Anaesthesia-like condition and/or potentiation of hexobarbital sleep produced by pungent agents in normal and capsaicin-desensitized rats.

Naturally occurring pungent agents (zingerone, capsaicin), beside their hypothermic action, produced an anaesthesia-like state and/or potentiated hexobarbital sleeping time in rats. This effect was correlated to the sensory stimulating potency of these substances; actually non-pungent capsaicin congeners induced neither hypothermia nor anaesthesia. Capsaicin desensitization known to impair the function of the hypothalamic warmth detectors, greatly inhibited or completely abolished these responses. The anaesthetic action of some synthetic ketones possessing sensory stimulating effect was also greatly inhibited or abolished by capsaicin.