Effects of Dietary Macronutrient Composition on FNDC5 and Irisin in Mice Skeletal Muscle.

BACKGROUND: Fibronectin type III domain containing 5 (FNDC5) and its protein product Irisin are therapeutic targets for obesity-associated disorders. Irisin plays an important role in energy regulation, inducing browning of white adipocytes, and improving obesity. We aimed to investigate the association between muscle Irisin expression and dietary quality. METHODS: Twenty-eight female mice were divided into four groups and fed the following experimental diets for 60 days: standard diet (SD), high-carbohydrate diet (HCD), high-fat diet (HFD), and high-protein diet (HPD). We evaluated body weight, food intake, serum total cholesterol, triacylglycerol, and glucose. We also performed glucose tolerance and insulin sensitivity tests. Expression of FNDC5 was evaluated by quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR) of soleus muscle. Western blot was used to assess Irisin protein expression. RESULTS: The major finding of the present study was that HFD and HCD were associated with a downregulation of FNDC5. In addition to these results, we noted a significant reduction in skeletal muscle Irisin level. HPD prevented reductions of both FNDC5 and Irisin levels, as well as increased brown adipose tissue, compared to the control group. CONCLUSIONS: In conclusion, we observed that the HPD type of diet can change both FNDC5 expression and Irisin levels. Thus, the HPD might be the most appropriate diet to achieve high amounts of Irisin, a target molecule for the treatment of obesity and its co-morbidities.

Angiotensin converting enzyme 2 activator (DIZE) modulates metabolic profiles in mice, decreasing lipogenesis.

Recent studies have shown that angiotensin-converting enzyme 2 (ACE2)/angiotensin (Ang) -(1-7)/Mas axis activation is able to improve the metabolic profile, enhance glucose tolerance and insulin sensitivity, improve metabolic parameters, and counteract deleterious effects of Ang II. The effects of endogenous ACE 2 activation on the metabolic profile of mice are poorly studied. In this study, 12 weeks old male mice were treated with the ACE 2 activator (diminazene aceturate, DIZE, 1 mg/kg/day, gavage) or saline (control) for 30 days followed by glucose tolerance tests, insulin sensitivity tests, and blood analysis. Epididymal ACE2, ACE, angiotensinogen, acetyl-CoA carboxylase (ACC), and fatty acid synthase (FAS) were measured by quantitative RT-PCR. ACE 2 activation treatment lowered body weight (DIZE vs control) (28.69 vs 30.28g, P < 0.001), serum cholesterol (140,0 vs 177.5; P < .05), and serum triglycerides (75,00 vs 165,0; P < .05) as well as epididymal (0.008 vs 0.016; P < .05) and retroperitoneal (0.0024 vs. 0.0068; P < .01) adipose tissue weights. These effects were associated with significantly increased epididymal ACE 2 and decreased ACE and angiotensinogen (AGT) expression. Additionally, DIZE decreased adipogenesis-related gene transcription, such as ACC and FAS mRNA. In conclusion, these results indicate that activation of ACE2 by oral DIZE treatment improves the metabolic profile and reduces fat deposition in mice. These results, along with the reduction of lipogenesis markers open a new perspective for metabolic disorder pharmacotherapy.