Gene expression alterations produced by opioid self-administration in the mouse striatum

Chronic exposure to opioids induces adaptations in brain function that lead to the formation of the behavioral and physiological symptoms of drug dependence and addiction. Genome wide analysis of molecular effects of protracted morphine or saccharin intake in C57BL/6J mice over a period of 7 months provides an opportunity to observe the alterations in the brain that accompany long-term drug addiction. Microarray experiment was designed to compare chronic and acute effects of protracted morphine or saccharin self-administration. Therefore we have analyzed 4 groups: animals chronically drinking saccharin with a saline or morphine injection, and mice chronically drinking morphine with saline or morphine injection. Animals were sacrificed 4 hours after receiving either a saline (10 ml/kg) or morphine (20 mg/kg, ip) injection.