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

ABSTRACT

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. Both systemic capsaicin pretreatment and intravenous administration of CGRP receptor antagonist, human CGRP-(8-37), completely abolished the stimulatory effect of hepatic blood flow induced by intracisternal injection of TRH analog (RX-77368; p-Glu-His-(3,3'-dimethyl)-Pro-NH2, 100 ng), assessed by the hydrogen gas clearance method. These data demonstrate the involvement of capsaicin-sensitive afferent neurons and CGRP in the central TRH-induced stimulation of hepatic blood flow.