High-Dose Astaxanthin Supplementation Suppresses Antioxidant Enzyme Activity during Moderate-Intensity Swimming Training in Mice

Abstract

Exercise-induced reactive oxygen and nitrogen species are increasingly considered as beneficial health promotion. Astaxanthin (ASX) has been recognized as a potent antioxidant suitable for human ingestion. We investigated whether ASX administration suppressed antioxidant enzyme activity in moderate-intensity exercise. Seven-week-old male C57BL/6 mice (n = 8/group) were treated with ASX (5, 15, and 30 mg/kg BW) combined with 45 min/day moderate-intensity swimming training for four weeks. Results showed that the mice administrated with 15 and 30 mg/kg of ASX decreased glutathione peroxidase, catalase, malondialdehyde, and creatine kinase levels in plasma or muscle, compared with the swimming control group. Beyond that, these two (15 and 30 mg/kg BW) dosages of ASX downregulated gastrocnemius muscle erythroid 2p45 (NF-E2)-related factor 2 (Nrf2). Meanwhile, mRNA of Nrf2 and Nrf2-dependent enzymes in mice heart were also downregulated in the ASX-treated groups. However, the mice treated with 15 or 30 mg/kg ASX had increased constitutive nitric oxidase synthase and superoxide dismutase activity, compared with the swimming and sedentary control groups. Our findings indicate that high-dose administration of astaxanthin can blunt antioxidant enzyme activity and downregulate transcription of Nrf2 and Nrf2-dependent enzymes along with attenuating plasma and muscle MDA.

Keywords: antioxidant; astaxanthin; chronic exercise; oxidative stress; physical adaption.

Figure 1

The experimental design and flow diagram for evaluation of astaxanthin.

Figure 2

Effects of astaxanthin on the GPx, CAT, and SOD activity in swimming training mice. (A) and (B) display GPx activity in plasma and gastrocnemius muscle among different groups, respectively. (C) exhibits CAT activity in gastrocnemius muscle among various groups, respectively. (D) shows SOD activity in plasma among different groups Values are means ± SD (n = 8). The symbol * indicates a significant difference at p < 0.05, and ** indicates a significant difference at p < 0.01.

Figure 3

Effects of astaxanthin on the MDA level, CK activity, and Nrf2-Keap1 factors’ transcriptional level in swimming training mice. (A) and (B) show the amount of MDA in plasma and muscle among different groups, respectively. (C) represents CK activity in plasma among different groups. (D) outlines transcriptional levels of Nrf2 and Keap1 factors among different groups, in which the fold changes are expressed in relation to the mean of the SEC group. Values are expressed as Box-and-Whisker plots, in which the bottom and top of the box present the first and third quartile, respectively; the band inside the box is always the second quartile (the median); lines extending vertically from the boxes (whiskers) stand for the upper and lower extreme (the highest and lowest number in a set of data), and plus signs indicate the mean for each group. The symbol * indicates a significant difference at p < 0.05, and ** indicates a significant difference at p < 0.01.

Figure 4

Effects of astaxanthin on transcription of Nrf2 and Nrf2-dependent enzymes in swimming training mice heart. (A) exhibits mRNA levels of Nrf2 among different groups, (B) presents GCLM transcriptional levels among different groups and (C) exhibits GCLC transcriptional levels among different groups. (D) shows NQO-1 transcriptional level among different groups and (E) shows HMOX-1 transcriptional level among different groups. Values are expressed as Box-and-Whisker plots, in which the bottom and top of the box present the first and third quartile, respectively; the band inside the box is always the second quartile (the median); lines extending vertically from the boxes (whiskers) stand for the upper and lower extreme (the highest and lowest number in a set of data), and plus signs indicate the mean for each group. The symbol * indicates a significant difference at p < 0.05, and ** indicates a significant difference at p < 0.01.

Figure 5

Effects of astaxanthin on NOS activity in plasma in swimming training mice. (A) exhibits tNOS levels among different groups, (B) exhibits cNOS levels among different groups, and (C) presents iNOS level among different groups. Values are means ± SD (n = 8). The symbol * indicates a significant difference at p < 0.05, and ** indicates a significant difference at p < 0.01.