Baker David, Pryce Gareth, Visintin Cristina, Sisay Sofia, Bondarenko Alexander I, Vanessa Ho W S, Jackson Samuel J, Williams Thomas E, Al-Izki Sarah, Sevastou Ioanna, Okuyama Masahiro, Graier Wolfgang F, Stevenson Lesley A, Tanner Carolyn, Ross Ruth, Pertwee Roger G, Henstridge Christopher M, Irving Andrew J, Schulman Jesse, Powell Keith, Baker Mark D, Giovannoni Gavin, Selwood David L
Neuroimmunology Unit, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
Department of Neuroinflammation, UCL Institute of Neurology, University College London, London, UK.
Br J Pharmacol. 2017 Aug;174(16):2662-2681. doi: 10.1111/bph.13889. Epub 2017 Jul 7.
Our initial aim was to generate cannabinoid agents that control spasticity, occurring as a consequence of multiple sclerosis (MS), whilst avoiding the sedative side effects associated with cannabis. VSN16R was synthesized as an anandamide (endocannabinoid) analogue in an anti-metabolite approach to identify drugs that target spasticity.
Following the initial chemistry, a variety of biochemical, pharmacological and electrophysiological approaches, using isolated cells, tissue-based assays and in vivo animal models, were used to demonstrate the activity, efficacy, pharmacokinetics and mechanism of action of VSN16R. Toxicological and safety studies were performed in animals and humans.
VSN16R had nanomolar activity in tissue-based, functional assays and dose-dependently inhibited spasticity in a mouse experimental encephalomyelitis model of MS. This effect occurred with over 1000-fold therapeutic window, without affecting normal muscle tone. Efficacy was achieved at plasma levels that are feasible and safe in humans. VSN16R did not bind to known CB /CB /GPPR55 cannabinoid-related receptors in receptor-based assays but acted on a vascular cannabinoid target. This was identified as the major neuronal form of the big conductance, calcium-activated potassium (BK ) channel. Drug-induced opening of neuronal BK channels induced membrane hyperpolarization, limiting excessive neural-excitability and controlling spasticity.
We identified the neuronal form of the BK channel as the target for VSN16R and demonstrated that its activation alleviates neuronal excitability and spasticity in an experimental model of MS, revealing a novel mechanism to control spasticity. VSN16R is a potential, safe and selective ligand for controlling neural hyper-excitability in spasticity.
我们最初的目标是研发出能控制因多发性硬化症（MS）导致的痉挛，同时避免大麻相关镇静副作用的大麻素类药物。VSN16R是以抗代谢物方法合成的一种花生四烯乙醇胺（内源性大麻素）类似物，用于识别针对痉挛的药物。
在完成最初的化学合成后，采用了多种生化、药理学和电生理学方法，利用分离细胞、基于组织的分析以及体内动物模型，来证明VSN16R的活性、疗效、药代动力学和作用机制。在动物和人体中进行了毒理学和安全性研究。
VSN16R在基于组织的功能分析中具有纳摩尔活性，并且在MS小鼠实验性脑脊髓炎模型中能剂量依赖性地抑制痉挛。这种效应在超过1000倍的治疗窗口内出现，且不影响正常肌张力。在人体可行且安全的血浆水平下即可实现疗效。在基于受体的分析中，VSN16R不与已知的CB1/CB2/GPR55大麻素相关受体结合，而是作用于一种血管大麻素靶点。该靶点被确定为大电导钙激活钾（BK）通道的主要神经元形式。药物诱导的神经元BK通道开放导致膜超极化，限制了过度的神经兴奋性并控制了痉挛。
我们确定BK通道的神经元形式是VSN16R的靶点，并证明其激活可减轻MS实验模型中的神经元兴奋性和痉挛，揭示了一种控制痉挛的新机制。VSN16R是一种用于控制痉挛中神经过度兴奋的潜在、安全且选择性的配体。
