Exercise-induced 3′-sialyl lactose in breast milk is a critical mediator to improve metabolic health and cardiac function in mouse offspring
Many studies have discussed the metabolic benefits of exercise in different health conditions, such as pregnancy. However, the mechanism of how these benefits get transferred to newborns is still unclear. The author’s Harris and colleagues (2020) published a paper titled “Exercise-induced 3′-sialyl lactose in breast milk is a critical mediator to improve metabolic health and cardiac function in mouse offspring” in the journal “Nature Metabolism”. The summary of the study paper is given below:
Objectives:
To identify the breast-milk component that transmits the metabolic effects of exercise to offspring.
Method:
Six-week-old C57BL/6 female mice were included in the study. They were subdivided into singular housing into standard cages (SED) or cages containing an exercise wheel (TRAIN). All mothers have prescribed a high-fat diet and the exercise-training criterion consisting of voluntary wheel-running 2 weeks before conception and continuous 3weeks of gestation. Cross fostering is used to investigate the effect of exercise-trained milk on metabolic health. Genetic modification is used to lack 3′-sialyl lactose (3′SL) in mice to study whether 3′-SL was the predominant component responsible for the improved metabolic and cardiac phenotype in offspring from exercise-trained dams. For further confirmation, 3’SL supplementation is also incorporated. 3’ SL supplementation and high-fat diet were also provided to male mice to investigate the protective effect of 3’SL in the development of obesity or metabolic disease.
Findings:
Maternal exercise during pregnancy helps in providing metabolic protection to offspring, and these benefits continue beyond childhood. Additionally, maternal exercise has been shown to reduce age-related impairments in glucose metabolism, increases in adiposity, and cardiovascular disorders in the offspring. The cross-fostering and genetic manipulation between sedentary mothers and exercising mothers indicated that the intrauterine environment of exercised mothers does not appear to be important for the potent metabolic effects in the offspring. This supports the hypothesis that the mediating factors are probably present in breast milk. Benefits similar to the offspring of exercise-trained dams were observed in offspring supplemented with exogenous 3′SL daily and was on a high-fat diet. Along with already mentioned metabolic benefits, the supplementation was also found to terminate the effect of a high-fat diet on body weight and glucose tolerance. The study concludes that 3’SL can be used as an exercise ‘mimetic’ for treating cardiac conditions such as hypertension and heart failure. Exercise during gestation also helps to improve cognitive function in offspring, 3‘SL may also show similar outcomes.
The compelling results of this study can be used as a novel therapeutic strategy in the treatment of metabolic disorders such as diabetes. Authors acknowledge future studies for investigating the therapeutic potential of 3’SL.
Limitation:
Investigators don’t highlight the explanation of the sex difference observed in metabolic benefits of maternal exercise or 3′SL supplementation. Whether the benefits were more pronounced in male offspring than female offspring? Additionally, the mechanism involved in providing protective functions from 3’SL is unknown. Organs and cell types affected by the molecule, whether there is a direct effect on adipose tissue cells and their interaction with other molecules is unclear.
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