Beta-endorphin and drug-induced reward and reinforcement.

Although drugs of abuse have different acute mechanisms of action, their brain pathways of reward exhibit common functional effects upon both acute and chronic administration. Long known for its analgesic effect, the opioid beta-endorphin is now shown to induce euphoria, and to have rewarding and reinforcing properties. In this review, we will summarize the present neurobiological and behavioral evidences that support involvement of beta-endorphin in drug-induced reward and reinforcement.

Transplantation of glial cell line-derived neurotrophic factor-expressing cells into the striatum and nucleus accumbens attenuates acquisition of cocaine self-administration in rats.

Neurotrophic factors, such as glial cell line-derived neurotrophic factor (GDNF), may play a role in drug-induced biochemical and behavioural adaptations that characterize addiction. We found that GDNF mRNA levels are lower in the striatum of rats that chronically self-administered cocaine. Therefore, we examined the effect of transplanted cells used as a biodelivery system for GDNF on cocaine self-administration in rats.