Gastric GDF15 levels are regulated by age, sex, and nutritional status in rodents and humans

AIM

Growth differentiation factor 15 (GDF15) is a stress response cytokine that has been proposed as a relevant metabolic hormone. Descriptive studies have shown that plasma GDF15 levels are regulated by short term changes in nutritional status, such as fasting, or in obesity. However, few data exist regarding how GDF15 levels are regulated in peripheral tissues. The aim of the present work was to study the variations on gastric levels of GDF15 and its precursor under different physiological conditions, such as short-term changes in nutritional status or overfeeding achieved by HFD. Moreover, we also address the sex- and age-dependent alterations in GDF15 physiology.

METHODS

The levels of gastric and plasma GDF15 and its precursor were measured in lean and obese mice, rats and humans by western blot, RT-PCR, ELISA, immunohistochemistry and by an in vitro organ culture system.

RESULTS

Our results show a robust regulation of gastric GDF15 production by fasting in rodents. In obesity an increase in GDF15 secretion from the stomach is reflected with an increase in circulating levels of GDF15 in rats and humans. Moreover, gastric GDF15 levels increase with age in both rats and humans. Finally, gastric GDF15 levels display sexual dimorphism, which could explain the difference in circulating GFD15 levels between males and females, observed in both humans and rodents.

CONCLUSIONS

Our results provide clear evidence that gastric GDF15 is a critical contributor of circulating GDF15 levels and can explain some of the metabolic effects induced by GDF15.

Uroguanylin: a new actor in the energy balance movie

Uroguanylin (UGN) is a potential target in the fight against obesity. The mature protein is released after enzymatic cleavage from its natural precursor, proUGN. UGN is mostly produced in the gut, and its production is regulated by nutritional status. However, UGN is also produced in other tissues such as the kidneys. In the past, UGN has been widely studied as a natriuretic peptide owing to its involvement in several different pathologies such as heart failure, cancer and gastrointestinal diseases. However, recent studies have suggested that UGN also acts as a regulator of body weight homeostasis because it modulates both food intake and energy expenditure. This ultimately results in a decrease in body weight. This action is mediated by the sympathetic nervous system. Future studies should be directed at the potential effects of UGN agonists in regulating body weight in human obesity.