Convulsant doses of cocaine alter immediate early gene and opioid peptide expression in rat limbic forebrain.

Rats were treated with escalating doses of cocaine until they experienced a convulsion and were euthanized 1 or 3 h after the last injection. Quantitative in situ hybridization histochemistry revealed that c-fos and zif/268 mRNAs were induced at 1 h in many limbic structures and declined 3 h after cocaine-induced convulsions. Preprodynorphin and preproenkephalin signals increased in many of the same structures 3 h, but not 1 h, after cocaine-induced convulsions.