Sensory interactions between capsaicin and temperature in the oral cavity

Abstract

The interaction between thermal and chemical stimulation in the oral cavity was studied in two experiments by measuring the perceived intensity of thermal sensations in the presence of capsaicin, and the perceived intensity of the ‘burning’ sensations produced by capsaicin at several solution temperatures. It is demonstrated in the first experiment that capsaicin intensifies sensations of warmth (particularly at moderateto-high temperatures) and slightly but consistently reduces the intensity of perceived cold. On the other hand, the burning sensation induced by capsaicin is enhanced by warming and inhibited by cooling. The second experiment confirmed the existence of a second inhibitory factor in addition to cooling, possibly of tactile origin. Viewed together the results of both experiments indicate that complex sensory interactions may take place in the trigeminal system during simultaneous chemical, thermal and mechanical stimulation.