The Influence Of Tanshinone On The EAAs-NMDA-Ca²⁺ Pathway In A Rat Models Of Spinal Cord Ischemia/reperfusion Injury

ObjectiveStudy on establishing a new spinal cord ischemia reperfusion injury model of rat and exploring the interventional effect of tanshinone on EAAs-NMDA-Ca2+ path in a rat model of spinal cord ischemia reperfusion injury.Methods1.Used the casting mould technology of blood vessel to make the casting sample of artery of rat, observed the blood support of spinal cord and established best position to block blood flow of abdominal aorta. Reconstructed model by blocking blood flow of abdominal aorta at the best position according to method of Zivin.Used the digital subtraction angiography cardiovascularly machine to observe and confirm the spinal was ischemic completely and the model was established. Observed the ischemia time of twenty, thirty, fourty and sixty minutes influence on spinal cord function and histopathology, in order to confirm best time of blocking blood flow of abdominal aorta for reconstructing model.2. A total of 128 Sprague Dawley rats were randomly divided into sham operation group (n=8),model group (n=40),tanshinone group (n=40) and Nimodipine(n=40) group. Rats in sham operation group were opened abdominal cavity without spinal cord ischemia and collected inferior vena cava blood and damaged L2-4 segment spinal cord.At hour 0.5,1,4,8,and 12 following perfusion, inferior vena cava blood and damaged L2-4 segment spinal cord of rats in the model, tanshinone and Nimodipine groups were collected to observe the change of Na+-K+-ATPase, glutamate transporters, glutamic acid content in blood serum and spinal cord, spinal cord function, NMDAR1 protein expression in the anterior horn cells of the spinal cord, moisture capacity of spinal cord,intraneuronal Ca2+ concentration and histopathology of spinal cord. Found out the impact of tanshinone.Results 1.The best position to block blood flow of abdominal aorta for reconstructing model was in the initial of right renal artery proximal part. It couldn't couse rat's paraplegia for blocking blood flow for 20 minutes. Blocking blood flow for 30 minutes, the paraplegia rate was 70% and the neural function has some recovery. Blocking blood flow for 40 minutes, the paraplegia rate was 90%, but neural function has little recovery.Blocking blood flow for 60 minutes, the neural function could not recovery.2.In model group Na+-K+-ATPase activity and glutamate transporters function began to drop 30 minutes after reperfusion, reached the low ebb 4 hours after reperfusion and then began to increase but it couldn't reach the normal level 12 hours after reperfusion(P<0.05). There was no difference between Nimodipine group and model group(P>0.05),Those of Tanshinone group were higher than model group(P<0.05). In model group content of glutamic acid in blood serum and spinal cord and NMDAR1 protein expression in the anterior horn cells of the spinal cord increased following 30-minute ischemia/30 minutes reperfusion injury to the spinal cord, reached a peak 4 hours after reperfusion, and then dropped but it couldn't reach the normal level 12 hours after reperfusion. There was no difference between Nimodipine group and model group(P>0.05),Those of Tanshinone group were lower than model group(P<0.05). In model group intraneuronal Ca2+ concentration and moisture capacity of spinal cord increased following 30-minute ischemia/1 hour reperfusion injury to the spinal cord, reached a peak 4 hours after reperfusion, and then dropped but it couldn't reach the normal level 12 hours after reperfusion.1,4,8,12 hours after reperfusion intraneuronal Ca2+ concentration of rat in tanshinone and Nimodipine group was lower than that of rat in model group(P<0.05).1 hour and 4 hours after reperfusion, intraneuronal Ca2+ concentration of rat in tanshinone group was lower than that of rat in Nimodipine group(P<0.05) but there was no difference between two groups 8 hours and 12 hours after reperfusion(P>0.05).4,8,12 hours after reperfusion moisture capacity of spinal cord of rat in tanshinone and Nimodipine group was lower than that of rat in model group(P<0.05).4 hours after reperfusion, moisture capacity of spinal cord of rat in tanshinone group was lower than that of rat in Nimodipine group(P<0.05) but there was no difference between two groups 8 hours and 12 hours after reperfusion(P>0.05).Tanshinone and Nimodipine could lessen edema of spinal cord both but effectiveness of tanshinone was better than that of Nimodipine 4 hours after reperfusion.3.Content of glutamic acid in blood serum and that in spinal cord was prominent positive correlation at 0.01 level. Content of glutamic acid in both blood serum and spinal cord and neural function were prominent negatively correlation at 0.01 level.Conclusions1.The best position to block blood flow of abdominal aorta for reconstructing model was in the initial of right renal artery proximal part. The time of best blocking is 30 minutes.2.Tanshinone could influence the anterior factors of EAAs-NMDA-Ca2+ path, thus reduced the nerve cell Ca2+ overload to protect neural function in SCII.3.Content of glutamic acid in blood serum might become a convenience, valid and micro-trauma index for diagnosis, treatment and evaluate curative effect of spinal cord ischemic reperfusion injury in clinic.