REGULATION OF GABA EXPRESSION BY NEUROTOXINS

GABA是成年人大脑中主要的抑制性神经递质。 GABA/A 受体由多个亚单位组成，在结构上与C1- 渠道 这些受体介导GABA的抑制作用， 引起C1内流导致超极化。 有机氯 杀虫剂阻断昆虫和脊椎动物中这些受体的功能 作为GABA结合位点的竞争性拮抗剂 （环二烯）或直接结合C1-通道（linodenes）。 GABA 作为神经元发育的营养信号，也可能影响 在大脑发育过程中自身受体的表达。工作 一种假设是，有机氯能够特异性靶向 GABA/A受体可能使发育中的神经系统，特别是 容易受到这些神经毒素的伤害 该假设将通过以下方式进行检验： 体内和体外模型，以确定是否暴露于 有机氯农药改变GABA/A的发育表达 受体、受体功能或表达这些受体的细胞的发育 受体（GABA受体细胞）。 对于我们的体内模型，农药将 对孕鼠给药，然后进行定量PCR分析 脑内编码GABA/A受体亚单位的mRNA转录水平 胚胎、新生儿和出生后发育的后代。 定量 然后将使用原位杂交进行更详细的分析 具体地区的影响。 受体功能将通过以下方式进行评价： 36/C1-通量测定。 如果杀虫剂改变了受体的表达或功能， 原代培养物将从胚胎脑区域产生， 这些培养物将被评估为适当的 体外模型，以便快速分析 农药对GABA/A受体表达、功能和发育的影响 GABA受体细胞 这些研究将提供重要信息 关于有机氯农药可能构成风险的问题， 通过改变大脑的表达能力， 或GABA/A受体的功能。

GABA is the main inhibitory neurotransmitter in the adult brain. GABA/A receptors, composed of multiple subunits, are structurally linked to C1- channels. These receptors mediate the inhibitory actions of GABA by causing C1-influx resulting in hyperpolarization. Organochlorine pesticides block functions of these receptors in insects and vertebrates by acting as competitive antagonists at the GABA binding site (cyclodienes) or binding directly to the C1- channel (lindane). GABA acts as a trophic signal for developing neurons, and may also influence the expression of its own receptors during brain development. The working hypothesis is that the ability of organochlorines to specifically target GABA/A receptors may make the developing nervous system especially vulnerable to these neurotoxins. This hypothesis will be tested using in vivo and in vitro models to determine whether exposure to organochlorine pesticides alters developmental expression of GABA/A receptors, receptor function, or development of cells that express these receptors (GABA-receptive cells). For our in vivo model, pesticides will be administered to pregnant rats followed by quantitative PCR to analyze levels of mRNA transcripts encoding GABA/A receptor subunits in brains of embryos, neonates and postnatally developing offspring. Quantitative in situ hybridization will then be used to allow a more detailed analysis of region-specific effects. Receptor function will be evaluated by 36/C1- flux assays. If pesticides alter receptor expression or function, primary cultures will be produced from embryonic brain regions where such effects are found. These cultures will be evaluated as an appropriate in vitro model to allow rapid analysis of the direct effects of pesticides on GABA/A receptor expression, function, and development of GABA-receptive cells. These studies will provide important information regarding the possibility that organochlorine pesticides may pose a risk to the developing brain by virtue of their ability to alter expression or function of GABA/A receptors.