Differential response to caloric restriction of retroperitoneal, epididymal, and subcutaneous adipose tissue depots in rats

Assessment of melatonin's therapeutic effectiveness against hepatic steatosis induced by a high-carbohydrate high-fat diet in rats

Several studies have demonstrated the protective effects of melatonin against metabolic diseases, such as liver steatosis. However, its therapeutic effects have received less scrutiny. The present study aimed to explore melatonin's therapeutic effectiveness in treating non-alcoholic fatty liver disease (NAFLD) induced by a high-carbohydrate high-fat (HCHF) diet in rats. The NAFLD was developed in male Wistar rats using an HCHF diet for 8 weeks. Afterward, they were given melatonin orally for four weeks at doses of 5 mg/kg, 10 mg/kg, and 30 mg/kg, along with the HCHF diet. In addition, six age-matched healthy rats received the highest dose of melatonin (30 mg/kg) for the same duration. Rats on the HCHF diet exhibited obesity, dyslipidemia, hyperglycemia, glucose intolerance, insulin resistance, inflammation, oxidative stress, and liver injury (steatosis). Melatonin treatment at 10 mg/kg and 30 mg/kg reduced body weight, adiposity index, oxidative damage, and inflammation but did not affect impaired glucose metabolism induced by the HCHF diet. Meanwhile, the highest dose of melatonin (30 mg/kg) reduced the liver steatosis index in HCHF rats but caused mild liver damage in healthy rats. In conclusion, using melatonin demonstrated positive outcomes in treating NAFLD induced by the HCHF diet in rats, with no noteworthy effects observed in healthy rats. A moderate dosage of 10 mg/kg of melatonin proved to be a safer and more efficient method for reducing HCHF diet-induced NAFLD in rats. Higher melatonin doses should be cautiously administered due to potential disruptions in lipid metabolism and the risk of liver complications.

The Metabolic Syndrome, a Human Disease

This review focuses on the question of metabolic syndrome (MS) being a complex, but essentially monophyletic, galaxy of associated diseases/disorders, or just a syndrome of related but rather independent pathologies. The human nature of MS (its exceptionality in Nature and its close interdependence with human action and evolution) is presented and discussed. The text also describes the close interdependence of its components, with special emphasis on the description of their interrelations (including their syndromic development and recruitment), as well as their consequences upon energy handling and partition. The main theories on MS's origin and development are presented in relation to hepatic steatosis, type 2 diabetes, and obesity, but encompass most of the MS components described so far. The differential effects of sex and its biological consequences are considered under the light of human social needs and evolution, which are also directly related to MS epidemiology, severity, and relations with senescence. The triggering and maintenance factors of MS are discussed, with especial emphasis on inflammation, a complex process affecting different levels of organization and which is a critical element for MS development. Inflammation is also related to the operation of connective tissue (including the adipose organ) and the widely studied and acknowledged influence of diet. The role of diet composition, including the transcendence of the anaplerotic maintenance of the Krebs cycle from dietary amino acid supply (and its timing), is developed in the context of testosterone and β-estradiol control of the insulin-glycaemia hepatic core system of carbohydrate-triacylglycerol energy handling. The high probability of MS acting as a unique complex biological control system (essentially monophyletic) is presented, together with additional perspectives/considerations on the treatment of this 'very' human disease.

The analysis of fatty acids and their derivatives in the liver of C57BL/6 mice with long-term caloric restrictions

