Intracerebroventricular CART peptide reduces rat ingestive behavior and alters licking microstructure

Intracerebroventricular administration of cocaine- and amphetamine-regulated transcript (CART) peptides reduces food intake and increases c-Fos in brain areas involved in the control of feeding. To discern behavioral mechanisms through which CART alters the microstructure of feeding, we injected CART-(55-102) (0.1, 0.5, 1, 2 mug, and saline controls) into the lateral ventricle of male Sprague-Dawley rats 5 min before dark onset and, using lickometers, monitored the ingestion of an Ensure liquid diet for the first 6 h of dark. At a threshold dose of 1 mg, CART dose dependently 1) decreased intake of Ensure in licks; 2) decreased meal size, but did not alter meal duration or number; 3) reduced initial lick rate of meals; and 4) significantly reduced burst number, licks/burst, and licks/cluster. CART dose dependently increased interlick interval (0.5 mg threshold, 192 +/- 4 vs. 183 +/- 3 ms, control; 1 mug: 201 +/- 1 ms; 2 mug: 214 +/- 6 ms). These data suggest that altered oral motor function, and possibly palatability perception, may be fundamental to the anorexigenic action of CART.