Cocaine, not morphine, causes the generation of reactive oxygen species and activation of NF-κB in transiently cotransfected heart cells

Abstract

This study was designed to determine levels of NF-κB reporter gene activity and free radical generation in cultured striated myocytes (H9C2 cells) exposed to cocaine or morphine in the presence of free radical scavengers. Cells were transiently transfected with a NF-κB reporter gene and changes in luciferase activity were detected by bioluminescence. Using confocal microscopy and 2′,7′-dichlorofluorescin diacetate, cocaine-induced or morphine-induced free radicals were quantified in H9C2 cells. Cocaine and morphine (0-1 × 10-2 M) were tested separately. Cocaine but not morphine significantly activated NF-κB reporter gene activity in H9C2 cells. Overexpression of IκB inhibited NF-κB reporter activity at low (1 × 10-4 M) but not high (1 × 10-2 M) cocaine concentrations. Free radicals were generated in H9C2 cells stimulated with cocaine but not with morphine. The production of free radicals and NF-κB reporter gene activity could be blocked with N-acetylcysteine, glutathione, and, to a lesser extent, lipoic acid. The results suggest that cocaine induces free radical production, which leads to the activation of NF-κB signal transduction and possible inflammatory responses. © Copyright 2003 by Humana Press Inc. All rights of any nature whatsoever reserved.