title: Distribution of type 1 cannabinoid receptor-expressing neurons in the septal-hypothalamic region of the mouse: colocalization with GABAergic and glutamatergic markers.
abstract: Type 1 cannabinoid receptor (CB1) is the principal mediator of retrograde endocannabinoid signaling in the brain. In this study, we addressed the topographic distribution and amino acid neurotransmitter phenotype of endocannabinoid-sensitive hypothalamic neurons in mice. The in situ hybridization detection of CB1 mRNA revealed high levels of expression in the medial septum (MS) and the diagonal band of Broca (DBB), moderate levels in the preoptic area and the hypothalamic lateroanterior (LA), paraventricular (Pa), ventromedial (VMH), lateral mammillary (LM), and ventral premammillary (PMV) nuclei, and low levels in many other hypothalamic regions including the suprachiasmatic (SCh) and arcuate (Arc) nuclei. This regional distribution pattern was compared with location of γ-aminobutyric acid (GABA)ergic and glutamatergic cell groups, as identified by the expression of glutamic acid decarboxylase 65 (GAD65) and type 2 vesicular glutamate transporter (VGLUT2) mRNAs, respectively. The MS, DBB, and preoptic area showed overlaps between GABAergic and CB1-expressing neurons, whereas hypothalamic sites with moderate CB1 signals, including the LA, Pa, VMH, LM, and PMV, were dominated by glutamatergic neurons. Low CB1 mRNA levels were also present in other glutamatergic and GABAergic regions. Dual-label in situ hybridization experiments confirmed the cellular co-expression of CB1 with both glutamatergic and GABAergic markers. In this report we provide a detailed anatomical map of hypothalamic glutamatergic and GABAergic systems whose neurotransmitter release is controlled by retrograde endocannabinoid signaling from hypothalamic and extrahypothalamic target neurons. This neuroanatomical information contributes to an understanding of the role that the endocannabinoid system plays in the regulation of endocrine and metabolic functions.
authors.affiliation: Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary. hrabovszky@koki.hu
authors.forename: Erik
authors.initials: E
authors.lastname: Hrabovszky
authors.forename: Gábor
authors.initials: G
authors.lastname: Wittmann
authors.forename: Imre
authors.initials: I
authors.lastname: Kalló
authors.forename: Tamás
authors.initials: T
authors.lastname: Füzesi
authors.forename: Csaba
authors.initials: C
authors.lastname: Fekete
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Liposits
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism* / Q000502:physiology; D007031:Hypothalamus / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D008297:Male; D051379:Mice; D009434:Neural Pathways / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D009474:Neurons / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D043884:Receptor, Cannabinoid, CB1 / Q000096:biosynthesis / Q000378:metabolism*; D020665:Septum of Brain / Q000737:chemistry / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism* / Q000502:physiology
chemical_list: D015415:Biomarkers; D043884:Receptor, Cannabinoid, CB1; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid