Mechanisms Of Action Of Psychoactive Drugs

精神药物的作用机制

• 批准号: 6533419
• 负责人: DE-MAW CHUANG
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF MENTAL HEALTH
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6533419
• 关键词: NMDA receptors; bipolar depression; carbamazepine; drug interactions; gel mobility shift assay; glutamates; laboratory rat; lithium; neuropharmacologic agent; neuroprotectants; neurotoxins; pharmacokinetics; phenytoin; psychopharmacologic agent; psychopharmacology; serotonin receptor; tissue /cell culture

Lithium was introduced into psychiatry 50 years ago and remains to be the most commonly used drug for the treatment of manic depressive illness. The precise mechanisms underlying its clinical efficacy remain to be defined. In a recent study, we explored the neuroprotective effects of lithium against excitotoxicity elicited by glutamate, a major excitatory amino acid neurotransmitter involved in the synaptic plasticity and pathogenesis of neurodegenerative and neuropsychiatric disorders. We found that long-term exposure to lithium chloride dramatically protects cultured rat cerebellar granule cells (CGCs), cerebral cortical and hippocampal neurons against glutamate-induced excitotoxicity which involves apoptosis mediated by N-methyl-D-aspartate (NMDA) receptors. In CGCs, the lithium neuroprotection occurs at therapeutically relevant concentrations (0.5-5.0 mM) and requires treatment for 6-7 days for complete protection to occur, while a 24-hr treatment is ineffective. The protection is specific for glutamate-induced excitotoxicity and can be attributed to inhibition of NMDA receptor-mediated calcium influx. Our results suggest that modulation of glutamate receptor hyperactivity represents, at least in part, the molecular mechanisms by which lithium alters brain function and exerts its clinical efficacy in the treatment for manic depressive illness. These novel actions of lithium also suggest that excessive glutamatergic neurotransmission may be the pathogenic mechanism underlying bipolar illness. We have studied the role of expression of genes involved in pro- apoptosis and cytoprotection. In CGCs, treatment with neuroprotective concentrations of lithium induces a time- dependent increase in the levels of mRNA and protein of the cytoprotective gene Bcl-2. Conversely, the levels of mRNA and protein of the pro-apoptotic genes, Bax and p53 are decreased by lithium. In contrast, glutamate treatment induces a rapid increase in the levels of Bax and p53 mRNA and protein. Pretreatment with lithium suppresses the glutamate-induced increase in Bax and p53 and maintains Bcl-2 at an elevated level. Additionally, glutamate induces a rapid, reversible decrease in the activity of a cell survival factor, Akt, through enhanced dephosphorylation due to activation of protein phosphatase PP2A. In contrast, lithium activates the PI 3-K/Akt signalling pathway and enhances the phosphorylation of glycogen synthase kinase 3. Pretreatment with lithium facilitates the recovery of glutamate-induced loss of Akt activity. Moreover, glutamate treatment induces a persistent decrease in the level of phospho-cyclic AMP response element binding protein (p-CREB). This glutamate-induced loss of p-CREB is due to activation of protein phosphatase PP1 and is effectively suppressed by long-term lithium pretreatment. In a more recent study we found that glutamate induces a robust activation of AP-1 binding, Jun N-terminal kinase (JNK) and p38 kinase. Suppression of these glutamate-induced activities using selective inhibitors results in neuroprotection, suggesting their roles in excitotoxicity. Moreover, long-term lithium-induced neuroprotection is concurrent with inhibition of glutamate-induced activation of AP-1 binding, JNK and p38 kinase. Collectively, our results suggest that glutamate excitotoxicity involves induction of pro-apoptotic genes and suppression of cytoprotective gene expression. Lithium neuroprotection is due, at least in part, to suppression of these glutamate-induced effects. In light of recent clinical observations that there are neuroanatomical and morphological abnormalities in the frontal cortex of the brain of bipolar patients, we have extended our studies to include primary cultures of cortical neurons prepared from embryonic rats. These cortical neuronal cultures are highly vulnerable to glutamate-induced apoptotic insults. Pretreatment with subtherapeutic or therapeutic concentrations of LiCl for 6 days robustly protects against glutamate excitotoxicity in these cultures. Thus, significant protection was achieved at 0.1-0.2 mM with a nearly complete protection at 1.0 mM. Interestingly, valproate, another mood-stabilizer, also induces a dose- and time-dependent protection against glutamate excitotoxicity. The lithium neuroprotection in cortical neurons is also associated with a reduction in NMDA receptor-mediated calcium influx, and this lithium-induced action is correlated with a decrease in tyrosine phosphorylation at position 1472 of the NR2B subunit of the receptor. Additionally, we have expanded from our in vitro cell culture studies by using animal models of cerebral ischemia and Huntington's disease. We found that subcutaneous injection of rats with LiCl for 16 days reduces the size of ischemic brain infarct volume by more than 50% in rats subjected to permanent occlusion of the left middle cerebral artery. In a more recent study, we employed a rat focal ischemia paradigm in which the left middle cerebral artery is subjected to transient occlusion followed by reperfusion and found that lithium is neuroprotective even when administrated after the onset of the ischemic attack. This lithium neuroprotection is dose-dependent in the range of 0.5 to 3 mEq given subcutaneously. Moreover in ischemic rats treated with lithium, the level of cytoprotective heat shock protein 70 in neurons of the cerebral cortex is markedly increased compared with the control. Conversely, the levels of Bax in glia of the cortical and subcortical areas of ischemic rats are elevated and this increase is suppressed by lithium treatment. In the Huntington's disease animal model, we injected quinolinic acid, a partial agonist of the NMDA receptor, into the left side of rat striatum. This treatment results in about 70% lesion of the striatum which involves the loss of GABAnergic neurons expressing dopamine D-1 receptors. This quinolinic acid-induced lesion requires activation of the transcription factor NF-kB and induction of p53, c-Myc and cyclin D1 and is protected by metabotropic receptor agonists and prostaglandin A1. Our results show that chronic lithium treatment for 16 days or one day pretreatment decreases the size of striatal lesion by 40-50%. In addition, lithium neuroprotection effects are associated with over-expression of Bcl-2 in affected areas and other brain structures. Thus, our in vitro and in vivo studies raise the possibility that lithium, in addition to its use for bipolar depressive illness, may have expanded use for the treatment of neurodegenerative diseases, particularly those linked to excitotoxicity.

锂于50年前被引入精神病学，仍然是治疗躁狂抑郁疾病的最常用药物。其临床疗效的基础机制仍有待定义。在最近的一项研究中，我们探讨了锂对谷氨酸引起的兴奋性毒素的神经保护作用，谷氨酸是一种主要的兴奋性氨基酸神经递质，涉及神经退行性和神经精神疾病的突触可塑性和发病机理。我们发现，长期暴露于氯化锂可以极大地保护培养的大鼠小脑颗粒细胞（CGC），脑皮质和海马神经元，以防止谷氨酸诱导的兴奋性毒性，涉及涉及由N-甲基 - d-甲酸 - 大种酸盐（NMDA）受体介导的凋亡。在CGC中，锂神经保护发生在治疗相关浓度（0.5-5.0 mm）下，需要进行6-7天的治疗以进行全面保护，而24小时治疗无效。该保护是针对谷氨酸诱导的兴奋性毒性的特异性，可以归因于NMDA受体介导的钙涌入的抑制。我们的结果表明，谷氨酸受体多动的调节至少部分代表了锂可以改变脑功能并在躁狂抑郁疾病治疗中施加临床功效的分子机制。锂的这些新作用还表明，过度的谷氨酸能神经传递可能是双极疾病的致病机制。我们研究了与凋亡和细胞保护作用有关的基因表达的作用。在CGC中，用神经保护浓度的锂治疗可诱导细胞保护基因Bcl-2的mRNA和蛋白质水平的时间依赖性增加。相反，锂，Bax和p53的mRNA和蛋白质水平通过锂降低。相反，谷氨酸治疗诱导BAX和p53 mRNA和蛋白质的水平迅速增加。用锂预处理抑制谷氨酸诱导的BAX和p53的增加，并将Bcl-2保持在升高的水平。此外，谷氨酸通过蛋白质磷酸酶PP2A的激活而促进细胞存活因子Akt的活性（AKT）的活性快速，可逆的降低。相反，锂激活PI 3-K/AKT信号通路，并增强糖原合酶激酶3的磷酸化3.锂的预处理促进谷氨酸诱导的Akt活性丧失的恢复。此外，谷氨酸治疗可诱导磷酸循环AMP反应元件结合蛋白（P-CREB）的持续下降。这种谷氨酸诱导的P-CREB丧失是由于蛋白质磷酸酶PP1的激活，并通过长期锂预处理有效抑制。在最近的一项研究中，我们发现谷氨酸诱导AP-1结合，JUN N末端激酶（JNK）和p38激酶的强大激活。使用选择性抑制剂对这些谷氨酸诱导的活性的抑制会导致神经保护，这表明它们在兴奋性毒性中的作用。此外，长期锂诱导的神经保护是同时抑制谷氨酸诱导的AP-1结合，JNK和p38激酶的激活。总体而言，我们的结果表明，谷氨酸兴奋性涉及促凋亡基因的诱导和细胞保护基因表达的抑制。锂神经保护至少部分归因于这些谷氨酸诱导的作用。鉴于最近临床观察到双极患者大脑额叶皮质中存在神经解剖学和形态异常，我们扩展了研究，包括由胚胎大鼠制备的皮质神经元的原发性培养物。这些皮质神经元培养物高度容易受到谷氨酸引起的凋亡损伤的影响。 LICL的亚治疗或治疗浓度进行6天的预处理可稳健地防止这些培养物中的谷氨酸兴奋性。因此，在0.1-0.2毫米处获得明显的保护，在1.0毫米处几乎完全保护。有趣的是，另一种情绪稳定器的丙戊酸酯也诱导了针对谷氨酸兴奋性毒性的剂量和时间依赖性保护。皮质神经元中的锂神经保护也与NMDA受体介导的钙涌入的降低有关，并且这种锂诱导的作用与受体NR2B亚基NR2B亚基1472的酪氨酸磷酸化的降低相关。此外，我们通过使用脑缺血和亨廷顿氏病的动物模型从体外细胞培养研究中扩展。我们发现，用LICL皮下注射16天的大鼠可将缺血性脑梗塞体积的大小降低超过50％以上的大鼠，后者长期阻塞左中部大脑动脉。在最近的一项研究中，我们采用了大鼠局灶性缺血范式，其中左脑中动脉受到短暂性闭塞，然后进行再灌注，发现锂即使在缺血性发作发作后也进行了神经保护。该神经保护性的剂量依赖性在0.5至3 meq的范围内，皮下为0.5至3 mEq。此外，与对照组相比，在用锂处理的缺血性大鼠中，脑皮质神经元中的细胞保护热蛋白70水平显着增加。相反，缺血性大鼠皮质和皮质下区域的胶质细胞中的Bax水平升高，锂治疗抑制了这种增加。在亨廷顿氏病动物模型中，我们将NMDA受体的部分激动剂（NMDA受体的部分激动剂）注入了大鼠纹状体的左侧。这种治疗可导致大约70％的纹状体病变，涉及表达多巴胺D-1受体的GABAN能神经元的丧失。这种喹啉酸诱导的病变需要激活转录因子NF-KB并诱导p53，c-Myc和Cyclin D1，并受到代谢性受体激动剂和前列腺素A1的保护。我们的结果表明，慢性锂治疗16天或一天预处理可将纹状体病变的大小降低40-50％。另外，锂神经保护作用与受影响区域和其他大脑结构的Bcl-2过表达有关。因此，我们的体外和体内研究增加了锂除了用于双极抑郁疾病的使用外，还可能扩大用于治疗神经退行性疾病的使用，尤其是与兴奋性毒性相关的疾病。