ANABOLIC STEROIDS AND CEREBELLAR GABAA RECEPTORS

合成代谢雄激素类固醇（AAS）是青少年以及精英运动员中越来越受欢迎的滥用物质。AAS在中枢神经系统中的作用知之甚少，然而，最近在啮齿动物中的研究表明，AAS在青春期前和成年动物的前脑区域的神经元中诱导γ-氨基丁酸A型（GABAA）受体介导的电流的快速和可逆的调制。 此外，AAS调节前脑电流的能力是区域特异性的，并且取决于受体亚基组成。 包含不同亚基同种型的GABAA受体的表达在整个脑中是异质的，并且以区域特异性和发育方式进行调节。 因此，了解由不同亚基组成的GABAA受体的差异AAS调制为了解AAS在中枢神经系统中的作用奠定了基础。 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和其他调节剂对GABAA受体介导的电流的功能性调节已被很好地表征，特别是在浦肯野细胞和颗粒细胞中。 此外，小脑是介导运动记忆和运动协调的重要结构，这两者都可能在AAS期间受到影响。 使用急性分离脑切片中神经元的全细胞膜片钳记录技术，将确定特定AAS诱导出生后大鼠浦肯野细胞和颗粒细胞中抑制性突触后电流（IPSC）的不同调制模式的能力。 第二，为了在单细胞水平上将AAS调节GABA能IPSC的能力的显著差异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来检测表达的亚基家族的比率。 最后，使用超快灌注膜片钳技术对转染细胞中表达的重组GABAA受体进行分析，确定AAS IPSC调节的亚基依赖性。

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.