Doxorubicin causes cachexia, sarcopenia, and frailty characteristics in mice.

While chemotherapy treatment can be lifesaving, it also has adverse effects that negatively impact the quality of life. To investigate the effects of doxorubicin chemotherapy on body weight loss, strength and muscle mass loss, and physical function impairments, all key markers of cachexia, sarcopenia, and frailty. Seventeen C57/BL/6 mice were allocated into groups. 1) Control (n = 7): mice were exposed to intraperitoneal (i.p.) injections of saline solution. 2) Dox (n = 10): mice were exposed to doxorubicin chemotherapy cycles (total dose of 18 mg/kg divided over 15 days). The body weight loss and decreased food intake were monitored to assess cachexia. To assess sarcopenia, we measured muscle strength loss using a traction method and evaluated muscle atrophy through histology of the gastrocnemius muscle. To evaluate physical function impairments and assess frailty, we employed the open field test to measure exploratory capacity. Doxorubicin administration led to the development of cachexia, as evidenced by a significant body weight loss (13%) and a substantial decrease in food intake (34%) over a 15-day period. Furthermore, 90% of the mice treated with doxorubicin exhibited sarcopenia, characterized by a 20% reduction in traction strength (p<0,05), a 10% decrease in muscle mass, and a 33% reduction in locomotor activity. Importantly, all mice subjected to doxorubicin treatment were considered frail based on the evaluation of their overall condition and functional impairments. The proposed model holds significant characteristics of human chemotherapy treatment and can be useful to understand the intricate relationship between chemotherapy, cachexia, sarcopenia, and frailty.

Continuous or interval aerobic exercise training reduces daily fructose intake in female Wistar rat / Exercício físico aeróbio contínuo ou intervalado reduz ingestão de frutose em ratas Wistar

ABSTRACT: Objctive: Fructose consumption has increased worldwide. Excessive fructose intake has been a risk factor for the increased metabolic syndrome disorder incidence. This study aimed to investigate the possible influence of two different exercise training methods, continuous and interval, on fructose intake. Methods: Thirty two-months-old female Wistar rats were divided into six groups: sedentary + water ; sedentary + fructose ; continuous training + water ; interval training + water ; continuous training + fructose ; interval training + fructose . Fructose was given in drinking water (10%). Continuous (40 minutes at 40% maximal speed) or interval training (28 minutes, 1 minute at 70%; 3 minutes at 35% maximal speed) sessions were carried out 3 days/week for 8 weeks. Results: Fructose consumption decreased food intake with a concomitant increase in fluid intake. Continuous and interval training did not modify food intake but progressively reduced fructose ingestion. In the 8th week, interval training + fructose and continuous training + fructose groups drank less fructose solution, 35% and 23%, respectively, than sedentary + fructose group. Conclusion: The findings indicate that both continuous and interval aerobic exercise training seem to modulate food behavior, possibly by mitigating the craving for sweetness, with interval training being more effective in reducing fructose intake than continuous exercise.

RESUMO: Objetivo: O consumo de frutose aumentou em todo o mundo. A ingestão excessiva de frutose tem sido implicada como um fator de risco do aumento da incidência de distúrbios da síndrome metabólica. Nesse contexto, este estudo teve como objetivo investigar a possível influência de dois métodos diferentes de treinamento físico, contínuo e intervalado, na ingestão de frutose. Metodos: Trinta ratas Wistar foram divididas em seis grupos: sedentário + água, sedentário + frutose, treinamento contínuo + água, treinamento intervalado + água, treinamento contínuo + frutose, treinamento intervalado + frutose. A frutose foi dada na água potável (10%). Foram realizadas sessões contínuas (40 minutos a 40% da velocidade máxima) ou intervaladas (28 minutos, 1 minuto a 70%; 3 minutos a 35%) três dias por semana durante oito semanas. Resultados: A ingestão de frutose diminuiu a ingestão alimentar, com um aumento concomitante da ingestão hídrica. O treinamento contínuo e intervalado não modificou a ingestão alimentar, mas reduziu progressivamente a ingestão de frutose. Na oitava semana, treinamento intervalado + frutose e treinamento contínuo + frutose beberam menos solução de frutose, 35% e 23%, respectivamente, do que sedentário + frutose. Conclusão: Os achados indicam que tanto o treinamento aeróbico contínuo quanto o intervalado parecem modular o comportamento alimentar, possivelmente por meio da mitigação do desejo por sabor doce, sendo o treinamento intervalado mais eficaz para reduzir a ingestão de frutose do que o exercício contínuo.

