Abstract: The intention of this study was to explore the protective effect of mulberry juice concentrate (MJC) on D-galactose-induced damage in the rat spleen. A rat model of aging was induced by D-galactose. Wistar rats were randomly divided into 6 groups: normal control, model, positive control (VE), and low-, medium- and high-dose MJC treatment groups. The activities of total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px) and catalase (CAT), and malondialdehyde (MDA) level of spleen homogenate were measured by using test kit. The levels of tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in serum were determined; the spleen index and the expression levels of caspase-9 and caspase-3 were measured as well. Moreover, histomorphological examination was performed to evaluate the effect of MJC on oxidative damage in the rat spleen. The results showed that compared to the model group, the medium- and high-dose MJC groups could improve the activity of T-SOD, GSH-Px and CAT in spleen tissue (P < 0.05). MJC at all three doses decreased MDA level (P < 0.05) and TNF-α and IL-6 expression levels, and increased spleen index. High-dose MJC could significantly increased T-SOD, GSH-Px and CAT activity to 113.22, 90.17 and 7.67 U/mg protein, decreased MDA level to 13.59 nmol/mg, and enhanced spleen index to 4.12 mg/g compared to the model group, all of which reached the levels of the normal control group and positive control group (P > 0.05). In addition, the expression levels of TNF-α and IL-6 in the high-dose group were decreased to 56.95 and 76.83 pg/mL. The results of immunohistochemistry showed that the expression of caspase-9 and caspase-3 was attenuated by MJC at all doses, and the best effect was found at high dose. Hematoxylin and eosin staining also indicated that MJC could protect spleen structure, increase the number of lymphocytes and improve hyperemia. These results showed that mulberry juice concentrate has a significant protective effect on oxidative damage in the spleen of rats.

Key words: mulberry juice concentrate, D-galactose, oxidative damage, spleen