Cocaine, β-Endorphin, and δ-Opioid Receptors

The current chapter describes the role of β-endorphin and its opioid receptor type delta (DOR) in cocaine reward, reinforcement, and craving, and in new studies of relapse to cocaine usage. The studies described herein employed diverse techniques, including biochemical and molecular measurements of β-endorphin and DOR in addiction-related brain sites, and behavioral measurements conducted following elimination or augmentation of β-endorphin or DOR (via knockout mice and intracerebral or systemic pharmacological manipulations). The emerging data indicate a close relationship between cocaine-related behavior and changes in β-endorphin levels and DOR in the mesolimbic reward pathway, and particularly in the nucleus accumbens. The various findings imply that manipulation of β-endorphin and DOR can provide a breakthrough in the treatment of cocaine addiction.