title: Motor cortex-periaqueductal gray-spinal cord neuronal circuitry may involve in modulation of nociception: a virally mediated transsynaptic tracing study in spinally transected transgenic mouse model.
abstract: Several studies have shown that motor cortex stimulation provided pain relief by motor cortex plasticity and activating descending inhibitory pain control systems. Recent evidence indicated that the melanocortin-4 receptor (MC4R) in the periaqueductal gray played an important role in neuropathic pain. This study was designed to assess whether MC4R signaling existed in motor cortex-periaqueductal gray-spinal cord neuronal circuitry modulated the activity of sympathetic pathway by a virally mediated transsynaptic tracing study. Pseudorabies virus (PRV)-614 was injected into the left gastrocnemius muscle in adult male MC4R-green fluorescent protein (GFP) transgenic mice (n = 15). After a survival time of 4-6 days, the mice (n = 5) were randomly assigned to humanely sacrifice, and spinal cords and brains were removed and sectioned, and processed for PRV-614 visualization. Neurons involved in the efferent control of the left gastrocnemius muscle were identified following visualization of PRV-614 retrograde tracing. The neurochemical phenotype of MC4R-GFP-positive neurons was identified using fluorescence immunocytochemical labeling. PRV-614/MC4R-GFP dual labeled neurons were detected in spinal IML, periaqueductal gray and motor cortex. Our findings support the hypothesis that MC4R signaling in motor cortex-periaqueductal gray-spinal cord neural pathway may participate in the modulation of the melanocortin-sympathetic signaling and contribute to the descending modulation of nociceptive transmission, suggesting that MC4R signaling in motor cortex-periaqueductal gray-spinal cord neural pathway may modulate the activity of sympathetic outflow sensitive to nociceptive signals.
authors.affiliation: Cancer Center, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, P. R. China.
authors.forename: Da-Wei
authors.initials: DW
authors.lastname: Ye
authors.affiliation: Department of Anaesthesiology and Pain Medicine, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, P. R. China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Liu
authors.affiliation: Department of Anaesthesiology and Pain Medicine, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, P. R. China.
authors.forename: Tao-Tao
authors.initials: TT
authors.lastname: Liu
authors.affiliation: Department of Anaesthesiology and Pain Medicine, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, P. R. China.
authors.forename: Xue-Bi
authors.initials: XB
authors.lastname: Tian
authors.affiliation: Department of Anaesthesiology and Pain Medicine, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, P. R. China.
authors.forename: Hong-Bing
authors.initials: HB
authors.lastname: Xiang
mesh_terms: D000818:Animals; D049452:Green Fluorescent Proteins; D011558:Herpesvirus 1, Suid; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D009044:Motor Cortex / Q000166:cytology*; D018482:Muscle, Skeletal; D056347:Neuroanatomical Tract-Tracing Techniques / Q000379:methods; D009474:Neurons / Q000502:physiology; D059225:Nociception / Q000502:physiology*; D010487:Periaqueductal Gray / Q000166:cytology*; D044105:Receptor, Melanocortin, Type 4 / Q000378:metabolism*; D013116:Spinal Cord / Q000166:cytology*; D013119:Spinal Cord Injuries
chemical_list: D044105:Receptor, Melanocortin, Type 4; D049452:Green Fluorescent Proteins