Dutar P, Rascol O, Lamour Y
Laboratoire de Physiopharmacologie du Système Nerveux, INSERM U161, Paris, France.
Eur J Pharmacol. 1989 Dec 19;174(2-3):261-6. doi: 10.1016/0014-2999(89)90318-x.
The effects of omega-conotoxin GVIA (omega-CgTx), a peptide isolated from the venom of a marine mollusc, were studied in rat hippocampal neurons. Intracellular recordings from the CA1 area were made for the purpose in in vitro slice preparations. Omega-CgTx (0.1-1 microM) rapidly and irreversibly blocked the EPSP and the IPSPs elicited by electrical stimulation of Schaffer collaterals/commissural fibers. Omega-CgTx also blocked the slow cholinergic EPSP induced by electrical stimulation of cholinergic afferents. The postsynaptic effects of baclofen or carbachol remained unchanged in the presence of omega-CgTx and other postsynaptic calcium-dependent events such as afterhyperpolarization were not affected by omega-CgTx. These results suggest a presynaptic action of omega-CgTx through the blockade of neurotransmitter release. Omega-CgTx might act in the hippocampus by blocking presynaptic N-type voltage-sensitive calcium channels.
对从海洋软体动物毒液中分离出的一种肽——ω-芋螺毒素GVIA（ω-CgTx）的作用，在大鼠海马神经元中进行了研究。为此目的，在体外脑片制备中对CA1区进行细胞内记录。ω-CgTx（0.1 - 1微摩尔）迅速且不可逆地阻断了由电刺激Schaffer侧支/联合纤维所诱发的兴奋性突触后电位（EPSP）和抑制性突触后电位（IPSP）。ω-CgTx还阻断了由电刺激胆碱能传入纤维所诱发的缓慢胆碱能EPSP。在存在ω-CgTx的情况下，巴氯芬或卡巴胆碱的突触后效应保持不变，并且其他突触后钙依赖性事件，如超极化后电位，不受ω-CgTx影响。这些结果表明ω-CgTx通过阻断神经递质释放发挥突触前作用。ω-CgTx可能通过阻断突触前N型电压敏感性钙通道在海马体中发挥作用。
