BINGE COCAINE ADMINISTRATION INDUCES A SUSTAINED INCREASE OF PRODYNORPHIN MESSENGER-RNA IN RAT CAUDATE-PUTAMEN

Other workers have established that cocaine injections increase the le vels of dynorphin peptides in the caudate putamen and substantia nigra of the rat brain. Using a quantitative solution hybridization protect ion assay for mRNA, we detected a significant increase in the concentr ation of prodynorphin mRNA in caudate putamen extracts of rats injecte d with cocaine following a 'binge' administration pattern designed to mimic human cocaine abuse. Increased prodynorphin mRNA was observed at the earliest time-point studied (50 h) and the lowest dose (10 mg/kg/ day) of cocaine tested and persisted through the 14 day period studied . No prodynorphin mRNA was detected in the substantia nigra.