Sato J, Morimae H, Takanari K, Seino Y, Okada T, Suzuki M, Mizumura K
Department of Neural Regulation, Research Institute of Environmental Medicine, Nagoya University, Japan.
Exp Brain Res. 2000 Aug;133(4):442-9. doi: 10.1007/s002210000451.
To clarify the mechanism by which changes in chronic pain are induced by cold environments, rats rendered neuropathic by a chronic constriction injury (CCI) to the sciatic nerve were exposed to low ambient temperature (LT; 7 degrees C decrease from 22 degrees C) in a climate-controlled room. LT exposure aggravated pain-related behaviors in CCI rats, i.e., decreased the threshold to von Frey hair and paw pressure stimulation, prolonged the duration of foot withdrawal to pinprick stimulation, and increased the cumulative duration of guarding posture. Lumbar sympathectomy (SYX) did not inhibit LT-induced augmentations of pain-related behaviors in CCI rats. LT exposure decreased the skin temperatures of both hind paws to the same degree in the sham-operated control and SYX rats, while in the CCI and SYX+CCI rats it caused a larger temperature decrease in the injured paw than in the uninjured one. These results indicate that LT exposure augments abnormalities in pain-related behaviors of neuropathic rats, and also suggest that sympathetic nervous activity is not a predominant factor in the augmenting mechanism.
为阐明寒冷环境诱发慢性疼痛变化的机制，将坐骨神经经慢性缩窄损伤（CCI）造成神经病理性疼痛的大鼠置于气候可控的房间内，使其暴露于低环境温度（LT；从22℃降低7℃）下。暴露于LT加重了CCI大鼠的疼痛相关行为，即降低了对von Frey毛发和爪部压力刺激的阈值，延长了对针刺刺激的足部撤回持续时间，并增加了警戒姿势的累积持续时间。腰交感神经切除术（SYX）并未抑制LT诱导的CCI大鼠疼痛相关行为的增强。在假手术对照组和SYX大鼠中，暴露于LT使双后爪皮肤温度降低程度相同，而在CCI大鼠和SYX + CCI大鼠中，它导致受伤爪的温度降低幅度大于未受伤爪。这些结果表明，暴露于LT会加剧神经病理性大鼠疼痛相关行为的异常，也提示交感神经活动不是增强机制中的主要因素。
