Role of G-gamma-7 in striatal cannabinoid and D2 dopamine

G-gamma-7 在纹状体大麻素和 D2 多巴胺中的作用

• 批准号: 7742847
• 负责人: DANA E SELLEY
• 金额: $ 7.48万
• 依托单位: VIRGINIA COMMONWEALTH UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-01 至 2011-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7742847
• 关键词: Adenosine A2 Receptors; Adenylate Cyclase; Agonist; Amphetamines; Attenuated; Basal Ganglia; Behavior; Binding; Biochemical; Brain; Brain region; CNR1 gene; Cannabinoids; Cannabis; Cell Nucleus; Cerebellum; Chemicals; Cocaine; Corpus striatum structure; Cyclic AMP; Data; Desire for food; Disease; Dopamine; Dopamine D1 Receptor; Dopamine D2 Receptor; Dopamine Receptor; Drug Addiction; Drug abuse; Endocannabinoids; Enzymes; Exhibits; Forskolin; Future; G Protein-Coupled Receptor Signaling; G-Protein Signaling Pathway; G-Protein-Coupled Receptors; GTP gamma S; GTP-Binding Protein Regulators; GTP-Binding Protein alpha Subunits, Gs; GTP-Binding Protein gamma Subunits; GTP-Binding Proteins; Genetic; Globus Pallidus; Guanosine Triphosphate; Heterogeneity; Heterotrimeric GTP-Binding Proteins; Hippocampus (Brain); Hydrolysis; Immunoblotting; Ion Channel; Knock-out; Knockout Mice; Learning; Marijuana; Mediating; Mediation; Membrane; Memory; Midbrain structure; Molecular; Motivation; Motor Activity; Movement; Movement Disorders; Mus; Neurons; Nucleus Accumbens; Opiates; Opioid; Output; Pain; Parkinsonian Disorders; Physiologic Thermoregulation; Play; Prefrontal Cortex; Preparation; Protein Isoforms; Proteins; Psychological reinforcement; Receptor Activation; Receptor Inhibition; Regulation; Relative (related person); Rewards; Role; Schizophrenia; Second Messenger Systems; Signal Pathway; Signal Transduction; Signaling Protein; Specificity; Stream; Substance abuse problem; Substantia nigra structure; Synapses; System; Testing; Work; addiction; attenuation; base; dimer; drug of abuse; endogenous cannabinoid system; monoamine; motor control; motor disorder; nerve supply; neuromechanism; neuropsychiatry; neurotoxicity; neurotransmission; protein activation; public health relevance; putamen; receptor; receptor coupling; receptor expression; receptor function; research study; response; second messenger; transcription factor

DESCRIPTION (provided by applicant): Cannabinoid CB1 receptors in the CNS mediate psychoactive effects of marijuana and are a critical component of the endogenous cannabinoid system, which is involved in motivation and reward, motor control, appetite, learning and memory, and pain and thermoregulation. Control of motor and motivational behaviors by the endocannabinoid system is thought to be largely mediated by CB1 receptors in the striatum/basal ganglia (striatum/BG). Within this system, CB1 receptors have been found to interact with dopaminergic neurotransmission, and are colocalized with D2 receptors in subpopulations of medium spiny GABAergic neurons. Both CB1 and D2 receptors are G-protein-coupled receptors (GPCRs) that inhibit adenylyl cyclase (AC) activity via Gi/o activation, and under certain circumstances can stimulate adenylyl cyclase through Gs/olf activation. The G-protein gamma subunit type 7 (Gng7) is highly expressed in striatum/BG relative to other brain regions, and has been shown to play a role in D1 receptor stimulation of adenylyl cyclase and to regulate G-alpha-olf expression as determined in Gng7 knockout (KO) mice. However, potential involvement of Gng7 in inhibitory regulation of AC by GPCRs has not been examined. Our preliminary findings indicate that AC inhibition by striatal CB1 and D2 receptors is diminished in Gng7 knockout mice, suggesting a role for this G-gamma subunit in inhibitory Gi/o signaling. Alternatively, Gng7 KO could, by concomitant reduction in G-olf, alter the proportion of striatal AC activity that can be inhibited by Gi/o. The proposed R03 project will test the hypothesis that CB1 and D2-mediated inhibition of AC is attenuated in Gng7 knockout mice because G-gamma-7 plays a role in inhibitory Gi/o signaling. Aim 1 will determine the extent of loss of adenylyl cyclase inhibition by CB1 and D2 receptors in subregions of the striatum/BG in Gng7 knockout mice, including caudate-putamen, nucleus accumbens and globus pallidus, as well as other CB1 and D2 containing regions such as prefrontal cortex and hippocampus. Cerebellum, which expressed CB1 receptors but does not express Gng7, will serve as negative control region. Aim 1 will also determine whether the effect of loss of Gng7 on AC inhibition is limited to CB1 and D2 receptors or is seen with other striatal GPCRs (e.g. opioid). Aim 2 will determine whether CB1- or D2-stimulated Gi/o-protein activity is diminished in regions in which AC inhibition is diminished in Gng7 KO mice, as determined by agonist-stimulated [35S]GTPgammaS binding. Whether any reduction in G-protein activation is due to a loss in receptor expression will be tested by immunoblotting of CB1 and D2 receptors. Aim 2 will also test the alternative hypothesis that attenuated AC inhibition is due to concomitant reduction in G-olf in Gng7 KO mice, by determining G-protein activation and AC inhibition by CB1 and D2 receptors in heterozygous G-alpha-olf KO mice. These studies will serve as a basis for a future a R01 application that will more extensively investigate the relationship between CB1 and D2 receptors in the regulation of striatal function, and the contribution of this regulation to control of motor and motivational behavior. These studies will help to determine molecular mechanisms contributing to neuropsychiatric disorders such as substance abuse and schizophrenia, as well as motor disorders. PUBLIC HEALTH RELEVANCE: Marijuana (cannabis) and other abused drugs produce their rewarding effects through the regulation biochemical signaling pathways in a brain region known as the striatum. This region is also involved in control of voluntary movement and habitual behavior, and is also under the control of a chemical messenger known as dopamine. A key protein in these signaling pathways in striatum is the G-protein gamma type 7 subunit. This project will determine the role of this protein in the biochemical effects of cannabinoid and dopamine receptor activation by studying mice that have been genetically altered to not express this protein. These studies will provide information that contributes to our understanding of the neural mechanisms of drug addiction and possibly neuropsychiatric and movement disorders, such as schizophrenia and Parkinsonism.

