Modulation of Mitochondrial Dynamics in Primary Hippocampal Cultures of 5xFAD Mice by Mdivi-1, MFP, and Exogenous Zinc.

Background: Mitochondrial dynamics-the balance between fission, fusion, and mitophagy-are essential for maintaining cellular homeostasis and are increasingly implicated in the pathogenesis of Alzheimer's disease (AD).

Methods: Here, we investigated the effects of targeted modulation of mitochondrial fission and fusion on mitochondrial morphology and metabolic status in primary hippocampal cultures derived from 5xFAD transgenic mice. Mitochondrial dynamics were modulated using the fission inhibitor Mitochondrial Division Inhibitor 1 (Mdivi-1), the fusion promoter mitochondrial fusion promoter M1 (MFP M1), and exogenous zinc as a fission activator. We evaluated mitochondrial morphology, lipofuscin accumulation, beta-amyloid (Aβ42) levels, and reactive oxygen species (ROS). The general condition of the cultures was assessed morphologically using neuronal and astrocytic markers.

Results: Modulating mitochondrial dynamics altered mitochondrial morphology, decreased Aβ42, lipofuscin, and ROS levels, and improved cellular organization. Treatments with MFP and Mdivi-1 promoted mitochondrial hyperfusion without complete network integration and were associated with reduced astrogliosis and increased neuronal density. In contrast, zinc induced dose-dependent mitochondrial fragmentation and astrocytic clasmatodendrosis, with lower concentrations enhancing Aβ clearance and higher concentrations inducing toxicity.

Conclusions: Mitochondrial fusion and fission significantly influence lipofuscin and amyloid accumulation in 5xFAD cultures, underscoring their potential as therapeutic targets in neurodegenerative diseases. We propose that mitochondrial morphology acts as a key regulator of both cellular homeostasis and disease pathology.