神经病理性疼痛大鼠脊髓背角蛋白激酶Cγ及Cα表达的变化

Changes in expression of protein kinase Cγand Cαin dorsal horn of spinal cord in rat with neuropathic pain

目的评价慢性神经收缩损伤(CCI)和脊神经结扎(SNL)模型大鼠脊髓背角蛋白激酶Cγ及Cα表达的变化,以探讨其在神经病理性疼痛中枢敏化中的作用。方法24只SD大鼠随机分为假手术组、CCI组和SNL组,CCI组于左肢制备CCI模型,SNL组于左肢制备SNL模型。分别于术前2 d、术后2、4、7 d行机械痛阈和辐射热痛阈测定。术后7 d测痛后大鼠灌注固定,采用免疫组化法检测脊髓背角蛋白激酶Cγ、Cα和Fos蛋白的表达。结果与假手术组相比,CCI组和SNL组术后4、7 d机械痛阈和辐射热痛阈降低,术后7 d脊髓背角蛋白激酶Cγ、Cα和Fos蛋白表达增加(P<0．05)。与CCI组相比,SNL组机械痛阈、辐射热痛阈在各时间点差异无统计学意义,蛋白激酶Cα和Fos蛋白表达差异亦无统计学意义(P>0．05),而蛋白激酶Cγ表达升高(P<0．05)。结论神经病理性疼痛大鼠脊髓背角蛋白激酶Cγ及Cα表达的增加,可能是产生中枢敏化的机制之一。

Objective To investigate the changes in the expression of protein kinase Cγ and Cα （PKCγ, PKCα） in the dorsal horn of spinal cord in a rat with neuropathic pain, Methods Twenty-four healthy SD rats weighing 150-250 g were randomly divided into 3 groups （ n = 8 each） ： group Ⅰ sham operation; group Ⅱ chronic constrictive injury （CCI） and group Ⅲ spinal nerve ligation （SNL）, CCI was produced by placing 4 loose ligatures on the sciatic nerve at 1 mm intervals with 4-0 catgut and SNL by ligation and transaction of L5 spinal nerve. The threshold to yon Frey hair stimulation and radiant heat were measured before operation （baseline） and on the 2nd, 4th and 7th day after operation. The animals were killed after measurement of pain threshold. The lumbar segment （L4,6） of the spinal cord was removed for determination of the expression of PKCγ, PKCα and Fos protein by immuno-histochemistry. Results The mechanical and thermal withdrawal latencies were significantly decreased on the 4th and 7th day after operation as compared to the baselines values before operation in CCI and SNL groups. But there was no significant difference in the withdrawal latencies to mechanical and thermal stimuli between CCI and SNL groups. The expression of PKCγ, PKCα and Fos protein was significantly higher in CCI and SNL groups than in sham operation group. The expression of PKCα and Fos protein was not significantly different between CCI and SNL groups, while PKCγ expression was significantly higher in group SNL than in group CCI. Conclusion The increase in the expression of PKCγ and PKCα in the dorsal horn of spinal cord is involved in the mechanism of central sensitization in the neuropathic pain.