Longitudinal stability of retinal blood flow regulation in response to flicker stimulation and systemic hyperoxia in mice assessed with laser speckle flowgraphy

Junya Hanaguri,Lih Kuo,Satoru Yamagami,Harumasa Yokota,Taiji Nagaoka,Masahisa Watanabe

doi:10.1038/s41598-020-75296-y

Junya Hanaguri, Lih Kuo + Show 4 more

Open Access

https://doi.org/10.1038/s41598-020-75296-y

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Journal: Scientific Reports	Publication Date: Nov 13, 2020
Citations: 13	License type: open-access

Affiliation: Nihon University, Texas A&M University

Abstract

This study aimed to evaluate longitudinal changes in retinal blood flow in response to flicker stimulation and systemic hyperoxia in mice using a laser speckle flowgraphy (LSFG-Micro). The retinal blood flow in vascular area surrounding the optic nerve head was measured in 8-week-old male mice every 2 weeks until age 20-week. The coefficient of variation of retinal blood flow under resting condition was analyzed every 2 weeks to validate the consistency of the measurement. On day 1 of the experiment, retinal blood flow was assessed every 20 s for 6 min during and after 3 min flicker light (12 Hz) stimulation; on day 2, retinal blood flow was measured every minute for 20 min during and after 10 min systemic hyperoxia; and on day 3, electroretinography (ERG) was performed. Body weight, systemic blood pressure, and ocular perfusion pressure increased significantly with age, but the resting retinal blood flow and ERG parameters remained unchanged. Retinal blood flow significantly increased with flicker stimulation and decreased with systemic hyperoxia, independent of age. The LSFG-Micro provides consistent and reproducible retinal blood flow measurement in adult mice. Longitudinal assessments of retinal blood flow in response to flicker stimulation and systemic hyperoxia may be useful indexes for noninvasive monitoring of vascular function in retinas.

Highlights

This study aimed to evaluate longitudinal changes in retinal blood flow in response to flicker stimulation and systemic hyperoxia in mice using a laser speckle flowgraphy (LSFG-Micro)
During the period of the experiments, significant increasing trends were found for the body weight, systemic blood pressure (SBP), diastolic BP (DBP), mean BP (MBP) and ocular perfusion pressure (OPP) from 8 to 20 weeks of age (Table 1)
We found that the resting retinal blood flow remained relatively constant in mice from age 8 weeks to 20 weeks, whereas body weight and systemic BP increased significantly

Summary

Introduction

This study aimed to evaluate longitudinal changes in retinal blood flow in response to flicker stimulation and systemic hyperoxia in mice using a laser speckle flowgraphy (LSFG-Micro). The question remains unclear whether the responses of retinal blood flow to flicker stimulation and systemic hyperoxia, in relation to the function of neural retina (i.e., ERG), are altered longitudinally with age in the same subjects. To address these issues, we investigated and validated whether a LSFG-Micro can be used as a tool to consistently and reliably assess retinal circulation in response to flicker stimulation and systemic hyperoxia in mice. The longitudinal characterization of retinal blood flow was performed in mice from age 8 weeks to 20 weeks, the age that often used for biological research[15]

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