New Therapies for Essential Tremor from Cannabidiols Mechanisms

项目总结/摘要 原发性震颤影响0.5 - 0.9%的一般人群，约4.5%的65岁以上。 治疗震颤的药物是根据经验发现的重新使用的药物，通常缺乏效力，并且通常不好 容忍。在我们的项目中，我们研究抑制震颤的药物如何发挥作用以及通过什么分子作用 目标的许多患者报告大麻二酚抑制震颤。大麻二酚是非精神药物， 已显示出对癫痫的临床疗效，但可能引起不良反应，并诱导肝酶。 基于大麻二酚的作用机制，更有效和耐受性良好的震颤药物是 令人向往 为了评估小鼠的震颤，我们使用了震颤模型，它与原发性震颤有许多相似之处。 震颤我们的试验数据表明，大麻二酚强烈抑制骆驼蓬碱诱导的震颤，与 临床观察。大麻二酚具有多种作用，但其直接或间接激活的主要受体 是大麻素受体1型和2型，1型香草素受体，和血清素1a型受体。通过 将特异性受体拮抗剂沿着与大麻二酚共同给药， 作用机制。在初步实验中，我们发现香草素1和血清素1a受体的激活 都能调节大麻二酚的抗震颤作用。作为香草素1激动剂抑制震颤， 5-羟色胺1a受体拮抗剂，似乎大麻二酚激活香草素1受体是 5-羟色胺1a受体介导的震颤抑制。在目标1中，我们将寻求复制这些发现，并且还 找出缺乏5-羟色胺1a受体（敲除）的小鼠是否不能表现出震颤抑制， 大麻二酚或香草素1受体激动剂。 大麻二酚的大部分机制是由于抑制脂肪酸酰胺水解酶，从而导致 内源性大麻素anandamide，然后激活几个受体。我们在飞行员身上发现 实验表明，一种抑制这种酶的药物也能抑制震颤，这种作用需要香草素和 1和5-羟色胺1a受体激活。这表明，脂肪酸酰胺水解酶的抑制剂可能是 临床上用于治疗震颤。在Aim 2中，我们将尝试使用药物和基因敲除小鼠来复制这些发现 探索香草素1和辣椒素1a受体通过抑制这种抑制作用在震颤抑制中的作用。 酶，并且还评估大麻素施用是否通过相同的抑制震颤。 机制等 源自大麻二酚的机制的一种重要的潜在震颤疗法是施用 激活血清素1a受体的药物，而血清素1a受体通常抑制神经元放电。当位于血清素 细胞体，血清素1a自身受体激活减少细胞放电和血清素释放，从而减少 兴奋性突触后5-羟色胺2A受体的激活。突触后5-羟色胺1a受体在 抗抑郁药和其他作用。在初步研究中，我们发现自体感受器和突触后- 更倾向于5-羟色胺1a激动剂抑制震颤，而同时刺激两种受体的药物甚至更多。 有效在目标3中，我们将重复这些实验，并确定重复给药是否会导致 这些血清素激动剂中的任何一种都失去了抑制震颤的能力。我们会检测血清素1a 敲除小鼠，以证实它们实际上是通过激活血清素1a受体来抑制震颤。 该计划有望导致识别原发性震颤的新疗法： 脂肪酸酰胺水解酶、anandamide样药物和5-羟色胺1a受体激动剂。这些疗法 预计是有效的和良好的耐受性，应该很快可用于临床试验，也可能是 有益于焦虑和抑郁，这些症状在患有特发性震颤的退伍军人中很常见。

Project Summary/Abstract Essential tremor affects 0.5-0.9% of the general population and about 4.5% above age 65. Medications for tremor are re-purposed drugs found empirically, often lack potency, and are often not well tolerated. In our program we study how drugs that suppress tremor work and through what molecular targets. Many patients report that cannabidiol suppresses tremor. Cannabidiol is non-psychotropic and has shown clinical efficacy for epilepsy, but may cause adverse effects, and induces hepatic enzymes. More effective and well-tolerated medications for tremor, based on cannabidiol’s mechanism, are desirable. To assess tremor in mice, we use the harmaline tremor model, which has many similarities to essential tremor. Our pilot data indicate that cannabidiol robustly suppresses harmaline-induced tremor, consistent with clinical observations. Cannabidiol has many actions, but the main receptors activated by it directly or indirectly are cannabinoid receptors type 1 and 2, the type 1 vanilloid receptor, and the serotonin type 1a receptor. By co-administering specific receptor antagonists along with cannabidiol, it is possible to determine the mechanism of action. In pilot experiments we found that activation of vanilloid 1 and serotonin 1a receptors both mediate cannabidiol's anti-tremor effect. As a vanilloid 1 agonist suppresses tremor, an effect blocked by a serotonin 1a receptor antagonist, it appears that vanilloid 1 receptor activation by cannabidiol is upstream to serotonin 1a receptor-mediated tremor suppression. In Aim 1 we will seek to replicate these findings and, also find out whether mice lacking the serotonin 1a receptor (knockouts) fail to show tremor suppression by cannabidiol or the vanilloid 1 receptor agonist. Much of cannabidiol's mechanism is due to inhibition of fatty acid amide hydrolase, leading to elevation of the endogenous cannabinoid anandamide, which then activates several receptors. We found in pilot experiments that a drug that inhibits this enzyme also suppresses tremor, an effect that requires both vanilloid 1 and serotonin 1a receptor activation. This suggests that inhibitors of fatty acid amide hydrolase could be used clinically to treat tremor. In Aim 2 we will seek to replicate these findings, using drugs and knockout mice to explore the role of vanilloid 1 and serotonin1a receptors in tremor suppression through inhibition of this enzyme and also assess whether anandamide administration suppresses tremor through the same mechanisms. An important potential tremor therapy stemming from cannabidiol's mechanisms is the administration of drugs that activate serotonin 1a receptors, which generally inhibit neuronal firing. When located on serotonin cell bodies, serotonin 1a autoreceptor activation reduces cell firing and serotonin release, thereby reducing activation of excitatory post-synaptic serotonin 2a receptors. Post-synaptic serotonin 1a receptors play a role in antidepressant and other actions. In pilot studies we found that both autoreceptor- and postsynaptic- preferring serotonin 1a agonists suppress tremor, while a drug that stimulates both receptors was even more effective. In Aim 3 we shall replicate these experiments and, also determine whether repeated dosing causes any of these serotonin agonists to lose their ability to suppress tremor. We will test them in serotonin 1a knockout mice to confirm that they are in fact suppressing tremor by activating the serotonin 1a receptor. This program is expected to lead to the identification of new therapies for essential tremor: inhibitors of fatty acid amide hydrolase, anandamide-like drugs, and serotonin 1a receptor agonists. These therapies are anticipated to be potent and well tolerated, should be available soon for clinical trials, and may also be beneficial for anxiety and depression, conditions that are common in Veterans with essential tremor.