Caloric restriction (CR) is a dietetic intervention based on the reduction of daily calorie intake by 10-30 %. When subjected to CR, the organism adjusts its metabolism to the changing availability of key nutrients. However, fatty acids' content in organisms subjected to long-term CR has not been evaluated. The aim of the research was to analyze the influence of long-term CR on the contents of medium- and long-chain fatty acids, as well as on the contents of fatty acid derivatives in liver. The study was performed on C57BL female (n = 12) and male (n = 12) mice subjected to lifelong 30 % calorie restriction. Fatty acids were analyzed using gas chromatography, while fatty acid derivatives were analyzed with liquid chromatography. The dynamics of change of the lipid profile of the labeled fatty acids observed in the liver tissue confirms that lipolysis actively takes place in this organ when hungry. Moreover, it is highly possible that de novo synthesis of acids takes place, with the aim to ensure energy substrates to the body. Moreover, an increase of concentration was observed for fatty acid derivatives, those with anti-inflammatory properties (resolvin, LTX A4). However, there was no increase in the concentration of pro-inflammatory eicosanoids. The results suggest that it is important to take into consideration the introduction of appropriate supplements when using CR.

Butyrate restores the fat/lean mass ratio balance and energy metabolism and reinforces the tight junction-mediated intestinal epithelial barrier in prediabetic mice independently of its anti-inflammatory and epigenetic actions

Tissue/cellular actions of butyrate on energy metabolism and intestinal barrier in normal metabolic conditions or prediabetes are still unclear. In this work, we investigated the beneficial effect of dietary supplementation with sodium butyrate on energy metabolism, body mass composition, and intestinal epithelial barrier mediated by tight junction (TJ) in chow diet-fed normal and high-fat diet (HF)-fed prediabetic mice, considering the well-known butyrate action as an epigenetic and inflammatory regulator. Butyrate significantly reduced the fat/lean mass ratio, slightly ameliorated dyslipidemia, restored oral glucose tolerance, and increased basal energy expenditure in prediabetic HF-fed mice but had no effect on control animals. Such effects were observed in the absence of significant alterations in the hypothalamic expression of orexigenic and anorexigenic genes and motor activity. Also, butyrate suppressed the whitening effect of HF on brown adipose tissue but did not affect cell bioenergetics in immortalized UCP1-positive adipocytes in vitro. Butyrate reinforced the intestinal epithelial barrier in HF-fed mice and in Caco-2 monolayers, which involved higher trafficking of TJ proteins to the cell-cell contact region of the intestinal epithelia, without affecting TJ gene expression or the acetylation level of histones H3 and H4 in vivo. All metabolic and intestinal effects of butyrate in prediabetic mice occurred in the absence of detectable changes in systemic or local inflammation, or alterations in endotoxemia markers. Butyrate has no effect on chow diet-fed mice but, in the context of HF-induced prediabetes, it prevents metabolic and intestinal dysfunctions independently of its anti-inflammatory and epigenetic actions.

Effect of mitochondrial quantity and quality controls in white adipose tissue on healthy lifespan: Essential roles of GH/IGF-1-independent pathways in caloric restriction-mediated metabolic remodeling

Long-term caloric restriction is a conventional and reproducible dietary intervention to improve whole body metabolism, suppress age-related pathophysiology, and extend lifespan. The beneficial actions of caloric restriction are widely accepted to be regulated in both growth hormone/insulin-like growth factor 1-dependent and -independent manners. Although growth hormone/insulin-like growth factor 1-dependent regulatory mechanisms are well described, those occurring independent of growth hormone/insulin-like growth factor 1 are poorly understood. In this review, we focus on molecular mechanisms of caloric restriction regulated in a growth hormone/insulin-like growth factor 1-independent manner. Caloric restriction increases mitochondrial quantity and improves mitochondrial quality by activating an axis involving sterol regulatory element binding protein-c/peroxisome proliferator-activated receptor γ coactivator-1α/mitochondrial intermediate peptidase in a growth hormone/insulin-like growth factor 1-independent manner, particularly in white adipose tissue. Fibroblast growth factor 21 is also involved in this axis. Moreover, the axis may be regulated by lower leptin signaling. Thus, caloric restriction appears to induce beneficial actions partially by regulating mitochondrial quantity and quality in white adipose tissue in a growth hormone/insulin-like growth factor 1-independent manner.

