环氧酶2介导鞘内注射血小板活化因子诱发的触觉痛敏和热痛敏

Induction of Tactile Allodynia and Thermal Hyperalgesia by Intrathecally Administered Platelet-activating Factor Mediated by Cyclooxygenase-2 in Rats

目的:研究环氧酶(COX)及前列腺素(PGs)在鞘内注射血小板活化因子(PAF)诱导大鼠痛敏机制中的作用。方法:鞘内置管的雄性SD大鼠60只,随机分为脊液组(注射人工脑脊液),PAF组(鞘内注射PAF),盐水组(注射盐水),SC-560组(注射PAF及SC-560),NS-398组(注射PAF及NS-398),吲哚美辛组(注射PAF及吲哚美辛)各10只。各组注射前及鞘内给药后均检测大鼠机械缩爪阈值和热缩爪潜伏期,每15 min测1次,5 h后RT-PCR和放射免疫分析检测腰段脊髓COX-1,COX-2及COX-3的表达和PGE2的含量。结果:鞘内注射PAF后的PAF组迅速诱发大鼠触觉痛敏和热痛敏,并诱导脊髓COX-2表达增强和PGE2含量升高;与PAF组比较,NS-398组和吲哚美辛组能明显抑制PAF诱发的痛敏和脊髓PGE2含量升高。结论:鞘内注射PAF可诱发大鼠触觉异常痛敏和热痛敏;脊髓COX-2的激活和表达增强以及PGE2的产生可能参与其机制。

Objective：To investigate the roles of cyclooxygenase （COX） and prostaglandins （PGs） in development of tactile allodynia and thermal hyperalgesia induced by intrathecally administered platelet-aetivating factor （PAF）. Methods： Sixty SD rats with intrathecal PE-10 catheters were randomly divided into 6 groups with 10 in each： vehicle control group, PAF group, normal saline （NF） group, SC-560 group, NS-398 group, and indomethacin group. Paw withdrawal mechanical threshold and thermal latency were measured after PAF was administered intrathecally. Behavioral measurements were repeated every 15 rain in the following 5 h. RT-PCR and radioimmunoassay were used to detect the expression levels of COX-l, COX-2 and COX-3 mRNA, and concentrations of PGE2 in lumbar spinal cord respectively in 5 h. Results： Intratheeal administration of PAF induced development of tactile allodynia and thermal hyperalgesia rapidly, and increased the expression of COX-2 and concentrations of PGE2 in lumbar spinal cord in rats. NS-398 and indomethacin depressed the behavioral responses and the increase of PGE2 in spinal cord. Conclusion： Intrathecal administration of PAF may induce development of tactile allodynia and thermal hyperalgesia in rats possibly by activation and the increased expression of COX-2, and production of PGE2 in spinal cord.