By Molly Daw, Lauren Foley, Cassidy Shaw

Faculty Mentor: Dr. Parrish Waters

Abstract

Exercise is a powerful tool for both physical and mental well-being. Specifically, exercise plays a crucial role in addiction recovery and management of abstinence. The brain dopamine system is composed of neurons that originate in the ventral tegmental area and release dopamine in the nucleus accumbens (NAc). This system controls behaviors associated with reward and also responds strongly to exercise. Recent studies indicate that exercise may be an effective nonpharmacological treatment for substance use disorders. We investigated these possible effects of exercise using a motivation model in mice. Mice freely consume sweet substances (1.5% sucrose water), which elicits dopamine release in the NAc, activating this brain area. To test the ability of exercise to modulate motivation and NAc activity, we kept three groups of mice, one with no running wheel access, one with limited running wheel access, and one with unlimited running wheel access for six weeks. We tested all mice in a sucrose preference test, in which mice chose water or 1.5% sucrose. After testing, we removed the NAc from the mice and measured BDNF, a marker of cell activity. Exercise did not affect sucrose consumption behavior, perhaps due to the metabolic effects of exercise. The effect of exercise on NAc BDNF fell short of statistical significance but exhibited a strong trend toward exercise decreasing activation of the NAc. Our results demonstrate that while exercise may not significantly affect behavioral motivation, it may modulate neural activity in the NAc, suggesting a potential role for exercise to mediate reward-related signaling.