Effects of 6-OHDA lesions in the nucleus accumbens on the acquisition of self injection of heroin under schedule and non schedule conditions in rats.

Acquisition of heroin self injection is enhanced in bodyweight reduced rats if a non contingent food delivery schedule is operating (schedule-induced self injection). Dopamine depletion of the nucleus accumbens septum (NAS) reduces nicotine self injection and a number of other schedule-induced behaviours. In the present experiment 6-OHDA lesions in the NAS significantly reduced the levels of heroin self injection in 7 rats on a food delivery schedule compared with sham lesioned controls. The reduced heroin intake did not differ from that of lesioned or sham lesioned rats with no schedule present. The results confirm previous reports that intact dopaminergic neurones in the NAS are necessary for schedule-induced behaviours to occur, and demonstrate that components of the same behaviour which are not schedule-induced can continue without disruption in the presence of the lesions.