Chemical studies of peripheral nerve during Wallerian degeneration. 1. Lipids

Abstract

The concn. of cerebroside, total and free cholesterol, total phospholipin, monoaminophospholipin, lecithin, total fatty acid and neutral fat was detd. in degenerating cat sciatic nerves at intervals of time from 4 to 96 days after nerve section. From these figures the concn. of ester cholesterol, sphingomyelin, kephalin, essential lipid, myelin lipid, and total lipid was calculated. The wet wt. of the degenerating nerve increased rapidly, reaching a max. in 4 days and returning to normal after 64 days. The total lipid content of the nerve decreased steadily throughout the course of the degeneration. Neutral fat decreased rapidly, reaching a minimum between 4 and 8 days, and returned to normal by 32 days. The myelin lipids (cerebroside, free cholesterol and sphingomyelin) changed little during the first 8 days and then decreased rapidly, and to the same extent, between 8 and 32 days. Cholesterol changed little during the first 8 days. Between 8 and 32 days free cholesterol decreased rapidly and ester cholesterol, absent in control nerves, increased, reaching a max. by 16 days. Total phospholipin, which changed little during the first 8 days, decreased rapidly between 8 and 32 days. Sphingomyelin decreased at a similar rate, whereas kephalin decreased more rapidly and lecithin more slowly. The results are discussed with reference to the chemical nature of the lipids of "myelin" and to the changes that occur in the lipids when a nerve undergoes Wallerian degeneration.