The Study On Regulatory Mechanism Of GABA-activated Currents In Isolated Dorsal Root Ganglion Neurons In Rats With Neuropathic Pain By Sevoflurane

Objective:To observe the sevoflurane on chronic constriction injury (CCI) of sciatic nerve chronic pressure caused by nerve pathological pain rats, DRG neurons on the GABAa receptor activation current, the effect of sevoflurane in the spinal cord level, possible mechanisms of analgesia.Methods:(1) To make the CCI model group and the pseudo-operation group.(2) To detect the change of thermal withdrawal latency on operated side by Hot-plate test.(3) Useing whole-cell patch-clamp technique to record changes of GABA-activated currents in the CCI model group, the pseudo-operation group and non-control group.(4) Useing whole-cell patch-clamp technique to record the changes of GABA-activated currents by different concentrations of sevoflurane in the CCI model group and non-control group.Results:(1) CCI ipsilateral side produced significantly thermal withdrawal latency shorter (P<0.01).(2) GABA (1-1000μmol/L) caused concentration-dependent inward current on DRG neurons and the inward currents can be interrupted by selective GABAa receptors antagonist bicuculline (100μmol/L).(3) On the DRG neurons in the CCI model group, the pseudo-operation group and non-control group,1～100μmol/L GABA all caused concentration-dependent inward current, CCI group (1～100(μmol/L) GABA activated current amplitude were significantly less than control group and normal control group (P<0.01).(4) In non-control group, when the concentration of sevoflurane is100,300,1000,3000(μmol/L all enhanced the GABA activated current, and it is obvious that the enhancement effect by300μmol/L sevoflurane is the most obvious (P<0.05, n=6).(5) The enhancement of the GABA-activated currents by sevoflurane (100,300,1000μmol/L) related to the given dose of GABA, when10μmol/L was the most obvious (P<0.05, n=6).(6) The normal control group and CCI group of100μmol/L,30μmol/L,10μmol/L GABA activated current were enhanced by Sevoflurane (300μmol/L), and CCI group increased more obviously, the difference was statistically significant.(P<0.01).Conclusion:Sevoflurane GABAa receptor of DRG neurons have enhancement effect, and CCI group increased more obviously. And GABAa receptors are involved in the presynaptic inhibition, thus enhanced the function of GABAa receptor may be one of the mechanism of analgesia in the spinal cord level.