Effect of Different Exercise Loads on Testicular Oxidative Stress and Reproductive Function in Obese Male Mice

Abstract

This study is aimed at investigating the effect of different exercise loads on the reproductive function of obese male mice and the underlying mechanisms. Male mice with high-fat diet-induced obesity were divided into obesity control (OC), obesity moderate-load exercise (OME), and obesity high-load exercise (OHE) groups. The OME and OHE groups were subjected to swimming exercise 5 days per week over a duration of 8 weeks, with the exercise load progressively increased to 2 h per day in the OME group and 2 h twice per day in the OHE group. In the OC group mice without exercise regimen, we observed a decrease in mRNA expression of antioxidant enzymes, increase in free radical products, upregulation of mRNA and protein expression of nuclear factor-κB and proinflammatory cytokines, inhibition of mRNA and protein expression of testosterone synthases, decrease in the serum testosterone level and sperm quality, and increase in sperm apoptosis. Although both moderate-load exercise and high-load exercise reduced body fat, only moderate-load exercise effectively alleviated obesity-induced oxidative stress, downregulated the expression of nuclear factor-κB and proinflammatory cytokines, and reversed the decrease in mRNA and protein expression of testosterone synthases, serum testosterone level, and sperm quality. These changes were not observed in the OHE group mice. Obesity-induced testicular oxidative stress and inflammatory response decreased testosterone synthesis and sperm quality. Moderate-load exercise alleviated the negative effect of obesity on male reproductive function by decreasing testicular oxidative stress and inflammatory responses. Although high-load exercise effectively reduced body fat, its effects on alleviating oxidative stress and improving male reproductive function were limited.

Figure 1

Effect of high-fat diet and exercise on body weight and abdominal fat content. Data are mean ± SE; NC: normal control; OC: obesity control; OME: obesity moderate exercise; OHE: obesity high exercise, vs. NC: ^∗P < 0.05, ^∗∗P < 0.01; vs. OC: ^#P < 0.05, ^##P < 0.01; vs. OME: ^△P < 0.05, ^△△P < 0.01.

Figure 2

Effects of obesity and exercise on testosterone level and sperm quality. Data are mean ± SE; NC: normal control; OC: obesity control; OME: obesity moderate exercise; OHE: obesity high exercise. (e) Normal control (NC) group; (f) high-fat diet obesity control (OC) group; (g) obesity moderate-load exercise (OME) group; (h) obesity high-load exercise (OHE) group. Upper left (UL) region: necrotic cells; upper right (UR) region: late apoptotic cells; lower left (LL) region: live cells; lower right (LR) region: early apoptotic cells. vs. NC: ^∗P < 0.05, ^∗∗P < 0.01; vs. OC: ^#P < 0.05, ^##P < 0.01; vs. OME: ^△P < 0.05, ^△△P < 0.01.

Figure 3

Influence of high-fat diet and exercise on the testicular antioxidant system. T-OAC: total antioxidant capacity; SOD: superoxide dismutase; CAT: catalase; GSH-Px: glutathione peroxidase; GSH: glutathione. Data are mean ± SE; NC: normal control; OC: obesity control; OME: obesity moderate exercise; OHE: obesity high exercise, vs. NC: ^∗P < 0.05, ^∗∗P < 0.01; vs. OC: ^#P < 0.05, ^##P < 0.01; vs. OME: ^△P < 0.05, ^△△P < 0.01.

Figure 4

Effect of high-fat diet and exercise on the testicular oxidative stress product. MDA: malondialdehyde; H₂O₂: hydrogen peroxide; NOS: nitric oxide synthase; NO: nitric oxide. Data are mean ± SE; NC: normal control; OC: obesity control; OME: obesity moderate exercise; OHE: obesity high exercise, vs. NC: ^∗P < 0.05, ^∗∗P < 0.01; vs. OC: ^#P < 0.05, ^##P < 0.01; vs. OME: ^△P < 0.05, ^△△P < 0.01.

Figure 5

Effect of obesity and exercise on the mRNA expression of antioxidant enzymes. T-OAC: total antioxidant capacity; SOD: superoxide dismutase; CAT: catalase; GSH-Px: glutathione peroxidase. Data are mean ± SE; NC: normal control; OC: obesity control; OME: obesity moderate exercise; OHE: obesity high exercise, vs. NC: ^∗P < 0.05, ^∗∗P < 0.01; vs. OC: ^#P < 0.05, ^##P < 0.01; vs. OME: ^△P < 0.05, ^△△P < 0.01.

Figure 6

Effect of obesity and exercise on the mRNA level and protein expression of NF-κB, TNF-α, IL-1β, and IL-10 in the testicular tissue. NF-κB: nuclear factor κB; TNF-α: tumor necrosis factor-α; IL-1β: interleukin-1β; IL-10: interleukin-10. Data are mean ± SE; NC: normal control; OC: obesity control; OME: obesity moderate exercise; OHE: obesity high exercise; vs. NC: ^∗P < 0.05, ^∗∗P < 0.01; vs. OC: ^#P < 0.05, ^##P < 0.01; vs. OME: ^△P < 0.05, ^△△P < 0.01.

Figure 7

Influence of obesity and exercise on mRNA and protein expression of SF-1, StAR, and P450 in the testicular tissue. SF-1: steroidogenic factor-1; StAR: steroidogenic acute regulatory protein; and P450scc: P450 side chain cleavage (Cyp11a1). Data are mean ± SE; NC: normal control; OC: obesity control; OME: obesity moderate exercise; OHE: obesity high exercise, vs. NC: ^∗P < 0.05, ^∗∗P < 0.01; vs. OC: ^#P < 0.05, ^##P < 0.01; vs. OME: ^△P < 0.05, ^△△P < 0.01.