Dysregulation of lipolysis and lipid metabolism in visceral and subcutaneous adipocytes by high-fat diet: role of ATGL, HSL, and AMPK

Royal Jelly Exerts a Potent Anti-Obesity Effect in Rats by Activating Lipolysis and Suppressing Adipogenesis

Background/Objective: This study examined the anti-obesity effect of royal jelly (RJ) in rats fed with a high-fat diet by targeting the major pathways involved in adipogenesis and lipolysis. In addition, it examined whether this effect is AMPK-dependent. Methods: Five groups of adult male albino rats were used (n = 6 each as 1); the control rats were fed with a normal diet (2.9 kcal), and the other groups were as follows: control + RJ (300 mg/kg), HFD (4.75 kcal), HFD + RJ (300 mg/kg), and HFD + RJ (300 mg/kg) + dorsomorphin (an AMPK inhibitor) (0.2 mg/kg). Results: RJ was administered orally to all rats. With no changes in food and energy intake, RJ significantly reduced gains in body weight, fat weight, body mass index (BMI), the Lee index, abdominal circumference (AC), and the adiposity index (AI). It also reduced fasting glucose and insulin levels, HOMA-IR, and the circulatory levels of free fatty acids (FFAs), triglycerides, cholesterol, and LDL-c in the HFD-fed rats. RJ also increased serum glycerol levels and adiponectin levels, but reduced the serum levels of leptin, IL-6, and TNF-α. Moreover, RJ reduced the secretion of IL-6 and TNF-α from isolated WAT. At the tissue level, the HFD + RJ rats exhibited a smaller adipocyte size compared to the HFD rats. At the molecular level, RJ increased the phosphorylation of AMPK, SREBP1, and ACC-1 and increased the mRNA and protein levels of HSL and ATG in the WAT of the HFD rats. In concomitance, RJ increased the mRNA levels of PGC-α1, reduced the protein levels of PPARγ, and repressed the transcriptional activities of PPARγ, SREBP1, and C/EBPαβ in the WAT of these rats. All the aforementioned effects of RJ were prevented by co-treatment with dorsomorphin. Conclusions: RJ exerts a potent anti-obesity effect in rats that is mediated by the AMPk-dependent suppression of WAT adipogenesis and the stimulation of lipolysis.

Microencapsulated rice bran alleviates hyperlipidemia induced by high-fat diet via regulating lipid metabolism and gut microbiota

Hyperlipidemia has been suggested to be associated with dysregulation of lipid metabolism and gut microbiota. The present study prepared microencapsulated rice bran (MRB) with high stability based on in situ rice bran oil embedding and investigated the effects of MRB on lipid metabolism and gut microbiota in hyperlipidemic mice induced by high-fat diet (HFD). Results showed that compared to HFD fed mice, lipid levels in serum and hepatic lipid accumulation were reduced in mice fed with MRB, which was potentially associated with the fact that MRB decreased the expression of genes related to lipogenesis (Srebp1c, Acc, Hmgcr, and Fas) and increased the expression of genes related to lipid catabolism (Hsl, Atgl) and oxidation (Acox, Cpt1, Ucp1) (p < 0.05). In gut, MRB supplementation significantly elevated the abundance of beneficial bacteria, such as Dubosiella and Faecalibaculum. In addition, significant increase in short-chain fatty acid was observed in mice from MRB groups when compared to HFD groups (p < 0.05). Overall, this study suggested that MRB could alleviate the hyperlipidemia induced by HFD, which was related to the alteration of lipid metabolism and gut microbiota.

White adipocyte dysfunction and obesity-associated pathologies in humans

The prevalence of obesity and associated chronic diseases continues to increase worldwide, negatively impacting on societies and economies. Whereas the association between excess body weight and increased risk for developing a multitude of diseases is well established, the initiating mechanisms by which weight gain impairs our metabolic health remain surprisingly contested. In order to better address the myriad of disease states associated with obesity, it is essential to understand adipose tissue dysfunction and develop strategies for reinforcing adipocyte health. In this Review we outline the diverse physiological functions and pathological roles of human white adipocytes, examining our current knowledge of why white adipocytes are vital for systemic metabolic control, yet poorly adapted to our current obesogenic environment.

Antioxidant and Anti-Obesity Effects of Juglans mandshurica in 3T3-L1 Cells and High-Fat Diet Obese Rats

Juglans mandshurica Maxim. walnut (JMW) is well-known for the treatment of dermatosis, cancer, gastritis, diarrhea, and leukorrhea in Korea. However, the molecular mechanism underlying its anti-obesity activity remains unknown. In the current study, we aimed to determine whether JMW can influence adipogenesis in 3T3-L1 preadipocytes and high-fat diet rats and determine the antioxidant activity. The 20% ethanol extract of JMW (JMWE) had a total polyphenol content of 133.33 ± 2.60 mg GAE/g. Considering the antioxidant capacity, the ABTS and DPPH values of 200 μg/ml of JMWE were 95.69 ± 0.94 and 79.38 ± 1.55%, respectively. To assess the anti-obesity activity of JMWE, we analyzed the cell viability, fat accumulation, and adipogenesis-related factors, including CCAAT-enhancer-binding protein alpha (C/EBPα), sterol regulatory element-binding protein-1c (SREBP1c), peroxisome proliferator-activated receptor-gamma (PPARγ), fatty acid synthase (FAS), and acetyl-CoA carboxylase (ACC). We found that total lipid accumulation and triglyceride levels were reduced, and the fat accumulation rate decreased in a dose-dependent manner. Furthermore, JMWE suppressed adipogenesis-related factors C/EBPα, PPARγ, and SREBP1c, as well as FAS and ACC, both related to lipogenesis. Moreover, animal experiments revealed that JMWE could be employed to prevent and treat obesity-related diseases. Hence, JMWE could be developed as a healthy functional food and further explored as an anti-obesity drug.

