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Updated: Sep 28, 2026
Assaying DNA Damage in Hippocampal Neurons Using the Comet Assay
Published on: December 19, 2012
DNA damage profiling in motor neurons: a single-cell analysis by comet assay
1Department of Pathology, Division of Neuropathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA. martin1@jhmi.edu
Abstract:
We developed a method to measure DNA damage in single motor neurons (MN). A cell fraction enriched in viable alpha-motor neurons was isolated from adult rat spinal cord. This cell preparation was used to measure the vulnerability of the MN genome to different reactive oxygen species (ROS). MN were exposed in vitro to hydrogen peroxide, nitric oxide and peroxynitrite. Specific types of DNA lesions (e.g., abasic sites, single-strand breaks, and double-strand breaks) were measured using single-cell gel electrophoresis (comet assay). The MN genome was very susceptible to attack by ROS. Different ROS induced different DNA damage profiles in MN. MN were also isolated from adult rats with sciatic nerve avulsions to show that DNA damage emerges early during their degeneration in vivo. This study demonstrates that the comet assay is a feasible method for profiling DNA lesions in the genome of single MN. Viable mature MN can be isolated and used for in vitro models of MN genotoxicity and can be isolated from in vivo models of MN degeneration for profiling DNA damage on a single-cell basis.
Insights
Researchers developed a method to measure DNA damage in single motor neurons (MN). The motor neuron genome is highly susceptible to reactive oxygen species (ROS), with distinct damage profiles observed.
Area of Science:
- Neuroscience
- Genetics
- Toxicology
Background:
- Motor neurons (MN) are crucial for motor function.
- Understanding DNA damage in MN is vital for neurodegenerative diseases.
- Reactive oxygen species (ROS) are implicated in neuronal damage.
Purpose of the Study:
- To develop a method for measuring DNA damage in single motor neurons.
- To assess the susceptibility of the MN genome to various ROS.
- To investigate early DNA damage during in vivo MN degeneration.
Main Methods:
- Isolation of viable alpha-motor neurons from adult rat spinal cord.
- In vitro exposure of MN to hydrogen peroxide, nitric oxide, and peroxynitrite.
- Measurement of DNA lesions (abasic sites, single-strand breaks, double-strand breaks) using single-cell gel electrophoresis (comet assay).
- Isolation of MN from rats with sciatic nerve avulsions to study in vivo degeneration.
Main Results:
- The MN genome demonstrated high susceptibility to ROS-induced DNA damage.
- Different ROS generated distinct DNA damage profiles in MN.
- Early signs of DNA damage were observed in MN during in vivo degeneration following sciatic nerve avulsion.
Conclusions:
- The comet assay is a feasible method for profiling DNA lesions in single MN.
- Isolated viable mature MN can serve as a model for in vitro MN genotoxicity studies.
- MN isolated from in vivo degeneration models allow for single-cell DNA damage profiling.
