选择性前列腺素EP_1受体阻断剂抑制糖尿病大鼠隐神经中C单位的传入活动

目的　观察前列腺素E2 (prostaglandinsE2 ,PGE2 )的特异性受体EP1受体亚型拮抗剂SC192 2 0对糖尿病大鼠隐神经中C单位传入活动的影响。方法　在大鼠隐神经C单位感受野中心皮内注射EP1受体拮抗剂SC192 2 0 ,测定C单位对持续 1min阈刺激和阈上刺激的反应。结果　与对照组相比 ,糖尿病组大鼠C单位的机械阈值显著降低 (P <0 .0 1)。皮内注射SC192 2 0前后 ,持续阈刺激和阈上刺激所诱发的对照组大鼠C单位的传入放电无显著差异 ;持续阈刺激诱发的糖尿病大鼠C单位的传入放电在注射后明显减少 (P <0 .0 5 ) ,而持续阈上刺激诱发的传入放电则无显著变化。结论　EP1受体阻断剂可阻断PGE2 对C单位的敏化作用而缓解糖尿病大鼠的痛过敏 ,提示PGE2 在糖尿病痛过敏的外周机制中具有重要作用。

Selective prostaglandins EP1 receptor antagonist inhibits afferent activity of C unit of saphenous nerve in diabetic rats

Objective To observe the effect o f selective prostaglandins EP 1 receptor antagonist SC19220 on the afferent activity of C unit in the saphenous nerve of diabetic rats. Methods The response of C units to sustained 1 min threshol d and suprathreshold stimuli was measured following intradermal injection of EP 1 receptor antagonist SC19220 into the receptive field of C unit of the sa phenous nerve in control and diabetic rats. Results The mechanical threshold of C units in diabetic rat s was obviously decreased compared with that of control rats (P<0.01). The n umber of afferent discharges evoked by a sustained threshold and suprathreshold stimuli of C units in control rats was not significantly different before and af ter intradermal injection of SC19220. The number of afferent discharges during a sustained threshold was significantly decreased in the C units from diabetic ra ts (P< 0.05) after injection while the number of afferent discharges in r esponse to sustained suprathreshold was not obvious. Conclusion EP 1 receptor antagonist relieves hyperalge sia of diabetic rats by blocking PGE 2 to sensitize C units, suggesting tha t PGE 2 plays an important role in the peripheral mechanism of diabetic hyp eralgesia.