Steroid Regulation of Ion Channels

超出提供的空间。合成雄激素(AAS)是睾酮的合成衍生物，用于治疗性腺功能减退和消瘦障碍。虽然AAS仍然是宝贵的治疗工具，但非法使用超医用剂量的AAS已经使其临床使用黯然失色，不仅对精英运动员，而且对越来越多的“普通公民”，最令人不安的是，相当数量的青少年。在人类受试者和动物模型中长期使用AAS都与显著的行为变化有关；其中最显著的是性/生殖行为、攻击性和焦虑。前脑7-3氨基丁酸A型受体(GABAA)介导的神经传递在上述行为的表达中起着至关重要的作用。有趣的是，积极的情绪症状，包括欣喜，轻躁狂和减少焦虑也有报道，无论是在接触后立即或在使用AAS的过程中。这些效应让人想起苯二氮类药物、乙醇和神经类固醇的作用，并提示AAS使用中的一些早期积极行为表现也可能源于前脑GABA能传递的变构调节。我们先前已经表明，慢性AAS治疗以年龄和性别特异性的方式改变了基底前脑中GABAA受体的表达和功能。我们还表明，急性AAS给药通过变构调节迅速改变GABAA受体的功能，这种调节依赖于亚基组成。在目前的方案中，我们将利用转基因小鼠品系来确定E亚单位在AAS如何改变促性腺激素释放激素(GnRH)神经元的GABA能传递中所起的作用，GnRH神经元控制着下丘脑-垂体-性腺轴，因此是青春期开始和生殖成熟的关键调节因素。我们将利用一种特定的GABAA受体亚单位敲除小鼠品系来确定a亚单位在调节对焦虑表达至关重要的神经回路的AAS调节中的作用。最后，我们将评估GABAA受体的翻译后修饰如何调节AAS的变构调节，以及这些变化是否随着年龄、性别和激素状态的变化而变化。为此，我们将使用急性分离脑片的全细胞膜片钳记录结合单细胞实时聚合酶链式反应；对异种细胞中的重组受体进行超高速灌流；以及行为评估(行为学提升加迷宫)来评估AAS的抗焦虑效果。虽然AAS的行为行为已经被很好地记录下来，但这些影响的潜在神经底物并不是很清楚。我们的数据将产生重要的数据，有助于理解这些类固醇如何改变神经元功能，对生殖和心理健康产生影响，以及它们对滥用类固醇的男性与女性以及成人与儿童的影响有何不同。表演网站========================================Section End===========================================

EXCEED THE SPACE PROVIDED. Anabolic-androgenic steroids (AAS) are synthetic derivatives of testosterone developed for hypogonadism and treatment of wasting disorders. While still invaluable therapeutic tools, illicit use of suprapharmacological doses of AAS has overshadowed their clinical use, not only with respect to elite athletes, but also a growing number of "ordinary citizens", and most disturbingly, an appreciable number of adolescents. Chronic AAS use in both human subjects and animal models is associated with marked behavioral changes; the most notable of which are in sexual/reproductive behaviors, aggression and anxiety. Neurotransmission mediated by 7-3minobutyric acid type A (GABAA) receptors in the forebrain plays a crucial role in the expression of all of these behaviors. Interestingly, positive mood symptoms, including euphoria, hypomania and decreased anxiety are also reported, either immediately after exposure or early in the course of AAS use. These effects are reminiscent of the actions of benzodiazepines, ethanol and neurosteroids, and suggest that some of the early positive behavioral manifestations in AAS use may also arise from allosteric modulation of forebrain GABAergic transmission. We have previously shown that chronic AAS treatment alters GABAA receptor expression and function in the basal forebrain in an age- and sex-specific manner. We have also shown that acute AAS administration rapidly alters GABAA receptor function via allosteric modulation and that this modulation depends upon subunit composition. In the current proposal, we will take advantage of a transgenic mouse strain to determine the role of the E subunit in how the AAS alter GABAergic transmission in gonadotropin releasing hormone (GnRH) neurons that control the hypothalamic-pituitary-gonadal axis and are therefore the key regulators of pubertal onset and reproductive maturation. We will take advantage of a specific GABAA receptor subunit knockout strain of mice to determine the role of the a subunits in regulating AAS modulation of neural circuits important for the expression of anxiety. Finally, we will assess how posttranslational modifications of the GABAA receptor regulate allosteric modulation by the AAS and if these changes vary with the age,sex and hormonal state. To these ends we will use whole cell patch clamp recording from acutely isolated brain slices coupled with single cell real time PCR; ultrafast perfusion to recombinant receptors in heterologous cells, and behavioral assessment (ethological elevated plus maze) for anxiolytic effects of the AAS. While the behavioral actions of the AAS are well documented, the underlying neural substrates for these effects are not well known. Our data will generate data important for understanding how these steroids alter neuronal function to produce effects on reproductive and mental health, and how their effects differ in men vs. women and adults vs. children who abuse them. PERFORMANCE SITE ========================================Section End===========================================