Effect of dezocine on inflammatory responses of spinal cord in a rat model of incisional pain

Abstract

Objective To evaluate the effect of diazocine on the inflammatory responses of the spinal cord in a rat model of incisional pain. Methods Seventy-two pathogen-free healthy adult male Sprague-Dawley rats, weighing 240-300 g, were divided into 3 groups(n=24 each)using a random number table: control group(group C), incisional pain group(group IP)and dezocine group(group D). A 10 mm longitudinal incision was made through skin, fascia and muscle of the plantar aspect of the right hindpaw in isoflurane-anesthetized rats.Dezocine 1 mg/kg(diluted to 2 ml in 0.9% sodium chloride solution)was injected via the caudal vein at 15 min before skin incision in group D, and the equal volume of normal saline was injected via the caudal vein instead in group C. The mechanical paw withdrawal threshold(MWT)and thermal paw withdrawal latency(TWL)were measured at 12 h before skin incision(T0)and 2, 6 and 24 h after establishing the model(T1-3). The rats were sacrificed after measurement of the pain threshold at T3, and the spinal cord was removed for determination of the contents of interleukin-1beta(IL-1β), IL-6 and tumor necrosis factor-alpha(TNF-α)by enzyme-linked immunosorbent assay. Results Compared with group C, the MWT was significantly decreased and TWL was shortened at T1-3, and the contents of IL-1β, IL-6 and TNF-α were increased in IP and D groups(P<0.05). Compared with group IP, the MWT was significantly increased and TWL was prolonged at T1-3, and the contents of IL-1β, IL-6 and TNF-α were decreased in group D(P<0.05). Conclusion The mechanism by which dezocine reduces incisional pain is partially related to inhibiting inflammatory responses of the spinal cord of rats. Key words: Analgesics, opioid; Pain, postoperative; Spinal cord; Inflammation