Influence of brain histaminergic system on episodic growth hormone secretion in the rat

The effects of histamine and amodiaquine (a drug known to inhibit histamine-N-methyltransferase) on pulsatile growth hormone (GH) secretion were determined in unanaesthetized male rats. Intracerebroventricular (i.c.v.) administration of histamine (0.01, 0.05, 0.1 mumol/rat) caused a dose-related suppression of spontaneous pulses of rat GH (rGH) secretion. Amodiaquine (0.16 mumol/rat i.c.v.) also inhibited the pulses, but to a lesser degree. The results, which show the inhibitory effects of both exogenous histamine and increased levels of endogenous histamine on pulsatile rGH secretion, support the hypothesis that the histaminergic system also plays a role in physiological CNS control of rGH secretion.