Adipocyte-specific mTORC2 deficiency impairs BAT and iWAT thermogenic capacity without affecting glucose uptake and energy expenditure in cold-acclimated mice.

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.

PPARγ-induced upregulation of subcutaneous fat adiponectin secretion, glyceroneogenesis and BCAA oxidation requires mTORC1 activity.

The nutrient sensors peroxisome proliferator-activated receptor γ (PPARγ) and mechanistic target of rapamycin complex 1 (mTORC1) closely interact in the regulation of adipocyte lipid storage. The precise mechanisms underlying this interaction and whether this extends to other metabolic processes and the endocrine function of adipocytes are still unknown. We investigated herein the involvement of mTORC1 as a mediator of the actions of the PPARγ ligand rosiglitazone in subcutaneous inguinal white adipose tissue (iWAT) mass, endocrine function, lipidome, transcriptome and branched-chain amino acid (BCAA) metabolism. Mice bearing regulatory associated protein of mTOR (Raptor) deletion and therefore mTORC1 deficiency exclusively in adipocytes and littermate controls were fed a high-fat diet supplemented or not with the PPARγ agonist rosiglitazone (30 mg/kg/day) for 8 weeks and evaluated for iWAT mass, lipidome, transcriptome (Rnaseq), respiration and BCAA metabolism. Adipocyte mTORC1 deficiency not only impaired iWAT adiponectin transcription, synthesis and secretion, PEPCK mRNA levels, triacylglycerol synthesis and BCAA oxidation and mRNA levels of related proteins but also completely blocked the upregulation in these processes induced by pharmacological PPARγ activation with rosiglitazone. Mechanistically, adipocyte mTORC1 deficiency impairs PPARγ transcriptional activity by reducing PPARγ protein content, as well as by downregulating C/EBPα, a co-partner and facilitator of PPARγ. In conclusion, mTORC1 and PPARγ are essential partners involved in the regulation of subcutaneous adipose tissue adiponectin production and secretion and BCAA oxidative metabolism.

Immunometabolic responses according to physical fitness status and lifelong exercise during aging: New roads for exercise immunology.

Molecules such as cytokines, energetic substrates, and hormones found in the immune cell environment, especially lymphocytes and monocytes, are crucial for directing energy metabolism. In turn, changes in energy metabolism occur in a synchronized manner with the activation of certain signaling pathways, thereby this crosstalk is responsible for determining the functionality of immune cells. The immunometabolism field has grown over time and that is becoming increasingly promising in several populations; here we discuss the mechanisms involved in sedentary and physically active middle-aged individuals and master athletes. In this context, this review shows that the physical activity status and lifelong exercise seems to be good strategies for the promotion of metabolic and functional adaptations in T lymphocytes and monocytes, counteracting inflammatory environments caused by expanded adipose tissue and sedentary behavior, as well as delaying the immunosenescence caused by aging.

Resistance Training's Ability to Prevent Cancer-induced Muscle Atrophy Extends Anabolic Stimulus.

