OBJECTIVETo investigate the effect of hyperglycemia induced by different doses of strepzotozocin (STZ) on the liver, kidneys and eyes in rats.

METHODSFifty SD rats were divided equally into 5 groups to receive intraperitoneal injections with a single dose of STZ (40, 50, or 60 mg/kg), 3 doses of 25 mg/kg STZ (given at the interval of 24 h), or no treatment (blank control). The dynamic change of blood glucose was observed within 72 h after the first injection. Blood glucose was then monitored every 3 days and the general conditions of the rats were recorded. In the 9th week, fasting blood samples were collected for biochemical analysis and the pancreas, kidney, liver, and eye were examined for pathologies.

RESULTSWithin 72 h after STZ injection, blood glucose first slightly increased and then decreased and again increased to maintain a high level. Death occurred in rats receiving injections with 50 and 60 mg/kg STZ on the third day. In the surviving rats in the 4 STZ-injected groups, the success rate of modeling was 70%, 89%, 100%, and 100%, respectively. Blood glucose showed an inverse correlation with the body weight of the rats. Cataract was observed in the 10th week in rats injected with 40 mg/kg STZ and in the 8th week in the other groups. In the 9th week, the rats receiving 40 mg/kg STZ showed normal insulin, C-peptide, urea, UA, Cr, ALT, AST, TP, and ALB levels, but the rats in the other groups all showed variations in these biochemical indices, which corresponded to the pathological findings in the pancreas, kidneys, and liver.

CONCLUSIONSThree STZ doses of 25 mg/kg is optimal and efficient for inducing diabetes in rats with stable hyperglycemia. Both fasting and random blood glucose tests contribute to the evaluation of the complications of diabetes. The eyes are the most sensitive to hyperglycemia, followed by the kidneys and then by the liver.