Adenoviral delivery of prodynorphin inhibits experimental inflammatory pain induced by formalin in rats

Abstract

Some data support the notion that the up-regulation of spinal dynorphin expression is a common critical feature in neuropathic pain. It is not clearwhether the production of dynorphin A can be increased when more prodynorphin (PDYN) is present. The SD rats were randomly divided into 2 groups of 5 animals each: group Ad5 received Ad5, with 1 10 pfu in 100ml of PBS by the tail vein; group Ad5-PDYN received Ad5PDYN, with 1 10 pfu in 100ml of PBS by the tail vein. We investigated the changes in pain behaviors (Formalin-induced nociceptive behaviors), spinal PDYN mRNA expression and dynorphin A production on Formalin-induced pain in rats receiving the pretreatment of adenoviral delivery of PDYN. The adenoviral transfer of PDYN gene was sufficient to reduce pain behaviors resulting from formalin injection, and the PDYN mRNA levels of group Ad5-PDYN were markedly higher than those of group Ad5 in spinal cord, but meanwhile, endogenous dynorphin A protein in group Ad5-PDYNwas significantly lower than those in groupAd5 during Formalin-induced pain. Gene transfer of PDYN by recombinant adenovirus attenuates inflammatory pain.