Stimulation of Growth Hormone Secretion by Central Administration of Atrial Natriuretic Polypeptide in the Rat*

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Abstract
Intracerebroventricular (icv) injection of .alpha.-human atrial natriuretic polypeptide (.alpha.hANP) or .alpha.-rat ANP (0.6 and 3 nmol/rat) elicited an increase in plasma GH levels both in conscious freely moving rats and in urethane-anesthetized rats when given at the trough of spontaneous GH secretion. Antiserum specific for rat GRF did not affect the plasma GH increase induced by icv injection of .alpha.hANP. Intracerebroventricular injection of .alpha.ANP (3 nmol/rat) failed to stimulate GH secretion in conscious rats pretreated with cysteamine (30 mg/100 g BW, sc), a depletor of somatostatin (SRIF), and in conscious rats during constant iv infusion of SRIF (55 ng/ml). GH release induced by iv injection of synthetic rat GRF (200 ng/100 g BW) was exaggerated by .alpha.hANP (3 nmol/rat, icv) in conscious rats. These results suggest that central ANP stimulates pituitary GH secretion possibly by inhibiting SRIF release from the hypothalamus in the rat.