描述（由申请人提供）：中枢神经系统中的大麻素CB1受体介导了大麻的精神活性作用，并且是内源性大麻素系统的关键组成部分，该系统参与了动机和奖励，运动控制，食欲，学习和记忆和疼痛和疼痛和痛苦调节。内源性大麻素系统对运动和动机行为的控制被认为主要是由纹状体/基底神经节（纹状体/BG）中的CB1受体介导的。在该系统中，已经发现CB1受体与多巴胺能神经传递相互作用，并与D2受体共定位于中刺Gabaergic神经元的亚群中。 CB1和D2受体都是G蛋白偶联受体（GPCR），可通过GI/O激活抑制腺苷酸环化酶（AC）活性，在某些情况下可以通过GS/OLF激活刺激腺苷酸环化酶。 G蛋白γ亚基7型（GNG7）相对于其他大脑区域高度表达在纹状体/BG中，并且已显示在腺苷酸环化酶的D1受体刺激中起作用，并调节GNG7敲除（KO）小鼠中确定的G-Alpha-FOL表达。但是，尚未研究GNG7在GPCR对AC抑制性AC抑制调节中的潜在参与。我们的初步发现表明，纹状体CB1和D2受体的AC抑制在GNG7敲除小鼠中减少，这表明该G-Gamma亚基在抑制性GI/O信号传导中起作用。或者，GNG7 KO可以通过伴随G-FOL的降低来改变纹状体AC活性的比例，而GI/O可以抑制。拟议的R03项目将检验以下假设：CB1和D2介导的AC抑制AC在GNG7敲除小鼠中减弱，因为G-GAMMA-7在抑制性GI/O信号传导中起着作用。 AIM 1将确定GNG7基因敲除小鼠中纹状体/BG子区域中CB1和D2受体抑制腺苷酸环化酶抑制的程度，包括尾状 - 甲基-Putamen，Occumbens and Globus Pallidus，以及其他CB1和D2，以及其他CB1和D2，以及其他CORTAIREFRONT FREFRONTALECAL CORTAIRESION。小脑表达CB1受体但未表达GNG7，将作为阴性对照区域。 AIM 1还将确定GNG7损失对AC抑制的影响是否仅限于CB1和D2受体，还是与其他纹状体GPCR（例如阿片类药物）一起看到。 AIM 2将确定在GNG7 KO小鼠中AC抑制减少的区域中CB1或D2刺激的GI/O蛋白活性是否会降低，这是由激动剂刺激的[35S] GTPGAMMAS结合确定的。 G蛋白激活的任何降低是由于受体表达损失将通过CB1和D2受体的免疫印迹来测试。 AIM 2还将检验替代假设，即通过确定杂合子G-Alpha-FOL-KO小鼠中CB1和D2受体抑制GNG7 KO小鼠G-蛋白激活和AC抑制的AC抑制作用是GNG7 KO小鼠中G-FOL的降低。这些研究将作为未来A R01应用的基础，该应用将在纹状体功能调节中更广泛地研究CB1和D2受体之间的关系，以及该调节对控制运动和动机行为的贡献。这些研究将有助于确定导致神经精神疾病的分子机制，例如药物滥用和精神分裂症以及运动障碍。公共卫生相关性：大麻（大麻）和其他滥用药物通过调节的生化信号通路在称为纹状体的大脑区域中产生了奖励作用。该区域还参与了自愿运动和习惯行为的控制，并且在被称为多巴胺的化学信使的控制之下。纹状体中这些信号通路中的一个关键蛋白是G蛋白γ型7型亚基。该项目将通过研究已在遗传上改变以表达这种蛋白质的小鼠来确定该蛋白在大麻素和多巴胺受体激活的生化作用中的作用。这些研究将提供有助于我们理解药物成瘾的神经机制以及可能的神经精神病和运动障碍的信息，例如精神分裂症和帕金森氏症。