Dysfunction of the Brown Adipose Organ in HFD-Obese Rats and Effect of Tart Cherry Supplementation

Obesity has a great impact on adipose tissue biology, based on its function as a master regulator of energy balance. Brown adipose tissue (BAT) undergoes remodeling, and its activity declines in obese subjects due to a whitening process. The anti-obesity properties of fruit extracts have been reported. The effects of tart cherry against oxidative stress, inflammation, and the whitening process in the BAT of obese rats were investigated. Intrascapular BAT (iBAT) alterations and effects of Prunus cerasus L. were debated in rats fed for 17 weeks with a high-fat diet (DIO), in DIO supplemented with seed powder (DS), and with seed powder plus the juice (DJS) of tart cherry compared to CHOW rats fed with a normo-caloric diet. iBAT histologic observations revealed a whitening process in DIO rats that was reduced in the DS and DJS groups. A modulation of uncoupling protein-1 (UCP-1) protein and gene expression specifically were detected in the obese phenotype. An upregulation of UCP-1 and related thermogenic genes after tart cherry intake was detected compared to the DIO group. Metabolic adjustment, endoplasmic reticulum stress, protein carbonylation, and the inflammatory microenvironment in the iBAT were reported in DIO rats. The analysis demonstrated an iBAT modulation that tart cherry promoted. In addition to our previous results, these data confirm the protective impact of tart cherry consumption on obesity.

Abnormal metabolism in hepatic stellate cells: Pandora's box of MAFLD related hepatocellular carcinoma

Metabolic associated fatty liver disease (MAFLD) is a significant risk factor for the development of hepatocellular carcinoma (HCC). Hepatic stellate cells (HSCs), as key mediators in liver injury response, are believed to play a crucial role in the repair process of liver injury. However, in MAFLD patients, the normal metabolic and immunoregulatory mechanisms of HSCs become disrupted, leading to disturbances in the local microenvironment. Abnormally activated HSCs are heavily involved in the initiation and progression of HCC. The metabolic disorders and abnormal activation of HSCs not only initiate liver fibrosis but also contribute to carcinogenesis. In this review, we provide an overview of recent research progress on the relationship between the abnormal metabolism of HSCs and the local immune system in the liver, elucidating the mechanisms of immune imbalance caused by abnormally activated HSCs in MAFLD patients. Based on this understanding, we discuss the potential and challenges of metabolic-based and immunology-based mechanisms in the treatment of MAFLD-related HCC, with a specific focus on the role of HSCs in HCC progression and their potential as targets for anti-cancer therapy. This review aims to enhance researchers' understanding of the importance of HSCs in maintaining normal liver function and highlights the significance of HSCs in the progression of MAFLD-related HCC.

Pubertal glyphosate-based herbicide exposure aggravates high-fat diet-induced obesity in female mice

Glyphosate-based herbicides (GBH) are the most widely used pesticides globally. Studies have indicated that they may increase the risk of various organic dysfunctions. Herein, we verified whether exposure to GBH during puberty increases the susceptibility of male and female mice to obesity when they are fed a high-fat diet (HFD) in adulthood. From the 4th-7th weeks of age, male and female C57Bl/6 mice received water (CTL group) or 50 mg GBH /kg body weight (BW; GBH group). From the 8th-21st weeks of age, the mice were fed a standard diet or a HFD. It was found that pubertal GBH exposure exacerbated BW gains and hyperphagia induced by HFD, but only in female GBH-HFD mice. These female mice also exhibited high accumulation of perigonadal and subcutaneous fat, as well as reduced lean body mass. Both male and female GBH-HFD displayed hypertrophic white adipocytes. However, only in females, pubertal GBH exposure aggravated HFD-induced fat accumulation in brown adipocytes. Furthermore, GBH increased plasma cortisol levels by 80% in GBH-HFD males, and 180% in GBH-HFD females. In conclusion, pubertal GBH exposure aggravated HFD-induced obesity, particularly in adult female mice. This study provides novel evidence that GBH misprograms lipid metabolism, accelerating the development of obesity when individuals are challenged by a second metabolic stressor, such as an obesogenic diet.

ABHD6 suppression promotes anti-inflammatory polarization of adipose tissue macrophages via 2-monoacylglycerol/PPAR signaling in obese mice

OBJECTIVE

Pro-inflammatory polarization of adipose tissue macrophages (ATMs) plays a critical role in the pathogenesis of obesity-associated chronic inflammation. However, little is known about the role of lipids in the regulation of ATMs polarity and inflammation in response to metabolic stress. Deletion of α/β-hydrolase domain-containing 6 (ABHD6), a monoacylglycerol (MAG) hydrolase, has been shown to protect against diet-induced obesity and insulin resistance.

METHODS

Here we investigated the immunometabolic role of macrophage ABHD6 in response to nutrient excess using whole-body ABHD6-KO mice and human and murine macrophage cell-lines treated with KT203, a selective and potent pharmacological ABHD6 inhibitor.

RESULTS

KO mice on high-fat diet showed lower susceptibility to systemic diet-induced inflammation. Moreover, in the setting of overnutrition, stromal vascular cells from gonadal fat of KO vs. control mice contained lower number of M1 macrophages and exhibited enhanced levels of metabolically activated macrophages (MMe) and M2 markers, oxygen consumption, and interleukin-6 (IL-6) release. Likewise, under in vitro nutri-stress condition, inhibition of ABHD6 in MMe-polarized macrophages attenuated the expression and release of pro-inflammatory cytokines and M1 markers and induced the upregulation of lipid metabolism genes. ABHD6-inhibited MMe macrophages showed elevated levels of peroxisome proliferator-activated receptors (PPARs) and 2-MAG species. Notably, among different MAG species, only 2-MAG treatment led to increased levels of PPAR target genes in MMe macrophages.

CONCLUSIONS

Collectively, our findings identify ABHD6 as a key component of pro-inflammatory macrophage activation in response to excess nutrition and implicate an endogenous macrophage lipolysis/ABHD6/2-MAG/PPARs cascade, as a lipid signaling and immunometabolic pathway, which favors the anti-inflammatory polarization of ATMs in obesity.

