A re-evaluation of the neurochemical and antinociceptive effects of intrathecal capsaicin in the rat.

The effect of intrathecal administration of capsaicin in the rat on thermal nociceptive thresholds and on the content of substance P, somatostatin and glutamic acid decarboxylase in the dorsal horn of the spinal cord was determined. The results suggest that the depletion of spinal cord substance P induced by capsaicin may not by itself be sufficient to explain the observed changes in noxious thermal thresholds, which may be related instead to non-specific damage to the spinal cord.