The Influence of Physical Training on the Immune System of Rats during N-methyl-N-nitrosourea-Induced Carcinogenesis.

Abstract

To assess the effect of physical training on the selected parameters of the immune system regarding CD3, CD4, CD8, CD11, CD161, CD45A cell counts in rats treated with N-methyl-N-nitrosourea (MNU). Thirty-eight female Sprague-Dawley rats were injected intraperitoneally with MNU and were divided into three groups, i.e., sedentary control (SC), the group of moderate-intensity training (MIT) and the group of high-intensity training (HIT). Physical training was supervised immediately after MNU administration and was conducted 5 days per week for 12 weeks on a three-position treadmill. A significant difference was found between SC and training groups in terms of the number of induced tumors per rat (1.57 vs. 0.4, p = 0.05) and in the following lymphocyte subpopulations: CD4+/CD8+ (p = 0.01), CD3-/CD11b+ (p = 0.02), CD3-/CD161+ (p = 0.002), CD3-/CD161- (p = 0.002), CD3+/CD45RA+ (p = 0.003) and CD3-/CD45RA+ (p = 0.005). In terms of the intensity of physical training, the highest efficacy was found for MIT and the following lymphocyte subpopulations: CD3-/CD11b+ (SC vs. MIT, p < 0.001), CD3-/CD161+ (SC vs. MIT, p = 0.002), CD3-/CD161- (SC vs. MIT, p = 0.002), CD3+/CD45RA+ (SC vs. MIT, p = 0.02) and CD3-/CD45RA+ (SC vs. MIT, p < 0.001, MIT vs. HIT, p = 0.02). Furthermore, negative correlations were found between the number of apoptotic cells and CD3-/CD11b (r = -0.76, p = 0.01) in SC and between the number of induced tumors and CD3+/CD8+ (r = -0.61, p = 0.02) and between their volume and CD+/CD8+ (r = -0.56, p = 0.03) in the group of rats undergoing training. Physical training, particularly MIT, affected immune cell function and an altered immune response can be considered a mechanism underlying the effect of exercise on breast cancer development.