Inhibitory effect of central calcitonin-gene related peptide (CGRP) on pancreatic secretion in conscious rats

The inhibitory effect of central administration of calcitonin-gene related peptide (CGRP) on pancreatic secretion stimulated by bile-pancreatic juice diversion was determined in conscious rats. Rats were prepared with separat e cannulae for draining bile and pancreatic juice and with a duodenal cannu la and an extra-jugular vein cannula. In addition, another cannula was ster eotactically implanted into the left lateral cerebral ventricle, Rats were placed in restraint cages and experiments were conducted 4d after the opera tion without anesthesia. An injection of CGRP (1 nmol/10 mu l) into the lef t lateral cerebral ventricle (I.C.V.) inhibited pancreatic secretion as wel l as cholecystokinin (CCK) release induced by bile-pancreatic juice diversi on. Intravenous infusion of alpha- and beta-adrenergic receptor antagonist, phentolamine and propranolol did not reverse the inhibition of pancreatic secretion. Intravenous infusion of CGRP did not affect pancreatic secretion or plasma CCK concentrations. The inhibitory action of central CGRP (I.C.V .) on pancreatic secretion and CCK release stimulated by bile-pancreatic ju ice diversion is partially mediated by an cr-adrenergic mechanism, although its precise mechanism has not been elucidated.