Chemical studies of peripheral nerve during Wallerian degeneration. 2. Lipids after nerve crush (axonotmesis)

Abstract

The concns. of cerebroside, total and free cholesterol, total phospholipin, monoaminophospholipin, lecithin and neutral fat were detd. in cat sciatic nerves at intervals of 16-144 days after nerve crush (axonotmesis). From these figures the concns. of ester cholesterol, sphingomyelin, cephalin, myelin lipid and total lipid were calculated. The wet wt. of the nerve increased after the operation, reaching a max. in 32 days and returning to normal by 144 days. The total lipid content of the nerve decreased during the first 16 days, remained constant during the period 16-48 days and then increased gradually. Even after 144 days the concn. of total lipid was less than that of the control nerves. Neutral fat decreased rapidly during the first 16 days, but had returned to normal by 48 days. The myelin lipids (cerebroside, free cholesterol and spingomyelin) decreased during the first 32 days, remained constant during the period 32-96 days and then increased gradually. By 144 days the concn. of myelin lipid was 44% of the value for the control nerves. Both total and free cholesterol decreased during the first 32 days, free cholesterol more rapidly than total, for cholesterol ester, absent in control nerves, appeared during this period. The free cholesterol followed a course similar to that of myelin lipid while the cholesterol ester disappeared, none remaining at 144 days. Total phospholipin decreased during the first 32 days, remained fairly constant during the period 32-96 days and then increased gradually. Sphingomyelin followed a similar course, but cephalin decreased more rapidly and lecithin more slowly. Lecithin did not return to the nerve, the concn. at 144 days being similar to that at 64 days.