Increase of streptozocin toxicity by magnesium deficiency in the diabetic rat model

To study interactions between magnesium (Mg) and diabetes mellitus, female SD-rats weighing ca. 230 g were rendered Mg-deficient by offering a diet providing only 20% of the rat's requirement. After 14 days the animals were injected 75 mg streptozocin (STZ) per kg body weight intraperitoneally. Placebo-treated controls received the same diet, however their drinking-water was enriched with 20 mmol/l Mg as the magnesium-L-aspartate hydrochloride. Mg deficiency remarkably increased STZ-induced lethality from 3.8% to 61.1% on day 35. Pronounced hyperglycemia and necrosis of pancreatic beta cells also suggest an increased effect of STZ on the pancreas during Mg deficiency. The underlying mechanisms are discussed. Food consumption was decreased in Mg-deficient animals and steeply increased 7 days following STZ treatment. Similarly consumption of drinking-water also increased. Since diabetic rats lost body weight, relative and absolute Mg intake via food or drinking-water increased. In this way further Mg depletion of diabetic rats was prevented.