The effect of alloxan diabetes and insulin on the rate of protein synthesis in the rat submandibular gland.

The incorporation of radioactively labeled leucine into TCA-precipitable proteins by submandibular gland tissue slices from control, alloxan diabetic, and insulin supplemented diabetic rats was measured in vitro. Incorporation decreased in alloxan diabetes and could be restored to control levels within three hours after insulin administration. The effects of alloxan diabetes and insulin on 3H-leucine incorporation paralleled their effects on a secretory enzyme, peroxidase. Insulin in vitro stimulated the incorporation of 3H-leucine within 15 minutes of addition to the incubation medium. Further, the response to insulin was found to be dose-related. The conclusion drawn from these results is that insulin has a rapid, direct effect on the rate of protein synthesis in the rat submandibular gland.