GABA_A receptor mediated inhibitory effect of thiopental sodium on glutamate release from prefrontal cortical synaptosomes in rats / 中华麻醉学杂志

ABSTRACT

Objective To investigate the effect of thiopental sodium (TPS) on spontaneous and KCl-evoked glutamate release from prefrontal cortical synaptosomes in rats and the effect of bicuculline on this effect ofTPS.Methods SD rats of both sexes (200-250 g) were decapitated and brains were removed. The prefrontalcortex was dissected and added to ice-cold sucrose solution and homogenized. The homogenate was centrifuged at1000 g at 0℃-4℃ for 5 min. The supernatant was again centrifuged at 12 000 g for 20 min. The sediment wascrude synaptosomes, which was added to artificial cerebro-spinal fluid (ACSF). The crude synaptosomes weredivided into 5 groups (n = 8): control group and 4 TPS groups. In control group no TPS was added while in TPSgroups different concentrations of TPS was added and the final concentration of TPS was 10, 30, 100, 300?mol?L~(-1) respectively. The synaptosomes were then placed with or without KCl in water bath at 37℃ for 15 min. Thespontaneous or KCl-evoked glutamate release was measured using high-performance liquid chromatograph (HPLC).In another set of experiment bicuculline 0. 1 mmol?L~(-1) was added to ACSF in each group before 15 min water bathto see if it could antogonize the effect of TPS on glutamate release. Results TPS 30, 100 and 300 ?mol?L~(-1)could significantly inhibit the spontaneous or KCl-evoked glutamate release compared with control group (P0.05). Bicuculline 0. 1 mmol?L~(-1) had no effect on the glutamate release in control group but could antagonize the inhibitory effect of TPS on glutamate release. Afteraddition of bicucculline the glutamate released in control group was not significantly different from that in the TPSgroups.Conclusion TPS sodium can inhibit the spontaneous or KCl-evoked glutamate release from prefrontalcortical synaptosomes in a concentration-dependent manner. The inhibitory effect is mediated by GABA_A receptors.