Cannabinoid regulation of glycogen synthase kinase-3

描述（由申请人提供）：大麻是目前美国最常用的非法药物。大麻的使用，特别是青少年的使用，增加了晚年患精神分裂症样精神病的风险。此外，双相情感障碍患者的大麻使用率为20-40%，而普通人群为6%。这些数据和其他流行病学数据表明，使用大麻使易受影响的个人容易患上精神疾病。糖原合成酶激酶3（GSK-3）是边缘脑中重要的调节激酶; GSK-3的过度活性与双相情感障碍和精神分裂症有关。GSK-3被蛋白激酶（包括Akt）磷酸化和失活，是参与情绪调节和精神病的几种神经递质的下游组分。本提案中提出的数据表明，大麻成分，大麻素-1受体（CB 1 R）激活延长？9-四氢大麻酚（THC）显著降低神经元中的GSK-3磷酸化。由于磷酸化降低GSK-3活性，因此这些数据与THC暴露后GSK-3活性增强一致。第二种CB 1 R激动剂CP 55940也具有THC的这些作用。这些初步数据，连同文献中关于D2多巴胺受体信号传导的数据，被用来制定假设，即延长CB 1 R激活导致募集？arrestin;？-抑制蛋白起支架蛋白的作用，使Akt接近蛋白磷酸酶PP 2A。Akt被去磷酸化和失活，导致GSK-3活性的表达障碍。由于GSK-3过度活跃与情绪失调和精神病有关，这些数据导致THC介导的GSK-3活性增加有助于大麻使用和精神疾病之间的关系的假设。本项目的目的是检验CB 1 R介导的GSK-3激活通过以下途径发生的特定假设：抑制蛋白介导的Akt抑制是脑区域特异性的，并有助于THC和其他大麻素激动剂的焦虑和应激增强作用。本项目的具体目的是：（1）确定CB 1 R激动剂改变培养的原代神经元中GSK-3磷酸化状态的机制;（2）确定小鼠急性和慢性暴露于CB 1 R激动剂和拮抗剂对脑区域，特别是边缘系统区域Akt和GSK-3磷酸化和活性的影响：（3）确定？通过比较CB 1 R激动剂和拮抗剂在野生型和？抑制蛋白-2缺失小鼠。成功完成本提案中概述的研究将推进我们的长期目标，即确定大麻暴露使个人易患精神疾病的机制。 大麻是一种一年生植物，数千年来一直被人类用作药用和娱乐药物。虽然大多数使用大麻的人没有受到不利影响，但有些使用者会发展成严重的精神疾病，包括精神分裂症和双相情感障碍。在这项建议的研究将测试的假设，大麻的主要精神活性化学物质，？9-四氢大麻酚（THC）在大脑中产生糖原合成酶激酶的过度激活，这种机制有助于THC对情绪和认知的负面影响，并导致大麻使用者中精神障碍的发病率增加。

DESCRIPTION (provided by applicant): Cannabis sativa is currently the most commonly-used, illicit drug in the United States. Cannabis use, particularly by adolescents, increases the risk of developing schizophrenia-like psychoses in later life. In addition, people with bipolar disorder have a 20-40% lifetime prevalence of cannabis use, compared to 6% in the general population. These and other epidemiological data demonstrate that cannabis use predisposes susceptible individuals to the development of psychiatric disorders. Glycogen synthase kinase 3 (GSK-3) is emerging as an important regulatory kinase in the limbic brain; over-activity of GSK-3 has been linked to both bipolar disorder and schizophrenia. GSK-3 is phosphorylated and inactivated by protein kinases, including Akt and is a down-stream component of several neurotransmitters involved in mood regulation and psychosis. Data presented in this proposal demonstrate that prolonged cannabinoid-1 receptor (CB1R) activation by the cannabis constituent, ?9-tetrahydrocannabinol (THC), significantly decreases GSK-3 phosphorylation in neurons. Since GSK-3 activity is reduced by phosphorylation, these data are consistent with enhanced GSK-3 activity following THC exposure. A second CB1R agonist, CP55940 shared these effects of THC. These preliminary data, together with data in the literature regarding D2 dopamine receptor signaling, were used to formulate the hypothesis that prolonged CB1R activation results in recruitment of ?-arrestin; ?-arrestin functions as a scaffold protein, bringing Akt in proximity with the protein phosphatase, PP2A. Akt is dephosphorylated and inactivated, resulting in dysinhibition of GSK-3 activity. Since GSK-3 over-activity is associated with mood dysregulation and psychosis, these data lead to the hypothesis that THC-mediated increase in GSK-3 activity contributes to the relationship between cannabis use and psychiatric disorders. The objective of the current project is to test the specific hypothesis that CB1R-mediated activation of GSK-3 occurs through ?-arrestin-mediated inhibition of Akt; is brain region specific and contributes to the anxiogenic and stress-enhancing effects of THC and other cannabinoid agonists. The specific aims of this project are: (1) to determine the mechanism by which CB1R agonists alter the phosphorylation state of GSK-3 in primary neurons in culture; (2) the determine the effects of acute and chronic exposure of mice to CB1R agonists and antagonists on the phosphorylation and activities of Akt and GSK-3 in brain regions, particularly those of the limbic system: (3) to determine the role of ?-arrestin in the effects of CB1R agonists and antagonists in behavioral assays of anxiety and stress by comparing their effects in wild type and ?-arrestin-2 null mice. Successful completion of the studies outlined in this proposal will advance our long-term objective to determine the mechanisms by which cannabis exposure predisposes individuals to the development of psychiatric illness. PUBLIC HEALTH RELEVANCE: Cannabis sativa is an annual plant that has been used by humans for thousands of years as a medicinal and recreational drug. While most individuals who use cannabis are not adversely affected, some users develop serious psychiatric disorders, including schizophrenia and bipolar disorder. The studies in this proposal will test the hypothesis that the primary psychoactive chemical of cannabis, ?9-tetrahydrocannabinol (THC) produces an over-activation of the enzyme glycogen synthase kinase in the brain and that this mechanism contributes to negative effects of THC on mood and cognition and is responsible for the increased incidence of psychiatric disorders in cannabis users.