Paternal developmental thyrotoxicosis disrupts neonatal leptin leading to increased adiposity and altered physiology of the melanocortin system

Background

The genetic code does not fully explain individual variability and inheritance of susceptibility to endocrine conditions, suggesting the contribution of epigenetic factors acting across generations.

Methods

We used a mouse model of developmental thyrotoxicosis (Dio3-/- mouse) to analyze endocrine outcomes in the adult offspring of Dio3-/- males using standard methods for body composition, and baseline and fasting hormonal and gene expression determinations in serum and tissues of relevance to the control of energy balance.

Results

Compared to controls, adult females with an exposed father (EF females) exhibited higher body weight and fat mass, but not lean mass, a phenotype that was much milder in EF males. After fasting, both EF females and males exhibited a more pronounced decrease in body weight than controls. EF females also showed markedly elevated serum leptin, increased white adipose tissue mRNA expression of leptin and mesoderm-specific transcript but decreased expression of type 2 deiodinase. EF females exhibited decreased serum ghrelin, which showed more pronounced post-fasting changes in EF females than in control females. EF female hypothalami also revealed significant decreases in the expression of pro-opiomelanocortin, agouti-related peptide, neuropeptide Y and melanocortin receptor 4. These markers also showed larger changes in response to fasting in EF females than in control females. Adult EF females showed no abnormalities in serum thyroid hormones, but pituitary expression of thyrotropin-releasing hormone receptor 1 and thyroid gland expression of thyroid-stimulating hormone receptor, thyroid peroxidase and iodotyrosine deiodinase were increased at baseline and showed differential regulation after fasting, with no increase in Trhr1 expression and more pronounced reductions in Tshr, Tpo and Iyd. In EF males, these abnormalities were generally milder. In addition, postnatal day 14 (P14) serum leptin was markedly reduced in EF pups.

Discussion

A paternal excess of thyroid hormone during development modifies the endocrine programming and energy balance in the offspring in a sexually dimorphic manner, with baseline and dynamic range alterations in the leptin-melanocortin system and thyroid gland, and consequences for adiposity phenotypes. We conclude that thyroid hormone overexposure may have important implications for the non-genetic, inherited etiology of endocrine and metabolic pathologies.

Changes in Lipid Metabolism Enzymes in Rat Epididymal Fat after Chronic Central Leptin Infusion Are Related to Alterations in Inflammation and Insulin Signaling

Leptin inhibits food intake and reduces the size of body fat depots, changing adipocyte sensitivity to insulin to restrain lipid accrual. This adipokine may modulate the production of cytokines that could diminish insulin sensitivity, particularly in visceral adipose tissue. To explore this possibility, we examined the effects of chronic central administration of leptin on the expression of key markers of lipid metabolism and its possible relationship with changes in inflammatory- and insulin-signaling pathways in epididymal adipose tissue. Circulating non-esterified fatty acids and pro- and anti-inflammatory cytokines were also measured. Fifteen male rats were divided into control (C), leptin (L, icv, 12 μg/day for 14 days), and pair-fed (PF) groups. We found a decrease in the activity of glucose-6-phosphate dehydrogenase and malic enzyme in the L group, with no changes in the expression of lipogenic enzymes. A reduction in the expression of lipoprotein lipase and carnitine palmitoyl-transferase-1A, together with a decrease in the phosphorylation of insulin-signaling targets and a low-grade inflammatory pattern, were detected in the epididymal fat of L rats. In conclusion, the decrease in insulin sensitivity and increased pro-inflammatory environment could regulate lipid metabolism, reducing epididymal fat stores in response to central leptin infusion.

