[Effect of intracerebroventricular injection of adrenomedullin on catecholaminergic neurons and expression of c-fos in the rat brain nuclei involved in cardiovascular regulation].

AIM AND METHODS

Using double immunohistochemical method for Fos and tyrosine hydroxylase(TH) to examine the effects of intracerebroventricular (icv) administration of adrenomedullin (AM) on catecholaminergic neurons and the expression of c-fos gene in rat brain nuclei involved in cardiovascular regulation in order to define whether the effects of central administration of adrenomedullin (AM) were induced by activating the catecholaminergic neurons.

RESULTS

(1) Following icy administration of AM (3 nmol/kg), Fos-like immunoreactivity neurons were markedly increased in several brain areas of the rat, including the brainstem, the hypothalamus and the forebrain. (2) Following icy administration of AM (3 nmol/kg), double-labeled neurons for Fos and TH increased significantly in the area postrema (AP), the nucleus of the solitary tract (NTS), the nucleus paragigantocellularis lateralis (PGL) and the locus coeruleus (LC). (3) Pretreatment with calcitonin gene-related peptide receptor antagonism CGRP (8-37) (30 nmol/kg) significantly reduced the action of AM (3 nmol/kg) in the brain.

CONCLUSION

AM activates the nuclei involved in cardiovascular regulation in the forebrain, the hypothalamus and the brainstem, and that the central actions of AM are induced by activating the catecholaminergic neurons of brainstem nuclei involved in cardiovascular regulation. CGRP receptor can mediate the effects of AM in brain.