Evaluation of the biological effects of near infrared illumination and biomarker research on the late stages of Parkinson's disease in a novel mouse model

Parkinson’s disease (PD) is the secondary neurodegenerative disease around the world, affecting more than 6,5 million people. This disease is characterized by a myriad of motor and non motor dysfunctions that worsen over time. Until now, the disease etiology remains unclear, partly because existing PD animal models fail to mimick the physiopathology. Based on the administration of a pathogenic protein (alpha-synuclein) playing a key role in PD, a mouse model has recently been developed at Clinatec (CEA Grenoble) presenting chronic and progressive symptoms that aggravate over time. Neuroprotective effects of Near Infrared (NIR) illumination, also known as photobiomodulation, have been highlighted in various pathological conditions, notably in PD. Indeed, some preclinical studies have shown its efficiency on early PD stages, leading to a clinical trial initiated in 2021 at Clinatec. This study aims to demonstrate, on later PD stages, the efficacy of NIR on our alpha-synuclein animal model, and to finalize its characterization over time in order to shed light on some biomarkers of the disease. To do so, fourty-four 8-week-old BALB/cByJ male mice were included in the study and PD was induced to half of them. Locomotor coordination and exploratory activity of all mice were regularly assessed. NIR illumination was daily administered to treatment groups. Preliminary results underline that the NIR treatment can mitigate the locomotor deficits induced by the alpha-synuclein protein. Moreover, our study reveals that the administration of this latter might lead to a stress susceptibility, which is one of the clinical features of PD.