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Allopregnanolone suppresses mechanical allodynia and internalization of neurokinin-1 receptors at the spinal dorsal horn in a rat postoperative pain model

By Fujita Masahide, Fukuda Taeko, Sato Yasuhiro, Takasusuki Toshifumi and 田中 誠福田 妙子 and 田中 誠


BackgroundTo identify a new strategy for postoperative pain management, we investigated the analgesic effects of allopregnanolone (Allo) in an incisional pain model, and also assessed its effects on the activities of the primary afferent fibers at the dorsal horn.MethodsIn experiment 1, 45 rats were assigned to Control, Allo small-dose (0.16 mg/kg), and Allo large-dose (1.6 mg/kg) groups (n = 15 in each). The weight bearing and mechanical withdrawal thresholds of the hind limb were measured before and at 2, 24, 48, and 168 h after Brennan\u27s surgery. In experiment 2, 16 rats were assigned to Control and Allo (0.16 mg/kg) groups (n = 8 in each). The degree of spontaneous pain was measured using the grimace scale after the surgery. Activities of the primary afferent fibers in the spinal cord (L6) were evaluated using immunohistochemical staining.ResultsIn experiment 1, the withdrawal threshold of the Allo small-dose group was significantly higher than that of the Control group at 2 h after surgery. Intergroup differences in weight bearing were not significant. In experiment 2, intergroup differences in the grimace scale scores were not significant. Substance P release in the Allo (0.16 mg/kg) group was significantly lower than that in the Control group.ConclusionsSystemic administration of Allo inhibited mechanical allodynia and activities of the primary afferent fibers at the dorsal horn in a rat postoperative pain model. Allo was proposed as a candidate for postoperative pain management

Topics: 医学
Publisher: 'Korean Pain Society'
Year: 2018
DOI identifier: 10.3344/kjp.2018.31.1.10
OAI identifier:
Provided by: Tsukuba Repository

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