Rose polyphenols exert antiobesity effect in high-fat-induced obese mice by regulating lipogenic gene expression

Obesity presents a major risk factor in the development of cardiovascular diseases. Recent reports indicate that many kinds of polyphenols have the potential to prevent metabolic diseases. We hypothesized that rose polyphenols (ROSE) have the effect of improvement in lipid metabolism. In this study, we investigated whether rose polyphenols affected lipid metabolism and exerted antiobesity. To clarify the mechanism, C57BL/6J mice were fed a high-fat diet containing 0.25% ROSE for 35 days. Compared with the control group, body weight gain and adipose tissue weight in the 0.25% ROSE group were significantly decreased. Serum cholesterol and hepatic triglyceride concentrations significantly decreased, whereas fecal triglyceride was significantly increased in the 0.25% ROSE group. Liver stearoyl-CoA desaturase 1 (Scd1), 3-hydroxy-3-methylglutaryl-CoA reductase (Hmgcr), and acyl-CoA:cholesterol acyltransferase 1 (Acat1) mRNA as well as protein stearoyl-CoA desaturase 1 concentrations were significantly lower in the 0.25% ROSE group than that in the control group. The mRNA and the protein concentrations of adipose triglyceride lipase, hormone-sensitive lipase, and peroxisomal acylcoenzyme A oxidase 1 in white adipose tissue were significantly higher in the 0.25% ROSE group than that in the control group. The components in rose polyphenols were quantified by liquid chromatography-tandem mass spectrometry, and we consider that ellagic acid plays an important role in an antiobesity effect because the ellagic acid content is the highest among polyphenols in rose polyphenols. In summary, rose polyphenols exhibit antiobesity effects by influencing lipid metabolism-related genes and proteins to promote lipolysis and suppress lipid synthesis.

Can dietary proteins selectively reduce either the visceral or subcutaneous adipose tissues?

There is a considerable appeal for interventions that can selectively reduce either the visceral or subcutaneous white adipose tissues in humans and other species because of their associated impact on outcomes related to metabolic health. Here, we reviewed the data related to the specificity of five interventions to affect the two depots in humans and rodents. The interventions relate to the use of dietary proteins, monounsaturated fatty acids, polyunsaturated fatty acids, calorie restriction, or bariatric surgery. The available data show that calorie restriction and bariatric surgery reduce both visceral and subcutaneous tissues, whereas there is no consistency in the effect of monounsaturated or polyunsaturated fatty acids. Dietary proteins, more specifically, whey proteins show efficacy to reduce one or both depots based on how the proteins interact with other macronutrients in the diet. We provide evidence that this specificity is related to changes in the composition and the functional potential of the gut microbiota and the resulting metabolites produced by these microorganisms. The effect of the sex of the host is also discussed. This knowledge may help to develop nutritional approaches to deplete either the visceral or subcutaneous adipose tissues and improve metabolic health in humans and other species.

The ketogenic diet promotes triacylglycerol recycling in white adipose tissue and uncoupled fat oxidation in brown adipose tissue, but does not reduce adiposity in rats

The purpose of this study was to determine whether the weight-reducing and fat burning effects of the ketogenic diet (KD) could be attributed to alterations in the energy dissipating pathways of brown adipose tissue (BAT) uncoupled oxidation, and white adipose tissue (WAT) browning and triacylglycerol (TAG) recycling. To investigate this, male Wistar rats were fed one of the following three diets for either 8 or 16 weeks: a standard chow (SC), a high-fat, sucrose-enriched (HFS) obesogenic diet, or a KD. At the end of the intervention, subcutaneous inguinal (Sc Ing) and epididymal (Epid) fat, and interscapular and aortic BAT (iBAT and aBAT, respectively) were extracted. These tissues were used for the analysis of proteins involved in WAT browning and thermogenesis. Isolated adipocytes from WAT were assayed for basal and isoproterenol (Iso)-stimulated lipolysis and basal and insulin-stimulated lipogenesis, and BAT adipocytes were assayed for the determination of coupled and uncoupled glucose and palmitate oxidation. Adiposity similarly increased in HFS- and KD-fed rats at weeks 8 and 16. However, in HFS-fed animals insulin-stimulated lipogenesis and Iso-stimulated lipolysis were impaired in WAT adipocytes, whereas in KD-fed animals these pathways remained intact. The KD also significantly elevated WAT glycerol kinase levels, and favored TAG recycling under conditions of enhanced lipolysis. In BAT, the KD significantly increased uncoupling protein-1 levels and uncoupled fat oxidation. In summary, the KD preserved insulin sensitivity and lipolytic capacity in WAT and also upregulated energy-dissipating pathways in BAT, but it was not sufficient to prevent an increase in adiposity.

Photoperiod-Dependent Effects of Grape-Seed Proanthocyanidins on Adipose Tissue Metabolic Markers in Healthy Rats

SCOPE

Variations in photoperiod patterns drive metabolic adaptations in mammals, involving important changes in body weight and adiposity. Moreover, (poly)phenols can help heterotrophs adopt metabolic adaptations to face the upcoming environmental conditions. Particularly, proanthocyanidins from grape-seeds show photoperiod-dependent effects on different metabolic parameters. The present study aims to explore whether grape-seed proanthocyanidin extract (GSPE) consumption differently affects the expression of metabolic markers in WAT (subcutaneous and visceral depots) and BAT in a photoperiod-dependent manner.

METHODS AND RESULTS

GSPE (25 mg kg-1  day-1 ) is orally administrated for 4 weeks to healthy rats exposed to three photoperiods (L6, L12, and L18). In WAT, GSPE consumption significantly upregulates the expression of lipolytic genes in all photoperiods, being accompanied by increased serum concentrations of glycerol and corticosterone only under the L6 photoperiod. Moreover, adiponectin mRNA levels are significantly upregulated in response to GSPE regardless of the photoperiod, whereas Tnfα and Il6 expression are only downregulated in L6 and L18 photoperiods but not in L12. In BAT, GSPE upregulates Pgc1α expression in all groups, whereas the expression of Pparα is only increased in L18.

CONCLUSIONS

The results indicate that GSPE modulates the expression of important metabolic markers of WAT and BAT in a photoperiod-dependent manner.

Pharmacological inhibition of lipolysis prevents adverse metabolic outcomes during glucocorticoid administration

OBJECTIVE

Glucocorticoids are one of the most commonly prescribed classes of anti-inflammatory drugs; however, chronic treatment promotes iatrogenic (drug-induced) diabetes. As part of their physiological role, glucocorticoids stimulate lipolysis to spare glucose. We hypothesized that persistent stimulation of lipolysis during glucocorticoid therapy plays a causative role in the development of iatrogenic diabetes.

METHODS

Male C57BL/6J mice were given 100 μg/mL corticosterone (Cort) in the drinking water for two weeks and were fed either normal chow (TekLad 8640) or the same diet supplemented with an adipose triglyceride lipase inhibitor (Atglistatin - 2  g/kg diet) to inhibit the first step of lipolysis.

