损伤大鼠L5脊神经及其前后根对痛行为的影响

THE EFFECT OF LUMBAR 5 SPINAL NERVE AND ITS VENTRAL ROOT OR DORSAL ROOT INJURY ON THE PAIN RELATED BEHAVIORS IN RATS

摘要:

目的:观察大鼠腰5脊神经和脊神经根不同部位损伤对诱导神经病理性疼痛的不同作用。方法:采用腰5脊神经结扎加切断(lumbar5 spinal nerve ligation,L5 SNL)、腰5前根切除(lumbar5 ventral rhizotomy,L5 VR)和腰5背根切除(lumbar5 dorsal rhizotomy,L5 DR)诱导大鼠痛觉过敏,结合痛行为学测试观察病理性疼痛的发展过程。结果:(1)L5SNL可引起大鼠病理性疼痛。双侧后肢50%撤足阈值(paw withdrawal threshold,PWT)和撤足潜伏期(paw withdrawal latency,PWL)于术后1d明显下降,痛觉过敏的症状,在同侧后肢持续了5周,在对侧后肢也保持3周。(2)L5 VR也可诱导大鼠产生病理性疼痛。双侧后肢50%PWT和PWL于术后1d明显降低,并维持到了术后第5周。(3)L5DR没有引起大鼠产生痛觉过敏症状。与术前基础值和假手术组比较,L5DR后50%PWT和PWL均无明显变化。结论:选择性损伤运动纤维和损伤脊神经均能诱导大鼠产生病理性疼痛,但脊神经背根损伤不引起痛觉过敏。

Abstract:

Objective: To investigate the effect of different site and type of spinal nerve injury on the development of neuropathic pain. Methods: The lumbar 5 spinal nerve ligation plus transection and lumbar 5 ventral or dorsal rhizotomy was used. To elucidate the development of neuropathic pain, behavior test was performed before and after the animal operation. Results: (1) Lumbar 5 spinal nerve ligation plus transection induced neuropathic pain. The 50% paw withdrawal threshold (PWT) and paw withdrawal latency (PWL) were significantly decreased 1d after operation. The pain-related behaviors in ipsilateral hind paw was lasted for 5 weeks and maintained for 3 weeks in contralateral hind paw. (2) Lumbar 5 ventral rhizotomy led to mechanical allodynia and thermal hyperalgesia in bilateral hind paws. The significant decrease of PWT and PWL was observed 1d after operation and lasted for nearly 5 weeks. (3) Lumbar 5 dorsal rhizotomy failed to induce neuropathic pain behaviors. Compared with pre-operated baseline and sham operated group, the PWT and PWL in bilateral hind paws were not changed following L5 DR. Conclusion: The above data suggest that spinal nerve injury and even selective injury to motor fiber induced neuropathic pain, whereas the dorsal rhizotomy didn' t lead to pain related behaviors.