Intracerebroventricular CART peptide reduces rat ingestive behavior and alters licking microstructure

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Abstract
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 μg, 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 μg, 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 μg threshold, 192 ± 4 vs. 183 ± 3 ms, control; 1 μg: 201 ± 1 ms; 2 μg: 214 ± 6 ms). These data suggest that altered oral motor function, and possibly palatability perception, may be fundamental to the anorexigenic action of CART.