Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, Sagamihara, 252-5258, Japan.
Sci Rep. 2021 Mar 18;11(1):6242. doi: 10.1038/s41598-021-84646-3.
γ-Aminobutyric acid (GABA), the major inhibitory neurotransmitter in the central nervous system, exerts its effect through the activation of GABA receptors. GABA receptors are ligand-gated chloride channels composed of five subunit proteins. Mammals have 19 different GABA receptor subunits (α1-6, β1-3, γ1-3, δ, ε, π, θ, and ρ1-3), the physiological properties of which have been assayed by electrophysiology. However, the evolutionary conservation of the physiological characteristics of diverged GABA receptor subunits remains unclear. Zebrafish have 23 subunits (α1, α2a, α2b, α3-5, α6a, α6b, β1-4, γ1-3, δ, π, ζ, ρ1, ρ2a, ρ2b, ρ3a, and ρ3b), but the electrophysiological properties of these subunits have not been explored. In this study, we cloned the coding sequences for zebrafish GABA receptor subunits and investigated their expression patterns in larval zebrafish by whole-mount in situ hybridization. We also performed electrophysiological recordings of GABA-evoked currents from Xenopus oocytes injected with one or multiple zebrafish GABA receptor subunit cRNAs and calculated the half-maximal effective concentrations (EC50s) for each. Our results revealed the spatial expressions and electrophysiological GABA sensitivities of zebrafish GABA receptors, suggesting that the properties of GABA receptor subunits are conserved among vertebrates.
γ-氨基丁酸（GABA）是中枢神经系统中的主要抑制性神经递质，通过激活 GABA 受体发挥作用。GABA 受体是由五个亚基蛋白组成的配体门控氯离子通道。哺乳动物有 19 种不同的 GABA 受体亚基（α1-6、β1-3、γ1-3、δ、ε、π、θ 和 ρ1-3），其生理特性已通过电生理学进行了检测。然而，不同 GABA 受体亚基的生理特性在进化上的保守性仍不清楚。斑马鱼有 23 种亚基（α1、α2a、α2b、α3-5、α6a、α6b、β1-4、γ1-3、δ、π、ζ、ρ1、ρ2a、ρ2b、ρ3a 和 ρ3b），但这些亚基的电生理特性尚未被探索。在这项研究中，我们克隆了斑马鱼 GABA 受体亚基的编码序列，并通过全胚胎原位杂交技术研究了它们在幼鱼中的表达模式。我们还从注射了一种或多种斑马鱼 GABA 受体亚基 cRNA 的非洲爪蟾卵母细胞中进行了 GABA 诱导电流的电生理记录，并计算了每种亚基的半最大有效浓度（EC50）。我们的结果揭示了斑马鱼 GABA 受体的空间表达和电生理 GABA 敏感性，表明 GABA 受体亚基的特性在脊椎动物中是保守的。
