ETIOLOGIC PATHWAYS TO DOPAMINE DYSFUNCTION

本Conte Center应用的前提是谷氨酸能突触功能的皮层破坏是精神分裂症的最终共同途径，表现为精神分裂症相关行为、多巴胺失衡的内表型和青春期发病的大脑结构/功能畸变。该项目的目标是产生具有合理病因的小鼠模型，并询问这些模型是否与多巴胺能和谷氨酸能异常有关，这些异常与接受脑成像的患者所见的异常相似。这些模型是大脑皮质发育的时间中断，在妊娠第16天给予神经元dna甲基化剂甲基氧甲醇醋酸酯（MAM），连锁验证的神经发育模型，NRG1杂合子敲低，以及微妙的突触前皮质谷氨酸能缺陷，谷氨酸合成酶磷酸酯激活谷氨酸酶的限制性敲低或敲除。这些机械上不同的小鼠模型将被研究，以确定目标：目的1。多巴胺系统改变，观察急性和致敏范式下多巴胺能激动剂的行为反应，基线和安非他明刺激下纹状体和额叶皮层的多巴胺外排，多巴胺受体表达，酪氨酸羟酶阳性纤维的体视定量多巴胺能神经支配，纹状体和皮层中多巴胺调节基因表达的异常。目标2。皮质的谷氨酸能改变，观察额叶皮质依赖的认知/行为功能，使用MRI观察总体形态学和活动的变化，使用微阵列技术观察突触相关基因表达，通过rt-PCR和配体结合观察NMDA受体表达，以及谷氨酸能突触传递和可塑性。目标3。谷氨酸受体激活或直接刺激额叶皮质影响多巴胺神经元放电和多巴胺外排。目标4。精神分裂症相关改变的发展，观察断奶前和青春期的幼鼠，以验证青春期精神分裂症发病的相关发现。综上所述，本项目的小鼠模型和Kandel项目的小鼠模型应该能够确定精神分裂症发病机制中可能的最终共同途径，从而可以在小鼠中进行行为、化学、生理和基因表达等方面的研究，最有效地对其进行分析。由于候选基因可以通过与临床数据的相关性来验证，新的治疗方向应该变得明显。

The premise of this Conte Center application is that cortical disruption of glutamatergic synaptic function is the final common pathway in schizophrenia, manifesting in schizophrenia-associated behaviors, a dopamine-imbalance endophenotypes and adolescent-onset aberrations in brain structure/function. The goal of this project is to generate mouse models with a plausible etiology, and to ask whether the models are associated with dopaminergic and glutamatergic abnormalities replicating those seen in patients undergoing brain imaging. The models are an example of timed disruption of cerebral cortical development, administration of the neuronal DNA-methylating agent methylazoxymethanol acetate (MAM) at gestational day 16, a linkage-validated neurodevelopmental model, the NRG1 heterozygote knockdown, and a subtle presynaptic cortical glutamatergic deficit, a restricted knockdown or knockout of the glutamate-synthetic enzyme phosphate-activated glutaminase. These mechanistically distinct mouse models will be studied in concert with the goal of identifying: Aim 1. Dopamine system alterations, looking at the behavioral response to dopaminergic agonists in acute and sensitization paradigms, baseline and amphetamine-stimulated dopamine efflux in the striatum and frontal cortex using in vivo microdialysis, dopamine receptor expression, dopaminergic innervation of stereological quantification of tyrosine hydroxylase-positive fibers, and abnormalities in expression of genes regulated by dopamine in striatum and cortex. Aim 2. Glutamatergic alterations in cortex, looking at frontal-cortical dependent cognitive/behavioral functions, changes in gross morphology and activity using MRI, synapse-associated gene expression using microarray technology, NMDA receptor expression by rt-PCR and by ligand binding, and glutamatergic synaptic transmission and plasticity. Aim 3. glutamate receptor activation or direct stimulation of the frontal cortex affect dopamine neuron firing and dopamine efflux. Aim 4. Development of schizophrenia-associated alterations, looking at young mice prior to weaning and in adolescence, to verify adolescent onset of schizophrenia associated findings. Taken together, the mouse models in this Project together with those in Project by Kandel should identify a possible final common pathway in the pathogenesis of schizophrenia, which can be most effectively analyzed in mice with studies spanning behavior, chemistry, physiology and gene expression. As candidate genes can be validated by correlations with clinical data, new therapeutic directions should become evident.