Neurogenesis and apoptosis in the mature brain during formation and consolidation of long-term memory

Abstract

We measured the contents of the cell proliferation marker 5-bromo-2′ deoxyuridine (BrdU) in native and fragmented DNA (indicators of neoneurogenesis and neoapoptosis) in the cerebral cortex, hippocampus, and cerebellum of adult rats, as well as a marker of apoptosis, the internucleosomal DNA fragmentation at 1, 14, and 30 days after systemic administration of BrdU, which coincided with the beginning of a 4-day training in the Morris watermaze. We found that physical exercise and the emotional condition associated with swimming in the pool induced a substantial increase (more than two-fold) in the level of neoneurogenesis and neoapoptosis markers in all explored rat brain structures. The initial stage of long-term memory formation triggered a significant increase in apoptotic activity in the hippocampus and cerebellum. The consolidation of long-term spatial memory is associated with significant changes in indicators of differentiation and programmed cell death of new 14–30-day-old cells in the prefrontal cortex and cerebellum. We demonstrated the differences in the power and direction of correlations between proliferation, differentiation, and loss of “new” and “old” cells in the studied adult brain structures during physical exercise and the formation of long-term memory.