The role of peripheral nerve TNF? content in the development of neuropathic pain produced by chronic constriction injury of peripheral nerve in rats / 中华麻醉学杂志

ABSTRACT

Objective To investigate the changes in TNF? content of sciatic nerve induced by chronic constriction injury (CCI) of sciatic nerve to determine the role of TNFa in the development of neuropathic pain. Methods Eight-four female health SD rats weighing 250-300g were anesthetized with sodium barbiturate. Unilateral sciatic nerve was exposed and ligated at the middle of thigh. Three ligatures (chromic catgut 4.0) were placed around the sciatic nerve and tied. The distance between the two ligatures was about 1 mm. Sham operation was performed on the contralateral thigh. The sciatic nerve was exposed and mobilized but not ligated. The thermal nociceptive threshold was determined by measuring the withdrawal latency of hindpaw placed on a 58℃ hot plate on days 0.5, 1, 3, 5, 7, 9, 11, 13 and 14 after surgery. Animals were sacrificed on days 0.5, 1, 3, 7, 10 and 14 after surgery. Sciatic nerves were removed from both thighs and frozen at - 80℃ for determination of TNF? content. Sciatic nerve from healthy animals was used as control. The percentage of maximal possible response (% MPR) , was determined for each group (CCI, sham operation, control) % MPR= (new withdrawal latency- average baseline latency)/( 15-average baseline latency) . The distribution of TNF? between supernatant and sediment was also determined. Results The average baseline nociceptive threshold (withdrawal latency) was (7.9?0.2)s. There was significant different in %MPR between the two hindpaws on days 1, 3, 5, 7, 9 and 11 after surgery. The TNF? content of sciatic nerve from healthy rats was (40.62? 0.24) pg/mg protein. The TNF? content of the ligated sciatic nerve was elevated abruptly in 12h after ligation, then abruptly declined to a plateau but was still significantly higher than that of sham-operated side on days 1 and 3. There was no significant difference in TNF? content of sciatic nerve between control group and sham-operation group. The relative content of TNF? content in the sediment of ligated sciatic nerve gradually increased and reached the peak on day 7 and then gradually decreased. Conclusion The TNF? content of peripheral nerves plays an important role in the development of neuropathic pain. Membrane-combined TNF? is involved in the process of nerve repairing.