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.

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

Activation of cholinergic tone by pyridostigmine reverses the inhibitory effect of corticotropin-releasing hormone on the growth hormone-releasing hormone-induced growth hormone secretion

1992 ◽  
Vol 126 (2) ◽  
pp. 113-116 ◽  
Author(s):  
SM Corsello ◽  
A Tofani ◽  
S Della Casa ◽  
R Sciuto ◽  
CA Rota ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Inhibitory Effect ◽  
Normal Male ◽  
Corticotropin Releasing Hormone ◽  
Releasing Hormone ◽  
Gh Secretion ◽  
Cholinergic Tone ◽  
Ghrh Test

Previous studies have shown that corticotropin-releasing hormone (CRH) is capable of inhibiting growth hormone (GH) secretion in response to GH-releasing hormone (GHRH). In an attempt to clarify the mechanism of the CRH action, we have studied the effect of enhanced cholinergic tone induced by pyridostigmine on the CRH inhibition of the GH response to GHRH in a group of six normal men and six normal women. All subjects presented a normal GH response to 50 μg iv GHRH administration (mean peak±sem plasma GH levels 20±2.9 μg/l in men and 28.9±2.9 μg/l in women) with a further significant increase after pyridostigmine pretreatment (60mg orally given 60 min before GHRH) in men (GH peaks 43.1±6.9 μg/l, p<0.005) but not in women (GH peaks 39.2±3.0 μg/l). In the same subjects, peripherally injected CRH (100 μg) significantly inhibited the GH response to GHRH (GH peaks 8.1±0.6 μg/l in men, p<0.005 and 9.9±0.7 μg/l in women, p<0.005). Pyridostigmine (60 mg) given orally at the same time of CRH administration (60 min before GHRH) reversed the CRH inhibition of GHRH-induced GH secretion (GH peaks 35.3±8.2 μg/l in men and 35±3.3 μg/l in women) with a response not significantly different to that seen in the pyridostigmine plus GHRH test. Our data confirm that pyridostigmine is capable of potentiating the GHRH-induced GH release in normal male but not female subjects. In addition, our studies show that the potentiating action of pyridostigmine on the GHRH-induced GH secretion prevails on the inhibiting effect of CRH when the two drugs are given together 1 h before GHRH injection. Both CRH and pyridostigmine could exert their action by modifying, in opposite ways, somatostatin release from the hypothalamus.

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