Release of prolactin and LH and histamine-containing cells in brain

The effects of histamine released from mast cells by the compound 48/80, a degranulating agent, on plasma prolactin and LH levels, were examined in rats. Compound 48/80 given systemically (s.c.) at a dose of 2 mg/100 g b.w. significantly increased at 15 and 60 min after injection, both prolactin and LH release in ovariectomized, steroid-primed rats. Prolactin but not LH was also augmented in the plasma of male rats following s.c. administration of compound 48/80. There were no modifications of plasma prolactin levels in male rats at 15, 30 or 60 min after intraventricular injection of 50 microgram compound 48/80. Results suggest that the hormone effects were due to histamine released from median eminence mast cells after systemic injection of compound 48/80.