Novel mechanisms mediating the rapid antidepressant actions of glyoxylase 1 inhibitors

项目摘要抑郁症是世界范围内导致残疾的主要原因。N-甲基-D-天冬氨酸 受体(NMDAR)拮抗剂氯胺酮是唯一被批准用于临床的抗抑郁药 在几小时到几天内产生影响。然而，氯胺酮治疗并不是对所有患者都有效，并导致 有问题的副作用。迫切需要新型快速有效的抗抑郁药物。我们最近发现， 乙氧基酶1(GLO1)抑制剂在小鼠中诱导快速起效的抗抑郁作用。GLO1是一种无处不在的细胞 对糖酵解的非酶副产物甲基乙二醛(MG)进行解毒的酶。因此，GLO1抑制剂 治疗可提高MG的生理水平。MG是GABA-A受体的竞争性部分激动剂，并且 也直接激活原肌球蛋白受体激酶B(TrkB)，脑源性神经营养因子的受体 (BDNF)。氯胺酮和在啮齿类动物中诱导快速起效的抗抑郁作用的药物，触发活动- 依赖的BDNF释放导致TrkB激活；这一作用是他们快速起效的抗抑郁药所必需的 效果。这项提议旨在确定GLO1抑制剂背后的分子和电路机制- 诱导快速起效的抗抑郁作用。我们发现GLO1抑制剂治疗可诱导抗抑郁药 在24小时内通过与氯胺酮很大不同的机制起作用。例如, 氯胺酮等速效药物诱导a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic激活 酸(AMPA)受体，触发活性依赖的脑源性神经营养因子释放和皮质γ振荡。令人惊讶的是， 我们发现，GLO1抑制剂处理不会诱导γ振荡，因此很可能不会诱导AMPA 活化或活性依赖的BDNF释放。在目标1中，我们将检验GLO1抑制剂的假设 治疗通过增加MG水平来激活TrkB，从而“替代”BDNF的释放。我们预测 携带BDNF中Val66Met突变的小鼠将表明，这种突变阻止了活性依赖的BDNF的释放 快速起效的抗抑郁药对GLO1抑制剂的反应，而不是氯胺酮。我们还将检验这一假设 MPFC内TrkB受体的激活足以用于GLO1抑制剂介导的快速抗抑郁药物 效果。外侧缰核(LHb)的过度活动会产生抑郁样行为，并减少这种行为 过度运动有抗抑郁作用。我们的钙成像结果显示，无论是MG还是 从先天性无助大鼠的LHb切片中加入氯胺酮可以减少LHb神经元的过度活动。而氯胺酮 通过阻断NMDAR和低电压敏感的T型钙通道来介导这一效应，我们预测 GLO1抑制剂通过MG激活GABA-ARs来产生这种效应。在目标2中，我们将检验假设 LHb-GABA受体的激活足以介导GLO1介导的快速抗抑郁效应。最后， 我们将使用多光谱光度法来检验GLO1抑制剂介导的mPFC抑制的假设。 LHB投射足以诱导快速起效的抗抑郁作用。识别快速-的新机制 起病抗抑郁作用对于开发新的治疗药物是必不可少的。

PROJECT SUMMARY Depression is the leading cause of disability worldwide. The N-methyl-D-aspartate receptor (NMDAR) antagonist ketamine is the only agent approved for clinical use that induces antidepressant effects within hours to days. However, ketamine treatment is not effective in all patients, and induces problematic side effects. Novel rapid-acting antidepressant agents are greatly needed. We recently found that glyoxylase 1 (GLO1) inhibitors induce rapid-onset antidepressant effects in mice. GLO1 is a ubiquitous cellular enzyme that detoxifies methylglyoxal (MG), a non-enzymatic byproduct of glycolysis. Thus, GLO1 inhibitor treatment increases physiological levels of MG. MG is a competitive partial agonist at GABA-A receptors, and also directly activate tropomyosin receptor kinase B (TrkB), the receptor for brain derived neurotrophic factor (BDNF). Ketamine, and agents inducing rapid-onset antidepressant effects in rodents, trigger activity- dependent BDNF release leading to TrkB activation; this action is required for their rapid-onset antidepressant effects. This proposal aims to identify the molecular and circuit mechanisms that underlie GLO1 inhibitor- induced rapid onset antidepressant effects. We found that GLO1 inhibitor treatment induces antidepressant effects within 24 hours through mechanisms that are largely distinct from those of ketamine. For example, ketamine and other rapid-acting agents induce activation of a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, which triggers activity-dependent BDNF release and cortical γ oscillations. Surprisingly, we found that GLO1 inhibitor treatment does not induce γ oscillations, and thus likely does not induce AMPA activation or activity-dependent BDNF release. In Aim 1, we will test the hypothesis that GLO1 inhibitor treatment leads to TrkB activation by increasing levels of MG, thus “substituting” for BDNF release. We predict that mice carrying the Val66Met mutation in BDNF, which prevents activity-dependent BDNF release, will show rapid-onset antidepressant responses to GLO1 inhibitors, but not ketamine. We will also test the hypothesis that activation of TrkB receptors within the mPFC is sufficient for GLO1-inhibitor-mediated rapid antidepressant effects. Overactivity of the lateral habenula (LHb) produces depression-like behaviors, and reducing this overactivity has antidepressant effects. Our calcium imaging findings show that application of either MG or ketamine to LHb slices from congenitally helpless rats reduces LHb neuronal overactivity. While ketamine mediates this effect by blocking NMDARs and low-voltage-sensitive T-type calcium channels, we predict that GLO1 inhibitors produce this effect by activating GABA-ARs via MG. In Aim 2, we will test the hypothesis that activation of LHb GABA-ARs is sufficient to mediate GLO1-mediated rapid-onset antidepressant effects. Lastly, we will use multispectral photometry to test the hypothesis that GLO1 inhibitor-mediated inhibition of an mPFC- LHb projection is sufficient to induce rapid-onset antidepressant effects. Identifying novel mechanisms of rapid- onset antidepressant effects is essential for developing new therapeutics.