Nutrition and Selective Accumulation Processes Establish the Free Amino Acid Pool of Developing Chick Embryo Brain

Abstract

Control of the fetal amino acid supply resides in a series of interlocking metabolic and environmental factors which are difficult to isolate experimentally. Such factors typically include the diet and alimentary efficiency of the mother, the dynamic influences of her health and hormonal status on these processes, as well as the placental circulation and metabolism. Further control may be exercised by the fetus itself in the form of regulatory entry and/or transport mechanisms governing the transfer of specific (or all) amino acids from blood to embryo, and within the tissues proper. The manner in which these complex variables interact, and their relative importance for fetal brain development, remains uncertain (1, 2). Nevertheless, several lines of evidence seem to suggest a dominant role of the maternal metabolism in regulating the amino acid requirements for the fetus, with the latter only exercising a more selective control over this phenomenon.