The role of age and circadian rhythm in adult neurogenesis in zebrafish
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Abstract
Adult neurogenesis is process that occurs post- embryonically in the brain of most organisms. New neurons are born from precursors and then migrate to their final destinations, incorporating into existing neuronal networks. It is not known, however what role normal physiological processes such as aging or circadian rhythm play on this process. Here, we investigate the effects of these processes using as a model primary culture of neuronal cells derived from the zebrafish brain. We observe that cells derived from brain tissue of middle aged fish (1.5 and 2 year) showed significantly more growth and differentiation than cells derived from young fish (1 year). Additionally, various lighting regimes (constant light [LL], a 14/10 hour light-dark cycle [LD] and constant darkness [DD]) resulted in varying growth patterns of neuronal cells in culture. Cells maintained in LD had more cells with neuronal processes, total neuronal processes and cell to cell connections than cells maintained in LL or DD suggesting that disruption of the normal circadian clock negatively affects neuronal proliferation and growth. Administration of melatonin to the cells altered these effects. Cells maintained in LL show significant improvement in growth and differentiation with the addition of melatonin when compared to LD and DD demonstrating the neuroprotective effects of melatonin. Cells maintained in LD and DD had diminished growth with melatonin treatment when compared to their respective controls.
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Thesis (M.A.)--Boston University