Postnatal development of energy metabolism in the rat brain

The activities of cytochrome c oxidase and F0F1-ATPase as well as the conte nt of cytochromes cc(1), aa(3), and b were investigated in free brain mitoc hondria in the course of postnatal development and aging. The results show an increase of V-max of both enzymes during postnatal development (between day 5 and 30). During the following phase ending at the age of 6 months, a decrease of F0F1-ATPase and cytochrome c oxidase activity occurs. From 6 to 12 months of age the activity of these enzymes did not change. The K-M for both enzymes remained unchanged during the whole period observed. The cont ent of cytochromes increased from the low values found in young rats, reach ed the highest values at around one month, and decreased till the age of 3 months. Later, their content in brain mitochondria did not markedly change. Our results suggest that the metabolic maturation of brain mitochondria di ffers in several aspects from the same process in other tissues, mainly in the time course. This is probably due to the unique role of neural tissue i n the organism.