| Purpose:Through establishing model of secondary spinal cord injury in rats, injecting magnesium sulfate in order to detect the changes of the contents H2O,Mg2+,Ca2+in damaged spinal cord tissue, observing the changes of histopathology,ultrastructural changes and the Number of apoptotic cells per unit area ,To discuss the possible mechanism of protective effects of magnesium sulfate on the injuried spinal cord in rats model.Methods:Thirty Wister Rats were randomly divided into 3 groups: each group is 10. group A (control group); group B (Spinal cord injury) that is SCI; group C (Treatment group): the rats were injected 2% pentobarbitol sodium(2ml/kg)intraperitoneally. After anaesthetizing the rats, disinfect conventionally and spreads the turban.taking after-median incision,cut successively T10 spinous process and neural scute to expose dura. Creates a defection that length is about 4mm and width is 2mm. group A is laminectomy only and no trauma. group B and group C were made by using an improved Allen's weight-drop device. Attack intensity is 10×6(g.cm). After thirty minutes the animals of group B were injected with 1600mg/kg distilled water through Abdominal cavity injection and group C were injected with 1600mg/kg magnesium sulfate. Eight Wister Rats were choosed to kill from every group randomly to expose dura via original wound center after 48 hours .Takes damaged spinal cord tissue that length is about 1.5cm, the samples were divided two parts from its center , it's the former 1/3 was placed in 10% formalin to be fixed. the samples were taken out to make slices of the dyeing of HE and observed the changes of histopathology through light microscope. it's the latter 2/3 was used to detect the changes of the contents H2O,Mg2+,Ca2+.Taking out two slices from each rat,s slices in accordanceWith the relevant steps for TUNEL staining.The positive cells were quantitated by specific region of light microscope. the two remainder Rats of every group were killed and taken damaged spinal cord tissue in order to make TEM slices. The slices were observed through TEM.Results:The H2O and Ca2+ contents of injured spinal cord tissues in each SCI group were obviously increased compared to the control group (P<0.01), and group B was more than group C (P<0.05). the Mg2+ content were decreased obviously (P<0.01). Histopathological detection: through light microscope we can see that the boundary of white-gray of group A (control group) is very clear, the structure of Neurons and Myelin are normal;but injury group is dim. There are big laminated hemorrhage ,edema and area of necrosis ;the neurons in gray marrer decreased, there are reticular demyelinating in white matter. Part Nissl bodies and nucleus vanished; But group C (Treatment group) is less than group B (Spinal cord injury); Determination of apoptosis cells: there are not obvious apoptosis cells, many apoptosis cells can be seen in group C, but apoptosis cells of group C are less than group B(P<0.01); Through TEM we can see that the volume of nerve cells in group B decreased significantly, membrane is still complete, polyribosomes is less than other groups in cytoblastema, mitochondrial cristae space has expanded, apoptosis cells can be seen in groupB and groupC, demyelination of nerve fibers is obvious, but group C is less than group B significantly.Conclusion:The magnesium sulfate has played an ant-edema,ant-apoptosis role and has alleviated role of EAA. Earlly intervention with magnesium sulfate can decreased the secondary spinal cord injury, Thus the injuried spinal cord were protected effectively. |
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