Cocaine self-administration produced a significantly longer potentiation of glutamatergic transmission than food or sucrose self-administration. (A) AMPAR/NMDAR ratio in cocaine self-administering rats remained enhanced after 90 days of abstinence. However, in food and sucrose self-administering rats, increased AMPAR/NMDAR ratio is observed following 7d of abstinence but returned to Naïve levels by 21 days of abstinence. (B,C) Following 7d and 21d abstinence, mEPSC frequencies from Cocaine and Sucrose groups remained significantly enhanced relative to Naïve. In Food rats, (B), the mEPSC frequency was not significantly different than Naïve rats by 7 days of abstinence and remained unchanged at 21 days of abstinence (C). mEPSC frequencies from Cocaine continues to be significantly enhanced relative to Naïve at 3m abstinence. Dotted line represents averages from Naïve rats. * p < 0.05 versus Naive.