Aging reduces ABHD5 protein content in the adipose tissue of mice: The reversal effect of exercise

Dysfunction of the adipose tissue metabolism is considered as a significant hallmark of aging. It has been proposed that α-β hydrolase domain containing 5 (ABHD5) plays a critical role in the control of lipolysis. However, the role of ABHD5 in the control of lipolysis during aging or exercise is unknown. Here we combined the experimental mouse model with transcriptomic analyzes by using murine and human databases to explore the role of ABHD5 in the adipose tissue during aging and in response to exercise. Transcriptomic data revealed a downregulation of Abhd5 messenger RNA levels in the subcutaneous white adipose tissue (scWAT) over time in individuals from 20 to 69 years old. Aged mice displayed dramatic reduction of ABHD5 protein content and lipolytic-related proteins in the scWAT. Interestingly, 4 weeks of high-intensity interval training increased ABHD5 protein level and restored the lipolytic pathway in the scWAT of aged mice. Altogether, our findings demonstrated that aging affects ABHD5 content in the adipose tissue of mice and humans. Conversely, exercise increases ABHD5 activity, recovering the lipolytic activity in aged mice.

Aerobic Exercise Training Induces the Mitonuclear Imbalance and UPRmt in the Skeletal Muscle of Aged Mice

The impairment of the mitochondrial functions is a hallmark of aging. During aging, there is a downregulation of two mechanisms strictly associated with mitochondrial integrity, including the mitonuclear imbalance (eg, imbalance in mitochondrial- versus nuclear-encoded mitochondrial proteins) and the mitochondrial unfolded protein response (UPRmt). Here, we evaluated the effects of aerobic exercise in the mitonuclear imbalance and UPRmt markers in the skeletal muscle of old mice. We combined the physiological tests, molecular and bioinformatic analyzes to evaluate the effects of 4 weeks of aerobic exercise training on mitonuclear imbalance and UPRmt markers in the skeletal muscle of young (2 months) and aged (24 months) C57BL/6J mice. Initially, we found that aging reduced several mitochondrial genes in the gastrocnemius muscle, and it was accompanied by the low levels of UPRmt markers, including Yme1l1 and Clpp mRNA. As expected, physical training improved the whole-body metabolism and physical performance of aged mice. The aerobic exercise increased key proteins involved in the mitochondrial biogenesis/functions (VDAC and SIRT1) along with mitochondrial-encoded genes (mtNd1, mtCytB, and mtD-Loop) in the skeletal muscle of old mice. Interestingly, aerobic exercise induced the mitonuclear imbalance, increasing MTCO1/ATP5a ratio and UPRmt markers in the skeletal muscle, including HSP60, Lonp1, and Yme1L1 protein levels in the gastrocnemius muscle of aged mice. These data demonstrate that aerobic exercise training induced mitonuclear imbalance and UPRmt in the skeletal muscle during aging. These phenomena could be involved in the improvement of the mitochondrial metabolism and oxidative capacity in aged individuals.

TGF-β1 downregulation in the hypothalamus of obese mice through acute exercise

Obesity and aging lead to abnormal transforming growth factor-β1 (TGF-β1) signaling in the hypothalamus, triggering the imbalance on glucose metabolism and energy homeostasis. Here, we determine the effect of acute exercise on TGF-β1 expression in the hypothalamus of two models of obesity in mice. The bioinformatics analysis was performed to evaluate the correlation between hypothalamic Tgf-β1 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-β1 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-β1 mRNA in the hypothalamus and reduction of Pgc1α mRNA in BAT. Interestingly, an acute exercise session reduced TGF-β1 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-β1 expression, increasing Pgc1α mRNA in BAT in obese mice.

Chronic exercise reduces hypothalamic transforming growth factor-β1 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-β (TGF-β1). 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-β1 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-β1 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-β1 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-β1/IkB-α axis in the hypothalamus and improved the energy homeostasis in an animal model of obesity-associated to aging.

Effects of ninety minutes per week of continuous aerobic exercise on blood pressure in hypertensive obese humans

The main objective of this study was to examine the effect of continuous aerobic training (CAT) in hypertensive, obese people. Seven patients of average age (45.3±3.9 years), height (1.63±0.1 m), body weight (89.09±22.0 kg), and body mass index (33.44±8.6 kg/m2) were subjected to the training. CAT was performed in thrice-weekly nonconsecutive sessions (90 min per week) with intervals of 48 hr between each session. The training sessions entailed 30 min of walking at an intensity of 70%–80% of the maximum heart rate (MHR) on a treadmill over a period of eight weeks, giving a total of 24 sessions. Through correlation analyses, we found significant improvement in the systolic pressure (R=0.5675, P=0.0253) and diastolic pressure (R=0.7083, P=0.0088) when the last session was compared to the first session of training. We found no differences in the diastolic pressure and systolic pressure before, during and after 15 min of the protocol exercise. The program showed a large effect size (ES) for systolic pressure (ES=0.85) and a small ES for diastolic pressure (ES=0.33). We found no differences in the blood pressure (BP) and heart rate (HR) during and after the training of obese hypertensive humans, but we found a positively significant correlation between HR and BP in the last session and a large ES, suggesting that this protocol exercise might have significance effect in the long term.

