The Effect Of Tetramethylpyrazine On The Expression Of P-Selectin,Neutrophil Elastase After Acute Spinal Cord Injury In The Rat Model

Objective: To investigate the effect of Teramethylpyrazine (TMP) on spinal cord repair using the hypothesized working pathways of regulation P-selectin (P-sel) expression and neutrophil elastase (NE) concentrations in the acute spinal cord injury (ASCI) tissue in a Sprague Dawley (SD) rat model.Methods: 99 Sprague Dawley (SD) rats weighting 250-300g body weight (BWT) were divided randomly into three groups: 1) Sham operation group (group S, n=9); 2) Control group (group C, n=45); and 3) Tetramethylpyrazine group (group T, n=45). The C and T group animals were further divided into 9 sub-groups (n=5 per sub-group) each at 1, 3, 6, and 12 hrs and 1, 3, 5, 7, and 14 days of survival before euthanasia. Allen's weight drop method was used to establish the acute spinal cord injury (ASCI) rat model at T₁₀ section. 200mg/kg BWT of TMP was administered to the group T animals intraperitoneally and the group C were treated with the same volume of normal saline solution (NS) 30 minutes after injury. Each model was given the same dosage once a day until euthanasia or lasted for 5 days following the injury if the rats survived for more than 5 days. The function of spinal cord was evaluated with animal behavioral scores by measuring modified Rivilin inclined plane test,the Basso, Beattie, Bresnahan locomotor rating scale (BBB scale) and the combined behavioral score (CBS) at 1, 3, 5, 7, and 14 days postoperatively. The rats of three groups were euthanized to collect the spinal cord tissue samples from the injured segment with a length of 2cm at the each time point following the injury. The injured tissue samples were divided into two parts at the middle of the ordinate axis. One part of the sample was used for histological sections of 10μm thickness using microtome. These sections were analyzed for P-sel expression by immunohistochemistry method. The other part of the sample was used to test the concentrations of neutrophil elastase by enzyme-linked immunosorbent assay. Software SPSS15.0 was applied to determine if there was significant difference between the group T and group C results at each time point on the animal behavioral scores, the expression of P-sel and the concentrations of NE.Results: In the modified Rivlin inclined plane test, group T had significantly higher loxotic plate degree than that in group C at 7 and 14 days after ASCI (P<0.05). Group T had significantly higher BBB scores than that in group C at 5, 7 and 14 days after ASCI (P<0.05). In the combined behavioral score, group T had signifieantly lower scores than that in group C at 5, 7 and 14 days after ASCI (P<0.05). The amounts of P-sel positive vessels in group T were signifieantly less than those in group C at 1, 3, 5 and 7 days after ASCI (P<0.05). The concentrations of NE in the tissue were significantly lower in group T than those in group C at 6 and 12 hrs, and 1,3 and 7 days after ASCI (P<0.05).Conclusion: TMP has protective effect on the spinal cord tissue after acute injury; TMP can decrease the expression of the P-sel and lower the NE concentrations after acute spinal cord injury (ASCI).