咖啡因及相关化合物可阻断新鲜分离的大鼠海马神经元中抑制性氨基酸门控的氯离子电流。

Caffeine and related compounds block inhibitory amino acid-gated Cl- currents in freshly dissociated rat hippocampal neurones.

作者信息

Uneyama H, Harata N, Akaike N

机构信息

Department of Neurophysiology, Tohoku University School of Medicine, Sendai, Japan.

出版信息

Br J Pharmacol. 1993 Jun;109(2):459-65. doi: 10.1111/j.1476-5381.1993.tb13591.x.

DOI:10.1111/j.1476-5381.1993.tb13591.x

PMID:7689394

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC2175694/

Abstract

The effects of caffeine and related compounds on responses mediated by inhibitory amino acids were investigated in freshly dissociated rat hippocampal pyramidal neurones by conventional and nystatin perforated patch-clamp techniques. 2. Glycine and gamma-aminobutyric acid (GABA) evoked Cl- currents in hippocampal neurones. The half-maximum effective concentrations (EC50) of glycine and GABA were 8.5 x 10(-5) and 5 x 10(-6) M, respectively. 3. Caffeine reversibly inhibited both 10(-4) M glycine- and 10(-5) M GABA-induced Cl-currents in a concentration-dependent manner. The half-maximum inhibitory concentrations (IC50) of caffeine were 4.5 x 10(-4) M for the glycine response and 3.6 x 10(-3) M for the GABA response. 4. Caffeine shifted the concentration-response curve of IGly to the right without affecting the maximum response. 5. The inhibitory action of caffeine did not show voltage-dependency. 6. The blocking action of caffeine was not affected by intracellular perfusion with 5 mM BAPTA or by pretreatment with the protein kinase A inhibitor, H-8. This excludes the participation of Ca2+ or cyclic AMP in the inhibitory action of caffeine. 7. Caffeine failed to inhibit the augmentations of aspartate- and N-methyl-D-aspartate (NMDA) -gated current by glycine, suggesting that caffeine has no effect on the allosteric glycine binding site on the NMDA receptor. 8. The inhibitory effects of some xanthine derivatives on IGly were compared. The inhibitory potency of those compounds on IGly was in the order of pentoxifylline > theophylline > or = caffeine > paraxanthine > IBMX > or = theobromine > dyphylline. Xanthine had no effect. 9. The results indicate that methylxanthines including caffeine may act directly on the glycine receptor Cl- channel complex in rat hippocampal pyramidal neurones. The blockade of the inhibitory amino acid response by methylxanthines may be involved in the excitatory side effects of methylxanthines in the mammalian central nervous system.

摘要

采用传统的和制霉菌素穿孔膜片钳技术，在新鲜分离的大鼠海马锥体神经元中研究了咖啡因及相关化合物对抑制性氨基酸介导反应的影响。2. 甘氨酸和γ-氨基丁酸（GABA）可诱发海马神经元中的氯离子电流。甘氨酸和GABA的半数最大效应浓度（EC50）分别为8.5×10⁻⁵和5×10⁻⁶ M。3. 咖啡因以浓度依赖性方式可逆地抑制10⁻⁴ M甘氨酸和10⁻⁵ M GABA诱导的氯离子电流。咖啡因对甘氨酸反应的半数最大抑制浓度（IC50）为4.5×10⁻⁴ M，对GABA反应的IC50为3.6×10⁻³ M。4. 咖啡因使IGly的浓度-反应曲线右移，而不影响最大反应。5. 咖啡因的抑制作用不表现出电压依赖性。6. 用5 mM BAPTA进行细胞内灌注或用蛋白激酶A抑制剂H-8预处理，均不影响咖啡因的阻断作用。这排除了Ca²⁺或环磷酸腺苷参与咖啡因的抑制作用。7. 咖啡因未能抑制甘氨酸对天冬氨酸和N-甲基-D-天冬氨酸（NMDA）门控电流的增强作用，表明咖啡因对NMDA受体上的变构甘氨酸结合位点无作用。8. 比较了一些黄嘌呤衍生物对IGly的抑制作用。这些化合物对IGly的抑制效力顺序为：己酮可可碱＞茶碱≥咖啡因＞副黄嘌呤＞异丁基甲基黄嘌呤≥可可碱＞二羟丙茶碱。黄嘌呤无作用。9. 结果表明，包括咖啡因在内的甲基黄嘌呤可能直接作用于大鼠海马锥体神经元中的甘氨酸受体氯离子通道复合物。甲基黄嘌呤对抑制性氨基酸反应的阻断可能与甲基黄嘌呤在哺乳动物中枢神经系统中的兴奋副作用有关。