Adipose Tissue Aging and Metabolic Disorder, and the Impact of Nutritional Interventions

Adipose tissue is the largest and most active endocrine organ, involved in regulating energy balance, glucose and lipid homeostasis and immune function. Adipose tissue aging processes are associated with brown adipose tissue whitening, white adipose tissue redistribution and ectopic deposition, resulting in an increase in age-related inflammatory factors, which then trigger a variety of metabolic syndromes, including diabetes and hyperlipidemia. Metabolic syndrome, in turn, is associated with increased inflammatory factors, all-cause mortality and cognitive impairment. There is a growing interest in the role of nutritional interventions in adipose tissue aging. Nowadays, research has confirmed that nutritional interventions, involving caloric restriction and the use of vitamins, resveratrol and other active substances, are effective in managing adipose tissue aging’s adverse effects, such as obesity. In this review we summarized age-related physiological characteristics of adipose tissue, and focused on what nutritional interventions can do in improving the retrogradation and how they do this.

The effects of graded levels of calorie restriction XVIII: tissue specific changes in cell size and number in response to calorie restriction

Calorie restriction (CR) without malnutrition increases the health- and lifespan of diverse taxa. The mechanism(s) behind CR are debated but may be directly linked to body composition changes that maintain energy balance. During a deficit, energy is primarily obtained from white adipose tissue (WAT; utilized) whilst other tissues remain unchanged (protected) or grow (invested) relative to body mass. The changes in mass of 6 tissues from 48 male C57BL/6 mice following 3-months graded (10, 20, 30, or 40%) CR or fed ad libitum for 12 or 24hr a day were related to cell size (hypo/hypertrophy) and/or number (hypo/hyperplasia). Tissues studied were: retroperitoneal and subcutaneous WAT, brown adipose tissue (BAT) (utilized); lungs (protected), and stomach and caecum (invested). Methodology was based on number of nuclei/ tissue equalling the number of cells. Extracted DNA was quantified and used to estimate cell numbers (Total DNA/DNA per diploid nucleus) and size (Tissue mass/nuclei number). WAT utilization was caused solely by hypotrophy whereas BAT utilization resulted from reduced cell number and size. WAT cell size positively correlated with circulating hormones related to energy balance and BAT cell number and size positively correlated with body temperature. No changes were found in the lungs, consistent with their protected status, whereas hyperplasia appeared to be the dominant mechanism for invested alimentary-tract tissues. These findings indicate the pattern of change of cell size and number across increasing levels of short-term CR is tissue-specific.

Nutritional Regulation of Mammary Tumor Microenvironment

The mammary gland is a heterogeneous organ comprising of immune cells, surrounding adipose stromal cells, vascular cells, mammary epithelial, and cancer stem cells. In response to nutritional stimuli, dynamic interactions amongst these cell populations can be modulated, consequently leading to an alteration of the glandular function, physiology, and ultimately disease pathogenesis. For example, obesity, a chronic over-nutritional condition, is known to disrupt homeostasis within the mammary gland and increase risk of breast cancer development. In contrast, emerging evidence has demonstrated that fasting or caloric restriction can negatively impact mammary tumorigenesis. However, how fasting induces phenotypic and functional population differences in the mammary microenvironment is not well understood. In this review, we will provide a detailed overview on the effect of nutritional conditions (i.e., overnutrition or fasting) on the mammary gland microenvironment and its impact on mammary tumor progression.

miR-27a Regulates Sheep Adipocyte Differentiation by Targeting CPT1B Gene

Simple Summary

The content of intramuscular fat (IMF) is the main determinant of the nutritional and economic value of sheep meat. Therefore, lipid synthesis in sheep longissimus lumborum (LL) has become an important research focus. MicroRNA-27a (miR-27a) has been shown to play a crucial role in the proliferation and differentiation of adipocyte progenitor cells. In this study, we revealed that miR-27a significantly inhibited the formation of lipid droplets by targeting CPT1B to inhibit genes involved in lipid synthesis including PPAR γ, SCD, LPL, and FABP4. Here, we constructed a miR-27a-CPT1B regulatory network map, which revealed the interaction between miR-27a and CPT1B in lipid synthesis in ovine preadipocytes.

