Anti-opioid effects of neuropeptide FF receptors in the ventral tegmental area

Abstract

The present study investigates the modulatory effects of neuropeptide FF (NPFF) receptors on the mesolimbic dopaminergic pathway controlled by opioid receptors. A stable NPFF(2) receptor agonist, dNPA, was injected into the ventral tegmental area (VTA) and the release of dopamine and serotonin within the nucleus accumbens (NAc), induced by intraperitoneal injection of morphine, was monitored using the brain microdialysis, in non-constrained rat. dNPA decreased systemic morphine-induced elevation of dopamine and serotonin metabolites within the NAc. Furthermore, co-injected with morphine into the VTA, NPFF inhibited morphine-induced stereotypy 60-120min after the injection. This neurochemical and behavioural anti-opioid effect mediated by NPFF(2) receptors at the level of VTA suggests the involvement of NPFF in the rewarding effects of opiates on the mesolimbic dopamine system.