PURPOSE: This study aimed to determine the role of mammalian target of rapamycin (mTORC1) activation and catabolic markers in resistance training's (RT) antiatrophy effect during cachexia-induced muscle loss. METHODS: Myofiber atrophy was induced by injecting Walker 256 tumor cells into rats exposed or not exposed to the RT protocol of ladder climbing. The role of RT-induced anabolic stimulation was investigated in tumor-bearing rats with the mTORC1 inhibitor rapamycin, and cross-sectional areas of skeletal muscle were evaluated to identify atrophy or hypertrophy. Components of the mTORC1 and ubiquitin-proteasome pathways were assessed by real-time polymerase chain reaction or immunoblotting. RESULTS: Although RT prevented myofiber atrophy and impaired the strength of tumor-bearing rats, in healthy rats, it promoted activated mTORC1, as demonstrated by p70S6K's increased phosphorylation and myofiber's enlarged cross-sectional area. However, RT promoted no changes in the ratio of p70S6K to phospho-p70S6K protein expression while prevented myofiber atrophy in tumor-bearing rats. Beyond that, treatment with rapamycin did not preclude RT's preventive effect on myofiber atrophy in tumor-bearing rats. Thus, RT's ability to prevent cancer-induced myofiber atrophy seems to be independent of mTORC1's and p70S6K's activation. Indeed, RT's preventive effect on cancer-induced myofiber atrophy was associated with its capacity to attenuate elevated tumor necrosis factor α and interleukin 6 as well as to prevent oxidative damage in muscles and an elevated abundance of atrogin-1. CONCLUSIONS: By inducing attenuated myofiber atrophy independent of mTORC1's signaling activation, RT prevents muscle atrophy during cancer by reducing inflammation, oxidative damage, and atrogin-1 expression.

Mild-cold water swimming does not exacerbate white adipose tissue browning and brown adipose tissue activation in mice.

The present study investigated the effects of swimming physical training either thermoneutral or below thermoneutral water temperature on white (WAT) and brown (BAT) adipose tissue metabolism, morphology, and function. C57BL/6J male mice (n = 40; weight 25.3 ± 0.1 g) were divided into control (CT30), cold control (CT20), trained (TR30), and cold trained (TR20) groups. Swimming training consisted of 30-min exercise at 30°C (control) or 20°C (cold) water temperature. After 8-week training, adipose tissues were excised and inguinal (ingWAT) and BAT were processed for histology, lipolysis, and protein contents of total OXPHOS, PGC1α, and UCP1 by western blotting analysis. Swimming training reduced body weight gain independently of water temperature (P < 0.05). ingWAT mass was decreased for TR30 in comparison to other groups (P < 0.05), while for BAT, there was a significant increase in CT20 in relation to CT30, and both trained groups were significantly increased in relation to control groups (P < 0.05). ingWAT mean adipocyte area was smaller for trained groups, and seemed to present multilocular adipocytes. Lipolytic activity and protein content of UCP1, PGC1α, and mitochondrial markers were increased in trained groups for ingWAT (P < 0.05), independent of water temperature (P > 0.05), and these patterns were not observed for BAT (P > 0.05). Our findings suggest that mild-cold water exposure and swimming physical exercise seem to, independently, promote browning in ingWAT with no effects on BAT; however, the association of exercise and mild-cold water did not exacerbate these effects.

Moderate aerobic exercise-induced cytokines changes are disturbed in PPARα knockout mice.

