Antifatigue Effect of Luteolin-6-C-Neohesperidoside on Oxidative Stress Injury Induced by Forced Swimming of Rats through Modulation of Nrf2/ARE Signaling Pathways

Abstract

Luteolin-6-C-neohesperidoside (LN) is a flavonoid isolated from moso bamboo leaf. This study was performed to evaluate the antifatigue effect of LN on a rat model undergoing the weight-loaded forced swimming test (FST). Briefly, male Sprague-Dawley rats (20-22 weeks old) were forced to undertake exhaustive swimming every other day for 3 weeks. Each swimming session was followed by the administration of distilled water, LN (25-75 mg/kg), or ascorbic acid (100 mg/kg) 1 h later. Oral administration of LN significantly improved exercise endurance; normalized alterations in energy metabolic markers; and decreased serum lactic acid, lactate dehydrogenase, and blood urea nitrogen levels of rats that underwent FST. Moreover, LN enhanced the activities of antioxidant enzymes and antioxidant capacity, as measured by enzyme activity assays, RT-PCR, and Western blotting, as well as decreasing the levels of proinflammatory cytokines such as tumor necrosis factor-α, interleukin-1β (IL-1β), and IL-6 and increasing the level of anti-inflammatory (IL-10) in the liver and skeletal muscle. These results suggested that LN reduces both physical and mental effects of chronic fatigue, probably by attenuating oxidative stress injury and inflammatory responses in the liver and skeletal muscle. This study thus supports the use of LN in functional foods for antifatigue and antioxidant effects.

Figure 1

Chemical structure of luteolin-6-C-neohesperidoside (LN).

Figure 2

Effects of LN on the weight-loaded swimming time (a) and the ratio of exhausted swimming time (b) in FST rats. Values are the means ± SD (n = 10). ^∗P < 0.05, ^∗∗P < 0.01, and ^∗∗∗P < 0.001 compared with MC (model control group).

Figure 3

Effects of LN on the histological appearance of the liver (a) and skeletal muscle (b) are shown by photomicrographs. Representative histological sections of the liver and skeletal muscle were stained by hematoxylin and eosin (magnification ×100).

Figure 4

Effects of LN on stress-related production of oxidants and antioxidants in the liver and skeletal muscle. Levels of ROS (a), MDA (b), SOD (c), and GSH-Px (d) in the liver and skeletal muscle were determined by ELISA. ^##P < 0.01 and ^###P < 0.001 compared with NC (normal control group); ^∗P < 0.05, ^∗∗P < 0.01, and ^∗∗∗P < 0.001 compared with MC (model control group).

Figure 5

Effects of LN on pro- and anti-inflammatory cytokine levels in the liver and skeletal muscle. Levels of TNF-α (a), IL-1β (b), IL-6 (c), and IL-10 (d) in the liver and skeletal muscle were determined by ELISA. ^##P < 0.01 and ^###P < 0.001 compared with NC (normal control group); ^∗P < 0.05, ^∗∗P < 0.01, and ^∗∗∗P < 0.001 compared with MC (model control group).

Figure 6

Effects of LN on the mRNA of Nrf2 and HO-1 in the liver and skeletal muscle of FST rats. (a) Representative PCR bands. (b) Relative levels of mRNA. Data are expressed as means ± SD (n = 10). ^#P < 0.05 compared with NC (control group); ^∗P < 0.05, ^∗∗P < 0.01, and ^∗∗∗P < 0.001 compared with MC (model control group).

Figure 7

Effects of LN on antioxidant-related proteins. Levels of Nrf2 and HO-1 in the liver and skeletal muscle of FST rats were determined by Western blot (a). Respective protein adducts were quantified using ImageJ software (b). Data are expressed as means ± SD (n = 10). ^#P < 0.05 compared with NC (control group); ^∗P < 0.05, ^∗∗P < 0.01, and ^∗∗∗P < 0.001 compared with MC (model control group).