Photobiomodulation with near infrared light mitigates Alzheimer's disease-related pathology in cerebral cortex - evidence from two transgenic mouse models

Sivaraman Purushothuman; Daniel M Johnstone; Charith Nandasena; John Mitrofanis; Jonathan Stone

doi:10.1186/alzrt232

Photobiomodulation with near infrared light mitigates Alzheimer's disease-related pathology in cerebral cortex - evidence from two transgenic mouse models

Alzheimers Res Ther. 2014 Jan 3;6(1):2. doi: 10.1186/alzrt232. eCollection 2014.

Authors

Sivaraman Purushothuman¹, Daniel M Johnstone¹, Charith Nandasena¹, John Mitrofanis², Jonathan Stone¹

Affiliations

¹ Bosch Institute, University of Sydney NSW 2006, Australia ; Discipline of Physiology, Anderson Stuart Building F13, University of Sydney NSW 2006, Australia.
² Bosch Institute, University of Sydney NSW 2006, Australia ; Discipline of Anatomy & Histology, Anderson Stuart Building F13, University of Sydney NSW 2006, Australia.

Abstract

Introduction: Previous work has demonstrated the efficacy of irradiating tissue with red to infrared light in mitigating cerebral pathology and degeneration in animal models of stroke, traumatic brain injury, parkinsonism and Alzheimer's disease (AD). Using mouse models, we explored the neuroprotective effect of near infrared light (NIr) treatment, delivered at an age when substantial pathology is already present in the cerebral cortex.

Methods: We studied two mouse models with AD-related pathologies: the K369I tau transgenic model (K3), engineered to develop neurofibrillary tangles, and the APPswe/PSEN1dE9 transgenic model (APP/PS1), engineered to develop amyloid plaques. Mice were treated with NIr 20 times over a four-week period and histochemistry was used to quantify AD-related pathological hallmarks and other markers of cell damage in the neocortex and hippocampus.

Results: In the K3 mice, NIr treatment was associated with a reduction in hyperphosphorylated tau, neurofibrillary tangles and oxidative stress markers (4-hydroxynonenal and 8-hydroxy-2'-deoxyguanosine) to near wildtype levels in the neocortex and hippocampus, and with a restoration of expression of the mitochondrial marker cytochrome c oxidase in surviving neurons. In the APP/PS1 mice, NIr treatment was associated with a reduction in the size and number of amyloid-β plaques in the neocortex and hippocampus.

Conclusions: Our results, in two transgenic mouse models, suggest that NIr may have potential as an effective, minimally-invasive intervention for mitigating, and even reversing, progressive cerebral degenerations.