Momiyama Toshihiko
Division of Cerebral Structure, National Institute for Physiological Sciences, Myodaiji, Okazaki 444-8585, Japan.
Nihon Yakurigaku Zasshi. 2002 Apr;119(4):235-40. doi: 10.1254/fpj.119.235.
It is well established that neurotransmitter release is triggered by Ca2+ entry into the presynaptic terminals through voltage-dependent Ca2+ channels. In the mammalian central nervous system, multiple types of Ca2+ channels including N-type, P/Q-type and other types mediate fast synaptic transmission. Electrophysiological studies using type-specific antagonists for Ca2+ channels have estimated the relative contribution of N-, P/Q- and other types of Ca2+ channels in excitatory and inhibitory synaptic transmission in the hippocampus, cerebellum, spinal cord, brain stem, and striatum. A recent study has demonstrated that activation of presynaptic dopamine D2-like receptors selectively block N-type Ca2+ channels to reduce GABA release onto cholinergic interneurons in the rat striatum. In addition, it has been recently clarified that the contribution of N-type Ca2+ channels to synaptic transmission is restricted to the early postnatal period at synapses in auditory brain stem, cerebellum, or thalamus. Advanced morphological studies are necessary for the further understanding of the subcellular localization of each subtype of Ca2+ channels and receptors modulating the transmitter release through Ca2+ channel activity in relation to the release sites in the presynaptic terminals.
众所周知，神经递质的释放是由Ca2+通过电压依赖性Ca2+通道进入突触前终末所触发的。在哺乳动物中枢神经系统中，多种类型的Ca2+通道，包括N型、P/Q型和其他类型，介导快速突触传递。使用Ca2+通道特异性拮抗剂的电生理研究已经估计了N型、P/Q型和其他类型的Ca2+通道在海马体、小脑、脊髓、脑干和纹状体的兴奋性和抑制性突触传递中的相对贡献。最近的一项研究表明，突触前多巴胺D2样受体的激活选择性地阻断N型Ca2+通道，以减少大鼠纹状体中GABA释放到胆碱能中间神经元上。此外，最近已经阐明，N型Ca2+通道对突触传递的贡献仅限于听觉脑干、小脑或丘脑突触的出生后早期。为了进一步了解每种亚型的Ca2+通道和受体的亚细胞定位，这些通道和受体通过Ca2+通道活性调节与突触前终末释放位点相关的递质释放，先进的形态学研究是必要的。
