Department of Oral and Maxillofacial Surgery, University of Florida College of Dentistry, Gainesville, FL, USA Department of Neuroscience, University of Florida College of Medicine, McKnight Brain Institute, Gainesville, FL, USA Department of Orthodontics, University of Florida, Gainesville, FL, USA.
Pain. 2013 Nov;154(11):2547-2553. doi: 10.1016/j.pain.2013.07.041. Epub 2013 Aug 8.
Neuropathic pain is a debilitating condition resulting from damage to sensory transmission pathways in the peripheral and central nervous system. A potential new way of treating chronic neuropathic pain is to target specific pain-processing neurons based on their expression of particular receptor molecules. We hypothesized that a toxin-neuropeptide conjugate would alter pain by first being taken up by specific receptors for the neuropeptide expressed on the neuronal cells. Then, once inside the cell the toxin would inhibit the neurons' activity without killing the neurons, thereby providing pain relief without lesioning the nervous system. In an effort to inactivate the nociceptive neurons in the trigeminal nucleus caudalis in mice, we targeted the NK1 receptor (NK1R) using substance P (SP). The catalytically active light chain of botulinum neurotoxin type A (LC/A) was conjugated with SP. Our results indicate that the conjugate BoNT/A-LC:SP is internalized in cultured NK1R-expressing neurons and also cleaves the target of botulinum toxin, a component-docking motif necessary for release of neurotransmitters called SNAP-25. The conjugate was next tested in a murine model of Taxol-induced neuropathic pain. An intracisternal injection of BoNT/A-LC:SP decreased thermal hyperalgesia as measured by the operant orofacial nociception assay. These findings indicate that conjugates of the light chain of botulinum toxin are extremely promising agents for use in suppressing neuronal activity for extended time periods, and that BoNT/A-LC:SP may be a useful agent for treating chronic pain.
神经病理性疼痛是一种由周围和中枢神经系统感觉传输通路损伤引起的使人虚弱的病症。一种潜在的治疗慢性神经病理性疼痛的新方法是基于特定受体分子的表达来靶向特定的疼痛处理神经元。我们假设毒素-神经肽缀合物将通过首先被神经元细胞上表达的神经肽的特定受体摄取来改变疼痛。然后，一旦进入细胞，毒素将在不杀死神经元的情况下抑制神经元的活动，从而在不损伤神经系统的情况下缓解疼痛。为了使小鼠的三叉神经尾核中的伤害性神经元失活，我们使用 P 物质（SP）靶向 NK1 受体（NK1R）。肉毒杆菌神经毒素 A 型（LC/A）的催化活性轻链与 SP 缀合。我们的结果表明，缀合的 BoNT/A-LC：SP 在培养的 NK1R 表达神经元中被内化，并且还切割肉毒杆菌毒素的靶标，即释放神经递质所必需的组件对接基序 SNAP-25。该缀合物随后在紫杉醇诱导的神经病理性疼痛的小鼠模型中进行了测试。脑室内注射 BoNT/A-LC：SP 可降低操作性口腔疼痛测定法测量的热痛觉过敏。这些发现表明，肉毒杆菌毒素的轻链缀合物是用于抑制神经元活性的非常有前途的试剂，并且 BoNT/A-LC：SP 可能是治疗慢性疼痛的有用试剂。
