Novel mechanisms mediating the rapid antidepressant actions of glyoxylase 1 inhibitors

抑郁症是全球残疾的主要原因。N-甲基-D-天冬氨酸 受体（NMDAR）拮抗剂氯胺酮是唯一批准用于临床使用的药物，其诱导抗抑郁药 几小时到几天内的效果。然而，氯胺酮治疗并不是对所有患者都有效， 有问题的副作用。因此，迫切需要新的速效抗抑郁药。我们最近发现， 乙二醛酶1（GLO 1）抑制剂在小鼠中诱导快速起效的抗抑郁作用。GLO 1是一种普遍存在的细胞 解毒甲基乙二醛（MG）的酶，一种糖酵解的非酶副产物。因此，GLO 1抑制剂 治疗增加MG的生理水平。MG是GABA-A受体的竞争性部分激动剂， 也直接激活原肌球蛋白受体激酶B（Trk B），脑源性神经营养因子的受体 （BDNF）。氯胺酮和在啮齿动物中诱导快速起效的抗抑郁作用的药物，触发活性- 依赖性BDNF释放导致TrkB激活;这种作用是其速效抗抑郁药所必需的 方面的影响.该提案旨在确定GLO 1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GLO 1抑制剂治疗诱导抗抑郁药 在24小时内通过与氯胺酮大不相同的机制产生效果。比如说， 氯胺酮和其它速效剂诱导α-氨基-3-羟基-5-甲基-4-异恶唑丙酸活化 酸（AMPA）受体，其触发活性依赖性BDNF释放和皮质γ振荡。令人惊讶的是， 我们发现，GLO 1抑制剂处理不诱导γ振荡，因此可能不诱导AMPA 激活或活性依赖性BDNF释放。在目标1中，我们将检验GLO 1抑制剂 治疗通过增加MG水平导致TrkB活化，从而“替代”BDNF释放。我们预测 携带BDNF中Val 66 Met突变的小鼠会阻止活性依赖性BDNF的释放， 对GLO 1抑制剂的快速起效抗抑郁反应，而不是氯胺酮。我们还将检验假设 mPFC内TrkB受体的激活足以使GLO 1-受体介导的快速抗抑郁药 方面的影响.过度活跃的外侧缰（LHb）产生抑郁样行为，并减少这一点。 过度活跃有抗抑郁作用。我们的钙成像结果表明，无论是MG或 从先天性无助大鼠的氯胺酮到LHb切片减少LHb神经元过度活动。而氯胺酮 通过阻断NMDAR和低电压敏感性T型钙通道介导这种效应，我们预测， GLO 1抑制剂通过MG激活GABA-AR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GLO 1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法来检验GLO 1受体介导的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- 起效的抗抑郁作用对于开发新的治疗方法是必不可少的。

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.