Novel mechanisms mediating the rapid antidepressant actions of glyoxylase 1 inhibitors

项目摘要 抑郁症是全世界残疾的主要原因。 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物 几小时到几天内就会产生效果。然而，氯胺酮治疗并非对所有患者都有效，并且会导致 有问题的副作用。非常需要新型速效抗抑郁药。我们最近发现 乙二醛酶 1 (GLO1) 抑制剂可在小鼠体内诱导快速起效的抗抑郁作用。 GLO1是一种普遍存在的细胞 解毒甲基乙二醛 (MG) 的酶，甲基乙二醛是糖酵解的非酶副产物。因此，GLO1抑制剂 治疗会增加 MG 的生理水平。 MG 是 GABA-A 受体的竞争性部分激动剂，并且 还直接激活原肌球蛋白受体激酶 B (TrkB)，即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，会引发活性- 依赖性 BDNF 释放导致 TrkB 激活；他们的速效抗抑郁药需要采取这一行动 影响。该提案旨在确定 GLO1 抑制剂的分子和电路机制 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作用 24 小时内起效，其机制与氯胺酮大不相同。例如， 氯胺酮和其他速效药物诱导α-氨基-3-羟基-5-甲基-4-异恶唑丙酸的活化 酸 (AMPA) 受体，触发活性依赖性 BDNF 释放和皮质 γ 振荡。令人惊讶的是， 我们发现 GLO1 抑制剂治疗不会诱导 γ 振荡，因此可能不会诱导 AMPA 激活或活性依赖性 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 水平导致 TrkB 激活，从而“替代”BDNF 的释放。我们预测 携带 BDNF Val66Met 突变的小鼠将表现出，这种突变会阻止活性依赖性 BDNF 的释放 GLO1 抑制剂可快速起效抗抑郁反应，但氯胺酮则不然。我们还将检验假设 mPFC 内 TrkB 受体的激活足以实现 GLO1 抑制剂介导的快速抗抑郁药 影响。外侧缰核 (LHb) 的过度活跃会产生类似抑郁的行为，并减少这种行为 过度活动具有抗抑郁作用。我们的钙成像结果表明，应用 MG 或 氯胺酮对先天无助的大鼠的 LHb 切片可减少 LHb 神经元过度活跃。而氯胺酮 通过阻断 NMDAR 和低电压敏感 T 型钙通道介导这种效应，我们预测 GLO1 抑制剂通过 MG 激活 GABA-AR 来产生这种作用。在目标 2 中，我们将检验以下假设： LHb GABA-AR 的激活足以介导 GLO1 介导的快速起效的抗抑郁作用。最后， 我们将使用多光谱光度测定来检验 GLO1 抑制剂介导的 mPFC 抑制作用的假设 LHb 投射足以诱导快速起效的抗抑郁作用。确定快速的新机制 发挥抗抑郁作用对于开发新疗法至关重要。

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.