Changes in LDH isoenzymes of brain developing in situ and in vitro

Postnatal changes in lactate dehydrogenase activity and isoenzyme pattern studied in mouse cerebrum and rat cerebellum by quantitative microassay and acrylamide 'disc' gel electrophoresis were compared to those occurring in the same tissues growing in tissue culture. Both in vivo and in vitro there is a relative and absolute increase in those isoenzymes which migrate more rapidly toward the anode. These are associated with function at high relative oxygen concentrations and are characteristic of adult brain. Furthermore, increase of the slower moving isoenzymes was induced in the cultures, related to the oxygen gradient in the tissue. In vivo and in vitro the enzyme changes accompany structural and physiological developments such as neuropil growth, synapse formation and myelination, which have large energy requirements.