RESUMO

The renin-angiotensin system (RAS) is an endocrine system composed of two main axes: the classical and the counterregulatory, very often displaying opposing effects. The classical axis, primarily mediated by angiotensin receptors type 1 (AT1R), is linked to obesity-associated metabolic effects. On the other hand, the counterregulatory axis appears to exert antiobesity effects through the activation of two receptors, the G protein-coupled receptor (MasR) and Mas-related receptor type D (MrgD). The local RAS in adipose organ has prompted extensive research into white adipose tissue and brown adipose tissue (BAT), with a key role in regulating the cellular and metabolic plasticity of these tissues. The MasR activation favors the brown plasticity signature in the adipose organ by improve the thermogenesis, adipogenesis, and lipolysis, decrease the inflammatory state, and overall energy homeostasis. The MrgD metabolic effects are related to the maintenance of BAT functionality, but the signaling remains unexplored. This review provides a summary of RAS counterregulatory actions triggered by Mas and MrgD receptors on adipose tissue plasticity. Focus on the effects related to the morphology and function of adipose tissue, especially from animal studies, will be given targeting new avenues for treatment of obesity-associated metabolic effects.

Assuntos

RESUMO

Deletion of mechanistic target of rapamycin complex 2 (mTORC2) essential component rapamycin insensitive companion of mTOR (Rictor) by a Cre recombinase under control of the broad, nonadipocyte-specific aP2/FABP4 promoter impairs thermoregulation and brown adipose tissue (BAT) glucose uptake on acute cold exposure. We investigated herein whether adipocyte-specific mTORC2 deficiency affects BAT and inguinal white adipose tissue (iWAT) signaling, metabolism, and thermogenesis in cold-acclimated mice. For this, 8-wk-old male mice bearing Rictor deletion and therefore mTORC2 deficiency in adipocytes (adiponectin-Cre) and littermates controls were either kept at thermoneutrality (30 ± 1°C) or cold-acclimated (10 ± 1°C) for 14 days and evaluated for BAT and iWAT signaling, metabolism, and thermogenesis. Cold acclimation inhibited mTORC2 in BAT and iWAT, but its residual activity is still required for the cold-induced increases in BAT adipocyte number, total UCP-1 content and mRNA levels of proliferation markers Ki67 and cyclin 1 D, and de novo lipogenesis enzymes ATP-citrate lyase and acetyl-CoA carboxylase. In iWAT, mTORC2 residual activity is partially required for the cold-induced increases in multilocular adipocytes, mitochondrial mass, and uncoupling protein 1 (UCP-1) content. Conversely, BAT mTORC1 activity and BAT and iWAT glucose uptake were upregulated by cold independently of mTORC2. Noteworthy, the impairment in BAT and iWAT total UCP-1 content and thermogenic capacity induced by adipocyte mTORC2 deficiency had no major impact on whole body energy expenditure in cold-acclimated mice due to a compensatory activation of muscle shivering. In conclusion, adipocyte mTORC2 deficiency impairs, through different mechanisms, BAT and iWAT total UCP-1 content and thermogenic capacity in cold-acclimated mice, without affecting glucose uptake and whole body energy expenditure.NEW & NOTEWORTHY BAT and iWAT mTORC2 is inhibited by cold acclimation, but its residual activity is required for cold-induced increases in total UCP-1 content and thermogenic capacity, but not glucose uptake and mTORC1 activity. The impaired BAT and iWAT total UCP-1 content and thermogenic capacity induced by adipocyte mTORC2 deficiency are compensated by activation of muscle shivering in cold-acclimated mice.

