PKC激动剂佛波醇酯诱导大鼠伤害性感受并促进脊髓NO产生

PROTEIN KINASE C AGONIST PHORBOL 12-MYRSTATE-ACETATE INDUCES NOCICEPTION AND ENHANCES NITRIC OXIDE PRODUCTION IN THE SPINAL CORD OF RATS

目的:观察PKC激动剂PMA诱导大鼠伤害性感受作用及对脊髓NOS表达和NO生成的影响。方法:采用行为学方法观察大鼠痛反应;热甩尾法测定大鼠痛阈变化;采用NADPH-d组织化学法和硝酸还原酶法分别测定大鼠脊髓内NOS表达和NO含量。结果:鞘内注射PMA后,大鼠出现伤害性感受反应及痛阈降低,脊髓后角浅层和中央管周围灰质内NOS阳性细胞数目、阳性细胞胞体及突起的染色深度明显增加,脊髓NO含量亦明显增加。给予PKC选择性抑制剂CH预处理可阻断鞘内注射PMA诱导的上述改变。结论:脊髓神经元内PKC激活可诱导大鼠产生伤害性感受及热痛觉过敏,并可促进NO产生,其对NO产生的促进作用可能是其诱导痛觉过敏产生的机制之一。

Aim： To determine the involement of NO signal pathway in the development of hyperalgesia induced by activation of protein ki nase C（PKC ）, nociceptive responses and nitric oxide synthase（NOS） expression and nitric oxide（NO） content in the spinal cord were observed after administration of Phorbol 12-Myrstate -Acetate（PMA）, a PKC agonist, in rats. Methods： Nociceptive response was observed by behavioral approach. Pain threshold was assayed using thermal tail-flick test. NADPH-d histochemistry was used to investigate the changes of NOS expression. Nitrate/nitrite （NO3^- / NO2^- ） was assayed to represent NO content of lumbar enlargement of spinal cord. Results： Nociceptive response was induced and pain threshold decreased after intrathecal injection of PMA. The number of NADPH-d positive cells increased significantly in the superficial layer of the spinal cord dorsal horn（ Laminae Ⅰ - Ⅱ ） and the grey matter surrounding the central canal （Laminae X）, and the reactive degree of NADPH-d positive soma and processes and NO content of the lumbar enlargement of the spinal cord increased significantly after intrathecal injection of PMA. Pretreatment of PKC inhibitor chelerythrine chloride blocked the changes induced by PMA. Conclusion： The activation of PKC in the spinal cord neurons might induce spontaneous nociceptive responses and hyperalgesia in rats, as well as promote NOS expression and NO production, suggesting that increase in NO production is one of mechanisms of hyperalgesia induced by activation of PKC.