Trazodone hydrochloride attenuates thermal hyperalgesia in a chronic constriction injury rat model.

Abstract

Trazodone hydrochloride is used in the treatment of neuropathic pain. However, the analgesic effects of trazodone on neuropathic pain are controversial. The study was undertaken to determine the analgesic effect of trazodone on a chronic constriction injury model. We tested the effect of trazodone on thermal hyperalgesia due to a chronic constriction injury of the sciatic nerve in rats and examined the effects of lesions in the descending and ascending serotonergic system induced by 5,7-dihydroxytriptamine (5,7-DHT). The analgesic effects of trazodone showed a clear dose dependency. Furthermore, the analgesic effect of trazodone was observed in rats injected with 5,7-DHT into the dorsal raphe nucleus and medial raphe nucleus. The results suggest that a mainly serotonergic descending pain control pathway mediates the analgesic effects of trazodone.