ABSTRACT
Abstract-The antinociceptive effects of intrathecally (i.t.) administered high doses of spermine and spermidine, endogenous polyamines, were examined in the mouse capsaicin test. Spermine (2.5-10 nmol) and spermidine (10 and 15 nmol), when administered i.t. 5 min before the injection of capsaicin solution (1600 ng) into the plantar surface of a hindpaw, produced a significant reduction of the nociceptive behavioral response. Ifenprodil (2 and 4 nmol), an antagonist of the poly amine recognition site on N-methyl-D-aspartate (NMDA) receptor ion-channel complex, co-administered with spermine or spermidine significantly inhibited antinociception induced by both polyamines. These results indicate that spermine-and spermidine-induced antinociception may be mediated via the polyamine recognition site on NMDA receptor ion-channel complex in the mouse spinal cord.
