Exercise training attenuates acute hyperalgesia in streptozotocin-induced diabetic female rats

OBJECTIVES: We investigated the effects of chronic (eight weeks) low-to moderate-intensity swimming training on thermal pain sensitivity in streptozotocin-induced diabetic female rats. METHODS: Female Wistar rats (n = 51) were divided into the following groups: trained streptozotocin-induced diabetic rats [hyperglycemic trained (HT)], sedentary streptozotocin-induced diabetic rats [hyperglycemic sedentary (HS)], normoglycemic trained rats (NT) and normoglycemic sedentary rats (NS). Diabetes was induced by a single injection of streptozotocin (50 mg/kg, i.p.). One day after the last exercise protocol (60 min/day, five days/week for eight weeks) in the trained groups or after water stress exposure (ten min/twice a week) in the sedentary groups, the rats were subjected to a hot plate test. RESULTS: After eight weeks of swimming training, streptozotocin-induced diabetic rats presented a significantly lower body mass (trained: 219.5 +/- 29 g, sedentary: 217.8 +/- 23 g) compared with the normoglycemic groups (trained: 271 +/- 24 g, sedentary: 275.7 +/- 32 g). Interestingly, we did not find differences in blood glucose levels (mg/dl) between the trained and sedentary groups of the hyperglycemic or normoglycemic rats (HT: 360.2 +/- 66.6, HS: 391.7 +/- 66.7, NT: 83.8 +/- 14.0, NS: 77.5 +/- 10.1). In the hot plate test, the rats from the HT group presented a significantly lower latency than the other rats (HT: 11.7 +/- 7.38 s, HS: 7.02 +/- 7.38 s, NT: 21.21 +/- 7.64 s, NS: 22.82 +/- 7.82 s). CONCLUSION: Low-to-moderate swimming training for a long duration reduces thermal hyperalgesia during a hot plate test in streptozotocin-induced diabetic female rats.