Inhibitory Mechanisms in Homeostatic Neuronal Plasticity

本提案的目的是深入了解中枢神经元GAB能抑制的持久变化引起的神经元内稳态可塑性的机制。在中枢神经系统中，兴奋(E)和抑制(I)之间的平衡(E/I平衡)被广泛接受为依赖于其单个成分的微调，从而防止它倾覆。这一提议的总体假设可以概括为：具体影响两种类型的GABA能抑制(时相/突触和强直/突触)中的一种的变化将导致另一种类型的抑制以及神经元的内在和突触兴奋的明确的稳态变化。最终结果将是兴奋性的整体变化，能够抵消抵消抑制。这两种不同类型的抑制在功能上的不同变化预计会不同地抵消E/I平衡，从而导致 明显不同的代偿性抑制和兴奋性改变。在实验上，这两种类型的抑制将独立地通过药理学、分子生物学或遗传手段改变。由此产生的E/I平衡的补偿将使用从小鼠获得的长期器官型切片培养和急性脑片中的高分辨率电生理记录来研究。其他实验方法将包括合作解剖学、免疫细胞化学、药理学和分子生物学技术。 E/I平衡中的动态平衡改变将以一种高度特异的方式解决，使用针对特定GABAA受体(GABAAR)亚单位和第二信使系统的适当敲除和敲除小鼠。这些研究将进一步加深我们对中枢神经系统生理可塑性的理解，并将有助于为合理地预防GABAARs的病理性可塑性而进行的治疗进展奠定基础。了解停用变构GABAAR调节剂后的兴奋性惰性，了解神经类固醇、BZ和酒精的作用部位和可塑性，以及对 动态平衡抑制可塑性将促进药物的发现，用于治疗许多已知涉及GABA系统的严重丧失行为能力的神经和精神疾病。我们的发现可以为治疗焦虑、应激、苯二氮卓类停药和癫痫的新的和合理的靶向治疗方法提供基础。

The goal of the present proposal is to gain insight into the mechanisms governing homeostatic neuronal plasticity caused by lasting changes in the GAB Aergic inhibition of central neurons. The equilibrium between excitation (E) and inhibition (I) in the CNS (the E/I balance) is widely accepted to depend on the fine-tuning of its individual components, thus preventing it from tipping over. The overall hypothesis of this proposal can be summarized as follows: changes specifically affecting one of the two types of GABAergic inhibition (phasic/synaptic and tonic/extrasynaptic) will result in well-defined homeostatic changes in the other type of inhibition and in the intrinsic and synaptic excitation of neurons. The end result will be an overall change in excitability capable of balancing out the offset inhibition. Distinct changes in the two functionally separate types of inhibition are expected to differentially offset the E/I balance resulting in markedly different compensatory inhibitory and excitatory alterations. Experimentally, the two types of inhibition will be independently altered by pharmacological, molecular biological or genetic means. The resulting offset in the E/I balance will be studied using high resolution electrophysiological recordings in long-term organotypic slice cultures and acute brain slices obtained from mice. Other experimental approaches will include collaborative anatomical, immunocytochemical, pharmacological, and molecular biological techniques. Homeostatic alterations in the E/I balance will be addressed in a highly specific manner using appropriate knockin and knockout mice for specific GABAA receptor (GABAAR) subunits and second messenger systems. The proposed studies will further our understanding of the physiological plasticity in the CNS, and will help form the basis for therapeutical advances rationally aimed at preventing pathological plasticity of GABAARs. Awareness of the excitatory inertia following withdrawal from allosteric GABAAR modulators, knowledge about the site of action and plasticity of neurosteroids, BZ and alcohol, and a fundamental understanding of homeostatic inhibitory plasticity will advance drug discovery for the treatment of many severely incapacitating neurological and psychiatric disorders with known involvement of the GABA system. Our findings could provide the basis for novel and rationally targeted therapeutical approaches for the cure of anxiety, stress, benzodiazepine withdrawal, and epilepsy.