Expressional changes of neuropeptide Y and cholecystokinin in the arcuate and paraventricular nuclei after capsaicin administration.

Despite its toxicity, a great deal of attention has been paid to the anorexic effect of capsaicin in the treatment of obesity-related neurotransmitters/neuromodulators. To determine if capsaicin has any effects on the orexigenic or anorexigenic peptides, the neuropeptide Y (NPY)- and cholecystokinin (CCK)-immunoreactivities were demonstrated in the rat hypothalamus by immunohistochemistry after capsaicin administration. There was a significantly lower concentration of NPY immunopositive cells in the arcuate and paraventricular nuclei of the capsaicin treated rats. In contrast, the CCK expressions level was higher in the paraventricular nucleus of the capsaicin treated rats than in the control rats. These results suggest that capsaicin influence neuropeptides such as orexigenic NPY and anorexigenic CCK related to control food intake.