title: Melanocortin receptor 4 is induced in nerve-injured motor and sensory neurons of mouse.
abstract: 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.
authors.affiliation: Department of Anatomy and Neurobiology, Graduate School of Medicine, Osaka City University, Osaka, Japan.
authors.forename: Katsuhisa
authors.initials: K
authors.lastname: Tanabe
authors.forename: Kazushige
authors.initials: K
authors.lastname: Gamo
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Aoki
authors.forename: Keiji
authors.initials: K
authors.lastname: Wada
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kiyama
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005727:Ganglia, Spinal / Q000473:pathology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D020437:Hypoglossal Nerve Diseases / Q000378:metabolism / Q000473:pathology*; D017403:In Situ Hybridization / Q000379:methods; D008297:Male; D009074:Melanocyte-Stimulating Hormones / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D009046:Motor Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D020932:Nerve Growth Factor / Q000494:pharmacology; D016501:Neurites / Q000187:drug effects / Q000502:physiology; D009475:Neurons, Afferent / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010456:Peptides, Cyclic / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D044105:Receptor, Melanocortin, Type 4 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013997:Time Factors; D019824:beta-MSH / Q000494:pharmacology
chemical_list: C471568:11-Mrp-14-Nal-18-Cys-22-Asp-beta-MSH(11-22)NH2; D010456:Peptides, Cyclic; D012333:RNA, Messenger; D044105:Receptor, Melanocortin, Type 4; D019824:beta-MSH; D009074:Melanocyte-Stimulating Hormones; D020932:Nerve Growth Factor