The Putative Caloric Restriction Mimetic Resveratrol has Moderate Impact on Insulin Sensitivity, Body Composition, and the Metabolome in Mice

SCOPE

Data on resveratrol-(trans-3,5,4'-trihydroxystilbene)-induced caloric-restriction-(CR)-mimicking effects in mice receiving a high-fat diet (HFD) are contradictory. It is hypothesized that this can possibly stem from different bioactivities of resveratrol (RSV) microbial metabolites.

METHODS AND RESULTS

C57BL/6Rj mice are fed an ad-libitum HFD supplemented with RSV or its metabolites, dihydroresveratrol (DHR) and lunularin (LUN) (≈28 mg (dihydro)stilbene kg^-1 mouse per day). A 40% CR group was included in the study. While CR mice show robust changes in bodyweight and composition, hormone levels and mRNA expression, slight changes are found (more muscle, less adipose tissue) in body composition, leptin, and insulin levels in RSV-supplemented mice compared to ad libitum controls. LUN hardly and DHR does not change the hormone levels measured. Metabolome analysis of serum shows changes in CR mice but only slight, if any, changes in RSV-, DHR-, or LUN-supplemented mice compared to the controls. Evaluating the capability of RSV and its metabolites to inhibit carbohydrate-hydrolyzing enzymes in vitro, it is found that RSV reduced α-glucosidase activity to a stronger extent than DHR and LUN.

CONCLUSION

Decelerated carbohydrate breakdown by RSV may have contributed to the moderate impact of dietary RSV on mouse insulin sensitivity (lowered fasting and post-glucose-bolus insulin levels).

Resveratrol, lunularin and dihydroresveratrol do not act as caloric restriction mimetics when administered intraperitoneally in mice

Resveratrol as well as caloric restriction were shown to extend lifespan in some model organisms and may possibly delay onset of ageing-related diseases in humans. Yet, resveratrol supplementation does not always extend lifespan of animal models or improve health status of humans. Because of interindividual differences in human microbiota, resveratrol metabolite production in the gut differs. While some individuals produce lunularin and dihydroresveratrol in their gut, others produce dihydroresveratrol only. Therefore, we addressed the question whether these metabolites differ in their biological impact on ageing and intraperitoneally injected 13-month-old C57BL/6JRj mice on an ad-libitum (AL) HFD with resveratrol, dihydroresveratrol or lunularin (24 mg/kg bodyweight; 3 times/week). Compared to mice injected with vehicle (AL-control), resveratrol and dihydroresveratrol did not change bodyweight and had no impact on insulin or glucose levels while lunularin slightly reduced feed intake and bodyweight gain. CR-mice showed lowered cholesterol, insulin and leptin levels, elevated adiponectin and phosphorylated AMPK levels in liver as well as increased transcription of Pck1 and Pgc1α when compared to the AL-control. In contrast, injections with the test substances did not change these parameters. We therefore conclude that in our model, resveratrol, lunularin and dihydroresveratrol did not act as CR mimetics.