Cellular and subcellular distribution of protein-bound radioactivity in the rat brain during maturation after incorporation of [ 3H]leucine in vitro

Abstract

The in vitro incorporation of [ 3H]leucine into proteins of neuronal- and glial-enriched fractions and subcellular fractions of rat brain during maturation was investigated. No separation of neuronal- and glial-enriched fractions was obtained before 8–10 days of age. The protein yield of whole homogenate in adult rats was approximately twice that of 1-day-old animals. The yield of myelin protein increased 6-fold during the same period. The recovery of neuronal protein per g tissue did not change from the 10th day to adulthood, while during the corresponding time there was a 10-fold ] increase in the yield of glial protein. A significant increase in the protein-bound radioactivity of nuclei, synaptosomes, soluble proteins and microsomes was observed from day 1 to day 3 or 5 following parturition. A significant decrease in the specific radioactivity of all subcellular fractions was seen between day 3 or 5 and day 16 of age. During maturation the protein-bound radioactivity of neuronal- and glial-enriched fractions decreased. At all ages studied, the neuronal-enriched fraction had a higher protein-bound specific radioactivity than had the glial-enriched fraction, and this difference was accentuated during maturation.