RESULTS

Herein, we report for the first time that glucocorticoid administration promotes a unique state of substrate excess and energetic overload in skeletal muscle that primarily results from the rampant mobilization of endogenous fuels. Inhibiting lipolysis protected mice from Cort-induced gains in fat mass, excess ectopic lipid accrual, hyperinsulinemia, and hyperglycemia. The role lipolysis plays in Cort-mediated pathology appears to differ between tissues. Within skeletal muscle, Cort-induced lipolysis facilitated diversion of glucose-derived carbons toward the pentose phosphate and hexosamine biosynthesis pathways but contributed to <3% of the Cort-induced genomic adaptations. In contrast, Cort stimulation of lipolysis accounted for ∼35% of the genomic changes in the liver but had minimal impact on hepatic metabolites reported.

CONCLUSIONS

These data support the idea that activation of lipolysis plays a causal role in the progression toward iatrogenic diabetes during glucocorticoid therapy with differential impact on skeletal muscle and liver.

Paeonia lactiflora root decreases lipid accumulation through the induction of lipolysis and thermogenesis via AMPK activation in 3T3‑L1 cells

Obesity is associated with high risk of mortality globally because obesity is associated with development of diseases such as diabetes, dyslipidemia, fatty liver disease, hypertension, and cancer. The present study aimed to identify the mechanism of action related to the anti‑obesity activity of Paeonia lactiflora root (PLR) based on its effects on lipid droplet accumulation. The inhibitory activity on lipid accumulation was analyzed through Oil‑Red O staining, and the changes in levels of lipid accumulation‑related proteins were analyzed using Western blot analysis. And the contents of triacylglycerol and free glycerol were analyzed using an ELISA Kit. PLR significantly inhibited the accumulation of lipid droplets and triacylglycerol in differentiating 3T3‑L1 cells. PLR increased phosphorylated‑hormone sensitive lipase (HSL), HSL and adipose triglyceride lipase (ATGL) and decreases perilipin‑1 in differentiating and fully differentiated 3T3‑L1 cells. Furthermore, treatment of fully differentiated 3T3‑L1 cells with PLR resulted in increased free glycerol levels. PLR treatment increased levels of peroxisome proliferator‑activated receptor‑gamma coactivator‑1 alpha (PGC‑1α), PR domain containing 16 (PRDM16) and uncoupling protein 1 (UCP‑1) in both differentiating and fully differentiated 3T3‑L1 cells. However, the PLR‑mediated increase in lipolytic, such as ATGL and HSL, and thermogenic factors, such as PGC‑1a and UCP‑1, were decreased by inhibition of AMP‑activated protein kinase (AMPK) with Compound C. Taken together, these results suggest that PLR exerted anti‑obesity effects by regulating lipolytic and thermogenic factors via AMPK activation. Therefore, the present study provided evidence that PLR is a potential natural agent for the development of drugs to control obesity.

Antiobesity Effects of Lactobacillus paracasei Subsp. paracasei, L. casei 431 on High-Fat Diet-Induced Obese Rats

Obesity is currently regarded as a global concern, and the key objectives of the global health strategy include its prevention and control. Probiotic supplementation can help achieve these objectives. This study aimed to assess whether a probiotic strain Lactobacillus paracasei ssp. paracasei, Lactobacillus casei 431 (henceforth, L. casei 431) possesses antiobesogenic properties. High-fat diet-induced obese Sprague-Dawley rats were treated with L. casei 431 for 10 weeks, and the outcomes were compared with those of rats treated with the antiobesity medication orlistat. Body weights, epididymal fat, and tissues from mice were assessed. Furthermore, serological and histological analyses were performed. Epididymal fat accumulation was significantly reduced in groups administered L. casei 431 and orlistat. Furthermore, L. casei 431 and orlistat treatments lowered serum alanine transaminase, aspartate aminotransferase, and triglyceride (TG) levels. Hematoxylin and eosin staining of the liver and epididymal adipose tissues showed that the L. casei 431-treated groups exhibited reduced lipid buildup and adipocyte size. Furthermore, sterol regulatory element-binding protein 1c, adipose TG lipase, and lipoprotein lipase messenger RNA (mRNA) levels were upregulated, leading to lipid oxidation and degradation, in L. casei 431-supplemented groups. Furthermore, carnitine palmitoyltransferase 1, a major factor in lipolysis, was consistently upregulated at the protein level after L. casei 431 administration. Collectively, these results demonstrate the potential of L. casei 431 in alleviating obesity in rats through optimizing lipid metabolism and some related biomarkers.

Early metabolomic, lipid and lipoprotein changes in response to medical and surgical therapeutic approaches to obesity

BACKGROUND

Glucagon-like peptide-1 receptor agonists (GLP-1RA) and bariatric surgery have proven to be effective treatments for obesity and cardiometabolic conditions. We aimed to explore the early metabolomic changes in response to GLP-1RA (liraglutide) therapy vs. placebo and in comparison to bariatric surgery.

METHODS

Three clinical studies were conducted: a bariatric surgery cohort study of participants with morbid obesity who underwent either Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG) studied over four and twelve weeks, and two randomized placebo-controlled, crossover double blind studies of liraglutide vs. placebo administration in participants with type 2 diabetes (T2D) and participants with obesity studied for three and five weeks, respectively. Nuclear magnetic resonance spectroscopy-derived metabolomic data were assessed in all eligible participants who completed all the scheduled in-clinic visits. The primary outcome of the study was to explore the changes of the metabolome among participants with obesity with and without T2D receiving the GLP-1RA liraglutide vs. placebo and participants with obesity undergoing bariatric surgery during the three to five-week study period. In addition, we assessed the bariatric surgery effects longitudinally over the twelve weeks of the study and the differences between the bariatric surgery subgroups on the metabolome. The trials are registered with ClinicalTrials.gov, numbers NCT03851874, NCT01562678 and NCT02944500.

