Effects of mitochondrial fusion and fission regulation on mouse hippocampal primary cultures: relevance to Alzheimer's disease

Abstract

Background: Alzheimer's disease (AD) is a complex disease that begins long before the first well-known pathophysiological signs appear and requires, among other things, new diagnostic approaches. This is mainly due to the lack of an effective treatment due to the lack of understanding of the disease mechanisms and the absence of correct biological models reflecting the cause-and-effect relationships in pathogenesis. One of the dysfunctional changes in AD is the disruption of mitochondrial fission and fusion processes.

Methods: In this study, mitochondrial fusion and fission were regulated in primary neuro-astrocytic cultures of mouse hippocampus using mitochondrial fission inhibitor, mitochondrial fusion promoter and exogenous zinc. Changes in mitochondrial and cellular morphology were assessed, as well as lipofuscin levels as an early marker of mitochondrial dysfunction. Primary neuro-astrocytic hippocampal cultures from 5xFAD mice, a model of hereditary AD, were used for comparison.

Results: Use of the mitochondrial fusion promoter converts the mitochondrial network into a pool of fused mitochondria and results in a decrease in neuronal density by day 5 of exposure, with a concomitant decrease in astrocyte density by days 1 and 5 of exposure, accompanied by a decrease in lipofuscin fluorescence intensity in culture. The use of mitochondrial fission inhibitor resulted in the appearance of fused mitochondria and the disappearance of the pool of smallest mitochondria. This was accompanied by a decrease in neuronal density and an increase in astrocyte density with a concomitant increase in lipofuscin fluorescence intensity to the level of 5xFAD culture. Exogenous zinc induces mitochondrial fragmentation and at high concentrations leads to compensatory astrogliosis and neurodegeneration, while at low concentrations it decreases lipofuscin fluorescence intensity and affects culture morphology and changes in astrocyte immunoreactivity to GFAP.

Conclusion: The study demonstrates that changing the processes of mitochondrial dynamics affects the morphology of adult cell cultures and can lead to processes similar to those observed in 5xFAD transgenic cultures

Keywords: Mitochondria, mitochondrial fusion and fission, 5xFAD, lipofuscin, Alzheimer's disease, primaryhippocampal culture