MicroRNA expression in spinal cord ischemia-reperfusion injury after atorvastatin preconditioning in rats

English Keywords:Spinal cord  Ischemia-reperfusion injury  Atorvastatin  MicroRNA

English Abstract:

  【Abstract】 Objectives: To explore microRNA(miRNA, miR) expression in spinal cord ischemia-reperfusion(I/R) injury and the regulatory mechanism involving microRNA with statins precondition in rats. Methods: 18 male Sprague-Dawley(SD) rats were randomly divided into three groups. Experimental groups(n=6 per group) were as follows: sham, control(receiving only normal saline) and atorvastatin-pretreated(10mg/kg/day for 2 weeks before occlusion). Spinal cord I/R injury was induced in SD rats by occluding the descending thoracic aorta in control and atorvastatin-pretreated group, the sham group did not receive aorta occluding in operation. Neurological function was assessed by using BBB scores at 6, 12, 24 and 48h after operation. In 48h after operation, animals were sacrificed. In order to identify pathological changes and damage of the nervous tissue, lumbosacral spinal cord tissues were harvested for hematoxylin-eosin（HE） and 2, 3, 5, -triphenyltetrazolium chloride(TTC) staining, followed by quantitative measurement of ischemic area and cross-sectional area of spinal cord, and then calculation of ischemic percentages. MiRNA profile was also determined from isolated RNA by using miRNA microarrays, followed by validation with quantitative real-time PCR(qRT-PCR) in both sham and control group. Results: The BBB score in control group decreased significantly at each time point compared with ｔｈａｔ ｉｎ sham group(P<0.05). However, atorvastatin pretreatment induced a markedly improved BBB score at each time point compared with control group(P<0.05), but had obviously lower score than sham group(P<0.05 ). Spinal cord ischemic injury was identified by HE staining in both control and atorvastatin-pretreated group. However, the injury in atorvastatin-pretreated group was alleviated compared with ｔｈａｔ ｉｎ control ｇｒｏｕｐ. The ischemic percentage, characterized by pale TTC stains, wａｓ (2.1±0.1)%, (77.3±5.1)% and (43±3.2)% in sham, control and atorvastatin-pretreated group, respectively. The infarction in control ｇｒｏｕｐ increased significantly compared with ｔｈａｔ ｉｎ sham group(P＜0.05). Pretreatment with atorvastatin remarkably attenuated the infarction compared with control(P＜0.05). However, compared with sham group, the infarction in atorvastatin-pretreated group was significantly higher(P＜0.01). MiRNA microarrays showed a total of 48 typeｓ of miRNAs wａｓ significantly different from control group compared with sham group. Aｍｏｎｇ those, 38 miRNAs were up-regulated, with a 1.6-to 4.9 fold change, whereas 10 miRNAs were down-regulated. Compared with control group, a total of 13 types of miRNA levels was significantly different in atorvastatin-pretreated group. I/R injury samples pretreated with atorvastatin reversed the up or down regulation in control of 8 miRNAs, including miR-365, miR-323, miR-672*, miR-760-5p, miR-376b-5p, miR-369-5p, miR-210 and miR-199a. The miRNA expressions validated by qRT-PCR were similar to those in miRNA microarrays(P>0.05). Conclusions: Atorvastatin precondition can protect spinal cord against I/R injury. Altered expression of miRNAs may contribute to the mechanism of neuroprotection of statins in spinal cord I/R injury.