外周神经损伤后脊髓HDAC2表达的增加通过表观沉默降低mu阿片受体的表达

Increased expression of HDAC2 in the spinal cord of nerve injury reduces the expression of mu opioid receptor via epigenetic silencing

摘要:

目的 研究神经病理性疼痛时损伤侧脊髓背角去乙酰化酶2（HDAC2）表达的增加对吗啡镇痛以及mu阿片受体（MOR）表达的影响。方法：清洁级C57BL/6小鼠，采用随机数字表法随机分为8组，假手术组，手术组；手术组+溶剂组，手术组+苯胺异羟肟酸（SAHA）组；手术组+NC-siRNA组，手术组+HDAC2 siRNA组；AAV5-EGFP组，AAV5-HDAC2组。结果：1.手术组和假手术组相比我们发现术后7天吗啡的镇痛作用降低，损伤侧脊髓背角MOR蛋白的表达降低，MOR mRNAs水平降低，HDAC2蛋白的表达增加，HDAC2 mRNA水平增加，乙酰化的组蛋白H3（AH3）表达降低；2.在手术组术前30分钟鞘内注射去乙酰化酶抑制剂SAHA连续7天发现，和溶剂组相比SAHA可以提高脊髓背角MOR蛋白的表达，MOR mRNA的水平，降低HDAC2蛋白的表达，降低HDAC2 mRNA的水平，增加组蛋白H3的乙酰化水平，吗啡的镇痛效能增加；3.对手术组术前30分钟鞘内注射HDAC2 siRNA连续3天后发现，和NC-siRNA组相比，术后7天脊髓背角HDAC2蛋白的表达降低，HDAC2 mRNA水平降低降低，MOR的蛋白表达增加，MOR mRNA水平增加，乙酰化的H3水平增加，吗啡的镇痛效能增加；4.通过对正常小鼠鞘内注射AAV5-HDAC2对脊髓背角过表达HDAC2后我们发现在鞘内注射AAV5-HDAC2后28天脊髓背角的HDAC2的蛋白表达明显，HDAC2 mRNA的水平明显提高，乙酰化的组蛋白H3表达明显降低，MOR的蛋白水平降低，MOR的mRNA的水平明显降低，吗啡的镇痛效能降低。结论：外周损伤后HDAC2表达的增高导致损伤侧脊髓背角MOR的表达的降低。

Abstract:

Abstract Objective: Effects of increased expression of HDAC2 in spinal dorsal horn on morphine analgesia and mu opioid receptor expression in neuropathic pain. Methods: Clean-grade C57BL/6 mice were randomly divided into 8 groups: sham group, CCI group; CCI group + Vehicle group, CCI group + SAHA group; CCI+NC-siRNA group, CCI+HDAC2 siRNA group; AAV5-EGFP group, AAV5-HDAC2 group. Results: 1. Compared with the sham group, we found that the analgesic effect of morphine was reduced in CCI group. The expression of MOR protein in the injured side of spinal cord dorsal horn was decreased, the level of MOR mRNAs was decreased, and the expression of deacetylase (HDAC2) protein and HDAC2 mRNA levels increased. Acetylated histone H3 (AH3) of the injured side was decreased; 2. After intrathecal injection of deacetylase SAHA before surgery for 7 consecutive days in the CCI group, compared with vehicle group, SAHA improved the expression of MOR protein, MOR mRNA level, AH3 expression while decreased HDAC2 protein and HDAC2 mRNA level, resulting in enhanced morphine analgesia; 3. After intrathecal infusion of HDAC siRNA for 3 consecutive days in CCI group, it was found that compared with the NC-siRNA group, the expression of HDAC2 protein in the injured side spinal dorsal horn was decreased, HDAC2 mRNA level was decreased, the MOR protein expression was increased, the MOR mRNA level was increased, and the acetylated H3 was increased, resulting in enhanced morphine analgesia; 4. By over-expression of HDAC2 in the spinal dorsal horn via intrathecal injection of AAV5-HDAC2 into normal mice, we found that 28 days after the injection, HDAC2 had an augmentation in the injured side spinal dorsal horn. The expression of acetylated histone H3 was significantly decreased and the expression of MOR was decreased either, resulting in lower analgesic efficacy of morphine. Conclusion: The increased expression of HDAC2 after peripheral injury leads to a decrease in the expression of MOR in the injured ipsilateral spinal dorsal horn and lower analgesia efficacy of morphine.