Parris W C, Janicki P K, Johnson B W, Mathews L
Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee 37232-2125, USA.
Anesth Prog. 1994;41(4):95-9.
The aim of this study was to evaluate the effect of acute and repeated (5 days) treatment with various types of infrared (IR) diode lasers and probes (single- vs cluster-beam) on the pain response in rats with peripheral mononeuropathy produced by sciatic nerve ligation. Male Sprague-Dawley rats were anesthetized with sodium pentobarbital, and the mid-thigh was surgically exposed to reveal the sciatic nerve, around which four ligatures were loosely tied. On postoperative day 5, the skin over the sciatic nerve lesion was subjected to a 30-min daily local exposure from a 904-nm IR diode laser (700 Hz, average output power 10 mW) with a single-beam probe, a 830-nm IR diode laser (700 Hz) with either a single-beam (average output power 50 mW) or cluster-beam probe (average output power 15 mW), or placebo for 5 consecutive days. Two pain responses (foot-withdrawal time and the hind-paw elevation time) were measured on both sides using the radiant heat method on days 5 and 9. In addition, cold allodynia was measured on day 9 of treatment by placing the rats on a chilled metal plate (4 degrees C) and measuring the duration of elevation of either of the hind paws. On day 9, the animals were sacrificed for collection of the samples of brain and lumbar spinal cord for the determination of the tissue concentrations of dynorphin A1-8-like immunoactivity (DYN) using specific radioimmunoassay (RIA). The hind-paw withdrawal and elevation times on the right side in all groups subjected to the various methods of IR laser irradiation did not differ significantly as compared with the placebo-treated group when measured on days 5 and 9 after surgery. No statistically significant differences in withdrawal response and elevation time of the unaffected left hind paw were noted either. The measurement of cold allodynia similarly failed to reveal any effect in laser-treated groups versus placebo. The RIA analysis found that tissue concentrations of DYN were significantly elevated in the spinal cord ipsilaterally to the ligation side, as compared with the contralateral side, in all rats with sciatic nerve ligation. All modalities of IR diode laser treatment did not produce any significant difference in the brain and spinal cord level of DYN on postoperative day 9 in all treatment groups. It is concluded that repeated IR diode laser treatment did not reduce hyperalgesia induced by sciatic nerve ligation in rats.
本研究的目的是评估用各种类型的红外（IR）二极管激光器和探头（单光束与簇状光束）进行急性和重复（5天）治疗，对坐骨神经结扎所致周围性单神经病大鼠疼痛反应的影响。雄性Sprague-Dawley大鼠用戊巴比妥钠麻醉，手术暴露大腿中部以显露坐骨神经，在其周围松散地结扎四个结扎线。术后第5天，对坐骨神经损伤部位上方的皮肤，使用单光束探头，每日用904nm红外二极管激光器（700Hz，平均输出功率10mW）局部照射30分钟，或使用单光束（平均输出功率50mW）或簇状光束探头（平均输出功率15mW）的830nm红外二极管激光器（700Hz），或安慰剂，连续照射5天。在第5天和第9天，使用辐射热法测量双侧的两种疼痛反应（缩足时间和后爪抬高时间）。此外，在治疗第9天，将大鼠置于冰冷的金属板（4℃）上，测量任一后爪抬高的持续时间，以测量冷痛觉过敏。在第9天，处死动物以收集脑和腰脊髓样本，使用特异性放射免疫测定法（RIA）测定强啡肽A1-8样免疫活性（DYN）的组织浓度。在手术后第5天和第9天测量时，与安慰剂治疗组相比，接受各种红外激光照射方法的所有组右侧的后爪缩足和抬高时间均无显著差异。未受影响的左后爪的缩足反应和抬高时间也未发现统计学上的显著差异。冷痛觉过敏的测量同样未显示激光治疗组与安慰剂组之间有任何差异。RIA分析发现，与对侧相比，所有坐骨神经结扎大鼠结扎侧同侧脊髓中DYN的组织浓度显著升高。在术后第9天，所有治疗组中，所有红外二极管激光治疗方式在脑和脊髓水平的DYN上均未产生任何显著差异。结论是，重复红外二极管激光治疗并未减轻大鼠坐骨神经结扎所致的痛觉过敏。