Abstract

MiRNAs are vital regulators and play a major role in cell differentiation, biological development, and disease occurrence. In recent years, many studies have found that miRNAs are involved in the proliferation and differentiation of adipocytes. The objective of this study was to evaluate the effect of miR-27a and its target gene CPT1B on ovine preadipocytes differentiation in Small-tailed Han sheep (Ovis aries). Down-regulation of miR-27a significantly promoted the production of lipid droplets, while overexpression of miR-27a led to a reduction in lipid droplet production. In addition, inhibition of miR-27a led to a significant increase in the expression of genes involved in lipid synthesis, including PPAR γ, SCD, LPL, and FABP4. Target Scan software predicted that CPT1B is a new potential target gene of miR-27a. Further experiments revealed that CPT1B gene expression and protein levels were negatively correlated with miR-27a expression. Overexpression of miR-27a led to a significant decrease in CPT1B mRNA levels and inhibited the accumulation of lipid droplets and vice versa. Moreover, overexpression of CPT1B promoted the synthesis of lipid droplets in ovine preadipocytes. Furthermore, luciferase reporter assays confirmed CPT1B to be a miR-27a direct target gene. This study confirmed that miR-27a increases the expression of genes related to lipid synthesis in ovine preadipocytes by targeting CPT1B, thereby promoting the synthesis of lipid droplets. The results of this study can be used to be exploited in devising novel approaches for improving the IMF content of sheep.

Prolonged caloric restriction ameliorates age-related atrophy in slow and fast muscle fibers of rat soleus muscle

Aging causes loss of skeletal muscle mass and function, which is called sarcopenia. While sarcopenia impairs the quality of life of older adults and is a major factor in long-term hospitalization, its detailed pathogenic mechanism and preventive measures remain to be identified. Caloric restriction (CR) suppresses age-related physiological and pathological changes in many species and prolongs the average and healthy life expectancy. It has recently been reported that CR suppresses the onset of sarcopenia; however, few studies have analyzed the effects of long-term CR on age-related skeletal muscle atrophy. Thus, we investigated the aging and CR effects on soleus (SOL) muscles of 9-, 24-, and 29-month-old ad libitum-fed rats (9AL, 24AL, and 29AL, respectively) and of 29-month-old CR (29CR) rats. The total muscle cross sectional area (mCSA) of the entire SOL muscle significantly decreased in the 29AL rats, but not in the 24AL rats, compared with the 9AL rats. SOL muscle of the 29AL rats exhibited marked muscle fiber atrophy and increases in the number of muscle fibers with a central nucleus, in fibrosis, and in adipocyte infiltration. Additionally, although the decrease in the single muscle fiber cross-sectional area (fCSA) and the muscle fibers' number occurred in both slow-type and fast-type muscle fibers, the degree of atrophy was more remarkable in the fast-type fibers. However, CR suppressed the muscle fiber atrophy observed in the 29AL rats' SOL muscle by preserving the mCSA and the number of muscle fibers that declined with aging, and by decreasing the number of muscle fibers with a central nucleus, fibrosis and denervated muscle fibers. Overall, these results revealed that advanced aging separately reduces the number and fCSA of each muscle fiber type, but long-term CR can ameliorate this age-related sarcopenic muscle atrophy.

Phenotypic and genotypic changes in obesity and type 2 diabetes of male KK mice with aging

Research into the prevention and treatment of age-related metabolic diseases are important in the present-day situation of the aging population. We propose that an elderly diabetic mouse model may be useful to such research as it exhibits deterioration of glucose and lipid metabolism. Although the KK mouse strain is commonly used as a model of moderate obesity and type 2 diabetes, the utility of this strain as an elderly obese and diabetic model mouse for research into aging remains unclear. The present study aimed to investigate age-related changes of glucose and lipid metabolism in male KK mice fed a standard chow diet. We demonstrate that 40 weeks KK mice exhibit age-related dysfunctions, such as development of insulin resistance associated with pancreatic islet hypertrophy and decreased lipolysis in white adipose tissue (WAT) compared with 15 weeks KK mice. However, aging does not appear to cause mitochondrial dysfunction of brown adipose tissue. Unexpectedly, hyperglycemia, potential glucose uptake in insulin-sensitive organs, hepatic lipid accumulation, hypertrophy of adipocytes, and inflammation in epididymal WAT did not worsen but rather compensated in 40 weeks KK mice. Our data indicate that the use of male KK mice as an elderly obese and diabetic mouse model has some limitations and in order to represent a useful elderly obese and diabetic animal model, it may be necessary to induce deterioration of glucose and lipid metabolism in KK mice through breeding with high-sucrose or high-fat diets.

