van Zundert B, Albarran F A, Aguayo L G
Laboratory of Neurophysiology, Department of Physiology, University of Concepción, Concepción, Chile.
J Pharmacol Exp Ther. 2000 Oct;295(1):423-9.
Five-day-old cultures of mouse glycinergic spinal interneurons were chronically treated with 100 mM ethanol and the glycine and gamma-aminobutyric acid (GABA)(A) receptors were assayed using whole-cell recordings and fluorescence-imaging techniques. Control neurons displayed a glycine(50) of 19 +/- 0.6 microM and a Hill coefficient of 3.1 +/- 0.3. Chronic ethanol treatment did not significantly change these parameters. The maximal responses were 310 +/- 80 pA/pF in control and 440 +/- 19 pA/pF in treated cells, and the fluorescence intensity associated to a monoclonal glycine receptor antibody was unchanged. Strychnine inhibited the glycine current with smaller potency (29%) in treated neurons, thus the IC(50) increased from 14 +/- 2 nM in control to 18 +/- 6 nM in treated neurons. Zn(2+) (10 microM) potentiated the glycine current by 43 +/- 33% in control, but only by 18 +/- 13% in treated neurons. Interestingly, no change on the inhibition produced by a high concentration of Zn(2+) was found in treated neurons. The inhibitory effect of picrotoxin on the glycine receptor, associated to a homomeric receptor, was eliminated with chronic ethanol, suggesting a faster switch to beta-subunit-containing receptors. Unlike glycine receptors, the sensitivity of GABA(A) receptors to GABA, pentobarbital, diazepam, and Zn(2+), as well as the fluorescence intensity associated to a high-affinity benzodiazepine analog was unchanged by chronic ethanol. In conclusion, we found that glycine receptors in spinal interneurons were altered by chronic ethanol treatment and this may reflect the expression of different subunits in control and treated neurons. GABA(A) receptors were resistant to the treatment.
对培养5天的小鼠甘氨酸能脊髓中间神经元用100 mM乙醇进行长期处理，并使用全细胞记录和荧光成像技术检测甘氨酸和γ-氨基丁酸（GABA）（A）受体。对照神经元的甘氨酸（50）为19±0.6 μM，希尔系数为3.1±0.3。长期乙醇处理并未显著改变这些参数。对照细胞的最大反应为310±80 pA/pF，处理后的细胞为440±19 pA/pF，与单克隆甘氨酸受体抗体相关的荧光强度未改变。士的宁在处理后的神经元中抑制甘氨酸电流的效力较小（29%），因此IC（50）从对照中的14±2 nM增加到处理后神经元中的18±6 nM。锌离子（10 μM）在对照中使甘氨酸电流增强43±33%，但在处理后的神经元中仅增强18±13%。有趣的是，在处理后的神经元中未发现高浓度锌离子产生的抑制作用有变化。荷包牡丹碱对与同聚体受体相关的甘氨酸受体的抑制作用在长期乙醇处理后消失，表明更快地转变为含β亚基的受体。与甘氨酸受体不同，GABA（A）受体对GABA、戊巴比妥、地西泮和锌离子的敏感性，以及与高亲和力苯二氮䓬类似物相关的荧光强度在长期乙醇处理后未改变。总之，我们发现脊髓中间神经元中的甘氨酸受体在长期乙醇处理后发生了改变，这可能反映了对照和处理后神经元中不同亚基的表达。GABA（A）受体对该处理具有抗性。
