The gamma-aminobutyric acid(B) (GABA(B)) receptor was first demonstrated on presynaptic terminals where it serves as an autoreceptor and also as a heteroreceptor to influence transmitter release by suppressing neuronal Ca(2+) conductance. Subsequent studies showed the presence of the receptor on postsynaptic neurones where activation produces an increase in membrane K(+) conductance and associated neuronal hyperpolarization. (-)-Baclofen is a highly selective agonist for GABA(B) receptors, whereas the established GABA(A) receptor antagonists, bicuculline and picrotoxin, do not block GABA(B) receptors. The receptor is G(i)/G(o) protein-coupled with mixed effects on adenylate cyclase activity. The receptor comprises a heterodimer with similar subunits currently designated 1 and 2. These subunits are coupled via coiled-coil domains at their C termini. The evidence for splice variants is critically reviewed. Thus far, no unique pharmacological or functional properties have been assigned to either subunit or the variants. The emergence of high-affinity antagonists for GABA(B) receptors has enabled a synaptic role to be established. However, the antagonists have generally failed to establish the existence of pharmacologically distinct receptor types within the GABA(B) receptor class. The advent of GABA(B1) knockout mice has also failed to provide support for multiple receptor types.

中文翻译：

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国际药理学联合会。XXXIII。哺乳动物γ-氨基丁酸（B）受体：结构和功能。

γ-氨基丁酸（B）（GABA（B））受体首先在突触前的终端上被证明，在这里它既可以作为自体受体，也可以作为异源受体，通过抑制神经元Ca（2+）电导来影响递质的释放。随后的研究表明该受体在突触后神经元上的存在，其中激活会增加膜K（+）电导和相关的神经元超极化。（-）-Baclofen是针对GABA（B）受体的高度选择性激动剂，而已建立的GABA（A）受体拮抗剂双小分子和苦瓜毒素不会阻断GABA（B）受体。该受体是G（i）/ G（o）蛋白偶联，对腺苷酸环化酶活性具有混合作用。该受体包含具有类似亚基的异二聚体，当前称为1和2。这些亚基在它们的C末端通过卷曲螺旋结构域偶联。剪接变体的证据已得到严格审查。迄今为止，尚未为亚基或变体赋予独特的药理或功能特性。GABA（B）受体的高亲和力拮抗剂的出现使突触的作用得以确立。但是，拮抗剂通常无法确定GABA（B）受体类别内药理学上不同的受体类型的存在。GABA（B1）基因敲除小鼠的出现也未能为多种受体类型提供支持。拮抗剂通常无法确定GABA（B）受体类别内药理学上不同的受体类型的存在。GABA（B1）基因敲除小鼠的出现也未能为多种受体类型提供支持。拮抗剂通常无法确定GABA（B）受体类别内药理学上不同的受体类型的存在。GABA（B1）基因敲除小鼠的出现也未能为多种受体类型提供支持。