Ursolic acid and mechanisms of actions on adipose and muscle tissue: a systematic review

This systematic review aimed at addressing the ursolic acid actions as an adjunctive treatment of the obesity-mediated metabolic abnormalities. To explore our aims, we used the literature search including clinical and animal studies using the Medline and Google Scholar (up to December 2015). Out of 63 screened studies, 17 presented eligibility criteria, such as the use of ursolic acid on adiposity, energy expenditure and skeletal muscle mass in mice and humans. In the literature, we found that several physiological and molecular mechanisms are implicated in the effects of ursolic acid on obesity, energy expenditure, hepatic steatosis, skeletal muscle mass loss and physical fitness, such as (1) increase of thermogenesis by modulation adipocyte transcription factors, activation of 5' adenosine monophosphate-activated protein kinase and overexpression of the uncoupling protein 1 thermogenic marker; (2) enhancement of skeletal muscle mass by activation in bloodstream growth hormone and insulin-like growth factor-1 concentrations secretion, as well as in the activation of mammalian target of rapamycin and inhibition of ring-finger protein-1; and (3) improvement of physical fitness by skeletal muscle proliferator-activated receptor gamma co-activator alpha and sirtuin 1 expression. Therefore, supplementation with ursolic acid may be an adjunctive therapy for prevention and treatment of obesity-mediated and muscle mass-mediated metabolic consequences.

Alzheimer-associated Aβ oligomers impact the central nervous system to induce peripheral metabolic deregulation

Alzheimer's disease (AD) is associated with peripheral metabolic disorders. Clinical/epidemiological data indicate increased risk of diabetes in AD patients. Here, we show that intracerebroventricular infusion of AD-associated Aβ oligomers (AβOs) in mice triggered peripheral glucose intolerance, a phenomenon further verified in two transgenic mouse models of AD. Systemically injected AβOs failed to induce glucose intolerance, suggesting AβOs target brain regions involved in peripheral metabolic control. Accordingly, we show that AβOs affected hypothalamic neurons in culture, inducing eukaryotic translation initiation factor 2α phosphorylation (eIF2α-P). AβOs further induced eIF2α-P and activated pro-inflammatory IKKβ/NF-κB signaling in the hypothalamus of mice and macaques. AβOs failed to trigger peripheral glucose intolerance in tumor necrosis factor-α (TNF-α) receptor 1 knockout mice. Pharmacological inhibition of brain inflammation and endoplasmic reticulum stress prevented glucose intolerance in mice, indicating that AβOs act via a central route to affect peripheral glucose homeostasis. While the hypothalamus has been largely ignored in the AD field, our findings indicate that AβOs affect this brain region and reveal novel shared molecular mechanisms between hypothalamic dysfunction in metabolic disorders and AD.

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.

Abstract 413: Hypothalamic Leptin Signaling And Blood Pressure Regulation In Obese Rats

The main function of Leptin is to inform the individual's nutritional status to hypothalamus, which in turn regulate food intake and energy expenditure. Such actions are orchestrated by phosphorylation of ObRb receptor on tyrosine 985 and 1138, the latter is related to metabolism and Stat3 pathway. Recently, it was demonstrated that high serum levels of leptin, which is seen in DIO, correlates strongly with hypertension. On the other hand, obese individuals have resistance to metabolic actions of leptin (satiety and thermogenesis).

To investigate the molecular hypothalamic pathways that characterize the selective activity of leptin on the effect of blood pressure (BP) increase, adults Sprague Dawley rats were fed with standard diet (SD) or HFD for three months and were submitted to chronic ICV injection of leptin (2μg/day) or saline (2μl) for 10 days. BP, food intake and energy expenditure were assessed before and after treatment.

SD+leptin group had reduced food intake from 109,48±8,48 to 57,3±7,04 kcal / day, increased energy expenditure from 85,6±1,87 to 94,4±0,58 kcal/day/kg^0,75 and consequently weight reduction of 15,25±3,54 g (P <0.001 all) which did not occur in HFD+leptin. However, both SD and HFD group, leptin increased BP of 10.44±0.12% (from 103,7±0,7 to 114,8±0,8 mmHg) and 14.22±1.9% (from 118,6±1,3 to 132,2±1,5 mmHg), respectively.

As expected, obese animals had elevated levels of serum leptin when compared to SD group (SD: 2,24±0,38 ng/dl and HFD: 9,88±1,82 ng/dl, p<0,05). Additionally, we evaluate the main activated signal pathways by leptin in hypothalamus. SD+leptin group showed a significant increase in activity of Stat3, Akt and in MAPK expression. However, HFD+leptin group manifested an increase only on the expression of MAPK pathway. Both SD and HFD leptin-treated groups had higher ObRb tyr985 phosphorylation, which was not observed with the pObRb tyr1138. It was possible to see that ObRb tyr985 dependent pathway is responsive to leptin in SD and HFD, and ObRb tyr1138 as well as the related protein Stat3 and Akt are reduced in obese animals. Therefore, it may be suggested that in HFD-induced obesity hypothalamic pathway ObRb tyr985 / MAPK, unlike the other pathways, is not resistent and can be related to cardiovascular actions of leptin.

