DAILY INSULIN-TREATMENT RELIEVES LONG-TERM HYPERALGESIA IN STREPTOZOCIN DIABETIC RATS

Painful neuropathy is common in human diabetes. In rats, experimental diabetes results in altered pain sensitivity. We examined the effect o f chronic insulin treatment on diabetes-induced hyperalgesia in strept ozocin diabetic rats. A 20-week period of diabetes resulted in a 62% d ecrease in paw withdrawal thresholds compared with age-matched normal rats. Daily injections of insulin progressively reversed mechanical hy peralgesia to normal values parallel to the correction of hyperglycaem ia. When the treatment was stopped, mechanical hyperalgesia reappeared , but never reached the degree of hyperalgesia observed before insulin treatment, suggesting that indirect mechanisms underlie the effect of normoglycaemia on nociception. The present data suggest that appropri ate blood glucose control can help relieve pain in long-term diabetes through indirect mechanisms.