Whey Protein Concentrate WPC-80 Improves Antioxidant Defense Systems in the Salivary Glands of 14-Month Wistar Rats

Abstract

Whey protein concentrate (WPC) is characterized by powerful antioxidant properties, but its effect on redox homeostasis of salivary glands of aging organisms is still unknown. In this study, we are the first to evaluate the antioxidant barrier of salivary glands of 14-month Wistar rats fed WPC-80. Total antioxidant status (TAS), total oxidant status (TOS), oxidative stress index (OSI), activities of glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase (CAT) as well as concentrations of reduced glutathione (GSH) are estimated in the submandibular and parotid glands of rats administered WPC-80 intragastrically for a period of 7 and 14 days. We demonstrate a significant increase in GSH, GPx and SOD in the salivary glands of rats fed WPC-80 for 14 days and a significant increase in TAS, GPx and SOD in the parotid glands of rats fed WPC-80 for 7 days compared to control rats. The beneficial effects of WPC-80 on salivary glands are also demonstrated by lower TOS and OSI in the parotid glands of rats fed WPC-80 compared to the submandibular glands. In summary, we demonstrate that WPC-80 improves redox homeostasis in salivary glands, particularly in the parotid glands of old rats.

Keywords: aging; oxidative stress; salivary antioxidants; salivary glands; whey.

Figure 1

Salivary gland mass of rats from control and experimental groups. Abbreviations: C7, C14, control groups; WPC7, WPC14, experimental groups treated WPC-80. Data are presented as a bar chart with the individual data points; ⁺ p < 0.05 of the C14 submandibular gland and ### p < 0.001 of the submandibular gland, respectively, for the same groups. Because the results were not normally distributed, the Mann–Whitney test was used to compare differences between the studied groups.

Figure 2

Total protein concentration of the submandibular and parotid glands of rats from control and experimental groups. Abbreviations: C7, C14, control groups; WPC7, WPC14, experimental groups treated WPC-80. Data are presented as a bar chart with the individual data points; ⁺⁺⁺ p < 0.001 of the C14 submandibular gland and ^### p < 0.001 of the submandibular gland, respectively, for the same groups. Because the results were not normally distributed, the Mann-Whitney test was used to compare differences between the studied groups.

Figure 3

Total antioxidant status (A), total oxidant status (B) and oxidative stress index (C) in the salivary glands of rats from control and experimental groups. Abbreviations: C7, C14, control groups; WPC7, WPC14, experimental groups treated WPC-80; OSI, oxidative stress index; TAS, total antioxidant status; TOS, total oxidant status. Data are presented as a bar chart with the individual data points; ⁺⁺⁺ p < 0.001 of the C7 submandibular gland, *p < 0.05 of the WPC7 submandibular gland, ** p < 0.01 of the WPC7 submandibular gland, *** p < 0.001 of the WPC7 parotid gland and ^### p < 0.001 of the submandibular gland, respectively, for the same groups. Because the results were not normally distributed, the Mann–Whitney test was used to compare differences between the studied groups.

Figure 4

Glutathione peroxidase (A), superoxide dismutase (B) and catalase (C) activities in the salivary glands of rats from control and experimental groups. Abbreviations: C7, C14, control groups; WPC7, WPC14, experimental groups treated WPC-80; CAT, catalase; GPx, glutathione peroxidase; SOD, superoxide dismutase. Data are presented as a bar chart with the individual data points; ⁺ p < 0.05 of the C14 submandibular gland or of the C7 parotid gland, ⁺⁺ p < 0.01 of the C14 submandibular gland, ⁺⁺⁺ p < 0.001 of the C7 parotid gland, * p < 0.05 of the WPC14 parotid gland, *** p < 0.001 of the WPC14 parotid gland, and ^## p < 0.01 and ^### p < 0.001 of the submandibular gland, respectively, for the same groups. Because the results were not normally distributed, the Mann–Whitney test was used to compare differences between the studied groups.

Figure 5

Reduced glutathione (GSH) content in the salivary glands of rats from control and experimental groups. Abbreviations: C7, C14, control groups; WPC7, WPC14, experimental groups treated WPC-80; GPx, glutathione peroxidase. Data are presented as a bar chart with the individual data points; ⁺ p < 0.05 of the C14 submandibular gland or of the C7 parotid gland; ⁺⁺⁺ p< 0.001 of the C14 parotid gland, and ^# p < 0.05 and ^### p < 0.001 of the submandibular gland, respectively, for the same groups. Because the results were not normally distributed, the Mann–Whitney test was used to compare differences between the studied groups.