The nuclear transcriptional factor peroxisome proliferator activated receptor alpha (PPARα) plays a role in regulating genes involved in lipid metabolism, adipogenesis and inflammation. We aimed to assess the role of PPARα on exercise-mediated locally produced cytokines in adipose fat deposits and skeletal muscle. C57BL/6 (WT) and PPARα knockout (PPARα-/-) mice were examined. Each genotype was randomly subdivided into three groups: non-exercised, and euthanized 2 or 24 h after a moderate aerobic exercise session (run on a treadmill at 60% of maximum speed for 1 h). Fat content in gastrocnemius muscle and lipolytic activity in isolated adipose tissue from mesenteric (MEAT) and retroperitoneal (RPAT) adipose tissue were evaluated. In addition, Interleukin 6 (IL-6), interleukin 10 (IL-10), tumor necrosis factor α (TNF-α) and monocyte chemoattractant protein 1 (MCP-1) content were evaluated by ELISA. WT mice showed a maximum lipolysis rate, as well as higher IL-6, IL-10, and IL10/TNF-α ratio values 2 h post-exercise (RPAT only) compared with PPARα-/- mice. Taken together, our data suggests that PPARα knockout mice exhibited reduced lipolysis and anti-inflammatory response in adipose tissue following exercise, PPARα appears to play an important role in immunomodulatory and lipolysis signaling after acute moderate exercise.

Creatine supplementation in Walker-256 tumor-bearing rats prevents skeletal muscle atrophy by attenuating systemic inflammation and protein degradation signaling.

PURPOSE: The aim of this study was to investigate the effects of creatine supplementation on muscle wasting in Walker-256 tumor-bearing rats. METHODS: Wistar rats were randomly assigned into three groups (n = 10/group): control (C), tumor bearing (T), and tumor bearing supplemented with creatine (TCr). Creatine was provided in drinking water for a total of 21 days. After 11 days of supplementation, tumor cells were implanted subcutaneously into T and TCr groups. The animals' weight, food and water intake were evaluated along the experimental protocol. After 10 days of tumor implantation (21 total), animals were euthanized for inflammatory state and skeletal muscle cross-sectional area measurements. Skeletal muscle components of ubiquitin-proteasome pathways were also evaluated using real-time PCR and immunoblotting. RESULTS: The results showed that creatine supplementation protected tumor-bearing rats against body weight loss and skeletal muscle atrophy. Creatine intake promoted lower levels of plasma TNF-α and IL-6 and smaller spleen morphology changes such as reduced size of white pulp and lymphoid follicle compared to tumor-bearing rats. In addition, creatine prevented increased levels of skeletal muscle Atrogin-1 and MuRF-1, key regulators of muscle atrophy. CONCLUSION: Creatine supplementation prevents skeletal muscle atrophy by attenuating tumor-induced pro-inflammatory environment, a condition that minimizes Atrogin-1 and MuRF-1-dependent proteolysis.

Effects of Walking Training with Restricted Blood Flow on HR and HRV Kinetics and HRV Recovery.

The aim of this study was to investigate the effects of walking training with and without blood flow restriction (BFR) on heart rate (HR) and heart rate variability (HRV) kinetics and HRV recovery. Twenty-one men (53.5±3.2 years; 82.4±13.5 kg; 168.5±7.2 cm) were randomly assigned to two training groups: walk training group with (BFR-W; n=11) and without (NOR-W; n=10) BFR. Before and after training, all subjects underwent body composition evaluation, incremental test, and one constant load test. Walking training was performed 3 times/week, during 6 weeks. Each session was composed by 5 sets of 3-min walking and 1-min rest between the sets. All parameters of HR on- and off-kinetics and RMSSD15 0 parameter of HRV on-kinetics were improved for BFR-W group after training (p<0.05), with an interaction effect for HR on-kinetics parameters and RMSSD15 0 parameter (p<0.05). Also, parameters of time and frequency domain of HRV recovery were also improved in BFR-W after training (p<0.05), with no interaction effect (p>0.05). Additionally, in BFR-W group, RMSSD60s values were improved in some moments after training (p<0.05). Therefore, this study demonstrates that a 6-week walking training with BFR improved cardiac autonomic responses on the onset and recovery of exercise.

Constitutive Activation of the Nutrient Sensor mTORC1 in Myeloid Cells Induced by Tsc1 Deletion Protects Mice from Diet-Induced Obesity.

