Patterson T A, Kim E K, Meldrum M J, Dawson R
Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville 32610, USA.
Neurochem Res. 1995 Feb;20(2):225-32. doi: 10.1007/BF00970548.
The major excitatory amino acid neurotransmitter in the mammalian brain is glutamate (GLU). GLU release from nerve terminals is both calcium-dependent and -independent, yet these mechanisms of release are not fully understood. Potassium, 4-aminopyridine (4-AP) and veratrine are commonly used depolarizing agents that were studied for their ability to stimulate GLU efflux from brain slices. These agents produced significant regional variations in GLU efflux from rat brain slices. Potassium was the most potent of the three secretogogues tested. 4-AP produced a significant GLU efflux only in the cerebellum. Veratrine produced consistent stimulation of GLU efflux from all brain regions tested. Potassium was the only depolarizing agent tested that stimulated GLU release from primary astroglial cultures of rat cerebral cortex. All three agents also demonstrated an ability to inhibit GLU reuptake in brain slice preparations. This data suggest that both GLU release and uptake are modulated in a regionally selective manner, and that commonly used depolarizing agents affect not only calcium-dependent neuronal release, but also uptake and glial responses.
哺乳动物大脑中主要的兴奋性氨基酸神经递质是谷氨酸（GLU）。神经末梢释放GLU既依赖钙也不依赖钙，然而这些释放机制尚未完全明确。钾、4-氨基吡啶（4-AP）和藜芦碱是常用的去极化剂，人们研究了它们刺激脑片释放GLU的能力。这些药剂使大鼠脑片的GLU释放产生显著的区域差异。钾是所测试的三种促分泌素中最有效的。4-AP仅在小脑中产生显著的GLU释放。藜芦碱能持续刺激所测试的所有脑区释放GLU。钾是所测试的唯一能刺激大鼠大脑皮层原代星形胶质细胞培养物释放GLU的去极化剂。这三种药剂还都显示出能够抑制脑片制剂中GLU的再摄取。这些数据表明，GLU的释放和摄取都以区域选择性的方式受到调节，并且常用的去极化剂不仅影响依赖钙的神经元释放，还影响摄取和胶质细胞反应。
