GABA binding in mammalian brain: inhibition by endogenous GABA.
GABA binding in mammalian brain: inhibition by endogenous GABA.
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GABA 在哺乳动物大脑中的结合：内源性 GABA 的抑制。
DOI：
10.1016/0024-3205(80)90111-3
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发表时间：
1980
期刊：
影响因子：
6.1
通讯作者：
R. Olsen
中科院分区：
文献类型：
--
作者：
C. Napias;M. Bergman;P. V. Van Ness;D. Greenlee;R. Olsen
γ-氨基丁酸（GABA）的受体样网站在哺乳动物脑匀浆中的钠独立的结合是更大的膜组分已彻底清洗缓冲液，或洗涤剂，冷冻和解冻几次，比新鲜的未清洗的膜。如先前所示（Greenlee，货车Ness，& Olsen，Life Sciences 22，1653（1978）），洗涤程序去除GABA结合的内源性抑制剂，这导致GABA结合亲和力明显改善到低亲和力位点类别（KD <170 nM），并且另外，出现高亲和力（KD <10 nM）位点类别。发现这种内源性抑制物质抑制两类GABA结合位点，但对GABA的高亲和力位点具有更大的效力。抑制剂级分的生物化学表征显示，活性是热稳定的，对胰蛋白酶和二硫化物还原化合物不敏感，可通过膜筛透析，所述膜筛将保留分子量为5000的分子，并且在小分子的位置（盐体积）从分子筛柱100%洗脱，与16，000分子量标记物清楚地分离。抑制剂被GABA酶灭活超过80%，表明大多数，也许所有的GABA结合的内源性抑制剂确实是GABA本身。在苯二氮卓类受体研究（因为它们在体外受GABA影响）以及在人类神经精神疾病、药物治疗或病变研究中对GABA或苯二氮卓类受体进行任何比较时，必须考虑从脑膜中清除内源性GABA的困难。
Sodium-independent binding of gamma aminobutyric acid (GABA) to receptor-like sites in mammalian brain homogenates was much greater in membrane fractions which had been thoroughly washed with buffer, or detergent, and frozen and thawed several times, than in fresh unwashed membranes. As previously shown (Greenlee, Van Ness, & Olsen, Life Sciences 22, 1653 (1978), the washing procedure removed endogenous inhibitors of GABA binding which led to an apparent improvement in GABA binding affinity to a low affinity class of sites (K D≅ 170 nM), and, additionally, the appearance of a high affinity (K D≅ 10 nM) class of sites. This endogenous inhibitory material was found to inhibit both classes of GABA binding sites, but with greater potency towards the high affinity sites for GABA. Biochemical characterization of the inhibitor fraction revealed that the activity was heat-stable, insensitive to trypsin and disulfide reducing compounds, dialyzeable through membrane sieves which would retain molecules with a molecular weight of 5000, and eluted 100% from a molecular sieve column in the position of small molecules (salt volume), clearly separated from a 16,000 molecular weight marker. The inhibitor was over 80% inactivated by the enzyme GABAse, indicating that most, and perhaps all of the endogenous inhibitor of GABA binding was indeed GABA itself. The difficulty in removing endogenous GABA from brain membranes must be considered in studies on benzodiazepine receptors (since they are affected in vitro by GABA) and in any comparison of GABA or benzodiazepine receptors in human neuropsychiatric disorders, drug treatment or lesion studies.