Chronic pain is a major health problem afflicting patients with a variety of disorders. Current management focuses largely on opiates. However, the vertebrate nervous system has an endogenous system of pain management, and if this could be augmented it would provide new ways of pain management. The principal investigator proposes to transfer the gene for serotonin type-3 (5HT3) receptors to rats by intrathecal injection of an adenovirus vector and test the resulting changes in carrageenan-induced inflammatory pain. The principal investigator will examine the dose-dependence and time course of the effects, and will evaluate cellular mechanisms by which the analgesic effects are produced.