NAD+ precursor increases aerobic performance in mice.

PURPOSE: Nicotinamide riboside (NR) acts as a potent NAD+ precursor and improves mitochondrial oxidative capacity and mitochondrial biogenesis in several organisms. However, the effects of NR supplementation on aerobic performance remain unclear. Here, we evaluated the effects of NR supplementation on the muscle metabolism and aerobic capacity of sedentary and trained mice. METHODS: Male C57BL/6 J mice were supplemented with NR (400 mg/Kg/day) over 5 and 10 weeks. The training protocol consisted of 5 weeks of treadmill aerobic exercise, for 60 min a day, 5 days a week. Bioinformatic and physiological assays were combined with biochemical and molecular assays to evaluate the experimental groups. RESULTS: NR supplementation by itself did not change the aerobic performance, even though 5 weeks of NR supplementation increased NAD+ levels in the skeletal muscle. However, combining NR supplementation and aerobic training increased the aerobic performance compared to the trained group. This was accompanied by an increased protein content of NMNAT3, the rate-limiting enzyme for NAD + biosynthesis and mitochondrial proteins, including MTCO1 and ATP5a. Interestingly, the transcriptomic analysis using a large panel of isogenic strains of BXD mice confirmed that the Nmnat3 gene in the skeletal muscle is correlated with several mitochondrial markers and with different phenotypes related to physical exercise. Finally, NR supplementation during aerobic training markedly increased the amount of type I fibers in the skeletal muscle. CONCLUSION: Taken together, our results indicate that NR may be an interesting strategy to improve mitochondrial metabolism and aerobic capacity.

Acute physical exercise increases APPL1/PI3K signaling in the hypothalamus of lean mice.

Adiponectin is an adipokine that acts in the control of energy homeostasis. The adaptor protein containing the pleckstrin homology domain, phosphotyrosine-binding domain, and leucine zipper motif 1 (APPL1) is a key protein in the adiponectin signaling. The APPL1 mediates a positive effect on the insulin signaling through the interaction with the phosphoinositide 3-kinase (PI3K). Thus, the present study aimed to explore the effects of an acute physical exercise session on the hypothalamic adiponectin signaling. Firstly, using bioinformatics analysis, we found a negative correlation between hypothalamic APPL1 mRNA levels and food consumption in several strains of genetically diverse BXD mice. Also, the mice and the human database revealed a positive correlation between the levels of APPL1 mRNA and PI3K mRNA. At the molecular level, the exercised mice showed increased APPL1 and PI3K (p110) protein contents in the hypothalamus of Swiss mice. Furthermore, the exercise increases co-localization between APPL1 and PI3K p110 predominantly in neurons of the arcuate nucleus of hypothalamus (ARC). Finally, we found an acute exercise session reduced the food intake 5 hr after the end of fasting. In conclusion, our results indicate that physical exercise reduces the food intake and increases some proteins related to adiponectin pathway in the hypothalamus of lean mice.

TGF-ß1 downregulation in the hypothalamus of obese mice through acute exercise.

Obesity and aging lead to abnormal transforming growth factor-ß1 (TGF-ß1) signaling in the hypothalamus, triggering the imbalance on glucose metabolism and energy homeostasis. Here, we determine the effect of acute exercise on TGF-ß1 expression in the hypothalamus of two models of obesity in mice. The bioinformatics analysis was performed to evaluate the correlation between hypothalamic Tgf-ß1 messenger RNA (mRNA) and genes related to thermogenesis in the brown adipose tissue (BAT) by using a large panel of isogenic BXD mice. Thereafter, leptin-deficient (ob/ob) mice and obese C57BL/6 mice fed on a high-fat diet (HFD) were submitted to the acute exercise protocol. Transcriptomic analysis by using BXD mouse reference population database revealed that hypothalamic Tgf-ß1 mRNA is negatively correlated with genes related to thermogenesis in brown adipose tissue of BXD mice, such as peroxisome proliferator-activated receptor gamma coactivator and is positively correlated with respiratory exchange ratio. In agreement with these results, leptin-deficient (ob/ob) and HFD-fed mice displayed high levels of Tgf-ß1 mRNA in the hypothalamus and reduction of Pgc1α mRNA in BAT. Interestingly, an acute exercise session reduced TGF-ß1 expression in the hypothalamus, increased Pgc1α mRNA in the BAT and reduced food consumption in obese mice. Our results demonstrated that acute physical exercise suppressed hypothalamic TGF-ß1 expression, increasing Pgc1α mRNA in BAT in obese mice.

