TRANSMITTER RELEASE IN A MODEL OF HYPERACTIVITY

申请人最近将小鼠突变体缺损鉴定为 一种新的活动过度的动物模型， 3倍于对照组小鼠。 她证明了多动症 缺损小鼠表达的SNAP是缺失SNAP的结果。 基因 该基因编码SNAP-25，这是一种神经元特异性蛋白质， 突触前神经末梢，在传递中起主要作用 release. SNAP-25是一个必不可少的机械组成部分， 在突触前膜上对接和固定突触囊泡， 准备好Ca 2+触发的递质胞吐。 因此， 发射机释放中的缺陷可能是由SNAP的减少引起的， 25的表达导致过度活跃的表达。 实际上 似乎是多巴胺能成分的多动症， 申请人还发现了严重的行为异常， 到多巴胺 据推测，在囊泡性 功能导致胞质多巴胺浓度增加 最终导致不受调节的非胞吐多巴胺释放 表现为多动症。 该提案侧重于Ca 2+介导的 多巴胺能神经递质释放和多巴胺能神经元功能 分离出引起过度活跃的突触事件 具体 目的是：1）确定囊泡神经递质的异常 release. 将记录单个释放事件，并进行药物诱导 修改后的版本进行评估。 2)评估以下方面的贡献： 运动产生的儿茶酚胺能神经传递 在缺损小鼠中表现为多动。这一贡献将受到考验 通过转基因拯救实验， 儿茶酚胺能细胞 3)在体内识别神经化学缺陷 大脑缺损小鼠的潜在多动症。 这些实验将 将体外鉴定的细胞缺陷与功能性 体内分析 4)为了确定参与的细胞机制， 使用经典的行为药理学。 吸毒 已知影响突触前多巴胺末梢，包括储存， 合成和释放，我们将建立多巴胺之间的直接联系， 终末功能障碍和活动过度。 的 小鼠突变体缺损代表了一种前所未有的模型， 研究单个已知基因对复合体的贡献 多因子表型，包括疾病， 注意力缺陷多动障碍和图雷特综合征。

The applicant has recently identified the mouse mutant coloboma as a novel animal model of hyperactivity with locomotor activity exceeding 3 times control mice. She has demonstrated that the hyperactivity expressed by coloboma mice is the result of a deletion of the Snap gene. This gene encodes SNAP-25, a neuron-specific protein found in presynaptic nerve terminals that plays a major role in transmitter release. SNAP-25 is a component of the machinery essential for docking and holding synaptic vesicles at the presynaptic membrane in readiness for Ca2+ triggered transmitter exocytosis. Thus, it is though likely that defects in transmitter release cause by a reduction in SNAP- 25 expression results in the expression of hyperactivity. In fact, there appears to be a dopaminergic component to the hyperactivity as the applicant has also identified gross behavioral abnormalities in response to dopamimetics. It is hypothesized that abnormalities in vesicular function result in an increased concentration of cytosolic dopamine leading the unregulated nonexocytotic dopamine release ultimately expressed as hyperactivity. This proposal focuses on Ca2+ mediated transmitter release and dopaminergin function in coloboma mice to isolate the synaptic events giving rise to hyperactivity. The specific aims are: 1) To define abnormalities in vesicular neurotransmitter release. Individual release events will be recorded and drug-induced alterations in release assessed. 2) To assess the contribution of catecholaminergic neurotransmission to the generation of locomotor hyperactivity in coloboma mice. This contribution will be tested through a transgenic rescue experiment by replacing SNAP-25 in only catecholaminergic cells. 3) To identify neurochemical defects in vivo underlying hyperactivity in coloboma mice. These experiments will integrate the cellular defects identified in vitro with a functional analysis in vivo. 4) To determine the cellular mechanisms involved in hyperactivity using classical behavior pharmacology. Using drugs known to affect presynaptic dopamine terminals, including storage, synthesis and release, we will establish a direct link between dopamine terminal dysfunction and hyperactivity via this in vivo assay. The mouse mutant coloboma represents an unprecedented model in which to study the contributions of a single known gene to a complex multifactorial phenotype in humans which includes disorders such as attention deficit hyperactivity disorder and Tourette syndrome.