ANORECTIC EFFECT OF AMYLIN IS NOT TRANSMITTED BY CAPSAICIN-SENSITIVE NERVE-FIBERS

Abdominal vagal and splanchnic afferents play an important role in the control of food intake in that they transmit various satiety signals to the central nervous system. Inasmuch as previous studies have shown that the anorectic effect of intraperitoneally injected amylin was no t abolished by subdiaphragmatic vagotomy, the aim of the present study was to elucidate the role of splanchnic afferents in mediating amylin 's anorectic effect after intraperitoneal injection. Rats were pretrea ted intraperitoneally with the neurotoxin capsaicin, which destroys pr imary sensory (vagal and splanchnic) afferents. Sham-treated rats serv ed as control. Capsaicin-pretreatment had no influence on the anorecti c effects of amylin (5 mu g/kg) and the related peptide, calcitonin ge ne-related peptide (CGRP; 5 mu g/kg), in 24-h food-deprived rats. Abol ition of cholecystokinin's (3 mu g/kg) anorectic effect agrees with pr evious studies and confirmed the effectiveness of the capsaicin pretre atment. In conclusion, the anorectic effects of intraperitoneally inje cted amylin and CGRP are not mediated by capsaicin-sensitive primary s ensory neurons. Both anorectic peptides are, therefore, most likely to act within the central nervous system. Previous studies suggest that the relevant receptors might be located in neurons of the area postrem a-nucleus of the solitary tract region.