Latrophilin-3 and ADHD: A new potential mechanism

描述(由申请人提供)：注意力缺陷多动障碍(ADHD)影响着540万儿童，每年花费&>720亿美元，但其病因尚不清楚。一种新的孤儿受体基因已经被发现，它传递了ADHD的高风险：LatroPhilin-3(LPHN3)。我们有了一个新的Lphn3基因敲除(KO)大鼠。这只大鼠表现出多动症和高反应性。但ADHD也会影响注意力和冲动控制。目的-1将测试Lphn3KO大鼠的注意和抑制控制。ADHD的治疗是用兴奋剂来治疗的，它可以增加注意力，减少注意力分散和活动。目的-2检测ADHD药物对Lphn3KO大鼠的影响。有效的ADHD药物通过作用于单胺再摄取和释放过程或受体，增加了多巴胺和去甲肾上腺素的信号(有些还增加了5-羟色胺)。目的-3是确定Lphn3干扰对单胺类物质、转运体和受体的影响。总体目的是确定Lphn3对ADHD的行为和神经化学表型的贡献。拟议的实验将产生关键数据，说明Lphn3如何导致与ADHD相关的每一种症状和神经化学变化。Lphn3可能成为开发调节Lphn3功能或其结合伙伴(Flrt3)以缓解ADHD潜在缺陷的药物的新靶点。因此，这代表了对ADHD原因的创新研究。我们是唯一拥有Lphn3KO大鼠和Pilot表型数据的群体。因此，我们在追求这一模式方面处于独特的地位。特异性AIM-1将确定Lphn3KO大鼠的ADHD样表型。将评估Lphn3功能丧失在延长的运动活动、感觉运动门控、认知灵活性/注意力(定势转移)、注意力/灵活性(连续表现测试)、工作记忆和对ADHD药物的反应中的作用。这些数据将证明ADHD表型的范围和严重性。特异性AIM-2将阐明Lphn3KO大鼠的神经化学变化。EXP-2a：KO和WT大鼠将通过免疫组织化学方法比较与ADHD有关的单胺类物质(多巴胺(通过酪氨酸羟基酶)、5-羟色胺和多巴胺β-羟基酶(用于NE))的变化，并作为对照GAD67(用于GABA)和NMDA-NR1(用于谷氨酸)。将对每个传送器进行染色。由于多巴胺D4和5HT2b受体被认为与ADHD有关，因此也将对它们进行评估。EXP-2b：一旦确定了变化的组织学区域，其他动物将通过蛋白质印迹分析这些区域。实验-2c：一旦来自AIM-2b的Western识别出显著的变化，这将被用来指导在行为测试后在AIM-2c中分析哪些标记物；然后将进行神经化学和行为数据之间的关联。此外，还将对Flt3进行RT-PCR，以确定它是否被Lphn3突变改变。这些实验将极大地推动ADHD研究领域的发展。

DESCRIPTION (provided by applicant): Attention Deficit Hyperactivity Disorder (ADHD) affects 5.4 million children at a cost >$72 billion/year, yet its etiology is poorly understood. A new gene for an orphan receptor has been identified that conveys high risk for ADHD: Latrophilin-3 (LPHN3). We have a new Lphn3 knock-out (KO) rat. This rat shows hyperactivity and hyper-reactivity. But ADHD also affects attention and impulse control. Objective-1 will test Lphn3 KO rats for attention and inhibitory control. ADHD is treated with stimulants, which increase attention and reduce distractibility and activity. Objective-2 is to test the effects of ADHD medications in Lphn3 KO rats. Effective ADHD medications increase dopamine and norepinephrine signaling (and some increase 5HT) by acting on monoamine reuptake and release processes or receptors. Objective-3 is to determine the effects of Lphn3 disruption on monoamines, transporters, and receptors. The overall purpose is to identify the contribution of Lphn3 to the behavioral and neurochemical phenotype of ADHD. The proposed experiments will generate essential data for how Lphn3 contributes to each of the symptoms and neurochemical changes associated with ADHD. Lphn3 could become a novel target for development of drugs that modulate Lphn3 function or its binding partner (Flrt3) to alleviate the underlying deficit in ADHD. As such this represents innovative research on a cause of ADHD. We are the only group with the Lphn3 KO rat and pilot phenotypic data. Therefore, we are uniquely position to pursue this model. Specific Aim-1 will determine the ADHD-like phenotype of Lphn3 KO rats. The role of Lphn3 loss of function in extended locomotor activity, sensorimotor gating, cognitive flexibility/attention (set shifting), attention/flexibility (continuous performance test), working memory, and response to ADHD medications will be assessed. The data will demonstrate the range and severity of ADHD phenotype. Specific Aim-2 will elucidate the neurochemical changes in Lphn3 KO rats. Exp-2a: KO and WT rats will be compared by immunohistochemistry for changes in monoamines implicated in ADHD (dopamine (by tyrosine hydroxylase), 5HT, and dopamine beta hydroxylase (for NE), and as controls GAD67 (for GABA) and NMDA-NR1 (for glutamate). Stains for each transporter will be performed. Because the dopamine D4 and 5HT2B receptors have been implicated in ADHD they will also be assessed. Exp-2b: Once histological regions of change are identified, other animals will have these regions analyzed by Western blot. Exp-2c: Once Westerns from Aim-2b identify significant changes, this will be used to guide which markers will be analyzed in Aim-2c in animals after behavioral testing; then correlations between neurochemical and behavioral data will be performed. In addition, RT-PCR for Flrt3 will be performed to determine it is altered by the Lphn3 mutation. These experiments will materially advance the field of ADHD research.