New insights into the role of the opioid system as mediator of drug addiction by studies in transgenic mice

Several pre-clinical and clinical studies have implicated the endogenous opioid system in the pathophysiology of drug addiction. To further delineate the role of opioid peptides, we have studied the effects of THC and ethanol in mice with genetic deletions of the genes encoding for enkephalin and dynorphin. Our results indicate that both opioid peptides are released after cannabinoid treatments and contribute to their analgesic effects. Furthermore, we will demonstrate that other cannabinoid effects (tolerance, motivation, dependence) are influenced by these opioid peptides. We have now started to extend our analysis to other drugs of abuse, including alcohol and nicotin. These novel results will also be presented.