Ontogeny of caudate-putamen functioning: behavioral relevance

描述（由申请人提供）：尾状核-壳核（CPu）是基底神经节的主要输入和处理成分。涉及基底神经节，特别是CPu的功能障碍与许多神经精神障碍有关，包括Tourette综合征，ADHD，自闭症和儿童强迫症。本研究的目的是采用个体发生学的研究策略，探讨多巴胺（DA）介导的断奶前、青春期和成年大鼠行为的成熟。在第一组实验（特定目标1）中，将DA药物输注到CPu的离散子区域后，评估运动活性和刻板性。预计DA激动剂和拮抗剂将在三个年龄组中诱导不同的行为效应模式，从而表明介导行为的神经机制经历了实质性的个体遗传修饰。在特定目的2和3中，将使用EEDQ，因为已知EEDQ是一种在断奶前和成年大鼠中引起明显年龄依赖性行为效应的药物。具体而言，注入EEDQ到背侧CPU衰减DA激动剂诱导的成年大鼠的运动，同时增强断奶前大鼠的运动活动。在行为实验（特定目标2）中，将选择性保护D1和/或D2受体免于EEDQ诱导的失活，以确定哪种受体类型负责引起断奶前和青春期大鼠的运动增强。非DA类药物也将被用来确定是否DA受体失活导致行为反应性的普遍增加，或是否由断奶前大鼠表现出的运动增强是唯一的DA激动剂。EEDQ的矛盾行为效应的神经基础将在具体目标3中确定。一种解释是，断奶前大鼠有大量的D2受体储备，使他们能够表现出DA激动剂诱导的行为，即使在大量的受体被EEDQ灭活。或者，可能存活的或新合成的DA受体是超敏感的，因此能够介导增强的运动反应。为了测试这些想法，D1激动剂刺激的腺苷酸环化酶活性和D2激动剂调节的乙酰胆碱释放将被用来估计D1和D2受体储备的大小在CPU的断奶前，青少年和成年大鼠。各种技术将被用来评估受体超敏感性，包括激动剂竞争和GTP？S结合试验，以及G？olf和RGS 9免疫印迹（这些蛋白质与超致敏D1和D2受体相关）。我们预测EEDQ诱导的受体超敏感性的年龄依赖性变化，可能是由D2受体的快速再增殖引起的，是DA受体失活产生的矛盾行为效应的原因。总之，这项拨款提案的目标是采用一种创新的现有技术组合来研究CPu介导行为的方式的个体发生变化。这种类型的个体发生学研究是必要的，以确定发育性神经精神障碍的神经基础。

DESCRIPTION (provided by applicant): The caudate-putamen (CPu) is the major input and processing component of the basal ganglia. Dysfunctions involving the basal ganglia, and the CPu in particular, have been linked to a number of neuropsychiatric disorders, including Tourette's syndrome, ADHD, autism, and pediatric obsessive-compulsive disorder. The goal of this project is to employ an ontogenetic research strategy to examine the maturation of dopamine (DA) mediated behaviors in preweanling, adolescent, and adult rats. In the first set of experiments (Specific Aim 1), locomotor activity and stereotypy will be assessed after DA drugs are infused into discrete subregions of the CPu. It is anticipated that DA agonists and antagonists will induce a different pattern of behavioral effects in the three age groups, thus indicating that the neural mechanisms mediating behavior undergo substantial ontogenetic modification. In Specific Aims 2 and 3, EEDQ will be utilized because it is a drug known to cause pronounced age-dependent behavioral effects in preweanling and adult rats. Specifically, infusing EEDQ into the dorsal CPu attenuates the DA agonist-induced locomotion of adult rats, while potentiating the locomotor activity of preweanling rats. In the behavioral experiments (Specific Aim 2), D1 and/or D2 receptors will be selectively protected from EEDQ-induced inactivation in order to determine which receptor type is responsible for causing locomotor potentiation in preweanling and adolescent rats. NonDA drugs will also be used to determine whether DA receptor inactivation causes a generalized increase in behavioral responsiveness or whether the locomotor potentiation exhibited by preweanling rats is unique to DA agonists. The neural basis of EEDQ's paradoxical behavioral effects will be determined in Specific Aim 3. One explanation is that preweanling rats have a substantial D2 receptor reserve that allows them to exhibit DA agonist-induced behaviors even after a large number of receptors are inactivated by EEDQ. Alternatively, it is possible that surviving or newly synthesized DA receptors are supersensitive and, thus, are capable of mediating a potentiated locomotor response. To test these ideas, D1 agonist-stimulated adenylyl cyclase activity and D2 agonist-modulated acetylcholine release will be used to estimate the size of D1 and D2 receptor reserves in the CPu of preweanling, adolescent, and adult rats. Various techniques will be used to assess receptor super sensitivity, including agonist competition and GTP?S binding assays, as well as G?olf and RGS9 immunoblotting (these proteins are associated with super sensitized D1 and D2 receptors). We predict that age- dependent changes in EEDQ-induced receptor super sensitivity, perhaps caused by a rapid repopulation of D2 receptors, is responsible for the paradoxical behavioral effects produced by DA receptor inactivation. In summary, the goal of this grant proposal is to employ an innovative combination of established techniques to examine ontogenetic changes in the way the CPu mediates behavior. This type of ontogenetic research is necessary to determine the neural bases of developmental neuropsychiatric disorders.