Developmental and functional heterogeneity of thermogenic adipose tissue

The obesity epidemic continues to rise as a global health challenge. Thermogenic brown and beige adipocytes dissipate chemical energy as heat, providing an opportunity for developing new therapeutics for obesity and related metabolic diseases. Anatomically, brown adipose tissue is distributed as discrete depots, while beige adipocytes exist within certain depots of white adipose tissue. Developmentally, brown and beige adipocytes arise from multiple embryonic progenitor populations that are distinct and overlapping. Functionally, they respond to a plethora of stimuli to engage uncoupling protein 1-dependent and independent thermogenic programs, thus improving systemic glucose homeostasis, lipid metabolism, and the clearance of branched-chain amino acids. In this review, we highlight recent advances in our understanding of the molecular and cellular mechanisms that contribute to the developmental and functional heterogeneity of thermogenic adipose tissue.

[Metabolic Alteration in Aging Process: Metabolic Remodeling in White Adipose Tissue by Caloric Restriction]

Caloric restriction (CR) improves whole-body metabolism, suppresses various age-related pathophysiological changes, and extends lifespan. The beneficial actions of CR are regulated in growth hormone (GH)/insulin-like growth factor-1 (IGF-1) signal-dependent and -independent manners. To clarify the GH/IGF-1-independent mechanism, we compared gene expression profiles in white adipose tissue (WAT) between CR and GH/IGF-1 suppression, and found that CR upregulated sterol regulatory element-binding protein 1c (SREBP-1c) regulatory gene expression. To validate the impact of SREBP-1c as a beneficial mediator of CR, we compared the responses to CR between wild-type and SREBP-1c knockout (KO) mice. CR extended lifespan, upregulated gene expression involved in FA biosynthesis, activated mitochondrial biogenesis, and suppressed oxidative stress predominantly in WAT. In contrast, most of these findings were not observed in KO mice. Furthermore, SREBP-1c was implicated in CR-associated mitochondrial activation through upregulation of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), a master regulator of mitochondrial biogenesis. Sirtuin-3 (SIRT3) regulates mitochondrial quality and is also involved in the beneficial actions of CR. We observed that CR upregulated the mature form of SIRT3 protein and mitochondrial intermediate peptidase (MIPEP), a mitochondrial signal peptidase (MtSPase), in WAT. MIPEP cleaved precursor form of SIRT3 to mature form, and activated certain mitochondrial matrix proteins, suggesting that MIPEP might contribute to maintenance of mitochondrial quality during CR via SIRT3 activation. Taken together, CR induces SREBP-1c-dependent metabolic remodeling, including enhancement of FA biosynthesis and mitochondrial activation, via PGC-1α, and improvement of mitochondria quality via Mipep in WAT, resulting in beneficial actions.

Impact of caloric restriction on AMPK and endoplasmic reticulum stress in peripheral tissues and circulating peripheral blood mononuclear cells from Zucker rats

