Effects of prenatal exposure to cocaine on conditional discrimination learning in adult rats.

Abstract

Adult male rats that were gestationally exposed to cocaine and control offspring were trained on an instrumental conditioning task for assessment of the acquisition and reversal of an appetitive conditional discrimination based on olfactory cues. Offspring were derived from Sprague-Dawley dams that had received subcutaneous injections of 40 mg/kg/3 cc cocaine hydrochloride (C40) daily on Gestational Days 8-20, pair-fed (PF) dams that were injected with saline, nutritional control dams (NC) that had received saline injections, and nontreated control dams (LC). There were no differences among the prenatal treatment groups in acquisition of the barpress response or response rate throughout all phases of training. All prenatal treatment groups required approximately the same number of sessions to criterion on the initial odor discrimination. In contrast, adult C40 offspring required more sessions to acquire the reversal of the conditional discrimination than did animals from the other treatment groups (PF, NC, and LC). In addition, even at criterion performance for acquisition of the reversal discrimination, C40 animals exhibited lower accuracy on the first 10 responses and made significantly more errors before the first reward. Taken together with previous results, these findings suggest that gestational exposure to cocaine results in long-lasting alterations in performance on conditioning tasks that are evident early in life and that persist into adulthood.