Astaxanthin affects oxidative stress and hyposalivation in aging mice

Abstract

Oral dryness, a serious problem for the aging Japanese society, is induced by aging-related hyposalivation and causes dysphagia, dysgeusia, inadaptation of dentures, and growth of oral Candida albicans. Oxidative stress clearly plays a role in decreasing saliva secretion and treatment with antioxidants such astaxanthin supplements may be beneficial. Therefore, we evaluated the effects of astaxanthin on the oral saliva secretory function of aging mice. The saliva flow increased in astaxanthin-treated mice 72 weeks after administration while that of the control decreased by half. The plasma d-ROMs values of the control but not astaxanthin-treated group measured before and 72 weeks after treatment increased. The diacron-reactive oxygen metabolites (d-ROMs) value of astaxanthin-treated mice 72 weeks after treatment was significantly lower than that of the control group was. The plasma biological antioxidative potential (BAP) values of the control but not astaxanthin-treated mice before and 72 weeks after treatment decreased. Moreover, the BAP value of the astaxanthin-treated group 72 weeks after treatment was significantly higher than that of the control was. Furthermore, the submandibular glands of astaxanthin-treated mice had fewer inflammatory cells than the control did. Specifically, immunofluorescence revealed a significantly large aquaporin-5 positive cells in astaxanthin-treated mice. Our results suggest that astaxanthin treatment may prevent age-related decreased saliva secretion.

Keywords: aquaporin-5; astaxanthin; hyposalivation; inflammation; oral dryness.

Fig. 1

Comparison of body weight of astaxanthin (AX) and control groups. Body weight of AX-treated group is significantly lower than that of control group 72 weeks after AX treatment (p<0.05).

Fig. 2

Comparison of saliva amounts between astaxanthin (AX) and control groups. Saliva flow of AX group was significantly higher than that of control group (p<0.05).

Fig. 3

Comparison of Diacron-reactive oxygen metabolites (D-ROMs) value of astaxanthin (AX) and control groups. D-ROMs value of AX group 72 weeks after AX administration was significantly lower than that of control group (p<0.05).

Fig. 4

Comparison of biological antioxidative potential (BAP) values of astaxanthin (AX) and control groups. BAP value of AX group 72 weeks after AX administration was significantly higher than that of control group.

Fig. 5

Changes in ratio of mandibular gland weight to whole body weight. No significant differences were observed in mandibular gland weight/body weight ratio between the astaxanthin (AX) and control groups.

Fig. 6

Changes in ratio of salivary flow to weight of mandibular gland. Ratio of saliva flow and mandibular gland weight was significantly higher in astaxanthin (AX) group than in control group.

Fig. 7

Hematoxylin and eosin (H&E) staining of astaxanthin (AX) group submandibular glands. Submandibular glands of AX-treated group had several large striated ducts (A). Striated ducts were filled with secretory granules present in acinar cells (B).

Fig. 8

Hematoxylin and eosin (H&E) staining of control group submandibular glands. Inflammatory cells infiltration (A) and atrophic acinar cells (B) were observed. Vacuolar or fatty degeneration (C) and fibrous connective tissue (D) were observed.

Fig. 9

Immunohistochemically stained image of aquaporin (AQP)-5-positive domain in the mandibular gland (A) Control group. (B) Astaxanthin (AX) group. Mandibular gland of AX group shows numerous AQP-5-positive cells while that of control group shows few.

Fig. 10

Positive area of aquaporin (AQP)-5. Positive domain of AQP-5 in astaxanthin (AX) group covered a larger area than that of control group.