G PROTEIN COUPLING IN ANTIDEPRESSANT DRUG ACTION

描述：(摘自申请人的摘要)虽然抗抑郁和抗双相情感药物作用的分子位点尚未确定，但这类药物的靶点越来越有可能位于神经递质受体的远端。这些靶点可能涉及G蛋白介导的信号转导系统，如腺苷环化酶和磷脂酶C。在这项研究中，大鼠和培养的细胞将长期使用各种抗抑郁药物(阿米替林、伊普利多、氟西汀、苯肼和氯丙嗪作为对照)。以前的研究表明，G蛋白(Gs)和腺苷环化酶之间的关联增加。培养的CG胶质瘤细胞经抗抑郁药物处理后，Gs和腺苷环化酶之间的偶联也增加。这使得我们可以得出结论，“突触前”成分不是抗抑郁作用所必需的。这些研究还表明，受体脱敏和Gs/腺苷环化酶偶联增加之间存在分离。虽然Gs-腺酰环化酶偶联的增加一直是抗抑郁治疗的结果，但Gs和腺酰环化酶似乎都不是抗抑郁作用的实际靶点。推测抗抑郁治疗增强Gs与腺酰环化酶偶联的作用可能是由于膜的扰动改变了Gts与细胞骨架(特别是微管蛋白)之间的关系。这将通过用去污剂对膜进行差异提取以及抗抑郁治疗对Gs和微管蛋白突触分布的影响以及它们的共同定位的电子显微镜检查来进行研究。将功能G蛋白与绝对含量与光亲和的GTP类似物叠氮苯胺基GTP(AAGTP)进行比较。腺酰环化酶相对于抗抑郁药物治疗的亚型特异性也将在转基因细胞中进行检测。Giα和转导蛋白的“显性负性”嵌合体已经被开发出来，它阻止了正常的微管蛋白-Gs相互作用。表达这一结构，结合抗抑郁药物治疗，将有助于验证微管蛋白-Gs相互作用对观察到的抗抑郁反应的重要性。人们希望，这些研究的成功完成将使人们更好地认识到许多不同的药物都具有抗抑郁作用。这些知识应该有助于设计更有效的抗抑郁药物治疗，并可能导致对情绪的分子基础的真正理解。

DISCRIPTION:(from applicant's abstract) While the molecular locus of antidepressant and anti-bipolar drug action has not yet been established, it has become increasingly likely that the targets of such drugs lie distal to neuro- transmitter receptors. These targets may involve G protein-mediated signal transduction systems such as adenylyl cyclase and phospholipase C. For this study, both rats and cultured cells will be treated chronically with a varity of antidepressants (amitriptyline, iprindole, fluoxetine, phenylzine and chlorpromazine as a control). Previous studies showed an increased association between a G protein (Gs) and adenylyl cyclase. Cultured Cg glioma cells treated with antidepressant drugs also showed increased coupling between Gs and adenylyl cyclase. This allowed the conclustion that the "presynaptic" component is not required for antidepressant effects. These studies also showed a dissociation between receptor desensitization and increased Gs/adenylyl cyclase coupling. Although increased Gs-adenylyl cyclase coupling consistently results from antidepressant treatment, neither Gs nor adenylyl cyclase appears to be the actual target for antidepressant action. It is hypothesized that the effect of antidepressant treatment on increasing the coupling between Gs and adenylyl cyclase may be due to a perturbation of the membrane which alters the relationship between GTs and the cytoskeleton (specifically tubulin). This will be investigated by subjecting the membrane to differential extraction with detergents as well as to an electron microscopic examination of the effect of antidepressant treatment on the synaptic distribution of Gs and tubulin as well as their co-localization. Functional G protein will be compared to the absolute content with the photoaffinity GTP analog, azidoanilido GTP (AAGTP). Subtype specificity of adenylyl cyclase relative to antidepressant treatment will also be examined in transfected cells. A "dominant negative" chimera of Gi alpha and tranducin, which blocks normal tubulin-Gs interaction has been developed. Expression of this construct, concommitant with antidepressant treatment will help to verify the importance of tubulin-Gs interaction for the observed antidepressant response. It is hoped that successful completion of these studies will allow a greater realization of how a number of diverse drugs all exert antidepressant effects. Such knowledge should assist in the design of more efficient antidepressant drug therapy and may lead to a true understanding of the molecular basis of mood.