RESULTS

Bariatric surgery had a more pronounced effect on weight and body mass index reduction (-14.19 ± 5.27 kg and - 5.19 ± 5.27, respectively, p < 0.001 for both) and resulted in more pronounced metabolomic and lipidomic changes compared to liraglutide therapy at four weeks postoperatively. Significant changes were observed in lipoprotein parameters, inflammatory markers, ketone bodies, citrate, and branched-chain amino acids after the first three to five weeks of intervention. After adjusting for the amount of weight loss, a significant difference among the study groups remained only for acetoacetate, β-hydroxybutyrate, and citrate (p < 0.05 after FDR correction). Glucose levels were significantly reduced in all intervention groups but mainly in the T2D group receiving GLP-1RA treatment. After adjusting for weight loss, only glucose levels remained significant (p = 0.001 after FDR correction), mainly due to the glucose change in the T2D group receiving GLP-1RA. Similar results with those observed at four weeks were observed in the surgical group when delta changes at twelve weeks were assessed. Comparing the two types of bariatric surgery, an intervention effect was more pronounced in the RYGB subgroup regarding total triglycerides, triglyceride-rich lipoprotein size, and trimethylamine-N-oxide (p for intervention: 0.031, 0.028, 0.036, respectively). However, after applying FDR correction, these changes deemed to be only suggestive; only time effects remained significant with no significant changes persisting in relation to the types of bariatric surgery.

CONCLUSIONS

The results of this study suggest that the early metabolomic, lipid and lipoprotein changes observed between liraglutide treatment and bariatric surgery are similar and result largely from the changes in patients' body weight. Specific changes observed in the short-term post-surgical period between bariatric vs. nonsurgical treated participants, i.e., acetoacetate, β-hydroxybutyrate, and citrate changes, may reflect changes in patient diets and calorie intake indicating potential calorie and diet-driven metabolomics/lipidomic effects in the short-term postoperatively. Significant differences observed between SG and RYGB need to be confirmed and extended by future studies.

An obesogenic diet impairs uncoupled substrate oxidation and promotes whitening of the brown adipose tissue in rats

Brown adipose tissue (BAT) is rich in mitochondria containing uncoupling protein 1 (UCP1), and dissipates energy through thermogenesis. However, even though BAT mass and its UCP1 content increase in rodents chronically fed a high-fat sucrose-enriched (HFS) diet, marked expansion of adiposity still occurs in these animals, suggesting insufficient BAT-mediated HFS diet-induced thermogenesis. Thus, the objective of this study was to investigate the metabolic and molecular mechanisms that regulate BAT thermogenesis in HFS-induced obesity. To accomplish this, rats were fed either a standard chow or HFS diet for 8 weeks. Subsequently, glucose and fatty acid metabolism and the molecular mechanisms underlying these processes were assessed in freshly isolated primary BAT adipocytes. Despite increasing BAT mass and its UCP1 content, the HFS diet reduced uncoupled glucose and palmitate oxidation in BAT adipocytes. It also markedly diminished tyrosine hydroxylase content and lipolysis in these cells. Conversely, glucose uptake, lactate production, glycerol incorporation into lipids, palmitate incorporation into triacylglycerol (TAG), phosphoenolpyruvate carboxykinase and glycerol kinase levels, and lipoprotein lipase and cluster of differentiation 36 gene expression were increased. In summary, a HFS diet enhanced glyceroneogenesis and shifted BAT metabolism toward TAG synthesis by impairing UCP1-mediated substrate oxidation and by enhancing fatty acid esterification in intact brown adipocytes. These adaptive metabolic responses to chronic HFS feeding attenuated BAT thermogenic capacity and favoured the development of obesity. KEY POINTS: Despite increasing brown adipose tissue (BAT) mass and levels of thermogenic proteins such as peroxisome proliferator-activated receptor γ coactivator 1α, carnitine palmitoyltransferase 1B and uncoupling protein 1 (UCP1), an obesogenic high-fat sucrose-enriched (HFS) diet attenuated uncoupled glucose and fatty acid oxidation in brown adipocytes. Brown adipocytes diverted glycerol and fatty acids toward triacylglycerol (TAG) synthesis by elevating the cellular machinery that promotes fatty acid uptake along with phosphoenolpyruvate carboxykinase and glycerol kinase levels. The HFS diet increased glucose uptake that supported lactate production and provided substrate for glyceroneogenesis and TAG synthesis in brown adipocytes. Impaired UCP-1-mediated thermogenic capacity and enhanced TAG storage in BAT adipocytes were consistent with reduced adipose triglyceride lipase and tyrosine hydroxylase levels in HFS diet-fed animals.

Effects of a Phytogenic Supplement Containing Olive By-Product and Green Tea Extracts on Growth Performance, Lipid Metabolism, and Hepatic Antioxidant Capacity in Largemouth Bass (Micropterus salmoides) Fed a High Soybean Meal Diet

A 10-week growth trial was conducted to investigate the effects of a phytogenic feed additive (PFA) containing olive by-products and green tea extracts supplemented to a reduced fishmeal/high soybean meal diet on the growth performance, hepatic antioxidant capacity, lipid metabolism, and liver health of largemouth bass (Micropterus salmoides). Three experimental diets were tested: (1) a control high fishmeal (40%) and low soybean meal (15.57%) diet (named HFM), (2) a reduced fishmeal (30%) and high soybean meal (30.97%) diet (named HSB), and (3) a HSB diet supplemented with the PFA at 500 mg/kg (named HSB+P). Each diet was assigned to four replicate tanks, each containing 30 largemouth bass (initial body weight, IBW = 48.33 ± 0.01 g). The results showed that increasing the soybean meal content in the diet did not negatively affect growth performance, whereas supplementation with PFA significantly increased weight gain and specific growth rate of largemouth bass compared to both HFM and HSB groups. Reducing fishmeal and increasing soybean meal in the diet caused oxidative stress with a higher content of ROS in the liver. However, the hepatic antioxidant capacity was enhanced, with reduced ROS and increased GSH-Px levels in the HSB+P group. Moreover, the decrease of plasma TG, LDL-C, and LDL-C/TC, and downregulation of lipogenesis and cholesterol synthesis gene expression in liver, indicated that supplementation with the PFA improved fish lipid metabolism. Protein retention efficiency was also significantly increased in largemouth bass fed the diet with PFA supplementation, which regulated (enhanced) AKT-mTOR phosphorylation. These results clearly indicated that a PFA containing olive by-product and green tea extracts can positively improve growth performance, protein retention efficiency, antioxidant capacity, and lipid metabolism of largemouth bass fed a reduced fishmeal/high soybean meal diet.

