Effects of Insulin on Aldose Reductase Activity in the Lens of Rats with Streptozotocin-Induced Diabetes

Tetsuhiro Nishigami, Masao Nagata, Minoru Endo, Kazuhiko Adachi, Yuji Sasaki and Akihiko Tamai

Department of Ophthalmology, Faculty of Medicine, Tottori University, Yonago 683, Japan

Sprague-Dawley rats (5 weeks old) were injected intravenously with 65 mg of streptozotocin (STZ)/kg body weight. The diabetic rats were injected subcutaneously with insulin successively or singularly and biochemical parameters in the lens were determined. Increases in aldose reductase (AR) activity and contents of sorbitol, glucose and fructose were found in the STZ-diabetic rats, compared with normal, control rats. When the STZ-diabetic rats were injected with 10 units of monotard insulin on each of 7 successive days, AR activity tended to decrease, and contents of sorbitol and fructose significantly decreased, but the glucose content did not significantly decreased, compared with STZ-diabetic rats given no insulin. There was no decrease in AR activity in the STZ-diabetic rats 3 h after an injection of 10 units of actrapid insulin. These results demonstrated that the successive administration of monotard insulin may decrease AR activity and sorbitol and fructose contents in the lens of STZ-diabetic rats without lowering glucose levels.

Key words: aldose reductase activity; fructose; insulin; sorbitol; streptozotocin-diabetic rat lens

RETURN