SEROTONIN RECEPTOR SUBTYPES--REGULATION AND INTERACTION

大脑中受体的调节在解释某些特定情况时很重要 精神治疗药物的效果。从历史上看，受体的研究 监管的重点是慢性暴露不足或过度暴露的影响 神经递质的受体。受体和受体的调节 反应也可能通过受体亚型之间的相互作用发生。 一种特定的神经递质。这样做的总体目标是 建议调查5-HT1a和5-HT1a之间的相互作用 5-HT2受体参与了它们的调节。治疗带来的结果 在5-HT1a受体介导的脱敏反应中也调节 5-HT2受体数目和/或5-HT2受体介导的敏感性 回应。第一个具体目标中提出的研究是设计的 利用在培养中保持的细胞，探索相互作用 在连接到每个亚型的第二信使系统之间发生 对监管现象的影响。蛋白激酶C的激活，以及 5-HT2受体所在的第二信使系统的组成部分 是偶联的，导致5-HT1a受体的脱敏。因此， 5-HT2受体激活可能在大鼠脑缺血再灌注损伤的脱敏中起作用 5-HT1a受体。P11细胞，表达偶联的5-HT2受体 磷脂酰肌醇(PI)的水解液，将5-HT1a导入 受体，以研究这些5-羟色胺之间的相互作用 受体亚型及其各自的第二信使系统 同一间牢房。5-HT2受体激活是否导致脱敏 5-HT1a受体介导的Forsklin刺激的腺酰化抑制作用 环化酶和/或5-HT1a受体结合的变化将被确定。 腺酰环化酶级联激活对5-羟色胺的影响 受体刺激的PI水解和5-HT2受体结合也将 被调查。5-HT1A受体在P11细胞中的调节 表达这两种5-羟色胺受体亚型将与其 中国仓鼠卵巢(CHO)细胞的表达调控 只有5-HT1a受体。在第二个具体目标中，研究是 建议在体内测试5-HT1A受体是否有调节作用 发生于5-HT2受体的激活，或由于 5-HT2受体的脱敏或下调以及是否 这需要完整的5-羟色胺能神经元才能发生。老鼠会 单次注射5-HT2受体激动剂DOI或 注射拮抗剂米安色林，或用5-羟色胺慢性治疗 HT2受体拮抗剂酮色林。DOI治疗引起激活 5-HT2受体，但当时没有下调5-HT2受体 什么时候会进行测量。相比之下，这些治疗方法 已有研究表明，拮抗剂可以下调5-HT2受体。这个 这两种5-羟色胺受体亚型的敏感性和功能将是 在相同的动物和相同的大脑区域进行评估，特别是 5-HT1a受体介导的大脑皮层腺酰环化酶抑制作用 匀浆和5-HT2受体刺激大脑皮层PI水解酶 切片。这种结合的方法应该提供重要的信息， 不仅有助于我们理解 5-羟色胺受体亚型及其各自的第二信使系统 而且在体内对5-HT1a受体的调节也是如此。

The regulation of receptors in brain is important in explaining certain effects of psychotherapeutic drugs. Historically, studies of receptor regulation have focused on the effect of chronic under- or over-exposure of a receptor to its neurotransmitter. The regulation of receptors and responses may also occur through interactions between receptor subtypes for a particular neurotransmitter. The overall objective of this proposal is to investigate whether interactions between the 5-HT1A and 5-HT2 receptors are involved in their regulation. Treatments that result in a desensitization of 5-HT1A receptor-mediated responses also regulate 5-HT2 receptor number and/or the sensitivity of 5-HT2 receptor-mediated responses. The studies proposed in the first specific aim are designed to explore, using cells maintained in culture, whether interactions between the second messenger systems linked to each subtype occur and contribute to regulatory phenomena. Activation of protein kinase C, an integral part of the second messenger system to which the 5-HT2 receptor is coupled, leads to the desensitization of the 5-HT1A receptor. Thus, 5-HT2 receptor activation may play a role in the desensitization of the 5-HT1A receptor. P11 cells, which express 5-HT2 receptors coupled to phosphoinositide (PI) hydrolysis, will be transfected with the 5-HT1A receptor in order to study the interactions between these serotonin receptor subtypes and their respective second messenger systems on the same cell. Whether activation of 5-HT2 receptors causes desensitization of 5-HT1A receptor-mediated inhibition of forskolin-stimulated adenylyl cyclase and/or changes in 5-HT1A receptor binding will be determined. The effect of activation of the adenylyl cyclase cascade on 5-HT2 receptor stimulated PI hydrolysis and 5-HT2 receptor binding will also be investigated. The regulation of 5-HT1A receptors in P11 cells expressing both serotonin receptor subtypes will be compared to its regulation in Chinese Hamster Ovary (CHO) cells, transfected to express only the 5-HT1A receptor. In the second specific aim, studies are proposed to test in vivo whether the regulation of 5-HT1A receptors occurs as a result of activation of 5-HT2 receptors, or as a result of the desensitization or down regulation of 5-HT2 receptors and whether intact serotonergic neurons are required for this to occur. Rats will receive a single injection of the 5-HT2 receptor agonist DOI, or single injection of the antagonist mianserin, or chronic treatment with the 5- HT2 receptor antagonist ketanserin. Treatment with DOI causes activation of 5-HT2 receptors but no down regulation of 5-HT2 receptors at the time when measurements will be done. By contrast, these treatments with antagonists have been shown to down regulate 5-HT2 receptors. The sensitivity and function of both serotonin receptor subtypes will be assessed in the same animal and in the same brain region, specifically 5-HT1A receptor-mediated inhibition of adenylyl cyclase in cortical homogenates and 5-HT2 receptor stimulated PI hydrolysis in cortical slices. This combined approach should provide important information that will contribute to our understanding not only of the interactions between serotonin receptor subtypes and their respective second messenger systems but also of the regulation of the 5-HT1A receptor in vivo.