EFFECTS OF ACUTE AND DELAYED-EFFECTS OF PRIOR CHRONIC COCAINE ADMINISTRATION ON REGIONAL RATES OF CEREBRAL PROTEIN-SYNTHESIS IN RATS

Single or repeated treatments with cocaine (15 mg/kg, i.p.) in rats mo dify rates of local cerebral protein synthesis (ICPSleu) measured with the [1-C-14]leucine method. A single dose of cocaine to naive rats re duced ICPSleu by about 10% throughout the brain; the most statisticall y significant reduction was in the nucleus accumbens, shell portion (P = .0003). A comparable dose of cocaine administered acutely after 1 w k of daily cocaine injections had no effects on ICPSleu. Delayed effec ts of prior chronic cocaine treatment were studied in experiments in w hich one rat of each pair received injections with saline for 8 days a nd the other cocaine, and on the 15th day ICPSleu was measured. In the se experiments delayed effects of the chronic cocaine treatment were o bserved; in the cocaine-treated rats ICPSleu was significantly increas ed in selective brain regions, i.e., prefrontal and primary olfactory cortex (P < .006). These results suggest that acute effects of a singl e dose of cocaine and residual effects of chronic cocaine treatment on ICPSleu are distinctly different and occur in different regions of th e brain.