Stimulation by serotonin of immunoreactive peptide histidine isoleucine release from rat hypothalamus in vitro

The effect of serotonin (5-HT) on the release of peptide histidine isoleucine-like immunoreactivity (PHI-LI) from rat hypothalamus was investigated in vitro with a perifusion system. A high potassium concentration (56 mM) stimulated PHI-LI release in a calcium-dependent manner. PHI-LI release was dose-relatedly stimulated by 5-HT (10(-6), 10(-5) and 10(-4) M). PHI-LI release induced by 5-HT (10(-5) M) was abolished by cyproheptadine (10(-4) M), a 5-HT antagonist. These results suggest that 5-HT has a stimulating effect on PHI release from the hypothalamus.