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Melanocortin receptor 4 is induced in nerve‐injured motor and sensory neurons of mouse
Author(s) -
Tanabe Katsuhisa,
Gamo Kazushige,
Aoki Shunsuke,
Wada Keiji,
Kiyama Hiroshi
Publication year - 2007
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2006.04432.x
Subject(s) - melanocortin , axotomy , neurite , melanocortins , nerve injury , sciatic nerve injury , sciatic nerve , motor neuron , biology , peripheral nerve injury , endocrinology , medicine , sensory neuron , in situ hybridization , dorsal root ganglion , neuron , neuroscience , microbiology and biotechnology , regeneration (biology) , sensory system , anatomy , messenger rna , spinal cord , hormone , gene , biochemistry , in vitro
We previously identified melanocortin receptor 4 (MC4R) in a search for genes associated with hypoglossal nerve regeneration. As melanocortins promote nerve regeneration after axonal injury, we investigated whether MC4R functions as a key receptor for peripheral nerve regeneration. In situ hybridization revealed that MC4R mRNA is induced in mouse hypoglossal motor neurons after axonal injury, whereas mRNAs for MC1R, MC2R, MC3R, and MC5R are not expressed either before or after nerve injury. This result was confirmed by RT‐PCR. The level of MC4R mRNA expression increased significantly from day 3 after axotomy, reached a peak on day 5, and decreased to the control level on day 14. Similar induction of MC4R was observed in axotomized mouse dorsal root ganglia (DRGs). MC4R mRNA expression was induced exclusively among the MCR family in the L4‐6 DRG after sciatic nerve injury. We further examined whether alpha‐melanocortin stimulating hormone (alpha‐MSH) promotes neurite elongation via MC4R. In mouse DRG neuron culture, alpha‐MSH significantly promoted neurite outgrowth at a concentration of 10 −8 mol/L. This neurite‐elongation effect was entirely inhibited by the addition of a selective MC4R blocker, JKC‐363. Therefore, it is concluded that alpha‐MSH could stimulate neurite elongation via MC4R in DRG neurons. The present results suggest that induction of MC4R is crucial for motor and sensory neurons to regenerate after axonal injury.