SCOPE: To test whether myeloid cells Tsc1 deletion and therefore constitutive activation of the nutrient sensor mTORC1 protects from high-fat diet (HFD)-induced obesity, glucose intolerance, and adipose tissue inflammation. METHODS AND RESULTS: Mice with Tsc1 deletion in myeloid cells (MTsc1KO) and littermate controls (MTsc1WT) were fed with HFD for 8 weeks and evaluated for body weight, glucose homeostasis, and adipose tissue inflammation. MTsc1KO mice were protected from HFD-induced obesity and glucose intolerance. MTsc1KO, however, displayed, independently of the diet, abnormal behavior, episodes of intense movement, and muscle spasms followed by temporary paralysis. To investigate whether obesity protection was due to myeloid cells Tsc1 deletion, bone marrow was transplanted from MTsc1WT and MTsc1KO into irradiated C57BL6/J mice. Mice transplanted with MTsc1KO bone marrow displayed reduced body weight gain, adiposity, and inflammation, and enhanced energy expenditure, glucose tolerance and adipose tissue M2 macrophage content upon HFD feeding, in the absence of abnormal behavior. In vitro, Tsc1 deletion increased in a mTORC1-dependent manner macrophage polarization to M2 profile and mRNA levels of fatty acid binding protein 4 and PPARγ. CONCLUSION: Constitutive mTORC1 activation in myeloid cells protects mice from HFD-induced obesity, adipose tissue inflammation, and glucose intolerance by promoting macrophage polarization to M2 pro-resolution profile and increasing energy expenditure.

Chronic inflammation in skeletal muscle impairs satellite cells function during regeneration: can physical exercise restore the satellite cell niche?

Chronic inflammation impairs skeletal muscle regeneration. Although many cells are involved in chronic inflammation, macrophages seem to play an important role in impaired muscle regeneration since these cells are associated with skeletal muscle stem cell (namely, satellite cells) activation and fibro-adipogenic progenitor cell (FAP) survival. Specifically, an imbalance of M1 and M2 macrophages seems to lead to impaired satellite cell activation, and these are the main cells that function during skeletal muscle regeneration, after muscle damage. Additionally, this imbalance leads to the accumulation of FAPs in skeletal muscle, with aberrant production of pro-fibrotic factors (e.g., extracellular matrix components), impairing the niche for proper satellite cell activation and differentiation. Treatments aiming to block the inflammatory pro-fibrotic response are partially effective due to their side effects. Therefore, strategies reverting chronic inflammation into a pro-regenerative pattern are required. In this review, we first describe skeletal muscle resident macrophage ontogeny and homeostasis, and explain how macrophages are replenished after muscle injury. We next discuss the potential role of chronic physical activity and exercise in restoring the M1 and M2 macrophage balance and consequently, the satellite cell niche to improve skeletal muscle regeneration after injury.

Adipocyte mTORC1 deficiency promotes adipose tissue inflammation and NLRP3 inflammasome activation via oxidative stress and de novo ceramide synthesis.

Mechanistic target of rapamycin complex (mTORC)1 activity is increased in adipose tissue of obese insulin-resistant mice, but its role in the regulation of tissue inflammation is unknown. Herein, we investigated the effects of adipocyte mTORC1 deficiency on adipose tissue inflammation and glucose homeostasis. For this, mice with adipocyte raptor deletion and controls fed a chow or a high-fat diet were evaluated for body mass, adiposity, glucose homeostasis, and adipose tissue inflammation. Despite reducing adiposity, adipocyte mTORC1 deficiency promoted hepatic steatosis, insulin resistance, and adipose tissue inflammation (increased infiltration of macrophages, neutrophils, and B lymphocytes; crown-like structure density; TNF-α, interleukin (IL)-6, and monocyte chemoattractant protein 1 expression; IL-1ß protein content; lipid peroxidation; and de novo ceramide synthesis). The anti-oxidant, N-acetylcysteine, partially attenuated, whereas treatment with de novo ceramide synthesis inhibitor, myriocin, completely blocked adipose tissue inflammation and nucleotide oligomerization domain-like receptor pyrin domain-containing 3 (NLRP3)-inflammasome activation, but not hepatic steatosis and insulin resistance induced by adipocyte raptor deletion. Rosiglitazone treatment, however, completely abrogated insulin resistance induced by adipocyte raptor deletion. In conclusion, adipocyte mTORC1 deficiency induces adipose tissue inflammation and NLRP3-inflammasome activation by promoting oxidative stress and de novo ceramide synthesis. Such adipose tissue inflammation, however, is not an underlying cause of the insulin resistance displayed by these mice.

