A developmental study of glycerol oxidation by rat brain

The rates of oxidation of several concentrations of [1,3-14C]glycerol to 14CO2 were measured in whole homogenates of brain from rats of different ages. The rates of oxidation of glycerol at concentrations from 0.1 to 20 mM were significantly lower with brains of neonatal animals than with adult rats, and increased to adult levels during the second to third week of life. The addition of unlabelled glucose decreased the rate of [1,3-14C]glycerol oxidation by about 40% at all ages and glycerol concentrations. Increasing the initial concentration of glycerol 200-fold from 0.1 to 20 mM resulted in more than a 100-fold increase in the rate of glycerol oxidation. This pattern of an increased rate of oxidation with increasing substrate concentration was in marked contrast to that previously found with other brain energy substrates which levelled off with increasing concentration. The data suggest that glycerol could be an important energy substrate in certain areas or cell types in adult rat brain, or that the ability to oxidize high concentrations of glycerol is a detoxification mechanism to prevent accumulation of excess free glycerol.