title: Melanocortin-4 receptor expression in the rostral ventromedial medulla involved in modulation of nociception in transgenic mice.
abstract: The rostral ventromedial medulla (RVM) is a prominent component of the descending modulatory system involved in the control of spinal nociceptive transmission. In the current study, we investigated melanocortin-4 receptor (MC4R) expression in the RVM, where the neurons involved in modulation of nociception reside. Using a line of mice expressing green fluorescent protein (GFP) under the control of the MC4R promoter, we found a large number of GFP-positive neurons in the RVM [nucleus raphe magnus (NRM) and nucleus gigantocellularis pars α (NGCα)]. Fluorescence immunohistochemistry revealed that approximately 10% of MC4R-GFP-positive neurons coexpressed tyrosine hydroxylase, indicating that they were catecholaminergic, whereas 50%-75% of those coexpressed tryptophan hydroxylase, indicating that they were serotonergic. Our findings support the hypothesis that MC4R signaling in RVM may modulate the activity of serotonergic sympathetic outflow sensitive to nociceptive signals, and that MC4R signaling in RVM may contribute to the descending modulation of nociceptive transmission.
authors.affiliation: Medical Association of Hubei Province, Wuhan, 430060, China.
authors.forename: Xu-Chu
authors.initials: XC
authors.lastname: Pan
authors.affiliation: Medical Association of Hubei Province, Wuhan, 430060, China.
authors.forename: Yong-Tang
authors.initials: YT
authors.lastname: Song
authors.affiliation: Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Liu
authors.affiliation: Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China. xianghongbing@gmail.com.
authors.forename: Hong-Bing
authors.initials: HB
authors.lastname: Xiang
authors.affiliation: Department of Dermatology, Guangdong Provincial Hospital of Traditional Chinese Medicine, Guangzhou, 510120, China. luchuanjian888@vip.sina.com.
authors.forename: Chuan-Jian
authors.initials: CJ
authors.lastname: Lu
mesh_terms: D000818:Animals; D005260:Female; D008297:Male; D008526:Medulla Oblongata / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D009434:Neural Pathways / Q000166:cytology / Q000378:metabolism; D009475:Neurons, Afferent / Q000166:cytology / Q000378:metabolism*; D059225:Nociception / Q000502:physiology*; D044105:Receptor, Melanocortin, Type 4 / Q000235:genetics / Q000378:metabolism*; D059326:Serotonergic Neurons / Q000378:metabolism*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*
chemical_list: C574273:MC4R protein, mouse; D044105:Receptor, Melanocortin, Type 4; D014446:Tyrosine 3-Monooxygenase