Distribution of type 1 cannabinoid receptor expressing neurons in the mouse hypothalamus. Relationship to the major GABA-ergic and glutamatergic hypothalamic cell populations
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1
Institute of Experimental Medicine, Hungarian Academy of Sciences, Hungary
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2
Department of Neuroscience , Pázmány Péter Catholic University, Hungary
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3
Tupper Research Institute and Department of Medicine, New England Medical Center, United States
Type 1 cannabinoid receptor (CB1) is the principal mediator of retrograde endocannabinoid signaling in the brain. In this study we present the detailed distribution map of endocannabinoid-sensitive hypothalamic neurons in mice. The detection of CB1 mRNA with in situ hybridization revealed the heaviest CB1 signal in the anterior hypothalamic area (AHA) and in the ventromedial, lateral mammillary and ventral premammillary nuclei (VMN, LM, PMV). Moderate or low expression levels were observed in many other regions, including the periventricular, arcuate and suprachiasmatic nuclei. To distinguish between the CB1-positive excitatory and inhibitory systems, the distribution pattern of CB1 mRNA signal was compared to those of glutamatergic and GABAegic neurons, identified by the expression of type 2 vesicular glutamate transporter (VGLUT2) and glutamic acid decarboxylase 65 (GAD65) mRNAs, respectively. Parallel visualization of VGLUT2 and CB1 mRNAs on neighboring sections showed that the sites with the highest CB1 signals (AHA, VMN, LM, PMV) were dominated by glutamatergic neurons. In addition, several hypothalamic sites including the arcuate and suprachiasmatic nuclei, which were mostly populated by GABA cells, also expressed the CB1 signal at moderate or low levels. This report provides a detailed anatomical map of hypothalamic neurons which express CB1 mRNA and are located in regions populated by glutamatergic and GABAergic cells. Transmitter release from the terminals of the CB1 expressing glutamatergic and GABAergic neurons are likely targets to retrograde endocannabinoid signaling via CB1.
Supported by OTKA (K69127, T73002) and the Sixth EU Research Framework Programme (contract LSHM-CT-2003-503041).
Conference:
12th Meeting of the Hungarian Neuroscience Society, Budapest, Hungary, 22 Jan - 24 Jan, 2009.
Presentation Type:
Poster Presentation
Topic:
Homeostatic regulatory mechanisms
Citation:
Hrabovszky
E,
Wittmann
G,
Kalló
I,
Liposits
Z and
Fekete
C
(2009). Distribution of type 1 cannabinoid receptor expressing neurons in the mouse hypothalamus. Relationship to the major GABA-ergic and glutamatergic hypothalamic cell populations.
Front. Syst. Neurosci.
Conference Abstract:
12th Meeting of the Hungarian Neuroscience Society.
doi: 10.3389/conf.neuro.01.2009.04.112
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Received:
03 Mar 2009;
Published Online:
03 Mar 2009.
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Correspondence:
Erik Hrabovszky, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary, hrabovszky.erik@koki.hun-ren.hu