Sex-specific retinal anomalies induced by chronic social stress in mice

Major depressive disorder (MDD) is one of the most common consequences of chronic stress. Still, there is currently no reliable biomarker to detect individuals at risk to develop MDD. Recently, the retina emerged as an effective way to approach the brain and investigate psychiatric disorders with the use of the electroretinogram (ERG). In this study, cones and rods ERGs were performed in male and female mice before and after chronic social defeat stress (CSDS). Mice were then divided as susceptible or resilient to stress. Significant results were only observed in rods ERGs. In males, susceptible mice showed prolonged a-wave implicit times at baseline that were shortened after CSDS. The a-wave was also decreased in both susceptible and resilient male mice after CSDS. In females, rod a-waves were shorter in susceptible than in control mice after CSDS resulting from the latter demonstrating delayed a-waves. Baseline ERGs were able to predict - to some extent - the expression of susceptibility and resilience before stress exposition in male and female mice. Overall, our findings suggest that retinal activity is a presumptive biomarker of stress response and that the ERG could potentially serve as a predicting tool of the stress response in mice.