Depletion of primary afferent substance P by capsaicin and dihydrocapsaicin without altered thermal sensitivity in rats

Abstract

Systemic administration of capsaicin and dihydrocapsaicin to adult rats of two different strains and of capsaicin to neonatal rats, depleted substance P levels in dorsal roots plus ganglia and in dorsal spinal cord. In no case was this depletion accompanied by substantially altered tail-flick latencies. The results are not consistent with a role of the neuropeptide in nociceptive thermal sensitivity in the rat.