CONDITIONED PLACE PREFERENCE AND LOCOMOTOR ACTIVATION PRODUCED BY INJECTION OF PSYCHOSTIMULANTS INTO VENTRAL PALLIDUM

The ventral pallidum (VP) is often viewed as an output structure of th e nucleus accumbens septi (NAS). However, VP, like NAS, receives a dop aminergic input from the ventral tegmental area. These experiments inv estigated some behavioral effects of microinjection into VP of drugs w hich enhance dopaminergic transmission. Injection of 25 mu g dopamine or 5-10 mu g amphetamine into VP produced hypermotility. In contrast, injection of 12.5-50 mu g cocaine initially suppressed, then increased , activity. Injection of 100 mu g cocaine only produced hypomotility i n the 1-h period examined. The hypomotility following cocaine seemed t o be a local anesthetic effect, because it was mimicked by 50-200 mu g procaine. Procaine did not, however, produce subsequent hypermotility . Conditioned place preference (CPP) was produced by 10 mu g amphetami ne and 50 mu g cocaine but not 100 mu g procaine. We conclude that inj ection of cocaine into VP, unlike similar injections into NAS, produce s CPP. These results support the idea of an involvement of dopamine in VP in reward and locomotor activation, independent of dopamine in NAS . The use of intracerebral injections of cocaine is complicated, howev er, by an apparent local anesthetic effect of the drug.