ELECTROPHYSIOLOGY OF CNS DOPAMINE RECEPTOR KNOCKOUT

大脑中的多巴胺能神经传递调节许多 重要的认知和行为功能。例如，精神分裂症 被认为是由于前脑多巴胺系统的不平衡。 分子生物学的最新进展已经鉴定出5种 不同的基因编码2个主要家族的多巴胺受体，D1和 D2.虽然激动剂和拮抗剂，区分成员之间的 D1和D2家族已经存在，但选择性药物还不存在 在家庭成员之间（例如，D2对D3对D4或D1对D5）。这 导致对多巴胺作用的部位和机制的混淆 在大脑中，关于确切的受体亚型介导 细胞的影响，并可能也有助于混合治疗 抗精神分裂症药物的疗效和副作用 今天 我们已经表明，在体内输注专门设计的反义核酸， 寡脱氧核苷酸互补的mRNA编码不同的 多巴胺受体产生高度区域性和受体特异性的前 或突触后“敲除”多巴胺D2或D3受体， 通过受体放射自显影。体内和体外电生理 技术将被用来确定D2和D3多巴胺的作用， 受体在调节脑实质电活动中起作用 黑质多巴胺能神经元和新纹状体神经元。随后的实验 将利用类似的方法实现D1和D4的敲除 受体。 多巴胺受体的位点和受体亚型介导了 安非他明对黑质细胞放电的抑制作用将是 测定体内细胞外和体外细胞内记录 将用于确认黑质体细胞树突的身份 自身感受器，并确定它在控制 黑质多巴胺神经元放电的速率和模式。体内和 体外细胞内记录将用于确定受体亚型- 多巴胺对新纹状体神经元的特异性作用，并确定 介导多巴胺作用的受体的位点和亚型 皮质纹状体突触传递 这项研究与基础和应用神经科学高度相关。 体内选择性受体敲除的反义方法的验证 电生理手段是必要的第一步， 将这种技术应用于各种研究问题。的 鉴定特定的多巴胺受体亚型， 介导了许多良好表征的生理反应， 多巴胺可能提供的信息将指导未来的研究， 新一代抗精神病药物的设计， 同时更有效，而且没有通常具有破坏性的副作用， 当今使用的神经抑制剂。

Dopaminergic neurotransmission in the brain modulates a number of important cognitive and behavioral functions. For example, schizophrenia is believed to result from an imbalance in forebrain dopamine systems. Recent advances in molecular biology have led to the identification of 5 different genes coding for dopamine receptors of 2 main families, D1 and D2. Although agonists and antagonists that discriminate between members of the D1 and D2 families exist, drugs do not yet exist that are selective among family members (e.g., D2 vs. D3 vs. D4 or D1 vs. D5). This has resulted in confusion about the sites and mechanisms of action of dopamine in the brain, about precisely which receptor subtypes mediate which cellular effects, and likely also contributes to the mixed therapeutic efficacy and unwanted side effects of antischizophrenic drugs in use today. We have shown that in vivo infusion of specifically designed antisense oligodeoxynucleotides complementary to the mRNA coding for different dopamine receptors produces a highly regional- and receptor-specific pre- or postsynaptic "knockout" of the dopamine D2 or D3 receptors as indexed by receptor autoradiography. In vivo and in vitro electrophysiological techniques will be used to determine the roles that D2 and D3 dopamine receptors play in the modulation of the electrical activity of substantia nigra dopaminergic neurons and neostriatal neurons. Subsequent experiments will utilize similar methods to achieve knockout of the D1 and D4 receptors. The site and receptor subtype of the dopamine receptor that mediates the inhibitory effects of amphetamine on nigral cell firing will be determined. In vivo extracellular and in vitro intracellular recordings will be used to confirm the identity of the nigral somadendritic autoreceptor and determine the role that it plays in the control of the rate and pattern of firing of nigral dopamine neurons. In vivo and in vitro intracellular recordings will be used to define receptor subtype- specific actions of dopamine on neostriatal neurons, and determine the site and subtype of the receptor that mediates dopamine's effect on corticostriatal synaptic transmission. This research is highly relevant to both basic and applied neuroscience. Validating the antisense approach to selective receptor knockout in vivo by electrophysiological means is a necessary first step towards the application of this technique to a variety of research issues. The identification of the particular dopamine receptor subtype(s) that mediates a number of well-characterized physiological responses to dopamine may provide information that will direct future research towards the design of a new generation of antipsychotic drugs that are simultaneously more effective and lack the often devastating side effects of the neuroleptics in use today.