ALLODYNIA-LIKE EFFECTS IN RAT AFTER ISCHEMIC SPINAL-CORD INJURY PHOTOCHEMICALLY INDUCED BY LASER IRRADIATION
ALLODYNIA-LIKE EFFECTS IN RAT AFTER ISCHEMIC SPINAL-CORD INJURY PHOTOCHEMICALLY INDUCED BY LASER IRRADIATION
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DOI：
10.1016/0304-3959(91)90186-2
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发表时间：
1991-05-01
期刊：
影响因子：
7.4
通讯作者：
WIESENFELDHALLIN, Z
中科院分区：
文献类型：
--
作者：
HAO, JX;XU, XJ;WIESENFELDHALLIN, Z
我们报告的行为表明，在光化学诱导的大鼠缺血性脊髓损伤后，无害性刷牙和机械压力会引起异常性疼痛。雌性大鼠静脉注射Erythoris B，激光束照射T10椎骨1、5或10分钟。这些手术引发血管内光化学反应，导致缺血性脊髓损伤。照射后，大多数大鼠观察到明显的异常性疼痛。在轻柔的触摸过程中，动物会发出强烈的声音，而在轻轻刷过胁腹时，动物会明显感到不安。在此期间，对冯弗雷毛测量的机械压力的发声阈值显着降低。在一些动物中，自发发声表明存在自发疼痛。不同动物的异常性疼痛持续时间从几个小时到几天不等。异常性疼痛的严重程度和持续时间似乎与照射持续时间无关。在假手术大鼠中，术后几小时内伤口周围也出现轻微的短暂性异常疼痛，全身吗啡（2 mg/kg，腹腔注射）可有效缓解。吗啡（2 mg/kg，腹膜内注射）也能部分缓解脊髓损伤大鼠照射后 4 小时的异常性疼痛。然而，吗啡即使在较高剂量（5 mg/kg，腹腔注射）下也未能缓解脊髓损伤大鼠在损伤后 24-48 小时的异常性疼痛。全身注射 GABA(B) 激动剂巴氯芬（0.01-0.1 mg/kg，腹腔注射），但不是 GABA(A) 激动剂蝇蕈醇（1mg/kg，腹腔注射），可有效缓解这一时期的异常性疼痛。 24 小时和照射前（20 mg/kg，皮下注射）用胍乙啶预处理并不能预防脊髓损伤大鼠中异常性疼痛的发生。目前的观察首次表明缺血性脊髓损伤可能导致皮肤机械性异常性疼痛。这种现象对吗啡有抵抗力，可能不涉及交感系统。脊髓损伤后3天对异常疼痛动物的组织学检查显示，照射5分钟的大鼠的背侧脊髓存在相当大的形态学损伤。该动物的相关背根也受到轻微影响，但背根神经节正常。然而，在照射1分钟的大鼠中，尽管存在强烈的异常性疼痛，但此时在脊髓、背根或背根神经节中未发现损伤。有人认为脊髓 GABA(B) 系统的功能缺陷可能与这种异常性疼痛样现象有关。激光诱导脊髓损伤后的异常性疼痛可能是一个有用的疼痛模型，用于测试镇痛药物对缺血性中枢性疼痛的功效。
We report behaviours suggesting the presence of allodynia elicited by non-noxious brushing and mechanical pressure following photochemically induced ischaemic spinal cord injury in the rat. Female rats were intravenously injected with Erythoris B and T10 vertebra was irradiated with a laser beam for 1, 5 or 10 min. These procedures initiated an intravascular photochemical reaction, resulting in ischaemic spinal cord injury. After irradiation a clear allodynia was observed in most rats. The animals vocalized intensely to light touch during gentle handling and were clearly agitated to light brushing of the flanks. The vocalization threshold in response to the mechanical pressure measured with von Frey hairs was markedly decreased during this period. In some animals the existence of spontaneous pain was suggested by spontaneous vocalization. The duration of the allodynia varied among animals from several hours to several days. The severity and duration of allodynia seemed not to be related to the duration of irradiation. In sham-operated rats a slight, transient allodynia was also noted around the wound within a few hours after surgery, which was effectively relieved by systemic morphine (2 mg/kg, i.p.). Morphine (2 mg/kg, i.p.) also partially relieved the allodynia in spinally injured rats 4 h after irradiation. However, morphine, even at a higher dose (5 mg/kg, i.p.), failed to alleviate the allodynia in spinally injured rats 24-48 h after the injury. Systemic injection of the GABA(B) agonist baclofen (0.01-0.1 mg/kg, i.p.), but not the GABA(A) agoinst muscimol (1mg/kg, i.p.), effectively relieved allodynia during this period. Pretreatment with guanethidine 24 h and just prior to the irradiation (20 mg/kg, s.c.) did not prevent the occurrence of allodynia in spinal cord injured rats. The present observation is the first to show that ischaemic spinal cord injury could result in cutaneous mechanical allodynia. This phenomenon is resistant to morphine and may not involve the sympathetic system. Histological examination of allodynic animals 3 days after spinal cord injury revealed considerable morphological damage in the dorsal spinal cord of a rat irradiated for 5 min. The related dorsal roots were also slightly affected in this animal, while the dorsal root ganglia were normal. However, in rats irradiated for 1 min, despite the existence of strong allodynia, no damage could be found at this time in the spinal cord, dorsal roots or dorsal root ganglia. It is suggested that functional deficits in the GABA(B) system in the spinal cord may be related to this allodynia-like phenomenon. Allodynia following laser-induced spinal cord injury may be a useful pain model for testing the efficacy of analgesic drugs against central pain of ischaemic origin.