Objective To investigate the effects of exogenous free and conjugated sialic acids (SA)on SA levels in blood and tissues and gut microbiota. Methods Eighteen healthy adult male SPF-grade SD rats were randomly divided into three groups (n=6 per group): a blank control group, a SA group, and a sialyllactose (3'-SL) group. The control group received saline by gavage, the SA group was administered 25.0 mg/(kg·d) of SA, and the 3'-SL group received 51.3 mg/(kg·d) of 3'-SL for 30 consecutive days. Plasma and erythrocyte membrane SA contents were measured on days 5, 10, 15, 20, 25, and 30. After the intervention, SA levels in the liver, spleen, kidney, and lung were assessed. The hepatic sialidase, sialyltransferase activity, and serum sialidase activity were detected. Immunohistochemistry was used to observe SA distribution in the lung. Additionally, gut microbiota, was analyzed. Results Compared with the control group, both the SA and 3'-SL groups showed increased plasma and erythrocyte membrane SA levels. The 3'-SL group exhibited significantly higher pulmonary SA content (P<0.05), increased alveolar SA distribution, and elevated hepatic sialidase levels (P<0.05). Gut microbiota analysis revealed an increase in some beneficial bacteria in both intervention groups. Conclusions upplementation with SA and 3'-SL significantly increased sialic acid levels, with 3'-SL showing higher efficacy. SA and 3'-SL also modulated gut microbiota composition, thereby possibly influencing some metabolism pathways indirectly.
Key words
sialic acid /
sialyllactose /
sialic acid content /
gut microbiota /
rat
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