Abstract: The influence of thyroxine (T 4 ) and tri-iodothyronine (T 3 ) on the secretion of GH in immature fowl was investigated. In birds pretreated with i.m. injections of T 4 (100 μg/day for 10 days or 250 μg/kg for 7 days) or T 3 (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 T 3 (25 and 250 μg/kg) or T 4 (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 T 3 or T 4 the increase in GH concentration after TRH treatment was significantly less than that in the controls. In birds pretreated for 60 min with T 3 or T 4 the GH response to TRH was inversely dose-related and lowest in T 3 -treated birds. These results demonstrate that T 3 and T 4 inhibit GH secretion in birds, which is an effect not observed in mammalian species.
Publication Year: 1983
Publication Date: 1983-02-01
Language: en
Type: article
Indexed In: ['crossref', 'pubmed']
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Cited By Count: 46
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