A Comprehensive Comparison of Different Selenium Supplements: Mitigation of Heat Stress and Exercise Fatigue-Induced Liver Injury

Abstract

This study aimed to compare the protective effects of different selenium supplements against heat stress and exercise fatigue-induced liver injury and to investigate the potential mechanisms of action. Selenium-enriched soybean protein (SePro), selenium-enriched soybean peptides (SePPs), and selenomethionine (SeMet) are organic selenium supplements in which selenium replaces the sulfur in their sulfur-containing amino acids. Common peptides (PPs) are obtained by enzymatic hydrolysis of soybean protein which was extracted from common soybean. The SePPs with higher hydrolysis degree and selenium retention were isolated via alkaline solubilization and acid precipitation and the enzymatic hydrolysis of alkaline protease, neutral protease, and papain. The results showed that SePPs could significantly increase the antioxidant levels in rats, inhibit lipid peroxidation, and reduce liver enzyme levels in rat serum, while the histological findings indicated that the inflammatory cell infiltration in the liver tissue was reduced, and new cells appeared after treatment with SePPs. Moreover, SePPs could increase glutathione (GSH) and GSH peroxidase (GSH-Px) in the liver, as well as protect the liver by regulating the NF-κB/IκB pathway, prevent interleukin 1β (IL-1β), interleukin 6 (IL-6), and tumor necrosis factor α (TNF-α) release in the liver. The SePPs displayed higher antioxidant and anti-inflammatory activity in vivo than SePro, SeMet, Sodium selenite (Na₂SeO₃), and PPs. Therefore, SePPs could be used as a priority selenium resource to develop heatstroke prevention products or nutritional supplements.

Keywords: exercise fatigue; heat stress; heatstroke; inflammation; oxidative damage; selenium-enriched soybean peptides.

FIGURE 1

Preparation of SePPs.

FIGURE 2

Effects of different selenium supplements on CAT (A), SOD (B), MDA (C), GSH (D), and GSH-Px (E) in rat serum. Values are expressed as the mean ± SD, results marked with the same letters were not significantly different (p > 0.05).

FIGURE 3

Effects of different selenium supplements on ALT (A) and AST (B) in rat serum. Values are expressed as the mean ± SD, results marked with the same letters were not significantly different (p > 0.05).

FIGURE 4

Effects of different selenium supplements on GSH (A) and GSH-Px (B) in rat liver. Values are expressed as the mean ± SD, results marked with the same letters were not significantly different (p > 0.05).

FIGURE 5

Histopathology of liver (H&E, × 100). Yellow arrows indicate hepatic sinusoids; blue arrows indicate necrosis of hepatocytes and disappearance of nuclei consolidation and lysis; white arrows indicate hepatic sinusoidal macrophages; black arrows indicate inflammatory cells; green arrows indicate neoplastic cells. (A) Control group, (B) Model group, (C) PC group, (D) SePro group, (E) SePPs group, (F) PPs group, (G) SeMet group, (H) Na₂SeO₃ group.

FIGURE 6

Effects of different selenium supplements on IL-1β (A), IL-6 (B), TNF-α (C), Western blot analysis (D), p-IκB (E), and p65 (F) in rat liver. Values are expressed as the mean ± SD, results marked with the same letters were not significantly different (p > 0.05).

FIGURE 7

Different selenium supplements inhibits inflammatory response by affecting NF-κB/IκB signaling pathway.