Oral magnesium administration prevents thermal hyperalgesia induced by diabetes in rats

Background: Peripheral neuropathy is a common complication of diabetes mellitus. It has been shown that hyperglycemia may contribute to its development but the exact pathophysiology underlying this complication is not fully understood. Since oral magnesium supplementation can normalize hyperglycemia induced by diabetes in rats, this study was designed to examine the effect of oral magnesium administration on thermal hyperalgesia in streptozocin-induced diabetic rats. Material and methods: Twenty-four male adult wistar rats were divided equally into control, magnesium-treated control, diabetic and magnesium-treated diabetic groups. In magnesium-treated diabetic rats, magnesium sulfate (10 g/l) was added into the drinking water once diabetes was established (10 days after STZ injection) and continued for 8 weeks. Mg-treated control animals received magnesium sulfate in the same dose and over the same time period. The other two groups; control and diabetic animals, only received tap water. At the end of the 8 weeks, thermal pain threshold was assessed by tail flick test and magnesium and glucose plasma levels were measured in all groups. Result: A significant decrease (p < 0.001) in thermal pain threshold and plasma magnesium levels and an increase in plasma glucose levels (p < 0.001) were seen in diabetic rats 8 weeks after diabetes induction. After 8 weeks of oral magnesium, thermal hyperalgesia was normalized and plasma magnesium and glucose levels were restored towards normal. Conclusion: It is concluded that oral magnesium administration given at the time of diabetes induction may be able to restore thermal hyperalgesia, magnesium deficiency and hyperglycemia and in diabetic rats. (c) 2005 Elsevier Ireland Ltd. All rights reserved.