Deafferentation affects short-term but not long-term control of food intake.

Deafferentation affects short-term but not long-term control of food intake (PHYSIOL BEHAV XX(X) 000-000, 2005). Rats were treated neonatally with capsaicin (CAP) to investigate the involvement of vagal afferents in food intake control and body weight regulation. In the first set of experiments, rats were offered increasing concentrations of sucrose (10-15-20-40%) in short-term feeding tests of 1 h. At the end, 10% was offered again to see whether CAP rats modified their intake after repeated exposure to different concentrations of sucrose solution. Results demonstrated that CAP animals overconsume persistently compared to vehicle (VEH) controls. This overconsumption is most pronounced and variable at 10% trials. Hypertonic 40% sucrose solution resulted in a small but significant drop in intake in CAP rats. Overall, if the concentration of sucrose solution is more than 10%, sucrose ingestion of CAP and VEH rats does not depend on the concentration of sucrose solution and remains relatively constant during all trials. In another experiment, rats were exposed to a high-fat condensed milk suspension (CMS) for 5 days. CAP rats initially overconsumed from this CMS compared to VEH. This was accompanied by a decreased intake in chow. However, over the 5 day period CAP animals adjusted their CMS and chow intake to control levels. During both experiments there were no differences in body weight gain between CAP and VEH. Together, these results suggest that capsaicin-sensitive vagal C-fibers are involved in the control of volume ingestion and short-term food intake control but are not required for long-term control of energy intake.