The activation of endoplasmic reticulum (ER) stress and a reduction of AMP-dependent protein kinase (AMPK) phosphorylation have been described in obesity. We hypothesize that a moderate caloric restriction (CR) might contribute to reducing ER stress and increasing AMPK phosphorylation in peripheral tissues from genetically obese Zucker fa/fa rats and in peripheral blood mononuclear cells (PBMCs). Zucker Lean and Zucker fa/fa rats were fed with chow diet either ad libitum (AL) (C, as controls) or 80% of AL (CR) for 2 weeks, giving rise to four experimental groups: Lean C, Lean CR, fa/fa C and fa/fa CR. CR significantly increased AMPK phosphorylation in the liver, perirenal adipose tissue (PRAT) and PBMCs from fa/fa rats but not in the subcutaneous AT (SCAT), suggesting a reduced response of SCAT to CR. Liver samples of fa/fa rats exhibited an increased mRNA expression of PERK, EIF-2α, XBP-1(s), Chop and caspase 3, which was significantly reduced by CR. PRAT exhibited an overexpression of Edem and PDIA-4 in fa/fa rats, but only PDIA-4 expression was reduced by CR. eIF-2α phosphorylation was significantly increased in all studied tissues from fa/fa rats and reduced by CR. A negative correlation was detected between p-AMPK and p-eIF-2α in the liver, PRAT and PBMCs from fa/fa rats but not in SCAT. This study shows that a moderate CR reduces ER stress and improves AMPK phosphorylation in several peripheral tissues and in circulating PBMCs, suggesting that alterations observed in PBMCs could reflect metabolic alterations associated with obesity.

Aerobic training induces differential expression of genes involved in lipid metabolism in skeletal muscle and white adipose tissues

Aerobic training induces adaptive responses in skeletal muscles and white adipose tissues, thus facilitating lipid utilization as energy substrates during a physical exercise session. However, the effects of training on cytokines levels and on transcription factors involved in lipid metabolism in muscle and different white adipose depots are still unclear; therefore, these were the aims of the present study. Nineteen adult male Wistar rats were randomly assigned to a trained group or a control, non-trained group. The 10-week training protocol consisted of running on a treadmill, during 1 hour per day, 5 days per week, at 75% of maximum aerobic speed. As expected, trained rats improved their aerobic performance and had augmented citrate synthase activity in the soleus, while the control rats did not. Although body weight was not different between groups, the adiposity index and white adipose depots (ie, epididymal and retroperitoneal) were reduced in trained rats. Training reduced serum concentration of insulin, but failed to change serum concentrations of glucose, triacylglycerol, total cholesterol, and nonesterified fatty acids. Training increased sterol regulatory element-binding protein-1c expression in the gastrocnemius and epididymal adipose tissue, and reduced peroxisome proliferator-activated receptor γ (PPARγ) expression in most of the tissues analyzed. The expression of PPARα and carnitine palmitoyltransferase 1 increased in the gastrocnemius and mesenteric adipose tissue but reduced in epididymal adipose tissue. Triacylglycerol content and tribbles 3 expression reduced in the gastrocnemius of trained rats. Tumor necrosis factor-α and interleukin-6 were increased in all adipose depots evaluated. Collectively, our data indicate that the 10-week aerobic training changed gene expression to improve muscle oxidative metabolism and facilitate lipid degradation in adipose tissues. Our data also highlight the existence of adaptive responses that are distinct between the skeletal muscle and white adipose tissue and between different adipose depots.

Role of OXCT1 in ovine adipose and preadipocyte differentiation

3-oxoacid CoA-transferase 1 (OXCT1) is a key enzyme in ketone body metabolism that is expressed in adipose and other tissues. The present study addressed the function of OXCT1 in adipose tissue from Tan sheep. The 1563 bp ovine OXCT1 coding sequence was cloned from ovine adipose tissue. The OXCT1 protein sequence was highly homologous to OXCT1 from other species. OXCT1 was highly expressed in kidney and at lower levels in small intestine, lung, spleen, heart, stomach, liver, tail adipose, and cartilage, but not in longissimus muscle. OXCT1 was expressed at higher levels in perirenal and tail adipose tissues than in subcutaneous adipose tissue. OXCT1 expression levels increased during the in vitro differentiation of adipocytes, but decreased dramatically at day 8. OXCT1 knockdown in ovine adipocytes promoted lipid accumulation, whereas overexpression did the converse. This study demonstrates that OXCT1 may play a role in adipogenesis and provides new insight on adipose deposition in sheep.

