The endocannabinoid system in brain reward processes

The endocannabinoid system in brain reward processes Food, drugs and brain stimulation can serve as strong rewarding stimuli and are all believed to activate common brain circuits that evolved in mammals to favour fitness and survival. For decades, endogenous dopaminergic and opioid systems have been considered the most important systems in mediating brain reward processes. Recent evidence suggests that the endogenous cannabinoid (endocannabinoid) system also has an important role in signalling of rewarding events. First, CB1 receptors are found in brain areas involved in reward processes, such as the dopaminergic mesolimbic system. Second, activation of CB1 receptors by plant‐derived, synthetic or endogenous CB1 receptor agonists stimulates dopaminergic neurotransmission, produces rewarding effects and increases rewarding effects of abused drugs and food. Third, pharmacological or genetic blockade of CB1 receptors prevents activation of dopaminergic neurotransmission by several addictive drugs and reduces rewarding effects of food and these drugs. Fourth, brain levels of the endocannabinoids anandamide and 2‐arachidonoylglycerol are altered by activation of reward processes. However, the intrinsic activity of the endocannabinoid system does not appear to play a facilitatory role in brain stimulation reward and some evidence suggests it may even oppose it. The influence of the endocannabinoid system on brain reward processes may depend on the degree of activation of the different brain areas involved and might represent a mechanism for fine‐tuning dopaminergic activity. Although involvement of the various components of the endocannabinoid system may differ depending on the type of rewarding event investigated, this system appears to play a major role in modulating reward processes. British Journal of Pharmacology (2008) 154, 369–383; doi:10.1038/bjp.2008.130; published online 14 April 2008 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png British Journal of Pharmacology Wiley

The endocannabinoid system in brain reward processes

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Publisher
Wiley
Copyright
2008 British Pharmacological Society
ISSN
0007-1188
eISSN
1476-5381
DOI
10.1038/bjp.2008.130
pmid
18414385
Publisher site
See Article on Publisher Site

Abstract

Food, drugs and brain stimulation can serve as strong rewarding stimuli and are all believed to activate common brain circuits that evolved in mammals to favour fitness and survival. For decades, endogenous dopaminergic and opioid systems have been considered the most important systems in mediating brain reward processes. Recent evidence suggests that the endogenous cannabinoid (endocannabinoid) system also has an important role in signalling of rewarding events. First, CB1 receptors are found in brain areas involved in reward processes, such as the dopaminergic mesolimbic system. Second, activation of CB1 receptors by plant‐derived, synthetic or endogenous CB1 receptor agonists stimulates dopaminergic neurotransmission, produces rewarding effects and increases rewarding effects of abused drugs and food. Third, pharmacological or genetic blockade of CB1 receptors prevents activation of dopaminergic neurotransmission by several addictive drugs and reduces rewarding effects of food and these drugs. Fourth, brain levels of the endocannabinoids anandamide and 2‐arachidonoylglycerol are altered by activation of reward processes. However, the intrinsic activity of the endocannabinoid system does not appear to play a facilitatory role in brain stimulation reward and some evidence suggests it may even oppose it. The influence of the endocannabinoid system on brain reward processes may depend on the degree of activation of the different brain areas involved and might represent a mechanism for fine‐tuning dopaminergic activity. Although involvement of the various components of the endocannabinoid system may differ depending on the type of rewarding event investigated, this system appears to play a major role in modulating reward processes. British Journal of Pharmacology (2008) 154, 369–383; doi:10.1038/bjp.2008.130; published online 14 April 2008

Journal

British Journal of PharmacologyWiley

Published: May 1, 2008

References

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