THE DEVELOPMENT OF OXIDATIVE-METABOLISM IN DIENCEPHALIC STRUCTURES OFTHE RAT - A QUANTITATIVE STUDY

A new method for quantitative determination of cytochrome oxidase (C.O .) activity was applied to diencephalic structures of the limbic syste m that are closely connected anatomically, that is, the mammillary bod ies (MB) and the anterior nucleus of the thalamus (AT). This method ma kes it possible to easily evaluate the oxidative metabolic capacity of brain regions, an index of their functionality. By using this techniq ue, we studied the postnatal development of both structures in Wistar rats of 14, 21, 30, and 120 days of age. Furthermore, animals of 730 d ays were included in order to evaluate the effects of aging on C.O. ac tivity of these structures. The results showed a significant increase in the C.O. activity of the subdivisions of the AT, its levels remaini ng constant until the adult age, with a significant decrease in its ac tivity in aged animals. In the MB, only the increase in C.O. activity of the medial mammillary nucleus (pars medialis) was significant until the adult age. A decrease of C.O. values with aging was significant o nly in the lateral mammillary nucleus. These data suggest that there i s a wide heterogeneity in the maturation and aging of brain oxidative metabolism in diencephalic structures.