Melatonin inhibits calcitonin gene-related peptide-induced vasodilation and increase in cAMP in rat middle cerebral arteries

The action of melatonin to alter calcitonin gene-related peptide (CGRP)-mediated vasodilation and stimulation of adenylate cyclase activity in middle cerebral arteries of rats was investigated. Concentration-dependent dilation of the rat middle cerebral artery produced by CGRP (EC,, of 9.4 X 10(-10) M) was significantly inhibited in the presence of 10(-8) M melatonin (EC,, of 3.4 x 10(-9) M). In addition, CGRP (10(-7) M)-mediated increase in adenylate cyclase activity was also significantly attenuated by the receptor mediated action of melatonin. These results indicate that melatonin may interact with CGRP to regulate cerebral arterial tone. (C) 2001 Elsevier Science B.V. All rights reserved.