Effect of quercetin and Abelmoschus esculentus (L.) Moench on lipids metabolism and blood glucose through AMPK-α in diabetic rats (HFD/STZ)

Phosphoenolpyruvate carboxykinase (PEPCK) is a key enzyme in the glyconeogenesis pathway. The AMP-activated protein kinase alpha (AMPK-α) pathway regulates PEPCK, which itself is activated by the AMP/ATP ratio and liver kinase B1 (KB1). The Abelmoschus esculentus (L.) Moench (okra) plant contains a large amount of quercetin that can function as an agonist or an antagonist. The aim of this study was to examine the effects of quercetin flavonoid and A. esculentus extract on the level of AMPK-α expression and associated metabolic pathways. The findings demonstrate that metformin, quercetin, and okra extract may significantly raise AMPK-α levels while significantly lowering PEPCK and hormone-sensitive lipase (HSL) levels, in addition to improving glucose and lipid profiles. By stimulating KB1, these substances increased AMPK-α activation. Additionally, AMPK-α activation improved insulin resistance and Glucose transporter type 4 (GLUT4) gene expression levels. Since AMPK-α maintains energy balance and its activity has not been reported to be inhibited so far, it could be a potent therapeutic target. PRACTICAL APPLICATIONS: The development of effective AMPK-α agonists and antagonists holds promise for the treatment of metabolic disorders like diabetes. Dietary polyphenols are a valuable source for developing new drugs. However, due to the lack of understanding of the underlying mechanisms of their effect on cells, their use in the treatment of diabetes is controversial. In addition to chemicals that have medicinal benefits, chemists are searching for less harmful substances. Using plants containing bioactive chemicals for this purpose can be a good alternative to chemical drugs.

The biological actions of prostanoids in adipose tissue in physiological and pathophysiological conditions

Adipose tissue has been established as an endocrine organ that plays an important role in maintaining metabolic homeostasis. Adipose tissue releases several bioactive molecules called adipokines. Inflammation, dysregulation of adipokine synthesis, and secretion are observed in obesity and related diseases and cause adipose tissue dysfunction. Prostanoids, belonging to the eicosanoid family of lipid mediators, can be synthesized in adipose tissue and play a critical role in adipose tissue biology. In this review, we summarized the current knowledge regarding the interaction of prostanoids with adipokines, the expression of prostanoid receptors, and prostanoid synthase enzymes in adipose tissues in health and disease. Furthermore, the involvement of prostanoids in the physiological function or dysfunction of adipose tissue including inflammation, lipolysis, adipogenesis, thermogenesis, browning of adipocytes, and vascular tone regulation was also discussed by examining studies using pharmacological approaches or genetically modified animals for prostanoid receptors/synthase enzymes. Overall, the present review provides a perspective on the evidence from literature regarding the biological effects of prostanoids in adipose tissue. Among prostanoids, prostaglandin E2 (PGE₂) is prominent in regards to its substantial role in both adipose tissue physiology and pathophysiology. Targeting prostanoids may serve as a potential therapeutic strategy for preventing or treating obesity and related diseases.

One week of overeating upregulates angiogenic and lipolytic gene expression in human subcutaneous adipose tissue from exercise trained and untrained adults

Effective storage of excess energy in abdominal subcutaneous adipose tissue during periods of overeating may help attenuate weight-gain-related insulin resistance. The objective of this study was to assess changes in the expression of factors regulating abdominal subcutaneous adipose tissue storage capacity in response to a brief exposure to overeating in nonobese adults. Because exercise can alter the expression of genes involved in regulating adipose tissue storage capacity, we compared the responses to overeating in regular exercisers (EX, n = 11) and nonexercisers (nonEX, n = 11). Abdominal subcutaneous adipose tissue samples and oral glucose tolerance tests were performed before and after participants ate 30% above their estimated daily energy requirements for 1 week. Both EX and nonEX gained ∼1 kg (P < 0.01), and Matsuda insulin sensitivity index was reduced ∼15% (P = 0.04) in both groups. Gene expression of factors involved in lipid metabolism (HSL, ATGL, DGAT, and PPARγ) and angiogenesis (HIF1α and KDR) were increased (P < 0.05), with no differences observed between EX and nonEX. In contrast, protein abundance of these factors did not change. The modest overeating stimulus did not increase markers of inflammation in the systemic circulation or adipose tissue. Overall, our findings indicate that a brief and modest overeating stimulus can impair insulin sensitivity and upregulate genes involved in abdominal adipose tissue storage capacity similarly in exercisers and nonexercisers. ClinicalTrials.gov ID#: NCT02701738.

Dysregulated lipolysis and lipophagy in lipid droplets of macrophages from high fat diet-fed obese mice

Obesity is associated with lipid droplet (LD) accumulation, dysregulated lipolysis and chronic inflammation. Previously, the caspase recruitment domain‐containing protein 9 (CARD9) has been identified as a potential contributor to obesity‐associated abnormalities including cardiac dysfunction. In the current study, we explored a positive feedback signalling cycle of dysregulated lipolysis, CARD9‐associated inflammation, impaired lipophagy and excessive LD accumulation in sustaining the chronic inflammation associated with obesity. C57BL/6 WT and CARD9^−/− mice were fed with normal diet (ND, 12% fat) or a high fat diet (HFD, 45% fat) for 5 months. Staining of LDs from peritoneal macrophages (PMs) revealed a significant increase in the number of cells with LD and the number of LD per cell in the HFD‐fed WT but not CARD9^−/− obese mice. Rather, CARD9 KO significantly increased the mean LD size. WT obese mice showed down regulation of lipolytic proteins with increased diacylglycerol (DAG) content, and CARD9 KO normalized DAG with restored lipolytic protein expression. The build‐up of DAG in the WT obese mice is further associated with activation of PKCδ, NF‐κB and p38 MAPK inflammatory signalling in a CARDD9‐dependent manner. Inhibition of adipose triglyceride lipase (ATGL) by Atglistatin (Atg) resulted in similar effects as in CARD9^−/− mice. Interestingly, CARD9 KO and Atg treatment enhanced lipophagy. In conclusion, HFD feeding likely initiated a positive feedback signalling loop from dysregulated lipolysis, CARD9‐dependent inflammation, impaired lipophagy, to excessive LD accumulation and sustained inflammation. CARD9 KO and Atg treatment protected against the chronic inflammation by interrupting this feedforward cycle.

