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PLoS One. 2008 May 21;3(5):e2202. doi: 10.1371/journal.pone.0002202.

Feeding induced by cannabinoids is mediated independently of the melanocortin system.

Author information

1
Division of Neuroscience, Oregon National Primate Research Center, Oregon Health & Science University, Portland, Oregon, United States of America.

Abstract

BACKGROUND:

Cannabinoids, the active components of marijuana, stimulate appetite, and cannabinoid receptor-1 (CB1-R) antagonists suppress appetite and promote weight loss. Little is known about how CB1-R antagonists affect the central neurocircuitry, specifically the melanocortin system that regulates energy balance.

METHODOLOGY/PRINCIPAL FINDINGS:

Here, we show that peripherally administered CB1-R antagonist (AM251) or agonist equally suppressed or stimulated feeding respectively in A(y) , which lack a functional melanocortin system, and wildtype mice, demonstrating that cannabinoid effects on feeding do not require melanocortin circuitry. CB1-R antagonist or agonist administered into the ventral tegmental area (VTA) equally suppressed or stimulated feeding respectively, in both genotypes. In addition, peripheral and central cannabinoid administration similarly induced c-Fos activation in brain sites suggesting mediation via motivational dopaminergic circuitry. Amperometry-detected increases in evoked dopamine (DA) release by the CB1-R antagonist in nucleus accumbens slices indicates that AM251 modulates DA release from VTA terminals.

CONCLUSIONS/SIGNIFICANCE:

Our results demonstrate that the effects of cannabinoids on energy balance are independent of hypothalamic melanocortin circuitry and is primarily driven by the reward system.

PMID:
18493584
PMCID:
PMC2386290
DOI:
10.1371/journal.pone.0002202
[Indexed for MEDLINE]
Free PMC Article

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