Role of calcitonin gene-related peptide and capsaicin-sensitive afferents in central thyrotropin-releasing hormone-induced hepatic hyperemia

The involvement of capsaicin-sensitive afferent neurons and calcitonin gene -related peptide (CGRP) in the central thyrotropin-releasing hormone (TRH)- induced hepatic hyperemia was investigated in urethane anesthetized rats. B oth systemic capsaicin pretreatment and intravenous administration of CGRP receptor antagonist, human CGRP-(8-37), completely abolished the stimulator y effect of hepatic blood flow induced by intracisternal injection of TRH a nalog (RX-77368; p-Glu-His-(3,3'-dimethyl)-Pro-NH2, 100 ng), assessed by th e hydrogen gas clearance method. These data demonstrate the involvement of capsaicin-sensitive afferent neurons and CGRP in the central TRH-induced st imulation of hepatic blood flow. (C) 1999 Elsevier Science B.V. All rights reserved.