CAPSAZEPINE, A VANILLOID RECEPTOR ANTAGONIST, INHIBITS NICOTINIC ACETYLCHOLINE-RECEPTORS IN RAT TRIGEMINAL GANGLIA

Vanilloid receptors are activated by capsaicin, the pungent ingredient in hot pepper. They are also specifically and competitively inhibited by capsazepine (CPZ). To determine whether CPZ is specific to vanillo id receptors, its effects were tested on the currents evoked by nicoti ne in rat trigeminal ganglia. We found that 10 mu M CPZ, a concentrati on frequently used to inhibit capsaicin's physiological responses attr ibuted to capsaicin, reversibly inhibits (40%) the magnitude of the cu rrents activated by 100 mu M nicotine. We conclude that 10 mu M capsaz epine can alter the effects of channels other than those activated by capsaicin, and thus caution must be used in attributing all the CPZ-se nsitive physiological effects to those only produced by blocking of va nilloid receptors. (C) 1997 Elsevier Science Ireland Ltd.