Bile acid receptor agonists INT747 and INT777 decrease oestrogen deficiency-related postmenopausal obesity and hepatic steatosis in mice.

Menopause is often followed by obesity and, related to this, non-alcoholic fatty liver disease (NAFLD). Two bile acid (BA) receptors, farnesoid X receptor (FXR) and G-protein-coupled receptor TGR5, have emerged as putative therapeutic targets for obesity and NAFLD. AIM OF THIS STUDY: to evaluate the efficacy of selective agonists INT747/obeticholic acid (FXR) and INT777 (TGR5) as novel treatments for the metabolic effects of oestrogen deficiency. Ovariectomized (OVX) or sham-operated (SHAM) mice were fed a high-fat diet (HFD) for 5weeks. During the last 4weeks two groups of OVX and SHAM mice received either INT747- or INT777-supplemented HFD. OVX mice had significantly higher bodyweight gain than SHAM mice, which was attenuated by INT747- or INT777-treatment. No significant changes in food intake or physical activity were found. OVX mice had significantly lower energy expenditure than SHAM mice; INT747- and INT777-treated OVX mice had intermediate energy expenditure. Liver triglyceride and cholesterol content was significantly increased in OVX compared to SHAM mice, which was normalized by INT747- or INT777-treatment. Significant changes in metabolic gene expression were found in liver (Cpt1, Acox1), muscle (Ucp3, Pdk4, Cpt1, Acox1, Fasn, Fgf21), brown adipocytes (Dio2) and white adipocytes (c/EBPα, Pparγ, Adipoq). For the first time, expression of FXR and induction of its target gene Pltp1 was shown in skeletal muscle. BA receptor agonists are suitable therapeutics to correct postmenopausal metabolic changes in an OVX mouse model. Potential mechanisms include increased energy expenditure and changes in expression patterns of key metabolic genes in liver, muscle and adipose tissues.

Tibolone impairs glucose and fatty acid metabolism and induces oxidative stress in livers from female rats.

Tibolone is a synthetic steroid that has been extensively prescribed to treat climacteric symptoms and to prevent postmenopausal osteoporosis. Because menopause is a condition associated with increased incidence of metabolic disturbances and hepatic steatosis, the aim of this work was to evaluate the actions of tibolone on the liver. The effects of tibolone on glucose and fatty acid metabolism and on several parameters linked to mitochondrial energy metabolism, including the induction of cellular oxidative stress, were investigated in livers from female Wistar rats. Tibolone was assayed at concentrations ranging from 5 to 100 µM. In perfused livers, tibolone inhibited oxygen uptake, stimulated glycogenolysis and glycolysis, and inhibited gluconeogenesis from L-lactate and ketogenesis from exogenous octanotate. Tibolone also caused pronounced increases in both the cytosolic and mitochondrial NADH/NAD+ratios. In isolated mitochondria, tibolone inhibited oxygen uptake due to ß-hydroxybutyrate and fatty acid oxidation without affecting the succinate oxidation. The inhibitory action of tibolone at complex I of the mitochondrial respiratory chain was suggested by the inhibition of the NADH-oxidase activity. Tibolone also induced oxidative stress in both perfused livers and isolated mitochondria, as indicated by the increased production of thiobarbituric acid reactive substances. These metabolic alterations may increase the risk of metabolic disturbances during tibolone administration, particularly in the postmenopausal condition.