Decreased intestinal polyp multiplicity is related to exercise mode and gender in <i>Apc</i>^<i>Min/+</i> mice

Abstract

Moderate-intensity treadmill running can alter male Apc Min/+ mouse polyp formation. This purpose of this study was to examine whether exercise mode differentially affects Apc Min/+ mouse intestinal polyp development in male and female mice. Male and female Apc Min/+ mice were randomly assigned to control, treadmill (18 m/min; 60 min/day; 6 days/wk), or voluntary wheel running (24-h access) groups. Nine weeks of training decreased total intestinal polyps by 29% in male treadmill runners (66 ± 9; P = 0.038) compared with male controls (93 ± 7). The number of large polyps (≥1-mm diameter) were also reduced by 38% in male treadmill runners (49 ± 6; P = 0.005) compared with male controls (79 ± 6). Treadmill running in female Apc Min/+ mice and wheel running in both genders did not affect polyp number or size. Spleen weight decreased in male treadmill runners (91 ± 9 mg; P = 0.011) and wheel runners (75 ± 6 mg; P = 0.004) compared with controls (141 ± 13 mg). Plasma IL-6 was reduced by 96% in male treadmill runners (1.2 ± 0.6 pg/ml) and 78% in male wheel runners (6.6 ± 3.3 pg/ml) compared with control mice (27.9 ± 2.8 pg/ml; P &lt; 0.05). Female mice responded similarly with an 86% decrease in plasma IL-6 with treadmill running (3.2 ± 1.2 pg/ml) and 90% decrease with wheel running (2.9 ± 2.0 pg/ml) compared with control mice (21.1 ± 5.3 pg/ml; P &lt; 0.05). The crypt depth-to-villus height ratio in the intestine, an indirect marker of intestinal inflammation, decreased by 21 ( P = 0.024) and 24% ( P = 0.029), respectively, in male and female treadmill runners but not wheel runners. Physical activity-induced attenuation of intestinal polyp number and size is dependent on exercise mode and differs between genders. The modulation of systemic and intestinal inflammation may also depend on exercise mode.