Protective effects of polyunsatutared fatty acids supplementation against testicular damage induced by intermittent hypobaric hypoxia in rats

Abstract

Background: Intermittent hypobaric hypoxia (IHH) induces changes in the redox status and structure in rat testis. These effects may be present in people at high altitudes, such as athletes and miners. Polyunsaturated fatty acids (PUFA) can be effective in counteracting these oxidative modifications due to their antioxidants properties. The aim of the work was to test whether PUFA supplementation attenuates oxidative damage in testis by reinforcing the antioxidant defense system. The animals were divided into four groups (7 rats per group): normobaric normoxia (~750 tor; pO2 156 mmHg; Nx); Nx + PUFA, supplemented with PUFA (DHA: EPA = 3:1; 0.3 g kg(-1) of body weight per day); hypoxic hypoxia (~428 tor; pO2 90 mmHg; Hx) and, Hx + PUFA. The hypoxic groups were exposed in 4 cycles to 96 h of HH followed by 96 h of normobaric normoxia for 32 days. Total antioxidant capacity (FRAP) and lipid peroxidation (malondialdehyde, MDA) in plasma and reduced (GSH)/oxidized glutathione (GSSG) ratio, tissue lipid peroxidation (TBARS) and antioxidant enzymes activity were assessed at the end of the study in testis. Also, SIRTUIN 1 and HIF-1 protein expression in testis were determined.

Results: IHH increased lipid peroxidation in plasma and HIF-1 protein levels in testis. In addition, IHH reduced FRAP levels in plasma, antioxidant enzymes activities and SIRTUIN 1 protein levels in testis. PUFA supplementation attenuated these effects, inducing the increases in FRAP, in the antioxidant enzymes activity and HIF-1 levels.

Conclusions: These results suggest that the IHH model induces a prooxidant status in plasma and testis. The molecular protective effect of PUFA may involve the induction of an antioxidant mechanism.

Figure 1

Effects of PUFA supplementation on antioxidant capacity and lipid peroxidation in plasma. FRAP levels (A) and malondialdehyde (MDA) (B) levels were assessed in plasma at the end of study. Normobaric (Nx, n = 7) and intermittent hypobaric hypoxia (Hx, n = 7). Supplemented rats: normobaric, Nx + PUFA (n = 7) and intermittent hypobaric hypoxia, Hx + PUFA (n = 7). Bars indicate mean ± SD. Significant differences: *p < 0.05 vs Nx; ^†p < 0.05 vs Hx.

Figure 2

Effects of PUFA supplementation on antioxidant enzymes activity in testis. Superoxide dismutase (SOD, A) and glutathione peroxidase (GSH-Px, B) activities were assessed in testis at the end of study. Normobaric (Nx, n = 7) and intermittent hypobaric hypoxia (Hx, n = 7). Supplemented rats: normobaric, Nx + PUFA (n = 7) and intermittent hypobaric hypoxia, Hx + PUFA (n = 7). Bars indicate mean ± SD. Significant differences: *p < 0.05 vs Nx; ^†p < 0.05 vs Hx; ^σp < 0.05 vs Nx + PUFA.

Figure 3

Effects of PUFA supplementation on oxidative stress markers in testis. TBARS levels (A) and (GSH/GSSG) ratio (B) were assessed in testis at the end of study. Normobaric (Nx, n = 7) and intermittent hypobaric hypoxia (Hx, n = 7). Supplemented rats: normobaric, Nx + PUFA (n = 7) and intermittent hypobaric hypoxia, Hx + PUFA (n = 7). Bars indicate mean ± SD. Significant differences: *p < 0.05 vs Nx; ^†p < 0.05 vs Hx; ^σp < 0.05 vs Nx + PUFA.

Figure 4

Effects of PUFA supplementation on SIRTUIN-1 and HIF-1. Protein Expression Level. A: Sirtuin-1 (SIRT-1) and B: HIF-1α levels were assessed in testis at the end of study. Normobaric (Nx, n = 7) and intermittent hypobaric hypoxia (Hx, n = 7). Supplemented rats: normobaric, Nx + PUFA (n = 7) and intermittent hypobaric hypoxia, Hx + PUFA (n = 7). Bars indicate mean ± SD. Significant differences: *p < 0.05 vs Nx.