mTORC1 inhibition with rapamycin exacerbates adipose tissue inflammation in obese mice and dissociates macrophage phenotype from function.

Genetic- and diet-induced obesity and insulin resistance are associated with an increase in mechanistic target of rapamycin complex (mTORC) 1 activity in adipose tissue. We investigated herein the effects of pharmacological mTORC1 inhibition in the development of adipose tissue inflammation induced by high-fat diet (HFD) feeding, as well as in the polarization, metabolism and function of bone marrow-derived macrophages (BMDM). For this, C57BL/6J mice fed with a standard chow diet or a HFD (60% of calories from fat) and treated with either vehicle (0.1% Me2SO, 0.2% methylcellulose) or rapamycin (2mg/kg/ day, gavage) during 30days were evaluated for body weight, adiposity, glucose tolerance and adipose tissue inflammation. Although rapamycin did not affect the increase in body weight and adiposity, it exacerbated the glucose intolerance and adipose tissue inflammation induced by HFD feeding, as evidenced by the increased adipose tissue percentage of M1 macrophages, naive and activated cytotoxic T lymphocytes, and mRNA levels of proinflammatory molecules, such as TNF-α, IL-6 and MCP-1. In BMDM in vitro, pharmacological mTORC1 inhibition induced phosphorylation of NFκB p65 and spontaneous polarization of macrophages to a proinflammatory M1 profile, while it impaired M2 polarization induced by IL-4+IL-13, glycolysis and phagocytosis. Altogether, these findings indicate that mTORC1 activity is an important determinant of adipose tissue inflammatory profile and macrophage plasticity, metabolism and function.

mTORC1 is Required for Brown Adipose Tissue Recruitment and Metabolic Adaptation to Cold.

In response to cold, brown adipose tissue (BAT) increases its metabolic rate and expands its mass to produce heat required for survival, a process known as BAT recruitment. The mechanistic target of rapamycin complex 1 (mTORC1) controls metabolism, cell growth and proliferation, but its role in regulating BAT recruitment in response to chronic cold stimulation is unknown. Here, we show that cold activates mTORC1 in BAT, an effect that depends on the sympathetic nervous system. Adipocyte-specific mTORC1 loss in mice completely blocks cold-induced BAT expansion and severely impairs mitochondrial biogenesis. Accordingly, mTORC1 loss reduces oxygen consumption and causes a severe defect in BAT oxidative metabolism upon cold exposure. Using in vivo metabolic imaging, metabolomics and transcriptomics, we show that mTORC1 deletion impairs glucose and lipid oxidation, an effect linked to a defect in tricarboxylic acid (TCA) cycle activity. These analyses also reveal a severe defect in nucleotide synthesis in the absence of mTORC1. Overall, these findings demonstrate an essential role for mTORC1 in the regulation of BAT recruitment and metabolism in response to cold.

Constitutive adipocyte mTORC1 activation enhances mitochondrial activity and reduces visceral adiposity in mice.

