Postnatal development of the complexes of the electron transport chain in isolated rat brain mitochondria

The postnatal development of the complexes of the electron transport chain in isolated rat brain mitochondria were investigated. Nonsynaptosomal brain mitochondria were isolated from rats aged 1-60 days, and the activities of mitochondrial complexes I, II-III, IV, V and citrate synthase were measured. There was a significant increase in the activity of complex I from postnatal day 1 to day 21, and in the activities of complex II-III, complex IV and citrate synthase from postnatal day 1 to day 60. In contrast, the activity of complex V increased significantly between postnatal day 1 and day 10 where it attained adult levels. These data are consistent with the increasing demand for mitochondrial ATP production as the brain develops and as aerobic glycolysis becomes the major pathway for energy production.