Phosphoglycerides and their acyl group composition in myelin and microsomes of rat spinal cord during development.

The phosphoglycerides and their acyl group composition in myelin and microsomes isolated from rat spinal cords were examined at various stages of the postnatal developmental period. In the immature cord, diacyl-GPC is the major phosphoglyceride in both microsomal and myelin fractions. The proportion of this phosphoglyceride decreased steadily with age during development and the decrease was marked by an increase in diacyl-GPE in microsomes and ethanolamine plasmalogen in both fractions. Marked changes in acyl group composition were observed in the microsomes during development of spinal cord, whereas acyl groups of myelin showed less extensive changes. A considerable amount of monoenoic fatty acid is already present in the myelin of 7-day-old cord. Acyl groups of diacyl-GPC in the microsomal fraction indicated a decrease in 16:0, 16:1,20:4(n-6) and an increase in 18:0, 18:1 and 20:1 with respect to development. On the other hand, microsomal diacyl-GPE and alkenylacyl-GPE indicated a decrease in 16:0, 18:0 and 20:4(n-6), but an increase in 18:1 and 20:1. An exception is the proportion of 22:6(n-3) which increased in diacyl-GPE and decreased in alkenylacyl-GPE during development. The lack of obvious acyl group changes in myelin phosphoglycerides after 7 days of age is in agreement with the results of deSousa & Horrocks (Devl Neurosci. 1, 114-120, 1979) that myelination in spinal cord took on an early course and reached the adult composition sooner than the cerebrum.