Nicotinamide riboside induces a thermogenic response in lean mice.

AIMS: Nicotinamide Riboside (NR) is a NAD+ booster with wide physiological repercussion including the improvement on glucose and lipid homeostasis, increasing the life expectancy in mammals. However, the effects of NR on metabolism are only partially known. Here, we evaluated the effects of NR on the thermogenic response, highlighting the brown adipose tissue (BAT) in lean mice. MAIN METHODS: Male C57BL/67 mice were supplement with NR (400 mg/Kg/day) during 5 weeks. The Comprehensive Lab Animal Monitoring System (CLAMS) and thermographic images were used to evaluated the physiological effects of NR treatment. The BAT were extracted and analyzed by Western Blotting and qPCR. Also, bioinformatics analyses were performed to establish the connection between the NAD+ synthesis pathway in BAT and thermogenic response in several isogenic strains of BXD mice. KEY FINDINGS: Transcriptomic analysis revealed that genes involved in NAD+ synthesis (Nampt and Nmnat1) in the BAT were negatively correlated with body weight and fat mass. The heat map showed a strong positive correlation between Nampt and Ucp1 mRNA in BAT and body temperature in several strains of BXD lean mice. The experimental approaches demonstrated that oral NR supplementation reduced the abdominal visceral fat depots, with discrete impact on oxygen consumption in C57BL/6J mice. Interestingly, NR significantly increased the body temperature, and this phenomenon was accompanied by high levels of UCP1 protein content and Pgc1α mRNA in BAT. SIGNIFICANCE: This study demonstrated the oral NR supplementation was sufficient to induce the thermogenic response in lean mice changing the BAT metabolism.

Exercise activates the hypothalamic S1PR1-STAT3 axis through the central action of interleukin 6 in mice.

Hypothalamic sphingosine-1-phosphate receptor 1 (S1PR1), the G protein-coupled receptor 1 of sphingosine-1-phosphate, has been described as a modulator in the control of energy homeostasis in rodents. However, this mechanism is still unclear. Here, we evaluate the role of interleukin 6 (IL-6) associated with acute physical exercise in the control of the hypothalamic S1PR1-signal transducer and activator of transcription 3 (STAT3) axis. Acute exercise session and an intracerebroventricular IL-6 injection increased S1PR1 protein content and STAT3 phosphorylation in the hypothalamus of lean and obese mice accompanied by a reduction in food consumption. Transcriptome analysis indicated a strong positive correlation between Il-6 and S1pr1 messenger RNA in several tissues of genetically diverse BXD mice strains and humans, including in the hypothalamus. Interestingly, exercise failed to stimulate the S1PR1-STAT3 axis in IL-6 knockout mice and the disruption of hypothalamic-specific IL-6 action blocked the anorexigenic effects of exercise. Taken together, our results indicate that physical exercise modulates the S1PR1 protein content in the hypothalamus, through the central action of IL-6.

Chronic exercise reduces hypothalamic transforming growth factor-ß1 in middle-aged obese mice.

Obesity and aging are associated with hypothalamic inflammation, hyperphagia and abnormalities in the thermogenesis control. It has been demonstrated that the association between aging and obesity induces hypothalamic inflammation and metabolic disorders, at least in part, through the atypical hypothalamic transforming growth factor-ß (TGF-ß1). Physical exercise has been used to modulate several metabolic parameters. Thus, the aim of this study was to evaluate the impact of chronic exercise on TGF-ß1 expression in the hypothalamus of Middle-Aged mice submitted to a one year of high-fat diet (HFD) treatment. We observed that long-term of HFD-feeding induced hypothalamic TGF-ß1 accumulation, potentiated the hypothalamic inflammation, body weight gain and defective thermogenesis of Middle-Aged mice when compared to Middle-Aged animals fed on chow diet. As expected, chronic exercise induced negative energy balance, reduced food consumption and increasing the energy expenditure, which promotes body weight loss. Interestingly, exercise training reduced the TGF-ß1 expression and IkB-α ser32 phosphorylation in the hypothalamus of Middle-Aged obese mice. Taken together our study demonstrated that chronic exercise suppressed the TGF-ß1/IkB-α axis in the hypothalamus and improved the energy homeostasis in an animal model of obesity-associated to aging.

iNOS promotes hypothalamic insulin resistance associated with deregulation of energy balance and obesity in rodents.

