As topochemically demonstrated, glutamate dehydrogenase is present within the dendritic layers of the rat hippocampus formation. Its activity increased in parallel to the postnatal maturation of synaptic structures. The results point to a contribution of glutamate dehydrogenase in the synthesis of transmitter glutamate. concomitantly, the activity of succinate and alpha-glycerophosphate dehydrogenase increased in the hippocampal dendritic areas during the postnatal development which is discussed expressing of metabolic activity. The results of the formazan elution technique reflect the topochemical findings in a quantitative manner.