Protective Effect Of PNS In Spinal Cord Hemisection Injury And Its CPLA2Related Mechanism

OBJECTIVE This study was to investigate the expression of cytosolic phospholipase A2(cPLA2) and glial fibrillary acidic protein (GFAP) in spinal tissues of rats with spinal cord injury after panax notoginseng saponins (PNS) treatment.METHODS A total of55healthy adult Sprague Dawley rats were divided randomly into three groups without discriminating of gender (1)Sham operation group (group S, n=5);(2) spinal cord injury group (group C, n=25);(3) PNS treatment group (group T, n=25).According to the survival time, SCI group and PNS group are divided in to5groups, which include survive for1day,3days,7days,14days and21days.The spinal cord injury models were made by T10hemisection while the Sham group just receive laminectomy without injurying the spinal cord.20mg/kg of PNS was injected to the T group intraperitoneally and the C group was treated with the same volume of saline vehicle (NS)15minutes after injury. Each model was given the same dosage once a day. Animal behavioral scores—modified by BBB score on spinal cord functional deficits were performed to the rats following SCI to analyze the difference between the two groups.At the corresponding time points following the injury, the rats of two groups were sacrificed and the spinal cord tissue samples were collected from the injured segment with the length of1cm. Each sample got2continuous histological sections of10um thickness through microtomy in the middle of the sample to test cPLA2and GFAP by immunohisto-chemistry method separately and Nissle staining.The number of positive cells in every section was counted,and the average positive cells of each group at the same time point were calculated. Software SPSS13.0was applied to analyze if there was significant difference between the two related groups at each time point and correlationship between the cPLA2and GFAP.RESULTS The BBB scores of the two groups are increased after the spinal cord injury, and the PNS group gets higher scores than the SCI group. All the time points show significant difference except the1day, and the P value for3d and7day is less than0.05with the value for14d and21d less than0.01.The Nissle staining for pathology test shows sham group is integrated in morphology, and the Nissle body is clear in cytoplasm. The SCI group shows damaged structures with cavities in grey matter and the Nissle body is fuzzy. The neural structure is relatively integrated and Nissle body can be seen clearly with more normal neurons in which the nucleolus is a little dense with complete karyotheca.The expression of cPLA2is increased after the first day of spinal cord injury with increased positive cells, swollen neurons and neural bodies, while the positive cells in PNS group is less, with lighter staining, less swollen neurons and more integrated tissue. At7d,14d and21d, the expression of cPLA2in SCI group is significantly increased than the PNS group(P<0.01), and at all time points the expression of cPLA2in PNS group is decreased than the SCI group. The expression of GFAP is increased after the first day in both groups with increased positive cells, swollen neurons and enlarged neural bodies, while the positive cells is fewer in PNS group with lighter staining, less swollen neurons and more integrated structure. At7d,14d and21d, the GFAP expression in SCI group is significantly increased than the PNS group(P<0.05), and at all the time points, GFAP in PNS group is more decreased than the SCI group. The cPLA2is significantly correlated with GFAP under Pearson correlation analysis (r=0.90, P=0.04), which explains the activation of astrocyte is associated with cPLA2.CONCULUSION The PNS can inhabit the expressions of the cPLA2and GFAP of the SD rats after SCI. It has neuroprotective effects on the second injury mechanism of the SCI, and it is associated with the activation of astrocyte.