Decreased intestinal polyp multiplicity is related to exercise mode and gender in ApcMin/+ mice

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 < 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 < 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.