Rat Sciatic Nerve Injury After The Study Of The Generation Mechanism Of Spontaneous Discharge

The mechanism of the neuropathic pain is not clear, CCI (Chronic Constriction Injury) model is a classic animal model for this research.The Structure of the injury nerve was observed, including the morphological changes, distribution and content changes in some cation channel protein expression in the injury site were detected, to explore the mechanism of the spontaneous discharge in the injury nerve.The abnormal behavior with the behavioral methods appeared, the spontaneous discharge frequency and rhythm changed after some cation channel blockers applied by the electrophysiological techniques, electron microscopy and conventional morphological staining techniques were used to define the end bulbs in the sciatic nerve injury local region, immunohistochemistry assay were used to detect the distribution of the NF-H and BK in the injury site, Western blotting were used to detect content of some special cation channel proteins in the injury region. The main results are as followings:ipsilateral limb had varying degress of abnormal behavior under the mechanical stimulation and thermal stimulation because of the constraction injury, electrophysiological technique found the frequency and rhythm of spontaneous discharge changed after the injury region imposed specific calcium-activated potassium ion channel blockers (TEA, Apamin, IBTX), the spontaneous firing rate decreased, rhythm had significant change and appeared steadily; immunohistochernical detection results show that distribution of NF-H protein in the contralateral normal tissue was uniform and regular, while it changed in the sciatic nerve injury site,NF-H concentrated in the region between the ligations, scattered and uneven, and gathered in a long oval-shaped structure, the later was similar to the end-bulb like structure, there were almost no expression of the BK channel in normal tissues, but appeared in the sciatic nerve injury site, distribution is similar to the NF-H’s, and there was the trend co-expression distribution of NF-H and BK in the sciatic injury nerve region; Western blotting showed that, with time course, there was the gradual increase in NF-H protein content after the operation4,7,14,28days, tended to return to normal tissue content, content of the BK channel protein were highest after operation4,7days, and were lower after14,28days, content of the SK channel protein were highest after operation7days, and were lower after4,14,28days, three proteins content had dynamic changes, calcium channel α2δ subunit only detected after4days, the subunit was not detected in the nerve after7,14,28days, and same in the control one. Conclusion:there was a close relationship between the local changes in sciatic injury nerve and the mechanism of the spontaneous discharge phenomenon of CCI rat, end bulb or the end-bulb like structure maybe were the apparatus where the spontaneous discharge initiated, and the emergence and content change of some specific cation channels in the injury region, should participate in the formation of spontaneous discharge mechanism.