ACUTE HIGH INTENSITY TREADMILL EXERCISE INCREASES APPETITE AND NPY/AgRP AND TH NEURON ACTIVITY IN UNTRAINED FEMALE MICE

Abstract

Acute High and Moderate Intensity Treadmill Exercise Increases Appetite and NPY/AgRP and TH Neuron Activity in Untrained Female Mice

Background: Exercise is commonly prescribed as a means for weight loss, however, exercise programs frequently have mixed success rates. Recent studies have shown exercise intensities differentially modulate appetite and appetite-regulating neurons in the hypothalamus. Furthermore, these studies have primarily focused on the effects in male mice, and the effects in female mice are unknown. As a result, this study examines the effects of different acute treadmill exercise intensities on appetite regulation in female mice.

Methods: 11 8-week old untrained female mice participated in a randomized-crossover trial of sedentary (sitting on top of running treadmill), low (10 m/min), moderate (14 m/min), and high (18 m/min) intensity acute treadmill exercise. The mice were fasted for 10 hours prior to each trial with 7 days between trials. Food intakes were measured at 1, 2, 3, 6, 12, 24, and 48 hours after exercise. An additional cohort of mice were perfused with PBS and formalin 3 hours post-exercise, and brains were extracted. Immunohistochemical detection for cFOS was performed to determine changes in NPY/AgRP, POMC, TH, and SIM1 neuron activity in response to exercise.

Results: Compared to sedentary trials, cumulative 24-hour food intake was greater following moderate and high intensity exercise, predominantly due to increased food intake 6-12 hours post-exercise. These increases in food intake were associated with increases in activity of the orexigenic NPY/AgRP and TH neuron populations in the arcuate nucleus of the hypothalamus. Interestingly, no effects on appetite were observed in response to low intensity exercise.

Conclusion: These results indicate that higher exercise intensities increase 24 hour food intake post-exercise in female mice, possibly explaining the low success rates of exercise-focused weight loss programs. Low intensity exercise may be a useful exercise regimen due to the absence of compensatory increases in appetite.