Effect of miR-145 on diabetic neuropathic pain by down-regulating Nav1.8 / 临床麻醉学杂志

ABSTRACT

Objective To observe the effect of miR-145 on pain threshold and explore the pos-sible underlying positive role of miR-145 in rats with diabetic neuropathic pain.Methods The total of 36 rats with diabetic neuropathic pain were randomly divided into three groups respectively with nor-mal control group (group N)(n=12 for each group)diabetic neuropathic pain(DNP)group (group D),DNP-NC group (group DN)and DNP-agomiR-145 group (group agomiR-145).The rats received agomiR-145 intrathecal injection in group agomiR-145 (10 μl,1×106TU/ml),or the negative control virus in group DN (10 μl,1×106TU/ml),or equal volume of normal saline in other two groups. Paw mechanical withdrawal threshold(MWT)and paw withdrawal latency(TWL)were measured on the day before intrathecal injection and day 1,days 3,7 and 14 after intrathecal injection.On the days 14 after pain-related behavioral test,the RNA expression of miR-145 in the dorsal root ganglion (DRG)was detected using reverse transcription-quantitative polymerase chain reaction(RT-PCR)as-say and the expression of Nav 1.8 in DRG were detected by fluorescent immunofluorescence.In addi-tion,a dual luciferase activity assay was used to testify the target genes of miR-145.Results MWT and TWL were decreased at 1 d before intrathecal injectionin groups D,DN and agomiR-145 than that in group N (P<0.05).The significant increase of MWT was observed in group agomiR-145 on day 3,7,14 than those in group D and group DN (P<0.05).TWL in group agomiR-145 was increased significantly on day 7 and day 14 compared with those in groups D and DN (P<0.05).Compared with group N,miR-145 expression level in DRG in groups D and DN were significantly lower (P<0.05).In addition,the protein expression of Nav1.8 was significantly increased in group D and DN compared with that in group N (P<0.05).Compared with groups D and DN,miR-145 expression was increased significantly and the expression of Nav1.8 in DRG was decreased significantly in group agomiR-145 (P<0.05).In addition,a dual luciferase reporter assay demonstrated that miR-145 can bind with the 3'-UTR region of Nav1.8 and regulate its expression.Conclusion Intrathecal agomiR-145 can effectively attenuate neuropathic pain of DNP rats,which may be related with down-regulation of Nav1.8 in DRG..