Maternal feeding associated to post-weaning diet affects metabolic and behavioral parameters in female offspring

Genetic and environmental factors related to maternal diet may predispose offspring to serious diseases. However, consequences of a maternal diet intervention during gestation and lactation, and its association with caloric restriction after weaning on the progeny are not completely known. In this context, the goal of the present study was to investigate how different maternal diets, control (CONT), hypercaloric (HD) or restrictive (RD) diets during gestation and lactation, may affect the metabolism and behavior of the offspring that was also submitted to RD. Experimental groups were abbreviated accordingly maternal/offspring diets: CONT/CONT, CONT/RD, RD/CONT, RD/RD, HD/CONT, HD/RD. Our results showed that glucose serum concentration is increased in mice from dams fed a HD. However, offspring from RD-fed dams showed lower insulin and leptin levels than the other groups, indicating a maternal diet effect. Moreover, animals from RD/CONT group showed a higher adipocyte area in comparison to both HD/CONT and CON/CONT. Offspring from RD-fed dams exhibited a decrease in lateral area locomotion in the open field test. Evaluation of anxiety-like behavior and recognition memory showed no significant difference among groups. Thus, maternal RD provides a beneficial response in metabolic parameters, but its effects on behavior is not completely clarified.

SREBP-1c-Dependent Metabolic Remodeling of White Adipose Tissue by Caloric Restriction

Caloric restriction (CR) delays the onset of many age-related pathophysiological changes and extends lifespan. White adipose tissue (WAT) is not only a major tissue for energy storage, but also an endocrine tissue that secretes various adipokines. Recent reports have demonstrated that alterations in the characteristics of WAT can impact whole-body metabolism and lifespan. Hence, we hypothesized that functional alterations in WAT may play important roles in the beneficial effects of CR. Previously, using microarray analysis of WAT from CR rats, we found that CR enhances fatty acid (FA) biosynthesis, and identified sterol regulatory element-binding protein 1c (SREBP-1c), a master regulator of FA synthesis, as a mediator of CR. These findings were validated by showing that CR failed to upregulate factors involved in FA biosynthesis and to extend longevity in SREBP-1c knockout mice. Furthermore, we revealed that SREBP-1c is implicated in CR-associated mitochondrial activation through the upregulation of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), a master regulator of mitochondrial biogenesis. Notably, these CR-associated phenotypes were observed only in WAT. We conclude that CR induces SREBP-1c-dependent metabolic remodeling, including the enhancement of FA biosynthesis and mitochondrial activation, via PGC-1α in WAT, resulting in beneficial effects.

Fat depot-specific differences of macrophage infiltration and cellular senescence in obese bovine adipose tissues

Obesity is associated with the chronic inflammation and senescence of adipose tissues. Macrophage is a key mediator of chronic inflammation that infiltrates obese adipose tissue and stimulates metabolic disorders. However, the fat depot-specific differences of macrophage infiltration and senescence, especially the influence on intramuscular adipose tissue, have remained unclear. We investigated the fat depot-specific differences of macrophage infiltration and senescence in obese bovine adipose tissue from three different anatomical sites (subcutaneous, intramuscular and visceral). Macrophage infiltrations and crown-like structures were observed in visceral adipose tissue, although there were few macrophages in subcutaneous and intramuscular adipose tissues. The positive reaction of senescence marker SA-βgal activity was observed in visceral adipose tissue. In contrast, the activity of SA-βgal in subcutaneous and intramuscular adipose tissues were low. The expression of p53 gene, the master regulator of cellular senescence, in visceral adipose tissue was higher than that of subcutaneous and intramuscular adipose tissue. At the cellular level, p53 gene expression was negatively correlated with the size of subcutaneous adipocytes. In contrast, p53 gene expressions were positively correlated with the size of intramuscular and visceral adipocytes. These results indicate that anatomical sites of obese adipose tissue affect macrophage infiltration and the senescent state in a fat depot-specific manner.