Inducible nitric oxide (iNOS)-mediated S-nitrosation of the metabolic signaling pathway has emerged as a post-translational modification that triggers insulin resistance in obesity and aging. However, the effects of S-nitrosation in controlling energy homeostasis are unknown. Thus, in the present study we aimed to evaluate the effects of S-nitrosation in insulin signaling pathway in the hypothalamus of rodents. Herein, we demonstrated that the intracerebroventricular infusion of the nitric oxide (NO) donor S-nitrosoglutathione (GSNO) promoted hypothalamic insulin signaling resistance and replicated the food intake pattern of obese individuals. Indeed, obesity induced S-nitrosation of hypothalamic IR and Akt, whereas inhibition of iNOS or S-nitrosation of insulin signaling pathway protected against hypothalamic insulin resistance and normalized energy homeostasis. Overall, these findings indicated that S-nitrosation of insulin signaling pathway is required to sustain hypothalamic insulin resistance in obesity.

Hypothalamic S1P/S1PR1 axis controls energy homeostasis in Middle-Aged Rodents: the reversal effects of physical exercise.

Recently, we demonstrated that the hypothalamic S1PR1/STAT3 axis plays a critical role in the control of food consumption and energy expenditure in rodents. Here, we found that reduction of hypothalamic S1PR1 expression occurs in an age-dependent manner, and was associated with defective thermogenic signaling and weight gain. To address the physiological relevance of these findings, we investigated the effects of chronic and acute exercise on the hypothalamic S1PR1/STAT3 axis. Chronic exercise increased S1PR1 expression and STAT3 phosphorylation in the hypothalamus, restoring the anorexigenic and thermogenic signals in middle-aged mice. Acutely, exercise increased sphingosine-1-phosphate (S1P) levels in the cerebrospinal fluid (CSF) of young rats, whereas the administration of CSF from exercised young rats into the hypothalamus of middle-aged rats at rest was sufficient to reduce the food intake. Finally, the intracerebroventricular (ICV) administration of S1PR1 activators, including the bioactive lipid molecule S1P, and pharmacological S1PR1 activator, SEW2871, induced a potent STAT3 phosphorylation and anorexigenic response in middle-aged rats. Overall, these results suggest that hypothalamic S1PR1 is important for the maintenance of energy balance and provide new insights into the mechanism by which exercise controls the anorexigenic and thermogenic signals in the central nervous system during the aging process.

Hypothalamic S1P/S1PR1 axis controls energy homeostasis.

Sphingosine 1-phosphate receptor 1 (S1PR1) is a G-protein-coupled receptor for sphingosine-1-phosphate (S1P) that has a role in many physiological and pathophysiological processes. Here we show that the S1P/S1PR1 signalling pathway in hypothalamic neurons regulates energy homeostasis in rodents. We demonstrate that S1PR1 protein is highly enriched in hypothalamic POMC neurons of rats. Intracerebroventricular injections of the bioactive lipid, S1P, reduce food consumption and increase rat energy expenditure through persistent activation of STAT3 and the melanocortin system. Similarly, the selective disruption of hypothalamic S1PR1 increases food intake and reduces the respiratory exchange ratio. We further show that STAT3 controls S1PR1 expression in neurons via a positive feedback mechanism. Interestingly, several models of obesity and cancer anorexia display an imbalance of hypothalamic S1P/S1PR1/STAT3 axis, whereas pharmacological intervention ameliorates these phenotypes. Taken together, our data demonstrate that the neuronal S1P/S1PR1/STAT3 signalling axis plays a critical role in the control of energy homeostasis in rats.