Assuntos

RESUMO

Concentrations of pro-thermogenic/anti-inflammatory inductors are influenced by fed/fasting, sedentary/trained states, and metabolic pattern. However, there is a lack of information on the interactions of these conditions, especially in humans. Thus, the present study aimed to evaluate the chronic and acute training responses as well as the fed/fasted states of serum pro-thermogenic/anti-inflammatory inducers in overweight type 2 diabetics individuals. Fifteen individuals with type 2 diabetes [body mass index (BMI): 29.61 ± 3.60 kg/m2; age: 50.67 ± 3.97 years] participated in the study. In the pre- and post-experimental periods, baseline clinical parameters analyses were performed. Pro-thermogenic/anti-inflammatory inductors were evaluated pre/post-baseline and before, shortly after, and after 30' and 60' in the first and last sessions of a 16-week combined training (CT) period. These inducers were also compared for fasting and feeding before and after the training period. CT has improved baseline physical fitness, metabolic pattern, and it has also increased interleukin (IL)33 and FNDC5/irisin. In the first training session, there was a decrease in IL4, IL13, and IL33, besides an increase in FNDC5/irisin, and natriuretic peptides. In the last training session, there was an increase in natriuretic peptides and bone morphogenic protein 4 (BMP4). Differences in responses between the first and last training sessions were observed at certain post-session times for IL4, IL33, and natriuretic peptides, always with higher concentrations occurring in the last session. In evaluating the area under the curve (AUC) of the first and last training session, FNDC5/irisin, natriuretics peptides, and meteorin-like showed increased areas in the last training session. The pre-training fed state showed an increase in IL4 and IL33, while in fasting there was an increase in meteorin-like, natriuretic peptides, and FNDC5/irisin. In the post-training, IL4, IL13, and IL33 were increased in the fed state, while meteorin-like, natriuretic peptides, and FNDC5/irisin remained increased in the fast. Adaptation to physical training and a better metabolic pattern favor an improvement in the acute secretory pattern in part of pro-thermogenic and anti-inflammatory substances analyzed. The fed and fasting states also interfere differently in these substances, where fasting interferes with the increase of myokines, while the fed state induces an increase in interleukins. Clinical Trial Registration: [http://www.ensaiosclinicos.gov.br/rg/RBR-62n5qn/], identifier [U1111-1202-1476].

RESUMO

Obesity is considered to significantly increase the risk of the development of a vast range of metabolic diseases. However, adipogenesis is a complex physiological process, necessary to sequester lipids effectively to avoid lipotoxicity in other tissues, like the liver, heart, muscle, essential for maintaining metabolic homeostasis and has a crucial role as a component of the innate immune system, far beyond than only being an inert mass of energy storage. In pathophysiological conditions, adipogenesis promotes a pro-inflammatory state, angiogenesis and the release of adipokines, which become dangerous to health. It results in a hypoxic state, causing oxidative stress and the synthesis and release of harmful free fatty acids. In this review, we try to explain the mechanisms occurring at the breaking point, at which adipogenesis leads to an uncontrolled lipotoxicity. This review highlights the types of adipose tissue and their functions, their way of storing lipids until a critical point, which is associated with hypoxia, inflammation, insulin resistance as well as lipodystrophy and adipogenesis modulation by Krüppel-like factors and miRNAs.

Assuntos

RESUMO

The obesity is a result of energy imbalance and the increase in thermogenesis seems an interesting alternative for the treatment of this disease. The mechanism of energy expenditure through thermogenesis is tightly articulated in the hypothalamus by leptin. The hypothalamic extracellular signal-regulated kinase-1/2 (ERK1/2) is a key mediator of the thermoregulatory effect of leptin and mediates the sympathetic signal to the brown adipose tissue (BAT). In this context, physical exercise is one of the main interventions for the treatment of obesity. Thus, this study aimed to verify the effects of acute physical exercise on leptin-induced hypothalamic ERK1/2 phosphorylation and thermogenesis in obese mice. Here we showed that acute physical exercise reduced the fasting glucose of obese mice and increased leptin-induced hypothalamic p-ERK1/2 and uncoupling protein 1 (UCP1) content in BAT ( P < 0.05). These molecular changes are accompanied by an increased oxygen uptake (VO 2 ) and heat production in obese exercised mice ( P < 0.05). The increased energy expenditure in the obese exercised animals occurred independently of changes in spontaneous activity. Thus, this is the first study demonstrating that acute physical exercise can increase leptin-induced hypothalamic ERK1/2 phosphorylation and energy expenditure of obese mice.

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