Effects of amphetamine isomers and neuroleptics on self-stimulation from the nucleus accumbens and dorsal noradrenergic bundle.

In an attempt to examine the possible role of noradrenergic (NA) and dopaminergic (DA) systems in intracranial self-stimulation (ICS), the rate-increasing effects of D- and L-amphetamine on ICS were determined in rats with nucleus accumbens electrodes (DA placement) or dorsal NA bundle electrodes (NA placement). The D-isomer produced a significantly greater increase in ICS than did the L-isomer in animals with dorsal NA bundle electrodes. In contrast, the amphetamine isomers were equipotent in facilitating ICS in animals with nucleus accumbens electrodes. These data, together with previous observations, suggest that there exists a correlation between equipotential effects of D- and L-amphetamine and DA electrode placements on the one hand, and prepotent effects of D-amphetamine and NA electrode placements on the other. Pimozide and haloperidol, which in low doses are thought to specifically block DA receptors, decreased ICS obtained from both DA and NA electrode placements. It is suggested that neuroleptic drugs may produce a general disruption of operant behavior and that the decrease in ICS produced by these agents does not therefore necessarily implicate dopaminergic mechanisms in the neurochemistry of reward.