SEROTONIN RECEPTOR SUBTYPES--REGULATION & INTERACTION

血清素受体亚型——调节

基本信息

批准号：
2430978
负责人：
JULIE Gorton HENSLER
金额：
$ 10.15万
依托单位：
UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
依托单位国家：
美国
项目类别：
财政年份：
1993
资助国家：
美国
起止时间：
1993-09-01 至 1999-05-31
项目状态：
已结题

项目摘要

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.

大脑中受体的调节对于解释某些现象很重要精神治疗药物的作用。历史上，受体的研究监管重点关注长期暴露不足或过度暴露的影响受体与其神经递质的关系。受体的调节和反应也可能通过受体亚型之间的相互作用发生对于特定的神经递质。本次活动的总体目标建议调查 5-HT1A 和 5-HT1A 之间是否存在相互作用 5-HT2 受体参与其调节。治疗结果在 5-HT1A 受体介导的反应脱敏中也调节 5-HT2受体数量和/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旨在使用培养物中维持的细胞来探索是否存在相互作用与每个亚型相关的第二信使系统之间发生有助于监管现象。蛋白激酶 C 的激活 5-HT2 受体的第二信使系统的组成部分耦合后，导致 5-HT1A 受体脱敏。因此， 5-HT2受体激活可能在脱敏中发挥作用 5-HT1A 受体。 P11 细胞，表达与偶联的 5-HT2 受体磷酸肌醇 (PI) 水解，将用 5-HT1A 转染受体以研究这些血清素之间的相互作用受体亚型及其各自的第二信使系统同一个细胞。 5-HT2受体激活是否导致脱敏 5-HT1A 受体介导的毛喉素刺激腺苷酸抑制作用将确定环化酶和/或 5-HT1A 受体结合的变化。腺苷酸环化酶级联激活对 5-HT2 的影响受体刺激的 PI 水解和 5-HT2 受体结合也将被调查。 P11细胞中5-HT1A受体的调节将表达两种血清素受体亚型与其中国仓鼠卵巢 (CHO) 细胞中的调控，转染表达仅5-HT1A受体。在第二个具体目标中，研究是提议测试体内是否对5-HT1A受体的调节由于 5-HT2 受体激活而发生，或由于 5-HT2受体的脱敏或下调以及是否要实现这一点，需要完整的血清素能神经元。老鼠会接受单次注射 5-HT2 受体激动剂 DOI，或单次注射注射拮抗剂米安色林，或用 5- HT2受体拮抗剂酮色林。 DOI 处理引起激活 5-HT2 受体，但当时没有下调 5-HT2 受体何时进行测量。相比之下，这些治疗方法拮抗剂已被证明可以下调 5-HT2 受体。这两种血清素受体亚型的敏感性和功能将在同一动物和同一大脑区域进行评估，特别是 5-HT1A 受体介导的皮质腺苷酸环化酶抑制匀浆和 5-HT2 受体刺激皮质中的 PI 水解切片。这种组合方法应该提供重要信息不仅有助于我们理解之间的相互作用血清素受体亚型及其各自的第二信使系统还涉及体内 5-HT1A 受体的调节。