The cerebellar GABAAR α6-R100Q polymorphism alters ligand binding in outbred Sprague-Dawley rats in a similar manner as in selectively bred AT and ANT rats.
The cerebellar GABAAR α6-R100Q polymorphism alters ligand binding in outbred Sprague-Dawley rats in a similar manner as in selectively bred AT and ANT rats.
复制标题
小脑 GABAARα6-R100Q 多态性以与选择性繁殖的 AT 和 ANT 大鼠类似的方式改变远交 Sprague-Dawley 大鼠的配体结合。
DOI：
10.1016/j.alcohol.2010.11.003
复制
发表时间：
2011
期刊：
影响因子：
--
通讯作者：
Uusi-Oukari,Mikko
中科院分区：
文献类型：
--
作者：
Kontturi,Leena-Stiina;Aalto,AskoJ;Wallner,Martin;Uusi-Oukari,Mikko
酒精耐受的AT和酒精不耐受的蚂蚁大鼠系是为了对酒精引起的运动损伤具有先天的敏感性而选择性培育的。小脑GABA受体α6亚单位等位基因α6-100R和α6-100Q分别在AT和ANT大鼠中分离。这种α6基因多态性可能解释了不同品系大鼠之间GABAARs的药理特性和密度的不同。在本研究中，我们使用了α6-100RR(RR)和α6-100QQ(QQ)纯合子的未选育的近交系SD大鼠，以表明这些RR和QQ大鼠在基因型之间表现出与AT和Ant大鼠相似的差异。不同的基因型对[3 H]Ro 15-4513和经典的苯二氮卓类药物(BZS)与小脑“安定不敏感”(DZ-IS)结合部位的亲和力不同，在小脑[3 H]蝇咪酚结合密度以及速尿对GABA抑制[3 H]EBOB结合的拮抗作用方面存在差异。结果提示，α6-R100Q多态参与了这些品系的差异以及先前发现的AT和ANT大鼠之间的差异。此外，α6-R100Q多态导致[~3H]Ro 15-4513与重组α6β3γ2S受体和小脑DZ-IS位点结合动力学显著不同。在含有∼6-100Q等位基因的DZ-IS∼6α6βγ2受体中，结合[~H]Ro 15-4513的速度是α的10倍，解离∼的速度是DZ-IS的3-4倍，平衡解离常数(Kd)是DZ-IS的2.5倍。结果表明，除了同源的α6-100R/Q(α1-101H)残基在BZ结合和疗效中起中心作用外，这个关键的BZ结合位点残基对BZ结合动力学也有重要影响。
The alcohol-tolerant AT and alcohol-nontolerant ANT rat lines have been selectively bred for innate sensitivity to ethanol-induced motor impairment. The cerebellar GABAAreceptor (GABAAR) α6 subunit alleles α6-100R and α6-100Q are segregated in the AT and ANT rats, respectively. This α6 polymorphism might explain various differences in pharmacological properties and density of GABAARs between the rat lines. In the present study, we have used nonselected outbred Sprague–Dawley rats homozygous for the α6-100RR (RR) and α6-100QQ (QQ) genotypes to show that these RR and QQ rats display similar differences between genotypes as AT and ANT rat lines. The genotypes differed in their affinity for [3H]Ro 15-4513 and classic benzodiazepines (BZs) to cerebellar “diazepam-insensitive” (DZ-IS) binding sites, in density of cerebellar [3H]muscimol binding and in the antagonizing effect of furosemide on GABA-induced inhibition of [3H]EBOB binding. The results suggest the involvement of α6-R100Q polymorphism in these line differences and in the differences previously found between AT and ANT rats. In addition, the α6-R100Q polymorphism induces striking differences in [3H]Ro 15-4513 binding kinetics to recombinant α6β3γ2s receptors and cerebellar DZ-IS sites. Association of [3H]Ro 15-4513 binding was ∼10-fold faster and dissociation was ∼3–4-fold faster in DZ-IS α6βγ2 receptors containing the α6-100Q allele, with a resulting change of ∼2.5-fold in equilibrium dissociation constant (KD). The results indicate that in addition to the central role of the homologous α6-100R/Q (α1-101H) residue in BZ binding and efficacy, this critical BZ binding site residue has a major impact on BZ binding kinetics.