Perioperative stress prolong post-surgical pain via miR-339-5p targeting oprm1 in the amygdala

The decreased expression of mu-opioid receptors (MOR) in the amygdala may be a key molecular in chronic post-surgical pain (CPSP). It is known that miR-339-5p expression in the amygdala of a stressed rat model was increased. Analyzed by RNAhybrid, miR-339-5p could target opioid receptor mu 1 (oprm1) which codes MOR directly. So, the authors hypothesized that miR-339-5p could regulate the expression of MOR via targeting oprm1 and cause the effects to CPSP. To simulate perioperative short-term stress, a perioperative stress prolongs incision-induced pain hypersensitivity without changing basal pain perception rat model was built. A pmiR-RB-REPORT™ dual luciferase assay was taken to verify whether miR-339-5p could act on oprm1 as a target. The serum glucocorticoid level of rats was test. Differential expressions of MOR, GFAP, and pERK1/2 in each group of the rats’ amygdala were tested, and the expressions of miR-339-5p in each group of rats’ amygdalas were also measured.杏仁核内μ阿片受体（mu-opioid receptors, MOR）的表达下调，可能是慢性术后疼痛（chronic post-surgical pain, CPSP）发生的关键分子事件。已有研究表明，应激大鼠模型的杏仁核中miR-339-5p的表达水平上调。经RNAhybrid靶基因预测软件分析发现，miR-339-5p可直接靶向编码MOR的阿片受体μ1型（oprm1）。据此，研究团队提出假说：miR-339-5p可通过靶向oprm1调控MOR的表达，进而参与慢性术后疼痛的发生发展过程。为模拟围手术期短期应激，研究者构建了一种可延长切口诱导的痛觉超敏时长、且不改变基础痛觉感知的大鼠模型。采用pmiR-RB-REPORT™双荧光素酶报告基因实验，验证miR-339-5p是否可靶向结合oprm1。检测各组大鼠的血清糖皮质激素水平。检测各组大鼠杏仁核内MOR、胶质纤维酸性蛋白（GFAP）以及磷酸化细胞外信号调节激酶1/2（pERK1/2）的表达差异，同时测定各组大鼠杏仁核内miR-339-5p的表达水平。