Whey protein sweetened with Stevia rebaudiana increases insulin-degrading enzyme, but not carcinoembryonic antigen-related cell adhesion molecule 1 expression in the liver from resistance-trained rats

Abstract

Abstract

Purpose

In this study, we investigated the effects of the supplementation with whey protein sweetened with Stevia upon insulin clearance markers in the liver and skeletal muscle of resistance-trained rats.

Methods

Male Wistar rats were assigned to four groups: sedentary (SC), trained (TC), trained receiving whey protein (TW), and trained receiving whey protein sweetened with Stevia (TWS). Resistance training consisted of four climbs on a leader, carrying a load of 50, 75, 90, and 100% of the maximum load capacity, 5 days per week. After an 8-week training, an insulin tolerance test (ITT) was performed to evaluate insulin sensitivity. Also, liver and skeletal muscle samples were collected to determine the content of specific proteins (Western blot).

Results

Insulin sensitivity increased in TC rats, but this effect was attenuated in TW and TWS groups. The expression of the major enzyme responsible for insulin degradation, insulin-degrading enzyme (IDE), increased in the liver, but not in the skeletal muscle from TWS compared to TC rats. However, the expression of carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1), a critical mediator for hepatic insulin clearance, was not altered, suggesting that this process was not modulated in the TWS rats.

Conclusion

Our results suggested that the supplementation with whey protein sweetened with Stevia does not change insulin clearance in resistance-trained rats. Also, our results show that it is important to be aware of a possible deleterious effect on insulin sensitivity induced by this supplementation, since the increased insulin sensitivity, induced by resistance training, was attenuated in TWS rats.