Investigation of neural mechanisms of 670 and 830nm laser acupuncture in pain relief, using rat

背景慢性疼痛在澳大利亚很常见，每年造成100亿美元的损失。药物疗法被广泛使用，但严重的副作用限制了使用。患者积极寻求非药物治疗，激光针灸是治疗慢性疼痛最常用的疗法之一，然而，其作用机制尚不清楚。我们之前的工作研究人员提出，激光针灸通过直接作用于神经来减少疼痛，改变疼痛信号传递到大脑的方式。为了研究这一点，我们(CI A和CI B)先前对神经细胞培养进行了一项红外激光研究。这是在CI B开展的一项使用相同激光波长治疗颈部疼痛的积极临床研究之后得出的结论。我们证实，激光暂时中断了神经运输系统，神经运输系统由一系列称为微管的微小管组成。它们充当线粒体运输的“单轨”系统，线粒体为所有神经功能提供能量。我们认为，这一系统的暂时中断，称为快速轴突运输，扰乱了疼痛信号沿神经的传导，导致疼痛缓解。重要的悬而未决的问题830 nm激光针灸缓解疼痛的机制在临床上仍然知之甚少。为了将其纳入主流临床实践，确定激光对周围神经的影响，特别是对疼痛纤维的影响是很重要的。我们从早期的研究中了解到，单次暴露会导致疼痛纤维发生显著但可逆的变化，包括轴突微管破裂、线粒体膜电位下降和快速轴突血流受阻。这些事件将导致传导故障。问题是，重复照射是否会导致同样的变化，与临床上提供的照射相当。这将为了解激光针灸的临床疗效提供科学依据。我们也不知道670 nm激光针灸是否会起到同样的作用。有证据表明，这可能更有效，因此这仍然是另一个重要的悬而未决的问题。此外，没有证据表明哪种波长是成本和时间有效的，因为希望提供更低的剂量。我们需要确定最有效的剂量和波长，以便可以像CIB所做的那样进行临床试验(Chow和Barnsley，2006)。

Background Chronic pain is common and costs $10 billion dollars per year in Australia. Drug therapies are widely used but serious side effects limit use. Patients actively seek non-drug treatments and laser acupuncture is one of the most commonly sought therapies for chronic pain, however, how it works is not well understood. Our previous work Researchers propose that laser acupuncture reduces pain by direct effects on nerves, altering how pain signals are transmitted to the brain. To investigate this we (CI A and CI B) previously undertook a study of infrared laser on nerve cell cultures. This followed on from a positive clinical study with the same laser wavelength in the treatment of neck pain, undertaken by CI B. We established that laser temporarily interrupts the nerve transport system, which is made up of a series of minute tubes, called microtubules. These act as a “monorail” system for transport of mitochondria, which provide energy for all nerve functions. We propose that temporary interruption of this system, called fast axonal transport, disrupts the conduction of pain signals along the nerve, resulting in pain relief. Important unanswered questions The mechanism by which 830nm laser acupuncture relieves pain clinically remains poorly understood. For its acceptance into mainstream clinical practice it is important to determine the effect of laser on the peripheral nerves and in particular the pain carrying fibres. We know from an earlier study that a single exposure causes significant but reversible changes in pain fibres including axonal microtubule disruption, decrease in mitochondrial membrane potential and block of fast axonal flow. These events would result in conduction failure. The question is whether the repeated irradiations, comparable to those delivered clinically result in the same changes. This would provide a scientific basis for understanding the clinical effectiveness of laser acupuncture. We also do not know if 670nm laser acupuncture would act in the same way. There is evidence that this may be more effective so that this remains another important unanswered question. Further, there is no evidence regarding which wavelength would be cost and time effective as it is desirable to deliver lower dose. We need to determine the most effective dose and wavelength so that clinical trials could be carried out as was done for the trials by CIB (Chow and Barnsley, 2006).