OCCURRENCE OF STEROL ESTERS IN THE CHICKEN BRAIN DURING PRENATAL AND POSTNATAL DEVELOPMENT

Abstract

The changes in brain constituents during development have been widely studied and data concerning lipids and other substances are now available. Some investigators have considered the possibility of correlating the maturation of the brain with the deposition of specific lipid fractions; but it is difficult to relate composition data to the functional development of the nervous system.An increase in the concentration of various lipids in the brain of different animal species during development has been demonstrated by many investigators, and these data have recently been reviewed by Sperry (1963). The concentration of cholesterol increases sharply during brain development: Folch ‐Pi (1955) found an increase of the order of 300‐400 per cent in mouse brain from birth to 90 days, and Mandel and Bieth (1951) demonstrated a 300 per cent increase of cholesterol concentration during the development of the rat brain from newborn to adult age. Mandel, Bieth and Stoll (1949) demonstrated that the cholesterol content increases from 1 to 5‐4 mg in the brain of the chick embryo from the 10th to 19th day of incubation.Most investigators agree that cholesterol is present in mature brain only in the free form (Cumings, 1957; Davison and Wajda, 1959) and Le Baron and Folch (1959) postulated that it is combined with the water soluble proteins in the myelin sheat. However, some investigators have found esterified cholesterol in developing brain. Mandelet al. (1949) found cholesterol esters in the brain of chick embryo and Adams and Davison (1959) in the cord of the chick embryo and in foetal human brain. JOHNSON, Mc Nabb and Rossiter (1948) and Brante (1949) found some esterified cholesterol in the infant human brain, while Cumings (1957) found trace amounts of cholesterol esters in adult white and infant grey matter. More recently Clarenburg, Chaikoff and Morris (1963) give values for cholesterol esters in the brain of the developing rabbit. However, there are no firm data on the changes in concentration of esterified cholesterol in the brain during development. We have, therefore, measured the sterol esters in the chick developing brain at different stages of embryonic and postnatal life.Recent investigations have shown that cholesterol is not the only sterol present in the developing brain, but there is a considerable amount of desmosterol (24‐dehydro‐cholesterol) in the brain of the chick embryo (Fish, Boyd and Stokes, 1962) and other animal species (Paoletti, Fumagalli, Grossi and Paoletti; 1965). Desmosterol is partially esterified in the chick brain and disappears from the brain during maturation (Fumagalli, Grafnetter, Grossi and Morganti, 1963).