Inhibitory effects of corymine, an alkaloidal component from the leaves of Hunteria zeylanica, on glycine receptors expressed in Xenopus oocytes
Inhibitory effects of corymine, an alkaloidal component from the leaves of Hunteria zeylanica, on glycine receptors expressed in Xenopus oocytes
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DOI：
10.1016/s0014-2999(97)01097-2
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发表时间：
1997-08-13
影响因子：
5
通讯作者：
Watanabe, H
中科院分区：
文献类型：
--
作者：
Leewanich, P;Tohda, M;Watanabe, H
我们之前曾报道，从泰国产的斑点叉叶中提取的生物碱化合物Corymine可以增强印防己毒素或士的宁引起的惊厥。因此，为了阐明柯里香碱的作用机制，我们检测了柯里香碱对γ-氨基丁酸(GABA)和甘氨酸受体的影响。我们使用表达这些受体的非洲爪哇卵母细胞和双电极电压钳方法。在注射大鼠脑和脊髓RNA的卵母细胞中表达的受体分别具有GABA(A)和甘氨酸受体的药理特性。在注射大鼠脑RNA的卵母细胞中，Corymine(1-100 mU M)部分地(20-30%)降低GABA反应，而在注射大鼠脊髓RNA的卵母细胞中，甘氨酸反应显著降低(高达80%)。这些观察结果表明，与GABA受体相比，Coryine对甘氨酸受体的抑制作用更强。柯里香碱对甘氨酸反应的ED50为10.8mU·M，在30mM时，使甘氨酸浓度-反应曲线右移，最大反应降低。这表明，Corymine对甘氨酸受体的作用既不是竞争性的，也不是纯粹的非竞争性的。这些观察结果表明，除了甘氨酸受体的甘氨酸识别部位外，还有一个结合部位是柯里香碱的作用部位。(C)1997年爱思唯尔科学公司。
We previously reported that corymine, an alkaloidal compound extracted from the leaves of Hunteria zeylanica native to Thailand, potentiated convulsions induced by either picrotoxin or strychnine. Therefore, to clarify the mechanism of action of corymine, the effects of corymine on gamma-aminobutyric acid (GABA) and glycine receptors were examined. We used Xenopus oocytes expressing these receptors and the two-electrode voltage-clamp method. The receptors expressed in oocytes injected with rat brain and spinal cord RNA showed the pharmacological properties of GABA(A) and glycine receptors, respectively. Corymine (1-100 mu M) partially (20-30%) reduced the GABA responses in oocytes injected with rat brain RNA, while marked (up to 80%) dose-dependent reductions were observed in the glycine responses in oocytes injected with rat spinal cord RNA. These observations suggest that corymine was more effective against the glycine receptors than the GABA receptors. The ED50 of corymine on the glycine response was 10.8 mu M. Corymine, at 30 mu M, caused a shift to the right, with a lower maximal response, of the glycine concentration-response curve. This indicated that the action of corymine on glycine receptors is neither competitive nor purely non-competitive. These observations suggest that a binding site other than the glycine recognition site of the glycine receptors is the site of action of corymine. (C) 1997 Elsevier Science B.V.