Resumo

MATHISON, Yaira  e  ISRAEL, Anita. Señalización de la Adrenomedulina en la eminencia media de la rata. AVFT [online]. 2006, vol.25, n.2, pp.45-53. ISSN 0798-0264.

Adrenomedullin (AM) is a 52 amino acid peptide widely distributed in the central nervous system which exerts several pharmacological actions through its interaction with three receptor subtypes, AM1, AM2 and the type 1 receptor of the calcitonin gene related peptide (CGRP1). The co-localization of AM and vasopressin in hypothalamic paraventricular and supraoptic nucleai, which Project to the median eminence, together with the presence of nitric oxide synthase activity and IR-cGMP neurons, suggest a role for NO/GMPc signaling in the AM actions in the CNS. Thus, we studied the effect of AM on receptor-mediated NO/cGMP signaling in rat median eminence (ME), a hypothalamic structure known to contain a rich plexus of nitric oxide synthase (NOS)-containing neurons and fibers. AM significantly increased cGMP formation NOS activity. Preincubation of AN-ME fragment with L-arginine analog, N-nitro-L-arginine (L-NAME) inhibited AM-stimulated cGMP formation. The addition of the selective AM receptor antagonist, AM(22-52), blocked AM-induced increase in NOS activity and cGMP generation, while CGRP(8-37), a selective CGRP1 receptor antagonist, was ineffective. Our results demonstrate that in median eminence fragments, adrenomedullin stimulate NO/cGMP signaling pathway through the interaction with the AM1 receptor, supporting the concept that adrenomedullin may represent an important regulator of reproductive and neuroendocrine and reproductive function.

Palavras-chave : adrenomedulin; nitric oxide; median eminence.