Mechanistic target of rapamycin complex 1 (mTORC1) loss of function reduces adiposity whereas partial mTORC1 inhibition enhances fat deposition. Herein we evaluated how constitutive mTORC1 activation in adipocytes modulates adiposity in vivo. Mice with constitutive mTORC1 activation in adipocytes induced by tuberous sclerosis complex (Tsc)1 deletion and littermate controls were evaluated for body mass, energy expenditure, glucose and fatty acid metabolism, mitochondrial function, mRNA and protein contents. Adipocyte-specific Tsc1 deletion reduced visceral, but not subcutaneous, fat mass, as well as adipocyte number and diameter, phenotypes that were associated with increased lipolysis, UCP-1 content (browning) and mRNA levels of pro-browning transcriptional factors C/EBPß and ERRα. Adipocyte Tsc1 deletion enhanced mitochondrial oxidative activity, fatty acid oxidation and the expression of PGC-1α and PPARα in both visceral and subcutaneous fat. In brown adipocytes, however, Tsc1 deletion did not affect UCP-1 content and basal respiration. Adipocyte Tsc1 deletion also reduced visceral adiposity and enhanced glucose tolerance, liver and muscle insulin signaling and adiponectin secretion in mice fed with purified low- or high-fat diet. In conclusion, adipocyte-specific Tsc1 deletion enhances mitochondrial activity, induces browning and reduces visceral adiposity in mice.

Neonatal streptozotocin-induced diabetes in mothers promotes metabolic programming of adipose tissue in male rat offspring.

AIMS: Maternal hyperglycemia during pregnancy can lead to fetal changes, like macrosomia or obesity in adultlife. Experimentalmodels of diabetes have been studied to evaluate the consequences of offspring lipidmetabolism. This study aimed to investigate the metabolic changes in adipose tissue of offspring of streptozotocininduced diabetic mothers during neonatal period. MAIN METHODS: Diabetes was induced in female rats by streptozotocin administration on 5th day of life. In adulthood, female rats were bred with control male rats. Male puppies were sacrificed on 12th week of life and epididymal (EP) and subcutaneous (SC) adipose fat pads were excised and weighted. Adipocytes were isolated and evaluated for basal and insulin-stimulated 2-deoxyglucose uptake, oxidation of glucose into CO2, and incorporationof glucose into lipids and lipolytic capacity. KEY FINDINGS: Bodyweight, EP fat padweight and diameter of adipocytes fromoffspring of diabeticmothers were increased in comparison to offspring of control mothers. EP adipocytes from offspring of diabetic mothers presented increased basal and insulin stimulated glucose uptake in comparison to control ones. Similar pattern was observed for glucose oxidation into CO2 and incorporation into lipids. However, significant difference in lipolytic capacity in vitrowas not observed. Protein content of GLUT4, insulin receptor and acetyl-CoA carboxylase was significantly increased in EP fat pad of offspring of diabetic mothers in relation to control group. SIGNIFICANCE: Metabolic programming occurred in the adipose tissue of offspring of diabetic mothers, increasing its capacity to store lipids with no changes in lipolytic capacity.

Omega-3 fatty acids protect from diet-induced obesity, glucose intolerance, and adipose tissue inflammation through PPARγ-dependent and PPARγ-independent actions.

SCOPE: We tested herein the hypothesis that peroxisome proliferator activated receptor γ (PPARγ) is a major mediator of omega-3 (n-3) protective actions against high-fat diet (HFD) induced obesity, glucose intolerance, and adipose tissue inflammation. METHODS AND RESULTS: C57BL6 wild-type and fat-1 transgenic (fat-1) mice were fed a low-fat diet (LFD) or HFD, treated or not with PPARγ antagonist, and evaluated for energy balance, adiposity, glucose tolerance, and adipose tissue inflammation. Fat-1 mice were protected from obesity, fasting hyperglycemia, glucose intolerance, and adipose tissue inflammation. PPARγ inhibition completely abolished fat-1 protection against HFD-induced glucose intolerance, but not obesity or adipose tissue inflammation. To investigate the role of myeloid cell as mediator of n-3 beneficial metabolic actions, mice with deletion (LyzM-PPARγ(KO)) or nondeletion (LyzM-PPARγ(WT)) of PPARγ in myeloid cells were fed either LFD or HFD (lard) or an HFD rich in n-3 (fish oil). Our findings indicate that myeloid cell associated PPARγ is not involved in the attenuation of HFD-induced glucose intolerance and adipose tissue inflammation induced by n-3. CONCLUSION: High endogenous n-3 fatty acid levels protect from HFD obesity, glucose intolerance, and adipose tissue inflammation. Among these, only protection against glucose intolerance is mediated by non-myeloid cell PPARγ.

