REGULATION OF DOPAMINE-D(2) RECEPTOR MESSENGER-RNA EXPRESSION IN THE OLFACTORY TUBERCLE BY COCAINE

The influence of acute and chronic cocaine treatment on the expression of dopamine D2 receptor (D2R) mRNA was examined in the rat basal gang lia by in situ hybridization histochemistry. No significant alteration s in D2R mRNA levels were observed in the striatum or the nucleus accu mbens following acute or chronic cocaine. In the olfactory tubercle, a cute cocaine (20 and 40 mg/kg, i.p.) was found to decrease D2R mRNA ex pression. Chronic cocaine (20 mg/kg, i.p. x 15 days), however, produce d an increase in D2R mRNA levels in this region which was detected 24 h, but not 7 days after withdrawal. Acute and chronic cocaine have dif ferent effects on the regulation of D2R gene expression in the olfacto ry tubercle.