Endoplasmic Reticulum Stress Induced Neuron Apoptosis In The Ischemia/Reperfusion Injury Of Rat Spinal Cord

Objective :The aim of this study was to observe the rules of cellular apoptosis change and GRP78,Caspase-12 expression in the rat spinal cord ischemia/reperfusion injury, so as to clarify the relationship between endoplasmic reticulum stress and neuron apoptosis after ischemia/reperfusion injury of rat spinal cord.Methods :Fifty six adult Wistar rats (250-300g) were randomly divided into 2 groups, including control group (n=6) and operation group (n=50). The spinal cord SCII model was established with a self-made device in the operation group. The operation process in control group was the same as the operation group except the ischemia/reperfusion of spinal cord. The segments of ischemia/reperfusion spinal cord were properly taken at an interval of 30min,3,7,11,23and 47h, respectively after reperfusion (n=10 for each group). The ischemia/reperfusion segments of spinal cord were examined by the methods of HE,Nissl,TUNEL staining, immunohistochemistry(IHC) test,Western blotting and image analysis. Results :HE and Nissl staining showed the edema of neurons and gliocytes, vacuolation in some neurons and spongy degeneration in the white matter of the injury spinal cord after 3h of spinal cord ischemia/reperfusion.IHC test and Western blotting showed the GRP78 expression was increased at 30min of reperfusion, and peaked at 7h,but began to decline at 11h post-reperfusion,and reduced significantly at 23h. The number of GRP78 positive neurons at 0.5, 3,7,11 and 23h groups was(19.4±1.34), (42.6±2.30), (82.4±2.07), (40.0±1.58) and (18.8±0.83), respectively and significantly higher than that of control group (P<0.05). In whole spinal cord Caspase-12 expression was increased at 3h after SCII, and peaked at 11h, but appeared to decline after ischemia/reperfusion for 23h,and reduced significantly at 47h.The neuron and gliocyte apoptosis was observed at each investigation time after ischemia/reperfusion.Conclusions :The apoptosis is an essential factor in the spinal cord injury during the period of the ischemia/reperfusion of spinal cord, endoplasmic reticulum stress is the most important way to induce cellular apoptosis ; Caspase-12 might be involved in the cellular apoptosis in the ischemia/reperfusion spinal cord.