Early-life stress is correlated with negative mental health outcomes, including illicit drug abuse. One mechanism that may contribute to drug abuse is stress-induced elevation of drug reward. Place conditioning paradigms show that exposure to uncontrollable stress as an adult enhances opiate conditioned place preference, CPP. The present work addressed whether early-adolescent, mid-adolescent, or adult stress amplified morphine CPP.
Male Sprague-Dawley rats were randomly assigned to stress or no stress conditions and received stress during early-, mid-adolescence, or adulthood. Stressors were unpredictable consisting of exposure to synthetic fox odor (trimethylthiazoline) and an elevated platform. Morphine place conditioning occurred during adulthood, and all animals received either morphine (15 mg/kg) on the initially non-preferred side or saline (1 ml/kg) on the initially preferred side. A post-test was conducted and time on non-preferred side was analyzed.
A 2 (S/NS) x 2 (pre-/post-test) x 3 (early-adolescent/mid-adolescent/adult) mixed ANOVA revealed a significant main effect of test, F(1,42)=115.90, p \u3c .001
