Computational Image Analysis of Glial Morphology Following Binge-induced Damage and Exercise-driven Recovery

Neuronal health is dependent upon proper functioning of glial cells. When this support system fails, neurons cannot function properly. Therefore, a more complete understanding of the role of glia in brain health and pathology is vital. Exercise augments the supportive capabilities of glia, which may account for the overall beneficial effect of exercise on brain health. Conversely, binge drinking damages vulnerable corticolimbic structures and causes cognitive impairments. In the present study, we used computational image analysis to examine the effects of binge alcohol consumption and exercise on the glia in the medial prefrontal cortex (mPFC). Twenty-four female Long Evans rats were exposed to a four-day binge before exercising voluntarily for four weeks. Rats were sacrificed 35 days after their last dose of alcohol. The tissue was stained for microglia (Iba1), neurons (NeuN), astrocytes (GFAP) and cell nuclei (DAPI). Fluorescent confocal microscope images were analyzed using FARSIGHT, a computational image analysis toolkit. We found that exercise increased the number of microglia and the amount of GFAP signal surrounding microglia. However, exercise following binge exposure resulted in a reduced number of microglia and stopped the increase of GFAP surrounding microglia. Additionally, the microglia arbors in binged animals did not fan out in all directions, but instead stayed closer together and extended out further; suggesting binge exposure caused a lasting change in microglia reactivity. Together, our results demonstrate enduring changes of binge alcohol consumption in the frontal cortex 35 days after a single binge episode. Furthermore, previous binge exposure appears to reduce the available plastic response of microglia and astrocytes.