ANABOLIC STEROIDS AND CEREBELLAR GABAA RECEPTORS

合成代谢-雄激素(AAS)是青少年以及精英运动员中越来越受欢迎的虐待物质。AAS在中枢神经系统中的作用尚不清楚，然而，最近在啮齿类动物身上的研究表明，AA型氨基酸对青春期前和成年动物前脑区神经元中的GABAA受体介导的电流产生快速和可逆的调制。此外，AAS调节前脑电流的能力是区域特有的，依赖于受体亚单位的组成。包含不同亚基异构体的GABAA受体在整个大脑中的表达是不同的，并以区域特异性和发育方式进行调节。因此，了解AAS对不同亚基组成的GABAA受体的差异调控为了解AAS在中枢神经系统中的作用奠定了重要的基础。小脑是GABAA受体变构调节的理想系统，因为不同亚基的细胞特异性表达模式以及其他调节剂对GABAA受体介导的电流的功能调节已经被很好地描述，特别是在浦肯野细胞和颗粒细胞中。此外，小脑是调节运动记忆和运动协调的基本结构，在AAS过程中这两者都可能受到影响。应用急性分离脑片神经元的全细胞膜片钳记录技术，观察特定的AAS对新生大鼠浦肯野细胞和颗粒细胞抑制性突触后电流(IPSCs)的不同调制模式。其次，为了在单细胞水平上将AAS调节GABA能IPSCs的能力与亚基基因表达的细胞特异性模式相关联，将使用单细胞RT-PCR来检测亚基家族表达的比率。最后，使用超快灌流膜片钳技术，在转基因细胞中表达重组GABAA受体，将确定AAS IPSC调节的亚基依赖关系。

Anabolic-androgenic steroids (AAS) are an increasingly popular substance of abuse among adolescents, as well as elite athletes. The actions of AAS in the central nervous system are poorly understood, however, recent studies in rodents indicate that AAS induce rapid and reversible modulation of gamma-aminobutyric acid type A (GABAA) receptor-mediated currents in neurons of forebrain regions of both prepubertal and adult animals. Moreover, the ability of AAS to modulate currents in the forebrain is region- specific and depends on receptor subunit composition. The expression of GABAA receptors comprising different subunit isoforms is heterogeneous throughout the brain and regulated both in a region-specific and developmental manner. Therefore, understanding differential AAS modulation of GABAA receptors composed of different subunits establishes the essential groundwork for understanding the actions of AAS in the central nervous system. The cerebellum is an ideal system for allosteric modulation of GABAA receptors because the cell-specific patterns of expression of different subunits and the functional modulation of GABAA receptor-mediated currents by other modulators have been well characterized, especially in Purkinje and granule cells. In addition, the cerebellum is the essential structure in mediating motor memory and motor coordination, both of which may be affected during AAS. Using whole-cell patch-clamp recording techniques of neurons in acutely isolated brain slices, the ability of specific AAS to induce different patterns of modulation upon inhibitory postsynaptic currents (IPSCs) in Purkinje cells and granule cells of postnatal rats will be determined. Second, to correlate, at the single cell level, significant differences in the ability of AAS to modulate GABAergic IPSCs with cell-specific patterns of subunit gene expression, single cell RT-PCR will be used to detect the ratio of subunit families expressed. Finally, using ultrafast perfusion patch-clamp technique on recombinant GABAA receptors expressed in transfected cells, the subunit dependence of AAS IPSC modulation will be determined.