Yohimbine, but not footshock stress, reinstates heroin seeking in the presence of a discriminative, drug-predictive cue
Animal models of stress-induced relapse typically employ the application of environmental [i.e. intermittent foot shock (FS)] or pharmacological [i.e. yohimbine (YOH)] stress to induce reinstatement to drug seeking. Stress-induced reinstatement has not been investigated using a procedure involving the presentation of discriminative, drug-predictive stimuli rather than response-contingent stimuli during self-administration. In this study, we tested whether FS and YOH could precipitate relapse in the absence of a response-contingent stimulus. Following extinction, YOH reinstated responding on the heroin-paired lever while FS was ineffective. Based on these results, we consider the efficacy of FS to reinstate drug seeking likely more limited by procedural factors (e.g. the temporal contingency of drug-related stimuli) compared to YOH, and therefore, a less reliable means of inducing stress experimentally. However, given that YOH also reinstated responding on the non-drug paired lever, it appears its effects are less selective possibly reflecting increases in activity and/or response generalization.