ABSTRACT
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.
Subject(s)
Hypothalamus/metabolism , Interleukin-6/metabolism , Physical Conditioning, Animal , Receptors, Lysosphingolipid/metabolism , STAT3 Transcription Factor/metabolism , Signal Transduction , Animals , Humans , Injections, Intraventricular , Interleukin-6/administration & dosage , Interleukin-6/genetics , Male , Mice, Inbred C57BL , Mice, Obese , RNA, Messenger/genetics , RNA, Messenger/metabolism , Receptors, Lysosphingolipid/genetics , Sphingosine-1-Phosphate ReceptorsABSTRACT
ß-Hydroxy-ß-methylbutyrate free acid (HMB-FA) has been suggested to accelerate the regenerative capacity of skeletal muscle after high-intensity exercise and attenuate markers of skeletal muscle damage. Herein a systematic review on the use of HMB-FA supplementation as an ergogenic aid to improve measures of muscle recovery, performance, and hypertrophy after resistance training was conducted. This review was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. We included randomized, double-blinded, placebo-controlled trials investigating the effects of HMB-FA supplementation in conjunction with resistance exercise in humans. The search was conducted using Medline and Google Scholar databases for the terms beta-hydroxy-beta-methylbutyrate, HMB free acid, exercise, resistance exercise, strength training, and HMB supplementation. Only research articles published from 1996 to 2016 in English language were considered for the analysis. Nine studies met the criteria for inclusion in the analyses. Most studies included resistance-trained men, and the primary intervention strategy involved administration of 3g of HMB-FA per day. In conjunction with resistance training, HMB-FA supplementation may attenuate markers of muscle damage, augment acute immune and endocrine responses, and enhance training-induced muscle mass and strength. HMB-FA supplementation may also improve markers of aerobic fitness when combined with high-intensity interval training. Nevertheless, more studies are needed to determine the overall efficacy of HMB-FA supplementation as an ergogenic aid.
Subject(s)
Muscle, Skeletal/drug effects , Muscle, Skeletal/physiology , Resistance Training , Valerates/administration & dosage , Adult , Dietary Supplements , Exercise/physiology , Female , Humans , MEDLINE , Male , Muscle Strength/drug effects , Physical Fitness , Randomized Controlled Trials as TopicABSTRACT
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.
Subject(s)
Energy Metabolism , Hypothalamus/metabolism , Lysophospholipids/metabolism , Receptors, Lysosphingolipid/metabolism , Sphingosine/analogs & derivatives , Animals , Homeostasis , Male , Mice , Mice, Inbred C57BL , Neurons/metabolism , Pro-Opiomelanocortin/metabolism , Rats , Rats, Wistar , Receptors, Lysosphingolipid/genetics , STAT3 Transcription Factor/metabolism , Signal Transduction , Sphingosine/metabolism , Sphingosine-1-Phosphate ReceptorsABSTRACT
Historically, in the 1950s, the chemist Linus Pauling established a relationship between decreased longevity and obesity. At this time, with the advent of studies involving the mechanisms that modulate appetite control, some researchers observed that the hypothalamus is the "appetite centre" and that peripheral tissues have important roles in the modulation of gut inflammatory processes and levels of hormones that control food intake. Likewise, the advances of physiological and molecular mechanisms for patients with obesity, type 2 diabetes mellitus, inflammatory bowel diseases, bariatric surgery and anorexia-associated diseases has been greatly appreciated by nutritionists. Therefore, this review highlights the relationship between the gut-central nervous system axis and targets for nutritional therapies.
