Decrease in myelin content of rabbit sciatic nerve with aging and diabetes.

Previous studies of the amount of peripheral nerve myelin have been based on histologic examination. In this study, myelin content was measured directly after quantitative isolation from sciatic nerve. There was a decrease in the amount of myelin beginning at nine months, the time of maximal myelin content in normal rabbits, and beginning at six months, the amount was decreased in diabetic as compared with control animals. Composition of myelin isolated from young (age three to four months) and old (age nine to thirteen months) rabbit sciatic nerves was also determined and is similar to that of other species. Although the composition was not affected by diabetes, with aging there was a significant decrease in the amount of cholesterol and an increase in glycolipid.