title: Inhibition of itch-related responses by selectively ablated serotonergic signals at the rostral ventromedial medulla in mice.
abstract: Descending control of nociceptive processing in the rostral ventromedial medulla (RVM) has been implicated in the inhibition and facilitation of spinal nociceptive transmission. Here we investigated the contribution of serotonergic (5-HT) pathway at the RVM to pruritic behavior. Selective lesion of the descending serotonergic pathway by intra-RVM injection of focal neurotoxin 5,7-dihydroxytryptamine (2 μg/0.5 μl) attenuated pruritic behavior at the 30-min observation period following an intradermal microinjection of compound 48/80 (100 μg/100 μl) in the nape of the neck. Intradermal microinjection of compound 48/80 resulted in a dramatic increase in itch behavior between naive group and saline group. 5,7-DHT-treated mice showed profound scratching deficits after intradermal injection of compound 48/80. 5,7-DHT treatment resulted in a significant decrease in the number of 5-HT positive neurons in the RVM by using intracisternal injection of the serotonin neurotoxin 5,7-DHT. These findings demonstrate that pruritic behavior is dependent in part on descending facilitation via the RVM, and identify a modulatory role of serotonergic pathway at the RVM for pruritic behavior.
authors: Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology Wuhan 430030, China.
authors: Cheng
authors: C
authors: Liu
authors: Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology Wuhan 430030, China.
authors: Tao-Tao
authors: TT
authors: Liu
authors: Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology Wuhan 430030, China.
authors: Zhi-Gang
authors: ZG
authors: He
authors: Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology Wuhan 430030, China.
authors: Bin
authors: B
authors: Shu
authors: Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology Wuhan 430030, China.
authors: Hong-Bing
authors: HB
authors: Xiang
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D008297:Male; D008526:Medulla Oblongata / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009434:Neural Pathways / Q000166:cytology / Q000378:metabolism*; D011537:Pruritus / Q000378:metabolism*; D059326:Serotonergic Neurons / Q000166:cytology / Q000378:metabolism*
keywords: Itch; serotonergic signals; the rostral ventromedial medulla