Pinealectomy interferes with the circadian clock genes expression in white adipose tissue.

Melatonin, the main hormone produced by the pineal gland, is secreted in a circadian manner (24-hr period), and its oscillation influences several circadian biological rhythms, such as the regulation of clock genes expression (chronobiotic effect) and the modulation of several endocrine functions in peripheral tissues. Assuming that the circadian synchronization of clock genes can play a role in the regulation of energy metabolism and it is influenced by melatonin, our study was designed to assess possible alterations as a consequence of melatonin absence on the circadian expression of clock genes in the epididymal adipose tissue of male Wistar rats and the possible metabolic repercussions to this tissue. Our data show that pinealectomy indeed has impacts on molecular events: it abolishes the daily pattern of the expression of Clock, Per2, and Cry1 clock genes and Pparγ expression, significantly increases the amplitude of daily expression of Rev-erbα, and affects the pattern of and impairs adipokine production, leading to a decrease in leptin levels. However, regarding some metabolic aspects of adipocyte functions, such as its ability to synthesize triacylglycerols from glucose along 24 hr, was not compromised by pinealectomy, although the daily profile of the lipogenic enzymes expression (ATP-citrate lyase, malic enzyme, fatty acid synthase, and glucose-6-phosphate dehydrogenase) was abolished in pinealectomized animals.

Palmitoleic acid (n-7) increases white adipocytes GLUT4 content and glucose uptake in association with AMPK activation.

BACKGROUND: Palmitoleic acid was previously shown to improve glucose homeostasis by reducing hepatic glucose production and by enhancing insulin-stimulated glucose uptake in skeletal muscle. Herein we tested the hypothesis that palmitoleic acid positively modulates glucose uptake and metabolism in adipocytes. METHODS: For this, both differentiated 3 T3-L1 cells treated with either palmitoleic acid (16:1n7, 200 µM) or palmitic acid (16:0, 200 µM) for 24 h and primary adipocytes from mice treated with 16:1n7 (300 mg/kg/day) or oleic acid (18:1n9, 300 mg/kg/day) by gavage for 10 days were evaluated for glucose uptake, oxidation, conversion to lactate and incorporation into fatty acids and glycerol components of TAG along with the activity and expression of lipogenic enzymes. RESULTS: Treatment of adipocytes with palmitoleic, but not oleic (in vivo) or palmitic (in vitro) acids, increased basal and insulin-stimulated glucose uptake and GLUT4 mRNA levels and protein content. Along with uptake, palmitoleic acid enhanced glucose oxidation (aerobic glycolysis), conversion to lactate (anaerobic glycolysis) and incorporation into glycerol-TAG, but reduced de novo fatty acid synthesis from glucose and acetate and the activity of lipogenic enzymes glucose 6-phosphate dehydrogenase and ATP-citrate lyase. Importantly, palmitoleic acid induction of adipocyte glucose uptake and metabolism were associated with AMPK activation as evidenced by the increased protein content of phospho(p)Thr172AMPKα, but no changes in pSer473Akt and pThr308Akt. Importantly, such increase in GLUT4 content induced by 16:1n7, was prevented by pharmacological inhibition of AMPK with compound C. CONCLUSIONS: In conclusion, palmitoleic acid increases glucose uptake and the GLUT4 content in association with AMPK activation.