The endocannabinoid system has been implicated in the regulation of a variety of physiological processes, including a crucial
involvement in brain reward systems and the regulation of motivational processes. Behavioral studies have shown that cannabinoid reward
may involve the same brain circuits and similar brain mechanisms with other drugs of abuse, such as nicotine, cocaine, alcohol and
heroin, as well as natural rewards, such as food, water and sucrose, although the conditions under which cannabinoids exert their rewarding
effects may be more limited. The purpose of the present review is to briefly describe and evaluate the behavioral and pharmacological
research concerning the major components of the endocannabinoid system and reward processes. Special emphasis is placed on data received
from four procedures used to test the effects of the endocannabinoid system on brain reward in animals; namely, the intracranial
self-stimulation paradigm, the self-administration procedure, the conditioned place preference procedure and the drug-discrimination procedure.
The effects of cannabinoid 1 (CB1) and cannabinoid 2 (CB2) receptor agonists, antagonists and endocannabinoid modulators in
these procedures are examined. Further, the involvement of CB1 and CB2 receptors, as well the fatty acid amid hydrolase (FAAH) enzyme
in reward processes is investigated through presentation of respective genetic ablation studies in mice. We suggest that the endocannabinoid
system plays a major role in modulating motivation and reward processes. Further research will provide us with a better understanding
of these processes and, thus, could lead to the development of potential therapeutic compounds for the treatment of rewardrelated
Keywords: Cannabinoids, addiction, anandamide, 2-arachidonoylglycerol, intracranial self-stimulation, self-administration, conditioned
place preference, drug discrimination.
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