Codon-optimized FAM132b gene therapy prevents dietary obesity by blockading adrenergic response and insulin action

BACKGROUND

FAM132b (myonectin) has been identified as a muscle-derived myokine with exercise and has hormone activity in circulation to regulate iron homeostasis and lipid metabolism via unknown receptors. Here, we aim to explore the potential of adeno-associated virus to deliver FAM132b in vivo to develop a gene therapy against obesity.

METHODS

Adeno-associated virus AAV9 were engineered to induce overexpression of FAM132b with two mutations, A136T and P159A. Then, AAV9 was delivered into high-fat diet mice through tail vein, and glucose homeostasis and obesity development of mice were observed. Methods of structural biology were used to predict the action site or receptor of the FAM132b mutant.

RESULTS

Treatment of high-fat diet-fed mice with AAV9 improved glucose intolerance and insulin resistance, and resulted in reductions in body weight, fat depot, and adipocyte size. Codon-optimized FAM132b (coFAM132b) reduced the glycemic response to epinephrine (EPI) in the whole body and increased the lipolytic response to EPI in adipose tissues. However, FAM132b knockdown by shRNA significantly increased the glycemic response to EPI in vivo and reduced adipocyte response to EPI and adipose tissue browning. Structural analysis predicted that the FAM132b mutant with A136T and P159A may form a weak bond with β2 adrenergic receptor (ADRB2) and may have more affinity for insulin and insulin-receptor complexes.

CONCLUSIONS

Our study underscores the potential of FAM132b gene therapy with codon optimization to treat obesity by modulating the adrenergic response and insulin action. Both structural biological analysis and in vivo experiments suggest that the adrenergic response and insulin action are most likely blockaded by FAM132b mutants.

Is Brain-Derived Neurotrophic Factor a Metabolic Hormone in Peripheral Tissues?

Simple Summary

The activity of brain-derived neurotrophic factor (BDF) in the central nervous system has been well-studied, but its physiological role in other organs has not been clearly defined. This review summarizes the current findings on the functionality of BDNF in various peripheral tissues and discusses several unresolved questions in the field.

Abstract

Brain-derived neurotrophic factor (BDNF) is an important growth factor in the central nervous system. In addition to its well-known activities in promoting neuronal survival, neuron differentiation, and synaptic plasticity, neuronal BDNF also regulates energy homeostasis by modulating the hypothalamus’s hormonal signals. In the past decades, several peripheral tissues, including liver, skeletal muscle, and white adipose tissue, were demonstrated as the active sources of BDNF synthesis in response to different metabolic challenges. Nevertheless, the functions of BDNF in these tissues remain obscure. With the use of tissue-specific Bdnf knockout animals and the availability of non-peptidyl BDNF mimetic, increasing evidence has reported that peripheral tissues-derived BDNF might play a significant role in maintaining systemic metabolism, possibly through the regulation of mitochondrial dynamics in the various tissues. This article reviews the autocrine/paracrine/endocrine functions of BDNF in non-neuronal tissues and discusses the unresolved questions about BDNF’s function.

α-Linolenic acid rich-chia seed modulates visceral adipose tissue collagen deposition, lipolytic enzymes expression, insulin signaling and GLUT-4 levels in a diet-induced adiposity rodent model

Given obesity and its associated metabolic disorders have reached epidemic proportions, the study of therapeutic strategies targeting white adipose tissue (WAT) are of main research interest. We previously shown that α-linolenic acid-rich chia seed was able to ameliorate a wide range of metabolic disorders including body fat accretion in sucrose-rich diet (SRD)-fed rats, an experimental model of visceral adiposity and insulin resistance. However, the mechanisms involved are not fully clarified. The aim of this study was to evaluate the effect of chia seed administration upon WAT remodeling and key enzymes that controls lipolysis, insulin signaling (tAKT, pAKT), and GLUT-4 levels in different visceral fat pad depots (epididymal -eWAT- and retroperitoneal -rWAT- adipose tissues) of SRD-fed rats. Results showed that chia seed reduces adipocytes hypertrophy, the increased lipid content and collagen deposition in both WAT. These changes were accompanied by a significant reduction of HSL and ATGL protein levels in eWAT and HSL protein levels in rWAT. Moreover, chia seed restored the altered expression pattern of the pAKT observed in SRD-fed rats, and modulated GLUT-4 levels. Chia seed could be a dietary intervention of great relevance with potential beneficial effects in the management of body fat excess and WAT function.

Comparison of visceral fat lipolysis adaptation to high-intensity interval training in obesity-prone and obesity-resistant rats

BACKGROUND/OBJECTIVES

Visceral obesity is one of the key features of metabolic syndrome. High-intensity interval training (HIIT) could effectively reduce visceral fat, but its effects show strong heterogeneity in populations with different degrees of obesity. The mechanism may be related to the differential adaptation to training between obesity phenotypes, namely obesity prone (OP) and obesity resistant (OR). The aim of the present study was to compare adaptive changes of visceral adipose lipolysis adaptation to HIIT between OP and OR animals and further explore the upstream pathway.

METHODS

OP and OR Sprague Dawley rats were established after feeding a high-fat diet for 6 weeks; they were then divided into HIIT (H-OP and H-OR) and control (C-OP and C-OR) groups. After 12 weeks of HIIT or a sedentary lifestyle, animals were fasted for 12 h and then sacrificed for histology as well as gene and protein analysis. Visceral adipocytes were isolated without fasting for catecholamine stimulation and β3-adrenergic receptor (β3-AR) blockade in vitro to evaluate the role of upstream pathways.

RESULTS

After training, there were no differences in weight loss or food intake between OP and OR rats (P > 0.05). However, the visceral fat mass, adipocyte volume, serum triglycerides and liver lipids of OP rats decreased by more than those of OR rats (P < 0.05). Meanwhile, the cell lipolytic capacity and the increase in the expression of β3-AR were higher in the OP compared with OR groups (P < 0.05). Although training did not increase sympathetic nervous system activity (P > 0.05), the cell sensitivity to catecholamine increased significantly in the OP compared with OR groups (P < 0.05). Following blocking β3-AR, the increased sensitivity disappeared.

CONCLUSION

With HIIT, OP rats lost more visceral fat than OR rats, which was related to stronger adaptive changes in lipolysis. Increased β3-AR expression mediated this adaptation.

