Photobiomodulation Therapy Restores Olfactory Function Impaired by Photothrombosis in Mouse Olfactory Bulb

Reham A Shalaby; Muhammad Mohsin Qureshi; Mohd Afzal Khan; S M Abdus Salam; Hyuk Sang Kwon; Kyung Hwa Lee; Euiheon Chung; Young Ro Kim

doi:10.1016/j.expneurol.2023.114462

Photobiomodulation Therapy Restores Olfactory Function Impaired by Photothrombosis in Mouse Olfactory Bulb

Exp Neurol. 2023 Sep:367:114462. doi: 10.1016/j.expneurol.2023.114462. Epub 2023 Jun 8.

Authors

Reham A Shalaby¹, Muhammad Mohsin Qureshi², Mohd Afzal Khan¹, S M Abdus Salam³, Hyuk Sang Kwon¹, Kyung Hwa Lee⁴, Euiheon Chung⁵, Young Ro Kim⁶

Affiliations

¹ Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology, South Korea.
² Division of Biophysics and Bioimaging, Princess Margret Cancer Center, Toronto, Ontario, Canada.
³ Department of Pathology, Chonnam National University, Hwasun Hospital and Medical School, BioMedical Sciences Graduate Program (BMSGP), South Korea.
⁴ Department of Pathology, Chonnam National University, Hwasun Hospital and Medical School, BioMedical Sciences Graduate Program (BMSGP), South Korea. Electronic address: mdkaylee@jnu.ac.kr.
⁵ Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology, South Korea; AI Graduate School, Gwangju Institute of Science and Technology, South Korea. Electronic address: ogong50@gist.ac.kr.
⁶ Department of Radiology, Harvard Medical School, Boston, MA, USA.

PMID: 37295546
DOI: 10.1016/j.expneurol.2023.114462

Abstract

An ischemic stroke typically accompanies numerous disorders ranging from somatosensory dysfunction to cognitive impairments, inflicting patients with various neurologic symptoms. Among pathologic outcomes, post-stroke olfactory dysfunctions are frequently observed. Despite the well-known prevalence, therapy options for such compromised olfaction are limited, likely due to the complexity of olfactory bulb architecture, which encompasses both the peripheral and central nervous systems. As photobiomodulation (PBM) emerged for treating ischemia-associated symptoms, the effectiveness of PBM on stroke-induced impairment of olfactory function was explored. Novel mouse models with olfactory dysfunctions were prepared using photothrombosis (PT) in the olfactory bulb on day 0. The post-PT PBM was performed daily from day 2 to day 7 by irradiating the olfactory bulb via an 808 nm laser with a fluence of 40 J/cm2 (325 mW/cm2 for 2 smin per day). The buried food test (BFT) was used to score behavioral acuity in food-deprived mice to assess the olfactory function before PT, after PT, and after PBM. Histopathological examinations and cytokine assays were performed on the mouse brains harvested on day 8. The results from BFT were specific to an individual, with positive correlations between the baseline latency time measured before PT and its alteration at the ensuing stages for both the PT and PT + PBM groups. Also, the correlation analysis in both groups showed highly similar, significant positive relationships between the early and late latency time change independent of PBM, implicating a common recovery mechanism. Particularly, PBM treatment accelerated the recovery of impaired olfaction following PT by suppressing inflammatory cytokines and enhancing both glial and vascular factors (e.g., GFAP, IBA-1, and CD31). PBM therapy during the acute phase of ischemia improves the compromised olfactory function by modulating microenvironments and inflammation status of the affected tissue.

Keywords: Buried food test; Ischemic stroke; Neuroinflammation; Olfactory bulb; Olfactory dysfunction; Photobiomodulation; Photothrombosis.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Disease Models, Animal
Ischemia
Low-Level Light Therapy*
Mice
Olfactory Bulb
Stroke*