Effects of midazolam on GABAA receptor-activated currents in isolated dorsal root ganglion neurons in rats / 中华麻醉学杂志

ABSTRACT

Objective To investigate the effects of midazolam on GABAA receptor-activated currents in isolated dorsal root ganglion (DRG) neurons in rats.Methods Sprague-Dawley rats of both sexes,weighing 200-250 g,aged 4 weeks,were used in the study.The DRG neurons were isolated and GABAA receptor-activated currents were recorded using the whole-cell patch-clamp technique.GABAA receptor-activated currents were recorded after administration of the mixture of midazolam 3.00 μmol/L (final concentration)and the different final concentrations (0.03,0.10,1.00,10.00,100.00 and 1000.00 μmol/L) of GABA,after different concentrations of midazolam (0.03,0.10,1.00,3.00,10.00 and 100.00 μmol/L) was given,after administration of the mixture of different final concentrations(0.03,0.10,1.00,3.00,10.00 and 100.00 μmol/L) of midazolam and GABA 100.00 μmol/L (final concentration),and after administration of the mixture of midazolam 1.00μmol/L (final concentration) and GABA 100.00 μmol/L (final concentration)at the preset time points of perfusion with different concentrations of midazolam (0,20,40,60 and 120 s of perfusion).The enhancement rate of the currents was calculated.Results No change in the membrane currents was found after midazolam was perfused in the neurons sensitive to GABA.GABAA receptor-activated currents were enhanced after administration of the mixture of different concentrations of GABA and midazolam.GABAA receptor-activated currents were enhanced after different concentrations of midazolam were given compared with that before administration,and the enhancement rate of the GABAA receptoractivated currents was gradually increased with the increase in the concentration of midazolam and reached the peak at the concentration of 3.00 μmol/L.The enhancement rate of the GABAA receptor-activated currents was gradually increased with the prolongation of perfusion time and peaked at 40 s of perfusion.Conclusion Midazolam can enhance the GABAA receptor-activated currents in rat dorsal root ganglion neurons,indicating that midazolam increases the role of GABA through increasing the activity of GABAA receptors and has analgesic effect at the spinal cord level.