Project 3: Elucidation of Biochemical and Behavioral Efficacies of Antipsychotics

在经典药理学中，激动剂激活单一线性信号转导途径，而拮抗剂阻断激动剂的作用并且不具有内在活性。在过去的几年里，人们已经清楚地认识到，信号转导途径不仅仅是信号传导的线性级联。相反，它们被组织成复杂的信号网络，需要高水平的调节来产生精确和独特的细胞反应。因此，一个给定的受体，通过各种配体诱导的功能构象，可以通过与不同的信号传导伙伴的相互作用，从事多种模式。以这种方式，给定的配体可以结合受体并充当一种信号传导途径的拮抗剂，同时充当另一种或多种信号传导途径的激动剂。 匡威。这种特性是针对几种G蛋白偶联受体（GPCR）建立的，这些受体是治疗干预的最重要靶点。重要的是，临床使用的药物中没有一种是在考虑到这些多重信号传导因素的情况下开发的。此外，激动剂和拮抗剂很少是完全选择性的，并且对于给定的受体，可以通过影响各种受体介导的过程来改变信号传导，例如与G蛋白的相互作用、脱敏、内化、下调和非G蛋白信号传导组分的受体介导的支架。不幸的是，这些特性的生理相关性还没有得到充分的认识。因此，识别化合物的功能选择性不仅有助于揭示不同的生物过程，而且还有助于揭示特定的功能结果。目前，功能选择性与精神病学的相关性尚不清楚。这对于抗精神病药物尤其重要，其中多巴胺（DA）D2受体（D2 R）拮抗作用基本上是所有这些药物的先决条件;然而，它们的其他内在活性尚不清楚。拟议研究的总体目标是检查对抗精神病化合物的行为反应，并阐明对于精神分裂症样行为的临床前遗传和药理学小鼠模型中的抗精神病功效至关重要的信号传导机制。对于行为，在DA转运蛋白（DAT）敲除（KO）、N-甲基-D-天冬氨酸（NMDA）受体NR 1亚基敲除（KD）和用苯丙胺（AMPH）或苯环己哌啶（PCP）处理以再现精神分裂症样状态的C57 BL/6小鼠中，抗精神病药物对运动活动、前脉冲抑制（PPI）、潜伏抑制（LI）和社会行为的影响。将进行信号转导通路的分子指纹分析（MFSTP）以分析抗精神病化合物对各种信号转导的影响 包括蛋白激酶A（PKA）和DA和cAMP调节的磷蛋白32（DARPP-32）、Akt/蛋白激酶B（PKB或Akt）和糖原合成酶激酶33（GSK 3）、磷脂酶C（PLC）和细胞外信号调节的有丝分裂原活化蛋白激酶（ERK）途径的模式。本项目#3中的实验将通过提供临床前模型来补充项目#1和#2中的实验，以测试各种抗精神病化合物对改善精神分裂症样行为的体内选择性和功效，并将这些反应与信号转导的改变相关联。我们的项目#3也将补充惠氏的核心项目，其中将在精神分裂症样和抗精神病药物治疗行为的大鼠模型中分析抗精神病药物反应。了解抗精神病药物的功能选择性的相关性，可能会提供新的目标，更少的副作用，更大的治疗选择性，并提高疗效治疗精神分裂症患者。

In classical pharmacology, an agonist activates a single linear signal transduction pathway, whereas an antagonist blocks the action of the agonist and possesses no intrinsic activity. Over the past few years, it has become clear that signal transduction pathways are not merely linear cascades for signaling. Instead, they are organized into complex signaling networks that require high levels of regulation to generate precise and unique cellular responses. Hence, a given receptor, through various ligand-induced functional conformations, can engage multiple modalities through interaction with different signaling partners. In this way, a given ligand can bind a receptor and act as an antagonist for one signaling pathway while serving as an agonist at another or the converse. This property is established for several G protein-coupled receptors (GPCRs) - the most important targets for therapeutic intervention. Importantly, none of the drugs in clinical use have been developed with these multiple signaling considerations in mind. Additionally, agonists and antagonists are rarely completely selective and, for a given receptor, may alter signaling by influencing various receptor-mediated processes such as interaction with G proteins, desensitization, internalization, down-regulation, and receptor-mediated scaffolding of non-G protein signaling components. Unfortunately, the physiological relevance of these properties is not fully appreciated. Thus, identifying the functional selectivity of compounds may help reveal not only distinct biological processes, but also specific functional outcomes. Currently, the relevance of functional selectivity to psychiatry is unknown. This is particularly important for antipsychotic drugs, where dopamine (DA) D2 receptor (D2R) antagonism is essentially a prerequisite for all these drugs; however, their other intrinsic activities are obscure. The overall goal of the proposed research is to examine behavioral responses to antipsychotic compounds and to elucidate signal transduction mechanisms that are essential for antipsychotic efficacy in preclinical genetic and pharmacological mouse models of schizophrenia-like behaviors. For behavior, effects of antipsychotic compounds on motor activity, prepulse inhibition (PPI), latent inhibition (LI), and social behavior in DA transporter (DAT) knockout (KO), N-methyl-D-aspartate (NMDA) receptor NR1-subunit knockdown (KD), and C57BL/6 mice treated with amphetamine (AMPH) or phencyclidine (PCP) to reproduce schizophrenia-like states. Molecular fingerprinting of signal transduction pathways (MFSTP) will be performed to analyze effects of antipsychotic compounds on various signal transduction modalities that include the protein kinase A (PKA) and DA and cAMP-regulated phosphoprotein 32 (DARPP-32), Akt/protein kinase B (PKB or Akt) and glycogen synthase kinase 33 (GSK3), phospholipase C (PLC), and extracellular signal-regulated mitogen activated protein kinase (ERK) pathways. The experiments in the present Project #3 will complement those in Projects #1 and #2 by providing preclinical models to test the in vivo selectivities and efficacies of various antipsychotic compounds on amelioration of schizophrenia-like behaviors and will correlate these responses to alterations in signal transduction. Our Project #3 will complement also the Core Project from Wyeth where antipsychotic responses will be analyzed in rat models of schizophrenia-like and antipsychotic-treated behaviors. Understanding the relevance of functional selectivity of antipsychotic drugs may provide novel targets with fewer side-effects, greater therapeutic selectivity, and enhanced efficacy for treating individuals with schizophrenia.