Davis R E, Wilmot G R, Cha J H
Mental Health Research Institute, University of Michigan, Ann Arbor 48104-1687.
Brain Res. 1992 Jan 31;571(1):73-8. doi: 10.1016/0006-8993(92)90510-g.
Kainic acid is supposed to be a specific agonist for a subclass of excitatory glutamate receptors in the vertebrate CNS. An investigation of (2 nM) [3H]kainic acid binding sites in goldfish brain, using quantitative autoradiography, has revealed evidence for two types of kainic acid receptors which differ in sensitivity to glutamic acid. L-Glutamic acid (0.1-1 mM) displaced over 95% of specific [3H]kainic acid binding elsewhere in the brain but only 10-50% in the cerebellum and cerebellar crest. These structures apparently contain [3H]kainic acid binding sites that are extremely insensitive to glutamic acid. The glutamic acid-insensitive [3H]kainic acid binding was not displaced by quisqualic acid, kynurenic acid, alpha-amino-3-hydroxy-5-methylisoxazolepropionic acid (AMPA), or N-methyl-D-aspartatic acid, but was completely displaced by the kainic acid analogue domoic acid. The data indicate that two types of high affinity binding sites for [3H]kainic acid exist in the goldfish brain: glutamic acid-sensitive and glutamic acid-insensitive. High affinity [3H]kainic acid binding may therefore not always represent binding to subsets of glutamic acid receptors.
海人酸被认为是脊椎动物中枢神经系统中一类兴奋性谷氨酸受体的特异性激动剂。利用定量放射自显影技术对金鱼脑中（2 nM）[³H]海人酸结合位点进行的一项研究揭示，存在两种对谷氨酸敏感性不同的海人酸受体。L - 谷氨酸（0.1 - 1 mM）能取代脑中其他部位超过95%的特异性[³H]海人酸结合，但在小脑和小脑嵴中只能取代10 - 50%。这些结构显然含有对谷氨酸极不敏感的[³H]海人酸结合位点。对谷氨酸不敏感的[³H]海人酸结合不能被喹啉酸、犬尿氨酸、α - 氨基 - 3 - 羟基 - 5 - 甲基异恶唑丙酸（AMPA）或N - 甲基 - D - 天冬氨酸取代，但能被海人酸类似物软骨藻酸完全取代。数据表明，金鱼脑中存在两种[³H]海人酸高亲和力结合位点：对谷氨酸敏感的和对谷氨酸不敏感的。因此，高亲和力[³H]海人酸结合可能并不总是代表与谷氨酸受体亚群的结合。
