Changes Of Gaba-activated Currents In Isolated Dorsal Root Ganglion Neurons In Rats With Neuropathic Pain

Objective: To investigate the changes of GABA-activated currents in isolated dorsal root ganglion neurons in rats with neuropathic pain.Methods: The neuropathic pain model was established by chronic constriction injury(CCI) 7 days before electrophysiological recording. The rat DRG neurons were enzymatically dissociated. Whole-cell patch clamp technique was used to record GABA-activated currents. The changes of currents of injured side and opposite side were expected to compared with control group.Results: (1) The currents of injured side of CCI group were notablely decreased compared with control group(GABA concentration, 0.01-1000μmol/ L) (P<0.01). 0.01-0.1μmol/ L GABA does not cause visible GABA-activated currents, 1μmol/ L GABA cause 0. 16±0. 01 nA (n = 3) GABA-activated currents, 10μmol/ L GABA cause 0. 59±0. 06 nA (n =7) GABA-activated currents,100μmol/ L GABA cause 0. 97±0. 05 nA (n = 8) GABA-activated currents,1000μmol/ L GABA cause 1. 18±0. 07 nA (n = 3) GABA-activated currents.(2) By the contrast, opposite side currents of CCI group increased significantly compared with control group(GABA concentration, 0.01-1000μmol/ L) (P<0.01). 0.01μmol/ L GABA cause 0. 14±0. 02 nA (n = 4) GABA-activated currents,0.1μmol/ L GABA cause 0. 29±0. 03 nA (n = 7) GABA-activated currents,1μmol/ L GABA cause 1. 53±0. 29 nA (n = 6) GABA-activated currents, 10μmol/ L GABA cause 2. 53±0. 31 nA (n =6) GABA-activated currents,100μmol/ L GABA cause 4. 27±0. 37 nA (n = 6) GABA-activated currents,1000μmol/ L GABA cause 4. 30±0. 22 nA (n = 4) GABA-activated currents.Conclusion: The data indicates that the chronic constriction injury both change the function of GABA_A recepters of injury side and opposite side. The decrease of presynaptic inhibition of GABA may be the possible reason of neuropathic pain.