6-Hydroxydopamine (6-OHDA) is a potent neurotoxin used to model Parkinson’s disease (PD) due to its selective toxicity toward dopaminergic neurons. While it is well established that 6-OHDA induces oxidative stress and neuronal death, the precise sequence of early axonal events remains poorly understood. This study leverages a microfluidic platform to isolate axons from cell bodies in murine mesencephalic cultures, enabling real-time analysis of axonal transport dynamics following 6-OHDA exposure.
We observed that 6-OHDA rapidly disrupts mitochondrial movement within 30 minutes, with a significant reduction in both the number of motile mitochondria and their velocity in both anterograde and retrograde directions. This effect was not restricted to dopaminergic neurons—non-dopaminergic axons exhibited comparable transport deficits—indicating a non-selective impact on axonal trafficking machinery.9-cis-Retinoic acid Endogenous Metabolite Concomitantly, mitochondrial membrane potential collapsed, as evidenced by reduced TMRE fluorescence, suggesting functional impairment of mitochondria prior to morphological changes.
Interestingly, mitochondrial size remained unchanged even after one hour of treatment, ruling out fragmentation as an initial cause of transport failure. Instead, the loss of motility appears linked to energy depletion or redox-sensitive disruption of motor proteins. The fact that antioxidants such as NAC and MnTBAP reversed transport defects strongly implicates reactive oxygen species (ROS) in this process.Nup93 Antibody site These findings align with previous reports showing that ROS scavengers protect against 6-OHDA-induced damage, reinforcing the role of oxidative stress in early axonal dysfunction.
Axonal transport of synaptic vesicles, labeled with synaptophysin-cerulean, was also severely impaired within 30 minutes, further underscoring the broad impact of 6-OHDA on cargo trafficking.PMID:34782292 Despite the early onset of transport failure, structural breakdown of microtubules—assessed via acetylated tubulin immunostaining—was not apparent until 6 hours post-treatment. By 24 hours, over 80% of DA and non-DA axons displayed fragmented microtubule tracks, indicating that cytoskeletal disintegration follows rather than precedes transport collapse.
Cell death in the somal compartment was minimal at 24 hours but significantly increased by 48 hours, confirming a retrograde degeneration pattern consistent with in vivo observations. Notably, when toxin was applied only to the axonal compartment, degeneration still progressed to the soma, demonstrating the feasibility of modeling retrograde pathology in vitro using this system.
Autophagy, assessed by LC3-GFP puncta formation, emerged later—around 9 hours after 6-OHDA exposure—suggesting it is a downstream consequence rather than a trigger of transport failure. While autophagosome formation occurred in both DA and non-DA neurons, the response was more pronounced in non-DA neurons, hinting at differential regulation of autophagy in distinct neuronal populations.
In conclusion, our results reveal that 6-OHDA initiates axonal degeneration through rapid, ROS-mediated disruption of mitochondrial and synaptic vesicle transport. This early dysfunction precedes microtubule disassembly and cell death, supporting a “dying-back” mechanism in PD pathogenesis. The delayed activation of autophagy may reflect a failed attempt to clear damaged organelles, leading to prolonged axonal stress. Targeting early transport deficits with antioxidants could represent a viable neuroprotective strategy, offering new insights into therapeutic interventions for Parkinson’s disease.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com