Abstract: Objective To compare sciatic nerve block durations between painful diabetic neuropathy (PDN) rats and nondiabetic ones, and to explore the potential mechanisms. Methods PDN model was established, 10 of which were injected normal saline (NS) adjacent to the right sciatic nerves and ropivacaine(n=5)/ bupivacaine(n=5) adjacent to the left sciatic nerves. Another 15 Control rats were treated in the same way as above. Sciatic nerves were carefully removed 2 days after the injection for HE staining. Results Both local anesthetic solutions produced significantly longer mean durations of sensory nerve block and motor nerve block in PDN rats than in nondiabetic rats (P<0.05). Histological study revealed a significantly higher nerve damage rate in PDN rats than in nondiabetic ones (P<0.05). Besides, nerve damage rates were significantly increased after the sciatic nerve block in PDN rats (P<0.05). Conclusion Susceptibility to nerve injury may exist in PDN rats, which, along with the diabetic neuropathy per se, may constitute the potential mechanism of block duration prolongation.

Key words: painful diabetic neuropathy, sciatic nerve block, nerve damage