RESUMEN
In rats, limited daytime wheel access suppresses feeding over the subsequent night [Lattanzio SB, Eikelboom R. Wheel access duration in rats: I. effects on feeding and running. Behav Neurosci 2003; 117:496-504.]. This phenomenon is known as the wheel-induced feeding suppression (WIFS). The classic antipsychotic, chlorpromazine, can minimize the severity of the related activity anorexia procedure, but is thought to act through a suppression of running [Routtenberg A. "Self-starvation" of rats living in activity wheels: adaptation effects. J Comp Physiol Psychol 1968; 66:234-8.]. We tested the effects of chlorpromazine (2mg/kg IP) on the acute WIFS in 40 adult male rats by administering the drug before or after 3h of daytime wheel access and measuring food consumption over the subsequent 24h. Control groups received saline injections or were exposed to locked wheels. While chlorpromazine did not attenuate feeding or change wheel running alone, it blocked their interaction, the acute WIFS. This procedure might be useful in screening drugs for anorexia nervosa where exercise is often elevated and feeding is suppressed.
Asunto(s)
Clorpromazina/farmacología , Antagonistas de Dopamina/farmacología , Conducta Alimentaria/efectos de los fármacos , Condicionamiento Físico Animal/psicología , Animales , Peso Corporal/efectos de los fármacos , Peso Corporal/fisiología , Ingestión de Líquidos/efectos de los fármacos , Ingestión de Líquidos/fisiología , Ingestión de Alimentos/efectos de los fármacos , Ingestión de Alimentos/fisiología , Masculino , Actividad Motora/fisiología , Ratas , Ratas Sprague-Dawley , Carrera/fisiologíaRESUMEN
Adult male rats given ad lib access to food and a running wheel show an initial feeding and weight suppression. Over 6-10 days feeding recovers, but body weight remains low. It is not clear which effect is primary, the wheel-induced feeding or weight change. To test this, rats were first restricted to 15g of food a day for 8 or 16 days to reduce their weight relative to control non-restricted rats. They were then returned to ad lib feeding and half the restricted and non-restricted control rats were introduced to the wheel either immediately (Experiment 1) or 4 days later (Experiment 2). Food intake, body weight, and wheel running were monitored throughout the experiments. At the return to ad lib feeding, prior food restriction elevated feeding. Both immediate and delayed wheel access suppressed feeding in both groups of wheel access rats compared to the appropriate control rats. Feeding history did not have a significant effect on wheel running. The wheel-induced reductions in feeding from baseline were similar in the weight reduced and normal weight animals suggesting that prior weight restriction did not prevent the onset of the wheel-induced feeding suppression. It is therefore suggested that the feeding suppression is not driven by a reduced weight set point.