Diet-induced obesity induces endoplasmic reticulum stress and insulin resistance in the amygdala of rats

Insulin acts in the hypothalamus, decreasing food intake (FI) by the IR/PI3K/Akt pathway. This pathway is impaired in obese animals and endoplasmic reticulum (ER) stress and low-grade inflammation are possible mechanisms involved in this impairment. Here, we highlighted the amygdala as an important brain region for FI regulation in response to insulin. This regulation was dependent on PI3K/AKT pathway similar to the hypothalamus. Insulin was able to decrease neuropeptide Y (NPY) and increase oxytocin mRNA levels in the amygdala via PI3K, which may contribute to hypophagia. Additionally, obese rats did not reduce FI in response to insulin and AKT phosphorylation was decreased in the amygdala, suggesting insulin resistance. Insulin resistance was associated with ER stress and low-grade inflammation in this brain region. The inhibition of ER stress with PBA reverses insulin action/signaling, decreases NPY and increases oxytocin mRNA levels in the amygdala from obese rats, suggesting that ER stress is probably one of the mechanisms that induce insulin resistance in the amygdala.

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Lower food intake in response to insulin in the amygdala is dependent on the PI3K/Akt pathway.

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Insulin decreases NPY and increases oxytocin mRNA levels via PI3K in vivo.

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Insulin receptor and Akt phosphorylation in the amygdala are disrupted in obese rats.

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Insulin resistance, ER stress and inflammation are present in the amygdala of obese rats.

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The inhibition of ER stress with PBA reverses insulin resistance in the amygdala from obese rats.

Acute exercise suppresses hypothalamic PTP1B protein level and improves insulin and leptin signaling in obese rats

Hypothalamic inflammation is associated with insulin and leptin resistance, hyperphagia, and obesity. In this scenario, hypothalamic protein tyrosine phosphatase 1B (PTP1B) has emerged as the key phosphatase induced by inflammation that is responsible for the central insulin and leptin resistance. Here, we demonstrated that acute exercise reduced inflammation and PTP1B protein level/activity in the hypothalamus of obese rodents. Exercise disrupted the interaction between PTP1B with proteins involved in the early steps of insulin (IRβ and IRS-1) and leptin (JAK2) signaling, increased the tyrosine phosphorylation of these molecules, and restored the anorexigenic effects of insulin and leptin in obese rats. Interestingly, the anti-inflammatory action and the reduction of PTP1B activity mediated by exercise occurred in an interleukin-6 (IL-6)-dependent manner because exercise failed to reduce inflammation and PTP1B protein level after the disruption of hypothalamic-specific IL-6 action in obese rats. Conversely, intracerebroventricular administration of recombinant IL-6 reproduced the effects of exercise, improving hypothalamic insulin and leptin action by reducing the inflammatory signaling and PTP1B activity in obese rats at rest. Taken together, our study reports that physical exercise restores insulin and leptin signaling, at least in part, by reducing hypothalamic PTP1B protein level through the central anti-inflammatory response.

Sugar intake is correlated with adiposity and obesity indicators and sedentary lifestyle in Brazilian individuals with morbid obesity

Obesity is a chronic disease characterized by increased accumulation of body fat. We evaluated the socioeconomic aspects, body composition, risk of metabolic complications associated with obesity, eating habits and lifestyle in both women and men adults and elderly with body mass index (BMI) > 40 kg/m². Among the subjects studied, 79% (n = 32) are female, 5% (n = 2) smokers, 39% (n = 16) use alcohol and only 24% (n = 10) are practitioners of physical exercise. The higher food intake was breads, followed by rice. The daily intake of fruits and vegetables is low. Positive correlation between consumption of sugar and BMI and abdominal circumference (AC) was observed. In summary, was found that morbidly obese patients that looking for nutritional counseling presents increased body fat, poor eating habits and sedentary lifestyle.

Targeted disruption of inducible nitric oxide synthase protects against aging, S-nitrosation, and insulin resistance in muscle of male mice

Accumulating evidence has demonstrated that S-nitrosation of proteins plays a critical role in several human diseases. Here, we explored the role of inducible nitric oxide synthase (iNOS) in the S-nitrosation of proteins involved in the early steps of the insulin-signaling pathway and insulin resistance in the skeletal muscle of aged mice. Aging increased iNOS expression and S-nitrosation of major proteins involved in insulin signaling, thereby reducing insulin sensitivity in skeletal muscle. Conversely, aged iNOS-null mice were protected from S-nitrosation-induced insulin resistance. Moreover, pharmacological treatment with an iNOS inhibitor and acute exercise reduced iNOS-induced S-nitrosation and increased insulin sensitivity in the muscle of aged animals. These findings indicate that the insulin resistance observed in aged mice is mainly mediated through the S-nitrosation of the insulin-signaling pathway.