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Updated: May 21, 2026
A Protocol for Transcranial Photobiomodulation Therapy in Mice
Published on: November 18, 2018
Survival of Dopaminergic Amacrine Cells after Near-Infrared Light Treatment in MPTP-Treated Mice
Cassandra Peoples1, Victoria E Shaw, Jonathan Stone
1Discipline of Anatomy & Histology F13, The University of Sydney, Sydney, NSW 2006, Australia.
Abstract:
We examined whether near-infrared light (NIr) treatment (photobiomodulation) saves dopaminergic amacrine cells of the retina in an acute and a chronic 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson disease. For the acute model, BALB/c mice had MPTP (100 mg/kg) or saline injections over 30 hours, followed by a six-day-survival period. For the chronic model, mice had MPTP (200 mg/kg) or saline injections over five weeks, followed by a three-week-survival period. NIr treatment was applied either at the same time (simultaneous series) or well after (posttreatment series) the MPTP insult. There were four groups within each series: Saline, Saline-NIr, MPTP, and MPTP-NIr. Retinae were processed for tyrosine hydroxylase (TH) immunochemistry, and cell number was analysed. In the MPTP groups, there was a significant reduction in TH(+) cell number compared to the saline controls; this reduction was greater in the acute (~50%) compared to the chronic (~30%) cases. In the MPTP-NIr groups, there were significantly more TH(+) cells than in the MPTP groups of both series (~30%). In summary, we showed that NIr treatment was able to both protect (simultaneous series) and rescue (posttreatment series) TH(+) cells of the retina from parkinsonian insult.
Insights
Near-infrared light (NIr) therapy, a form of photobiomodulation, protected and rescued retinal dopaminergic cells in mouse models of Parkinson disease. This innovative treatment offers potential for neuroprotection in Parkinson
Area of Science:
- Neuroscience
- Ophthalmology
- Biomedical Engineering
Background:
- Parkinson disease is characterized by the loss of dopaminergic neurons.
- Retinal dopaminergic amacrine cells are vulnerable to neurotoxic insults.
- 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a common neurotoxin used to model Parkinson disease.
Purpose of the Study:
- To investigate the neuroprotective effects of near-infrared light (NIr) treatment on retinal dopaminergic amacrine cells.
- To evaluate NIr therapy in both acute and chronic MPTP-induced mouse models of Parkinson disease.
Main Methods:
- BALB/c mice were subjected to acute (30-hour) or chronic (5-week) MPTP injections.
- NIr treatment was administered simultaneously with or after MPTP exposure.
- Retinal tyrosine hydroxylase (TH)-positive cells were quantified using immunochemistry.
Main Results:
- MPTP significantly reduced TH(+) cell numbers in both acute (~50%) and chronic (~30%) models.
- NIr treatment significantly increased TH(+) cell numbers in MPTP-exposed mice by approximately 30% in both models.
- NIr demonstrated both protective (simultaneous) and rescue (posttreatment) effects.
Conclusions:
- Near-infrared light (NIr) photobiomodulation effectively protects and rescues retinal dopaminergic amacrine cells from MPTP-induced neurotoxicity.
- NIr therapy presents a promising therapeutic strategy for neurodegenerative conditions affecting dopaminergic systems, including Parkinson disease.
- The study highlights the potential of NIr as a non-invasive intervention for retinal neuroprotection.
