M. Hayes
Keyword(s):  
Growth Hormone ◽  
Domestic Fowl ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Gallus Domesticus ◽  
Plasma Growth Hormone ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
Gh Secretion ◽  
Trh Analogues

Abstract. Variations in plasma growth hormone (GH) concentrations following iv or sc administration of synthetic thyrotrophin-releasing hormone (TRH, Pyr-His-Pro-NH2) have been followed in immature and adult domestic fowl. TRH markedly stimulated GH secretion in newly hatched (1 and 2 day old) chicks and in 6-week-old cockerels but in adult male or female birds of two strains had very little effect, if any. Intravenous injection of 4 TRH analogues (Pyr-His-Mep-NH2, Pyr-Meh-Mep-NH2, Pyr-Meh-Mep-NH and Pyr-Meh-Pro-NH2) were also potent GH secretagogues in 6-week-old birds. The stimulatory effect of TRH or the TRH-analogues on GH secretion was not dose-related.

Central action of thyrotrophin-releasing hormone on growth hormone secretion in domestic fowl

1990 ◽  
Vol 126 (1) ◽  
pp. 83-88 ◽  
Author(s):  
S. Harvey ◽  
R. W. Lea ◽  
C. Ahene
Keyword(s):  
Growth Hormone ◽  
Domestic Fowl ◽  
Hormone Secretion ◽  
Plasma Concentrations ◽  
Growth Hormone Secretion ◽  
Central Effect ◽  
Central Action ◽  
Thyrotrophin Releasing Hormone ◽  
Gh Secretion ◽  
Peripheral Plasma

ABSTRACT Peripheral plasma concentrations of GH in adult chickens were increased, in a dose-related manner, between 5 and 30 min after the intracerebroventricular (i.c.v.) injection of 0·1 or 10 μg TRH. In contrast, i.v. administration of comparable doses of TRH had no significant effect on circulating GH concentrations. [3H]3-methyl-histidine2-TRH ([3H]Me-TRH) was located in the pituitary gland and peripheral plasma within 5 min of its i.c.v. administration, although in amounts that were unlikely to affect directly pituitary function. [3H]Me-TRH rapidly accumulated in the hypothalamus following its i.c.v. administration (but not after i.v. injection), and the central effect of TRH on GH secretion in birds is therefore likely to be induced by effects at hypothalamic sites. Journal of Endocrinology (1990) 126, 83–88

Physiological control of growth hormone secretion by thyrotrophin-releasing hormone in the domestic fowl

1985 ◽  
Vol 105 (3) ◽  
pp. 351-355 ◽  
Author(s):  
H. Klandorf ◽  
S. Harvey ◽  
H. M. Fraser
Keyword(s):  
Domestic Fowl ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Physiological Control ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
Gh Secretion ◽  
Normal Sheep Serum ◽  
Plasma Gh

ABSTRACT Immature cockerels (4- to 5-weeks old) were passively immunized, with antiserum raised in sheep, against thyrotrophin-releasing hormone (TRH). The administration of TRH antiserum (anti-TRH) at doses of 0·5, 1·0 or 2·0 ml/kg lowered, within 1 h, the basal concentration of plasma GH for at least 24 h. The administration of normal sheep serum had no significant effect on the GH concentration in control birds. Although the GH response to TRH (1·0 or 10·0 μg/kg) was not impaired in birds treated 1 h previously with anti-TRH, prior incubation (at 39 °C for 1 h) of TRH (20 μg/ml) with an equal volume of anti-TRH completely suppressed the stimulatory effect of TRH (10 pg/kg) on GH secretion in vivo. These results suggest that TRH is physiologically involved in the hypothalamic control of GH secretion in the domestic fowl. J. Endocr. (1985) 105, 351–355

Effect of exogenous growth hormone administration on endogenous growth hormone secretion induced by a met-enkephalin analog

1996 ◽  
Vol 134 (1) ◽  
pp. 73-76 ◽  
Author(s):  
Giuseppe Fanciulli ◽  
Osvaldo Oliva ◽  
Paolo A Tomasi ◽  
Alessandra Pala ◽  
Alba Bertoncelli ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Endogenous Growth ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Inhibitory Effect ◽  
Growth Hormone Administration ◽  
Gh Secretion ◽  
Hormone Administration ◽  
Exogenous Growth ◽  
Serum Gh

Fanciulli G, Oliva O, Tomasi PA. Pala A. Bertoncelli A, Dettori A, Delitala G. Effect of exogenous growth hormone administration on endogenous growth hormone secretion induced by a met-enkephalin analog. Eur J Endocrinol 1996:134:73–6. ISSN 0804–4643 Exogenous growth hormone (hGH) administration in humans attenuates the endogenous growth hormone (GH) response to some pharmacological stimuli: in particular, pretreatment with hGH completely blocks the serum GH response to growth hormone-releasing hormone. In order to evaluate the mechanism(s) whereby opioids induce GH secretion in man, we gave the following treatments to six healthy male volunteers: (a) IV saline: (b) a met-enkephalin analog G-DAMME 250 μg IV as a bolus at time ′: (c) hGH 2 IU as an IV bolus at time −180′; (d) G-DAMME as above, preceded by hGH as above. In our study. G-DAMME stimulated GH secretion both basally (peak 17.9 ± 6.0 ng/ml) and, to a lesser extent, after hGH pretreatment (6.0 ± 2.7 ng/ml). Since in our study G-DAMME was able to partially overcome the inhibitory effect of hGH administration, it is suggested that opioids act through an inhibition of somatostatin release and not through a GHRH-dependent pathway. However, an additional direct effect of hGH on pituitary somatotrophes cannot be excluded. Giuseppe Delitala, Chair of Endocrinology, Viale S. Pietro 12, University of Sassari, 07100 Sassari. Italy

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