Can Exercise Reverse Binge Alcohol-Induced Brain Damage?
Binge pattern drinking is characterized by excessive alcohol intake, combined with multiple periods of intoxication and withdrawal. This excessive consumption produces gray and white matter cell loss and cognitive impairments, leading to a cycle of further alcohol consumption. Animal models implicate the hippocampus, important for learning and memory, as being particularly sensitive to alcohol induced-neurodegeneration. Furthermore, binge alcohol has been shown to induce cell death and inhibit adult neurogenesis. Voluntary running-wheel exercise has been shown to increase hippocampal neurogenesis and promote overall brain health. The current study investigates the effects of repeated binge alcohol exposure and the potential of voluntary exercise to aid in recovery during abstinence. Female Long Evans rats were exposed to 1 or 2 four-day binge alcohol exposures before exercising voluntarily for four weeks. Rats were sacrificed 35 days after their last dose of alcohol and examined for histological markers of neurogenesis (doublecortin (DCX+)) and cell survival, (number of remaining granule cells) in the dentate gyrus. Binge exposure resulted in a decrease in granule cells, an effect that was reversed by exercise. A single binge had no effect on DCX+ cells; however, a second binge significantly reduced the number of DCX+ cells. Exercise increased the number of DCX+ cells in controls, however there was no increase in single binge animals demonstrating a binge induced suppression of the neurogenic effect of exercise. We conclude that while exercise can restore binge alcohol induced loss of granule cells, repeated binge alcohol exposure decreases neuronal differentiation in the hippocampus after 5 weeks of abstinence. Exercise, which promotes neurogenesis in the alcohol-naïve brain, may have limited ability to do so in the binge-exposed brain.