Journal of neurochemistry
-
Journal of neurochemistry · Sep 2002
Suppression of the morphine-induced rewarding effect in the rat with neuropathic pain: implication of the reduction in mu-opioid receptor functions in the ventral tegmental area.
The present study was designed to investigate the rewarding effect, G-protein activation and dopamine (DA) release following partial sciatic nerve ligation in the rat. Here we show for the first time that morphine failed to produce a place preference in rats with nerve injury. Various studies provide arguments to support that the mesolimbic dopaminergic system, which projects from the ventral tegmental area (VTA) to the nucleus accumbens (N. ⋯ Acc stimulated by morphine was significantly suppressed by sciatic nerve ligation. These findings suggest that attenuation of the morphine-induced place preference under neuropathic pain may result from a decrease in the morphine-induced DA release in the N. Acc with reduction in the mu-opioid receptor-mediated G-protein activation in the VTA.