Fucoidan Oligosaccharide Supplementation Relieved Kidney Injury and Modulated Intestinal Homeostasis in D-Galactose-Exposed Rats.

A fucoidan oligosaccharide (FOS), a potent compound derived from algae, is known for its diverse biological activities, including prebiotic activity, anticancer activity, and antioxidative properties, and has demonstrated supportive therapeutic effects in treating kidney ailments. This study was conducted to explore the protective influence of FOS on kidney damage due to aging induced by D-galactose in Sprague Dawley (SD) rats. The low-dose FOS group was administered FOS (100 mg/kg) by gavage, and the high-FOS group received FOS (200 mg/kg) by gavage. The findings showed that FOS could effectively mitigate kidney damage and improve the pathological condition of kidney tissues caused by D-gal and enhance kidney function. Intervention with FOS significantly reduced serum creatinine, serum uric acid, and serum urea nitrogen levels, compared to the model group. The protective mechanism of FOS on D-gal-induced kidney injury may be to inhibit oxidative stress and improve impaired mitochondrial function by downregulating the AMPK/ULK1 signaling pathway. FOS could also modulate the expression of mitochondrial autophagy-related proteins (Beclin-1, P62, and LC3II/LC3I), thereby mitigate D-gal-induced excessive mitophagy in the kidney. Furthermore, FOS may protect against kidney injury by preserving intestinal homeostasis. FOS decreased serum lipopolysaccharide levels and enhanced intestinal mucosal barrier function. FOS upregulated the abundances of , , and , while it decreased the abundances of , , and . FOS supplementation modulated gut microbiota composition, increasing beneficial bacteria and reducing detrimental ones, potentially contributing to improved kidney function. FOS may safeguard against renal injury in D-gal-exposed rats by inhibiting kidney excessive mitophagy, preserving mitochondrial function, and regulating intestinal homeostasis.