Forced treadmill exercise in the male rat: effect on food intake and c-Fos expression

The current study investigated the effect of forced treadmill exercise intensity on food intake in rats, and then on c-Fos immunoreactivity in selected brain sites. In Experiment 1, male Sprague Dawley rats (n = 24) were exposed to three intensities of forced treadmill exercise (32.5, 54 and 75.8 m/min) and food intake was measured 1, 2 and 3 hrs post-exercise. All three exercise intensities significantly reduced food intake at all three timepoints (p < 0.05), with the maximum numerical effect observed at 54 m/min. In Experiment 2, the rats were exposed to forced treadmill exercise at 54 m/min and were then sacrificed 30 min post-exercise. Forced treadmill exercise significantly increased c-Fos expression in several brain areas associated with feeding, these areas were the central nucleus of the amygdala, the dorsal bed nucleus of the stria terminals, and in the paraventricular nucleus, the ventromedial, dorsomedial, and lateral hypothalamus. This is the first report of forced treadmill exercise in the male rat resulting in the expression of c-Fos in the dorsal bed nucleus of the stria terminalis and ventromedial hypothalamus. A brain site not associated with feeding behaviour, the frontal cortex, was analysed to control for false positives, this revealed no significant c-Fos expression following forced treadmill exercise.