Near-infrared light treatment reduces astrogliosis in MPTP-treated monkeys
We have reported previously that intracranial application of near-infrared light (NIr) reduces clinical signs and offers neuroprotection in a subacute MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) monkey model of Parkinson’s disease. In this study, we explored whether NIr reduces the gliosis in this animal model. Sections of midbrain (containing the substantia nigra pars compacta; SNc) and striatum were processed for glial fibrillary acidic protein (to label astrocytes; GFAP) and ionised calcium-binding adaptor molecule 1 (to label microglia; IBA1) immunohistochemistry. Cell counts were undertaken using stereology, and cell body sizes were measured using ImageJ. Our results showed that NIr treatment reduced dramatically (~75 %) MPTP-induced astrogliosis in both the SNc and striatum. Among microglia, however, NIr had a more limited impact in both nuclei; although there was a reduction in overall cell size, there were no changes in the number of microglia in the MPTP-treated monkeys after NIr treatment. In summary, we showed that NIr treatment influenced the glial response, particularly that of the astrocytes, in our monkey MPTP model of Parkinson’s disease. Our findings raise the possibility of glial cells as a future therapeutic target using NIr.
KeywordsSubstantia nigra Striatum Parkinson’s disease Photobiomodulation 670 nm
Glial fibrillary acidic protein
Ionised calcium-binding adaptor molecule 1
Substantia nigra pars compacta
Substantia nigra pars reticulata
We are forever grateful to Michael J Fox Foundation, Credit Agricole Sud Rhones Alpes, Fondation Philanthropique Edmond J Safra, France Parkinson and the French National Research Agency (ANR Carnot Institute), Tenix corp and Salteri family and our industry partners for funding this work. Daniel Johnstone is an Early Career Fellow of the NHMRC, Australia. We thank Sharon Spana, Diane Agay, Guillaume Barboux, Clément Perrin, Cyril Zenga and Mylène D’Orchymont for excellent technical assistance.
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