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Neurochemical characterization of neurons expressing melanin‐concentrating hormone receptor 1 in the mouse hypothalamus
Author(s) -
Chee Melissa J.S.,
Pissios Pavlos,
MaratosFlier Eleftheria
Publication year - 2013
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.23273
Subject(s) - melanin concentrating hormone , biology , hypothalamus , neuropeptide , arcuate nucleus , proopiomelanocortin , medicine , endocrinology , dynorphin , microbiology and biotechnology , receptor , opioid peptide , biochemistry , opioid
Melanin‐concentrating hormone (MCH) is a hypothalamic neuropeptide that acts via MCH receptor 1 (MCHR1) in the mouse. It promotes positive energy balance; thus, mice lacking MCH or MCHR1 are lean, hyperactive, and resistant to diet‐induced obesity. Identifying the cellular targets of MCH is an important step to understanding the mechanisms underlying MCH actions. We generated the Mchr1‐cre mouse that expresses cre recombinase driven by the MCHR1 promoter and crossed it with a tdTomato reporter mouse. The resulting Mchr1‐cre/tdTomato progeny expressed easily detectable tdTomato fluorescence in MCHR1 neurons, which were found throughout the olfactory system, striatum, and hypothalamus. To chemically identify MCH‐targeted cell populations that play a role in energy balance, MCHR1 hypothalamic neurons were characterized by colabeling select hypothalamic neuropeptides with tdTomato fluorescence. TdTomato fluorescence colocalized with dynorphin, oxytocin, vasopressin, enkephalin, thyrothropin‐releasing hormone, and corticotropin‐releasing factor immunoreactive cells in the paraventricular nucleus. In the lateral hypothalamus, neurotensin, but neither orexin nor MCH neurons, expressed tdTomato. In the arcuate nucleus, both Neuropeptide Y and proopiomelanocortin cells expressed tdTomato. We further demonstrated that some of these arcuate neurons were also targets of leptin action. Interestingly, MCHR1 was expressed in the vast majority of leptin‐sensitive proopiomelanocortin neurons, highlighting their importance for the orexigenic actions of MCH. Taken together, this study supports the use of the Mchr1‐cre mouse for outlining the neuroanatomical distribution and neurochemical phenotype of MCHR1 neurons. J. Comp. Neurol. 521:2208–2234, 2013. © 2012 Wiley Periodicals, Inc.