Cholecystokinin-induced suppression of locomotion is attenuated in capsaicin pretreated rats.

Cholecystokinin (CCK), a peptide found in both gastrointestinal endocrine cells and neurons, suppresses food intake and reduces locomotor behavior when injected systemically. Both the locomotor and ingestive effects of CCK are abolished by subdiaphragmatic vagotomy. Pretreatment of adult rats with capsaicin attenuates the reduced locomotor activity and reduced food intake which normally occurs following injection of exogenous cholecystokinin. Since capsaicin damages or destroys small-diameter, unmyelinated, sensory neurons, including vagal sensory fibers, these data support the interpretation that both CCK-induced suppression of food intake and CCK-induced reduction of locomotion are mediated by fine, unmyelinated sensory neurons.