Mechanism of Shikonin on spinal cord injury in rats based on TNFR/RIPK1 pathway
Objective To explore the effect of shikonin on the recovery of nerve function after acute spinal cord injury(SCI)in rats.Methods 96 male Sprague-Dawley(SD)rats were divided into 4 groups randomly:sham operation group(Group A),sham operation+shikonin group(Group B),SCI+DMSO(Group C),SCI+shikonin group(Group D).The acute SCI model of rats was made by clamp method in groups C and D.After subdural catheterization,no drug was given in group A.rats in groups B and D were injected with 100 mg·kg-1 of shikonin through catheter 30 min after modeling,and rats in group C were given with the same amount of DMSO,once a day until the time point of collection tissue.Basso-Beattie-Bresnahan(BBB)scores were performed on 8 rats in each group at 6,12,and 3 d after moneling,and oblique plate tests were performed on 1,3,7 and 14 d after modeling,and then spinal cord tissues were collected.Eight rats were intraperitoneally injected with propidine iodide(PI)1 h before sacrificed to detection PI positive cells at 24 h in each group.Eight rats were sacrificed in each group at 24 h after modeling,the spinal cord injury was observed by HE staining.The Nissl staining was used to observe survivor number of nerve cells.Western-blot technique was used to detect the expression levels of Bcl-2 protein and apoptosis related protein RIPK1.Results After modeling,BBB scores were normal in group A and B,but in group C and D were significantly higher than those in group A and B.And the scores in group D were higher than those in group C in each time point(P<0.05).At 12 h after modeling,the PI red stained cells in group D were significantly reduced compared with that in group C,and the disintegration of neurons was alleviated(P<0.05).HE and Nissl staining showed nerve cells with normal morphology in group A and B at 24h after operation.The degree of SCI and the number of neuronal survival in group D were better than those in group C,the differ-ence was statistically significant at 24h(P<0.05).The expression of Bcl-2 and RIPK1 proteins was very low in group A and B;The expression of RIPK1 was significantly increased in Group C and decreased in Group D,with a statistically significant dif-ference(P<0.05);The expression of Bcl-2 protein in group D was significantly higher than that in group C(P<0.05).Conclu-sion Shikonin can alleviate the pathological changes after acute SCI in rats,improve the behavioral score,and promote the re-covery of spinal nerve function.The specific mechanism may be related to the inhibition of TNFR/RIPK1 signaling pathway mediated necrotic apoptosis.