Air pollution and vision: Characterizing retinal function and dopamine utilization in ozone exposed rats

Title Air pollution and vision: Characterizing retinal function and dopamine utilization in ozone exposed rats
Author, Co-Author Carlos Garcia, A. Phillip Aitsebaomo, Jordan Wetz
Topic Ocular physiology
Year
2016
Day
Thursday
Program Number
165148
Room
Ballroom A-B
Affiliation
Abstract
PURPOSE: The impact of the air pollutant ozone (O3), a strong oxidant, on the retina is unknown. The purpose of this study is to compare retinal function and dopamine (DA) utilization in control and ozone-exposed Long Evans rats.

METHODS: Age- and sex-matched rats were separated into two groups (n=12 rats); six control (clean air) and six acute O3-exposed (0.4 ppm for 4 hours). In each rat, the scotopic and photopic electroretinogram (ERG) was measured. Recordings were performed under anesthesia (ketamine 70 mg/kg, xylazine 2.5 mg/kg, IP). Active corneal electrodes were designed for use in rats. A ground needle electrode was placed subcutaneously in the real flank of the animal. Pupils were dilated with 2.5% phenylephrine and 1% tropicamide eye drops. Lubrication and proper electrical conductance of the active electrodes were maintained. Rats were dark adapted for 30 minutes before scotopic responses were measured. The concentration of dopamine (DA), dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) was measured by HPLC in the retinas of both groups.

RESULTS: Data indicates exposure to O3 significantly (p < 0.05) reduced the scotopic and photopic a-wave amplitude (mean decrease =11 μV and 2.15 μV respectively), and increased the b-wave amplitude by 7.72 μV in the dark adapted ERG. The latency period of the scotopic ERG was significantly (p < 0.05) altered. Dopamine utilization was lower in the ozone exposed retinas as indicated by decreases in DA (2.9 ng/retina), DOPAC (2.3 ng/retina) and HVA (0.42 ng/retina).

CONCLUSIONS: This work demonstrates O3 air pollution may contribute to vision deficits in populations living in air-polluted environments and provides data for establishing air quality standards to better protect sensitive populations, and prevent the oxidative stress that often contributes to retinal neuronal dysfunction.

Affiliation of Co-Authors University of the Incarnate Word, The UNiversity of the INcarnate Word
Outline