Identification of the cannabinoid receptor type 1 in serotonergic cells of raphe nuclei in mice.

M. Häring, G. Marsicano, B. Lutz, K. Monory
Neuroscience. 2007-05-01; 146(3): 1212-1219
DOI: 10.1016/j.neuroscience.2007.02.021

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1. Neuroscience. 2007 May 25;146(3):1212-9. Epub 2007 Mar 23.

Identification of the cannabinoid receptor type 1 in serotonergic cells of raphe
nuclei in mice.

Häring M(1), Marsicano G, Lutz B, Monory K.

Author information:
(1)Department of Physiological Chemistry, Johannes Gutenberg University,
Duesbergweg 6, 55099 Mainz, Germany.

The endocannabinoid system (ECS) possesses neuromodulatory functions by
influencing the release of various neurotransmitters, including GABA,
noradrenaline, dopamine, glutamate and acetylcholine. Even though there are
studies indicating similar interactions between the ECS and the serotonergic
system, there are no results showing clear evidence for type 1 cannabinoid
receptor (CB1) location on serotonergic neurons. In this study, we show by in
situ hybridization that a low but significant fraction of serotonergic neurons in
the raphe nuclei of mice contains CB1 mRNA as illustrated by the coexpression
with the serotonergic marker gene tryptophane hydroxylase 2, the rate limiting
enzyme for the serotonin synthesis. Furthermore, by double immunohistochemistry
and confocal microscopy, we were able to detect CB1 protein on serotonergic
fibers and synapses expressing the serotonin uptake transporter in the
hippocampus and the amygdala. Our findings indicate that the CB1-mediated
regulation of serotonin release can depend in part on a direct cross-talk between
the two systems at single cell level, which might lead to functional implications
in the modulation of emotional states.

DOI: 10.1016/j.neuroscience.2007.02.021
PMID: 17383106 [Indexed for MEDLINE]

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