ABSTRACT
We examined the effects of intracerebroventricular ( i. c. v) administration of adrenomedullin (ADM) on catecholaminergic neurons and the expression of c-fos gene in rat brain nuclei involved in cardiovascular regulation using double immunohistochemical method for Fos and tyrosine hydroxylase (TH). The results showed that: ( 1 ) Following icy administration of ADM (3 nmol/kg) , double-labeled neurons for Fos and TH were significantly increased in the area postrema ( AP), the nucleus of the solitary tract ( NTS), the nucleus paragigantocelluaris laterialis (PGL) and the locus coeruleus (LC). (2) Pretreatment with calcitonin gene-related peptide receptor antagonis CGRP8-37 (30 nmol/kg) significantly reduced the action of ADM (3 nmol/kg) in the brain. The present study suggested that ADM might activate the neurons of the brain nuclei involved in cardiovascular regulation, and supported the hypothesis that the central action of ADM were induced by activating the catecholaminergic neurons of brainstem nuclei involved in cardiovascular regulation, CGRP receptor might mediate the effects of ADM.