The effect of GHRH on TSH release in rats in vivo and in vitro

Abstract

In man, GHRH has been shown to potentiate the TSH-releasing activity of TRH. To study the way by which GHRH affects TRH-stimulated TSH release, we examined the effect of GHRH (1-29)NH2 on basal and stimulated TSH secretion in intact male rats and superfused dispersed rat pituitary cells. In the intact rats, GHRH(1-29)NH2 potentiated TRH-stimulated TSH release in the evening, but potentiation was not observed in the morning and in dispersed pituitary cells. Basal TSH levels were not changed by GHRH(1-29)NH2. It is concluded that GHRH(1-29)NH2 potentiates the TSH-releasing activity of TRH in the evening in rats possibly through suprahypophyseal disinhibition.

Zika Virus Infection in Hypothalamus Causes Hormone Deficiencies and Leads to Irreversible Growth Delay and Memory Impairment in Mice

“…In contrast, most hormones related to the hypothalamus-pituitary-thyroid axis showed little change, except for an increase in TSH in the ZIKV group. Because no histopathological change was found in the pituitary, we speculate that the increased levels of GH and TSH might have been due to the overexpression of GHRH, which is essential for the expansion of the somatotrope lineage during pituitary development (Frohman and Kineman, 2002) and can potentiate the TSH-releasing activity of TRH (Looij et al, 1995). We cannot completely explain the cause of these differences on the basis of our present results.…”