Nicotinic-dopamine receptor interaction in a novel Parkinsonian mouse model.

项目摘要 帕金森病是由基底神经节多巴胺释放中断引起的， 黑质多巴胺能神经元的进行性死亡。流行病学数据表明 帕金森病在吸烟者中不太常见。此外，动物研究发现，尼古丁， 烟草烟雾的成瘾成分，保护DA能神经元免受化学损伤， 这种作用可能由神经元烟碱乙酰胆碱受体（nAChR）介导。nAChRs如何 调节DA神经传递和哪些nAChR亚型参与？为了解决这些问题 一种新的小鼠品系被工程化，表达一个单一的点突变，Leu9 'Ala，在假定的 烟碱受体α-4亚基的孔区。这种突变使得含有α-4-（"α- 4 *"）nAChR对激动剂敏感50倍，允许分离和扩增行为细胞。 以及涉及α-4 * nAChR的生理表型。最近的研究表明，α-4 β- 2 * nAChR可能在功能上直接与D2样受体相互作用; G蛋白偶联受体， 在中脑和纹状体神经元中表达，通常负调节活性。初步 数据表明，Leu9 ′ Ala小鼠中D2样受体的激活可诱发帕金森病症状， 在野生动物中不存在。具体目标1检验了Leu9 'Ala帕金森病患者 表型由D2样多巴胺受体的激活引起，并依赖于α-4 * nAChR 调变这将通过给予不同的多巴胺和烟碱受体拮抗剂来完成， 小鼠并测定帕金森氏症表型严重程度。具体目标2检验了以下假设： 相互作用发生在黑质和/或层中。在具体目标3中，将进行体内微透析。 用于测定多巴胺和乙酰胆碱的释放。最后，具体目标4检验了以下假设： Leu9 'Ala小鼠中的D2活化揭示了Gi/o偶联受体与D2受体之间的功能性相互作用。 中脑和/或纹状体神经元中的α-4 * nAChR。这将通过衡量以下方面的变化来实现： D2激活前后的神经元活性和烟碱反应。预计结果 从拟议的实验将不仅提供一个新的药理学，可逆的，帕金森氏症 疾病小鼠模型，而且，也增加了对烟碱受体介导的调节的理解， DA能神经传递。

Project Abstract Parkinson's disease is caused by the disruption of dopamine release in basal ganglia due to the progressive death of dopaminergic neurons in substantia nigra. Epidemiological data indicate Parkinson's disease is less prevalent in smokers. In addition, animal studies have found that nicotine, the addictive component of tobacco smoke, protects DAergic neurons from chemical insult and that this effect is likely mediated by neuronal nicotinic acetylcholine receptors (nAChRs). How do nAChRs modulate DA neurotransmission and which nAChR subtypes are involved? To address these questions a novel mouse line was engineered expressing a single point mutation, Leu9'Ala, within the putative pore region of the nicotinic receptor alpha-4 subunit. This mutation renders alpha-4-containing ("alpha- 4*") nAChRs 50-fold more sensitive to agonist allowing for the isolation and amplification of behavioral and physiological phenotypes that involve alpha-4* nAChRs. Recent studies suggest that alpha-4 beta- 2* nAChRs may functionally interact directly with D2-like receptors; G-protein coupled receptors that are expressed in midbrain and striatal neurons and, normally, negatively regulate activity. Preliminary data indicate that activation of D2-like receptors in Leu9'Ala mice elicits Parkinsonian symptoms that do not occur in wild-type animals. Specific aim 1 tests the hypothesis that the Leu9'Ala Parkinsonian phenotype is caused by activation of a D2-like dopamine receptor and is dependent on alpha-4* nAChR modulation. This will be done by administering different dopamine and nicotinic receptor antagonists to mice and assaying the Parkinsonian phenotype severity. Specific aim 2 tests the hypothesis that the interaction takes place in substantia nigra and/or stratum. In specific aim 3, in vivo microdialysis will be utilized to assay dopamine and acetylcholine release. Finally, specific aim 4 tests the hypothesis that D2 activation in Leu9'Ala mice uncovers a functional interaction between Gi/o coupled receptors and alpha-4* nAChRs in midbrain and/or striatal neurons. This will be achieved by measuring changes in neuron activity and nicotinic responses before and after D2 activation. It is anticipated that the results from the proposed experiments will not only provide a new pharmacological, reversible, Parkinson's disease mouse model, but, also increase understanding of nicotinic receptor mediated modulation of DAergic neurotransmission.