大鼠脑片放射性乙酰胆碱合成与释放的控制。神经营养药物的作用。

Control of synthesis and release of radioactive acetylcholine in brain slices from the rat. Effects of neurotropic drugs.

作者信息

Grewaal D S, Quastel J H

出版信息

Biochem J. 1973 Jan;132(1):1-14. doi: 10.1042/bj1320001.

DOI:10.1042/bj1320001

PMID:4722896

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1177553/

Abstract

Studies of the synthesis and release of radioactive acetylcholine in rat brain-cortex slices incubated in Locke-bicarbonate-[U-(14)C]glucose media, containing paraoxon as cholinesterase inhibitor, revealed the following phenomena: (a) dependence of K(+)-or protoveratrine-stimulated acetylcholine synthesis and release on the presence of Na(+) and Ca(2+) in the incubation medium, (b) enhanced release of radioactive acetylcholine by substances that promote depolarization at the nerve cell membrane (e.g. high K(+), ouabain, protoveratrine, sodium l-glutamate, high concentration of acetylcholine), (c) failure of acetylcholine synthesis to keep pace with acetylcholine release under certain conditions (e.g. the presence of ouabain or lack of Na(+)). 2. Stimulation by K(+) of radioactive acetylcholine synthesis was directly proportional to the external concentration of Na(+), but some synthesis and release of radioactive acetylcholine occurred in the absence of Na(+) as well as in the absence of Ca(2+). 3. The Na(+) dependence of K(+)-stimulated acetylcholine synthesis was partly due to suppression of choline transport, as addition of small concentrations of choline partly neutralized the effect of Na(+) lack, and partly due to the suppression of the activity of the Na(+) pump. 4. Protoveratrine caused a greatly increased release of radioactive acetylcholine without stimulating total radioactive acetylcholine synthesis. Protoveratrine was ineffective in the absence of Ca(2+) from the incubation medium. It completely blocked K(+) stimulation of acetylcholine synthesis and release. 5. Tetrodotoxin abolished the effects of protoveratrine on acetylcholine release. It had blocking effects (partial or complete) on the action of high K(+), sodium l-glutamate and lack of Ca(2+) on acetylcholine synthesis and release. 6. Unlabelled exogenous acetylcholine did not diminish the content of labelled tissue acetylcholine, derived from labelled glucose, suggesting that no exchange with vesicular acetylcholine took place. In the presence of 4mm-KCl it caused some increase in the release of labelled acetylcholine. 7. The barbiturates (Amytal, pentothal), whilst having no significant effects on labelled acetylcholine synthesis in unstimulated brain except at high concentration (1mm), diminished or abolished (at 0.25 or 0.5mm) the enhanced release of acetylcholine, due to high K(+) or lack of Ca(2+). The fall in tissue content of acetylcholine, due to lack of Ca(2+), was diminished or abolished by pentothal (0.25 or 0.5mm) or Amytal (0.25mm).

摘要

对在含有对氧磷作为胆碱酯酶抑制剂的洛克碳酸氢盐 - [U - (14)C]葡萄糖培养基中孵育的大鼠脑皮质切片中放射性乙酰胆碱的合成与释放进行的研究，揭示了以下现象：(a) K⁺或原藜芦碱刺激的乙酰胆碱合成与释放依赖于孵育培养基中Na⁺和Ca²⁺的存在；(b) 促进神经细胞膜去极化的物质（如高K⁺、哇巴因、原藜芦碱、L - 谷氨酸钠、高浓度乙酰胆碱）可增强放射性乙酰胆碱的释放；(c) 在某些条件下（如存在哇巴因或缺乏Na⁺），乙酰胆碱合成无法跟上乙酰胆碱释放的速度。2. K⁺对放射性乙酰胆碱合成的刺激与外部Na⁺浓度成正比，但在没有Na⁺以及没有Ca²⁺的情况下也会发生一些放射性乙酰胆碱的合成与释放。3. K⁺刺激的乙酰胆碱合成对Na⁺的依赖性部分是由于胆碱转运受到抑制，因为添加低浓度胆碱可部分抵消缺乏Na⁺的影响，部分是由于Na⁺泵活性受到抑制。4. 原藜芦碱可使放射性乙酰胆碱的释放大幅增加，而不会刺激总放射性乙酰胆碱的合成。在孵育培养基中没有Ca²⁺时，原藜芦碱无效。它完全阻断了K⁺对乙酰胆碱合成与释放的刺激。5. 河豚毒素消除了原藜芦碱对乙酰胆碱释放的影响。它对高K⁺、L - 谷氨酸钠和缺乏Ca²⁺对乙酰胆碱合成与释放的作用有阻断作用（部分或完全）。6. 未标记的外源性乙酰胆碱不会减少源自标记葡萄糖的标记组织乙酰胆碱的含量，这表明与囊泡乙酰胆碱没有发生交换。在存在4mM - KCl的情况下，它会使标记乙酰胆碱的释放有所增加。7. 巴比妥类药物（阿米妥、硫喷妥钠），除了在高浓度（1mM）时对未受刺激的脑中标记乙酰胆碱的合成没有显著影响外，可减少或消除（在0.25或0.5mM时）由于高K⁺或缺乏Ca²⁺导致的乙酰胆碱释放增加。由于缺乏Ca²⁺导致的组织中乙酰胆碱含量下降，可被硫喷妥钠（0.25或0.5mM）或阿米妥（0.25mM）减少或消除。