| To investigate the process of relapse to drug seeking caused by re-exposure to drugs, the consequences of recurring instances of stimuli-drug associations using heroin conditioned place preference (CPP) in rats were studied. Following initial conditioning and subsequent extinction, rats received a single reconditioning session (explicit compartment-heroin repairing), followed by a test of heroin-seeking 24h later. It was observed that: one session of reconditioning was sufficient to induce reacquisition, this effect was dose dependent, and long lasting. In order to investigate the neurobiological mechanisms mediating the reacquisition of an extinguished heroin CPP, rats underwent reversible inactivation of the basolateral amygdala (BLA), either 15 min or 6 hrs following heroin reconditioning. Inactivation of the BLA 15 min, but not 6 hr, following reconditioning completely blocked the reacquisition of heroin seeking. These results suggest an important role for the BLA in a putative learning process underlying rapid escalation of drug seeking occurring during relapse. |
