Class-specific responses of brown adipose tissue to steroidal and nonsteroidal mineralocorticoid receptor antagonists.

Aldosterone exerts deleterious effects on the cardiovascular system and promotes adipose tissue expansion via mineralocorticoid receptor (MR) activation. We previously demonstrated that administration of steroidal mineralocorticoid receptor antagonists (MRA) in mice fed a moderate high-fat diet is able to reduce white adipose tissue (WAT) expansion, stimulate browning of WAT and activate interscapular brown adipose tissue (iBAT). Here, we aimed to compare the metabolic and adipose tissue-specific effects of the novel non-steroidal MRA finerenone (Fine) and spironolactone (Spiro) in a mouse model of very high-fat diet (HFD)-induced obesity. C57BL/6 J male mice were fed a 60% HFD containing or not Spiro or Fine for 12 weeks. WAT and iBAT morphology and adipose tissue gene expression analysis were assessed. After 12 weeks, both groups of mice showed similar weight gain compared to the HFD group. Histological and molecular analyses of WAT did not show significant differences among all experimental groups; differently, iBAT histological analysis revealed that Fine was able to increase recruitment of brown adipocytes in this depot, whereas mice treated with Spiro failed to elicit any iBAT response, as indicated by no changes in lipid droplets size and iBAT density, compared to HFD. Increased iBAT recruitment could explain, at least in part, the improved insulin resistance observed in mice treated with Fine, as shown by a significant reduction in homeostasis model assessment of insulin resistance (HOMA) index. These findings were confirmed by gene expression analysis of ucp-1, pgc1-α, and beta-3 adrenoreceptor (Adrb3) in iBAT, revealing significantly higher expression of these thermogenic genes in HFD + Fine group compared to HFD, whereas Spiro did not modify their expression. In summary, we demonstrated that, differently from Fine, Spiro did not induce iBAT recruitment. Our current study suggests that Fine, through its direct effects on iBAT, represents a promising pharmacologic tool to treat human metabolic diseases associated with adipose tissue dysfunctions.

Nonsteroidal mineralcorticoid receptor antagonists: Novel therapeutic implication in the management of patients with type 2 diabetes.

Growing evidencehas described a correlation between aldosterone, obesity, and insulin resistance, suggesting that adipocyte-related factors and mineralocorticoid receptor (MR) overactivation may alter aldosterone secretion, potentially leading to obesity and glucose intolerance. Preclinical studies showed that pharmacological antagonism of MR prevents white adipose tissue dysfunction(s) and expansion, activates brown adipose tissue, and improves glucose tolerance. The clinical use of nonsteroidal MR antagonists has been shown to reduce the risk of diabetic kidney disease progression and cardiovascular events in patients with diabetes. This review aims to summarize the effects of pharmacological MR blockade on obesity and its associated metabolic comorbidities, with a particular focus on the therapeutic implications of nonsteroidal MR antagonists in the management of patients with diabetes.

A novel combined glucocorticoid-mineralocorticoid receptor selective modulator markedly prevents weight gain and fat mass expansion in mice fed a high-fat diet.

BACKGROUND: We have previously shown that antagonism of the mineralocorticoid receptor (MR) results in a potent antiadipogenic activity, in vitro and in vivo. Excessive glucocorticoid exposure is associated with obesity and related disorders in humans and mice. METHODS: In this study, responses to a novel combined glucocorticoid receptor (GR)/MR antagonist were investigated in a model of diet-induced obesity. Female 10-week-old C57BL/6J mice were fed with normal chow or a high-fat diet (HFD) for 9 weeks. Mice fed a HFD were concomitantly treated for 9 weeks with the GR antagonist mifepristone (80 mg kg(-1) per day) or the novel combined GR/MR antagonist CORT118335 (80 mg kg(-1) per day). Male, juvenile 6-week-old C57BL/6J mice fed HFD were treated with CORT118335 for 4 weeks. RESULTS: Mice fed a HFD showed a significant increase in total body weight and white fat mass, with impaired glucose tolerance and increased fat infiltration in livers. Interestingly, only CORT118335 completely prevented the HFD-induced weight gain and white fat deposition, whereas mifepristone showed no effect on body weight and modestly increased subcutaneous fat mass. Importantly, food intake was not affected by either treatment, and CORT118335 dramatically increased PGC-1α protein expression in adipose tissue, without any effect on UCP1. Both CORT118335 and mifepristone produced metabolic benefit, improving glucose tolerance, increasing adiponectin plasma levels, decreasing leptin and reducing mean adipocyte size. When tested in vitro, CORT118335 markedly reduced 3T3-L1 differentiation and reversed MR-mediated pro-adipogenic effects of aldosterone; differently, GR-mediated effects of dexamethasone were not antagonized by CORT118335, suggesting that it mostly acts as an antagonist of MR in cultured preadipocytes. CONCLUSIONS: Combined GR/MR pharmacological antagonism markedly reduced HFD-driven weight gain and fat mass expansion in mice through the increase in adipose PGC-1α, suggesting that both receptors represent strategic therapeutic targets to fight obesity. The effects of CORT118335 in adipocytes seem predominantly mediated by MR antagonism.