title: Growth hormone-releasing hormone and clonidine stimulate biosynthesis of growth hormone in neonatal pituitaries.
abstract: Comparative studies were performed to verify the effect of growth hormone releasing hormone (GHRH) or clonidine (CLON), a compound thought to act via release of endogenous GHRH, in stimulating GH biosynthesis in the pituitary from neonatal and adult rats. In vitro preincubation for 1 h with GHRH (hpGRF-40, 10(-8) M) increased the incorporation of L-[3H]leucine in the electrophoretic band of GH in the pituitary from 10-day-old rats, but not in the gland from adult rats. Ex-vivo treatment with GHRH or CLON for 5 days was effective in stimulating GH biosynthesis only in the pituitary from neonatal rats. These data demonstrate that neonatal somatotropes are particularly sensitive to the GH-synthesizing activity of GHRH or a GHRH-releasing stimulus.
mesh_terms: D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D003000:Clonidine / Q000494:pharmacology*; D013006:Growth Hormone / Q000096:biosynthesis*; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D010902:Pituitary Gland / Q000187:drug effects / Q000502:physiology*; D051381:Rats
chemical_list: D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; D003000:Clonidine