链脲佐菌素糖尿病大鼠尾神经中传入单位的反应特性

RESPONSIVE PROPERTY OF AFFERENT UNITS IN THE CAUDAL NERVE OF STREPTOZOTOCIN -DIABETIC RATS

实验观察了链脲佐菌素糖尿病大鼠尾神经中各种传入单位的反应特性，发现糖尿病大鼠的部分Ｃ单位和Ａδ单位具有自发放电，它们的机械阈值显著降低。糖尿病大鼠的Ｃ单位对持续１ｍｉｎ的机械性阈刺激的反应同对照组相似，而在阈上机械性刺激期间呈增频效应，撤除阈刺激和阈上刺激后后放电均明显增多。除Ｃ单位、Ａδ单位外，Ａβ机械感受性单位的传导速度也明显减慢，但在Ｃ单位、Ａδ单位和Ａβ机械感受性单位中，各种亚单位的比例同对照组相比无显著性差异。结果表明，糖尿病大鼠Ｃ单位和Ａδ单位机械阈值的降低有助于其行为伤害性阈值的下降，Ｃ单位和Ａδ单位的异常电活动是糖尿病大鼠产生对痛刺激敏感性升高和感觉异常的外周因素。

In the present study, the responsive properties of afferent units in caudal nerve of streptozotocin (STZ) induced diabetic rats were investigated. It was found that some of the C and Aδ units spontaneously discharged and their mechanical threshold was decreased significantly in diabetic rats. The response of the C units of diabetic and control rats to a 1 min sustained mechanical stimulus of threshold strength was similar, whereas, discharge frequencies during sustained suprathreshold mechanical stimulus were significantly greater in the C units of diabetic rats. After removal of threshold or suprathreshold mechanical stimulus, after discharges were also greater in C units of diabetic rats. Conduction velocity of C units, Aδ units and Aβ mechanical receptive units were also decreased in diabetic rats. However, there was no significant difference in the subunits of all kinds of receptive units between diabetic and control rats. The present data suggested that the C and Aδ units with lowered mechanical threshold contribute to the decrease of the behavioral nociceptive threshold of diabetic rats and abnormal discharge of the C and Aδ units may be a peripheral factor in hypersensitivity to painful stimuli and paresthesia of diabetic rats.