The Phenotype of the Adipocytes Derived from Subcutaneous and Visceral ADMSCs Is Altered When They Originate from Morbidly Obese Women: Is There a Memory Effect?

Adipose tissue is an abundant source of mesenchymal stem cells (ADMSCs). Evidence has suggested that depot-specific ADMSCs (obtained from subcutaneous or visceral adipose tissue-subADMSCs or visADMSCs, respectively) account for differential responses of each depot to metabolic challenges. However, little is known about the phenotype and changes in metabolism of the adipocytes derived from ADMSCs of obese individuals. Therefore, we investigated the phenotypic and metabolic characteristics, particularly the lipid profile, of fully differentiated adipocytes derived from ADMSCs of lean and obese (with/without metabolic syndrome) postmenopausal women. We observed a depot-specific pattern, with more pronounced changes present in the adipocytes obtained from subADMSCs. Namely, chronic oversupply of fatty acids (present in morbid obesity) triggered an increase in CD36/SR-B2 and FATP4 protein content (total and cell surface), which translated to an increased LCFA influx (3H-palmitate uptake). This was associated with the accumulation of TAG and DAG in these cells. Furthermore, we observed that the adipocytes of visADMSCs origin were larger and showed smaller granularity than their counterparts of subADMSCs descent. Although ADMSCs were cultured in vitro, in a fatty acids-deprived environment, obesity significantly influenced the functionality of the progenitor adipocytes, suggesting the existence of a memory effect.

Transdermal Delivery of Metformin Using Dissolving Microneedles and Iontophoresis Patches for Browning Subcutaneous Adipose Tissue

Obesity is a serious public health problem that is strongly associated with increased multiple comorbidities such as diabetes, cardiovascular disease, and some types of cancer. While current anti-obesity treatments have various issues, locally transforming energy-storing white adipose tissue (WAT) into energy-burning brown-like/beige adipose tissue, the so-called browning of WAT, has been suggested to enhance obesity treatment efficiency with minimized side effects. Metformin is a first-line antidiabetes drug and a potent activator of AMP-activated protein kinase. Emerging evidence has suggested that metformin might enhance energy expenditure via the browning of WAT and hence reduce body weight. Subcutaneous WAT is easier to access and has a stronger browning potential than other WAT depots. In this study, we used dissolvable poly (lactic-co-glycolic acid) microneedles (MN) to deliver metformin to the subcutaneous WAT in obese C57BL/6J mice with the assistance of iontophoresis (INT), and then investigated metformin-induced WAT browning and its subsequent thermogenesis effects. Compared with MN alone or INT alone, MN + INT had better anti-obesity activity, as indicated by decreasing body weight and fat gain, increased energy expenditure, decreased fat pad size, and improved energy metabolism through the browning of WAT. Browning subcutaneous WAT by delivering metformin and other browning agents using this MN + INT approach might combat obesity in an effective, easy, and safe regimen.

A Short-Term High-Fat Diet Improved the Survival of Fat Grafts in Mice by Promoting Macrophage Infiltration and Angiogenesis

Background: Adipose tissue is an ideal filler material that is widely used for soft tissue defects. But the low survival rate and complications associated with such grafts pose a serious challenge, which limits their clinical application. Adipose tissue is a metabolic diet-responsive tissue; however, the influence of diets on fat grafting remains ambiguous.

Methods: We extracted inguinal fat pads from C57/BL6 male mice, and transplanted them into the dorsal region of recipient mice (0.3 ml). Post-fat-grafting, mice (n = 54) were randomized into three groups, namely normal diet (ND), high carbohydrate diet (HC), and high-fat diet (HF). Structural changes were assessed by histological staining. Lipolysis activity and vascular regeneration of grafts on day 30 were analyzed using real-time polymerase chain reaction, immunofluorescence, and western blotting.

Results: The grafts of mice on HC and HF diets exhibited significantly fewer oil cysts and larger volume retention (0.18 ± 0.01, 0.21 ± 0.01, and 0.25 ± 0.01 ml, for ND, HC, and HF group, respectively, p < 0.05) on day 90. In comparison, grafts for the mice belonging to the HF groups exhibited higher expression of lipolysis-related genes, including adipose triglyceride lipase (ATGL), hormone-sensitive lipase (HSL), and carnitine palmitoyltransferase 1 (CPT1), on day 30. Furthermore, increased infiltration of macrophages (F4/80+) and the higher expression of angiogenesis genes were reported in the HF groups.

Conclusion: Altogether, the administration of short-term HF diet remarkably enhanced angiogenesis and improved the quality of fat grafts, which was characterized by fewer oil cysts and higher long-term volume retention. The possible mechanisms may be due to the increased macrophage infiltration, and the promoted angiogenesis in HF grafts.

Host Metabolic Changes during Mycobacterium Tuberculosis Infection Cause Insulin Resistance in Adult Mice

Tuberculosis (TB) is a highly infectious bacterial disease that primarily attacks the lungs. TB is manifested either as latent TB infection (LTBI) or active TB disease, the latter posing a greater threat to life. The risk of developing active TB disease from LTBI is three times higher in individuals with type 2 diabetes mellitus (T2DM). The association between TB and T2DM is becoming more prominent as T2DM is rapidly increasing in settings where TB is endemic. T2DM is a chronic metabolic disorder characterized by elevated blood glucose, insulin resistance, and relative insulin deficiency. Insulin resistance and stress-induced hyperglycemia have been shown to be increased by TB and to return to normal upon treatment. Previously, we demonstrated that adipocytes (or fat tissue) regulate pulmonary pathology, inflammation, and Mycobacterium tuberculosis (Mtb) load in a murine model of TB. Metabolic disturbances of adipose tissue and/or adipocyte dysfunction contribute to the pathogenesis of T2DM. Thus, pathological adipocytes not only regulate pulmonary pathology, but also increase the risk for T2DM during TB infection. However, the cellular and molecular mechanisms driving the interaction between hyperglycemia, T2DM and TB remain poorly understood. Here, we report the impact of Mtb infection on the development of insulin resistance in mice fed on a regular diet (RD) versus high-fat diet (HFD) and, conversely, the effect of hyperglycemia on pulmonary pathogenesis in juvenile and adult mouse models. Overall, our study demonstrated that Mtb persists in adipose tissue and that Mtb infection induces irregular adipocyte lipolysis and loss of fat cells via different pathways in RD- and HFD-fed mice. In RD-fed mice, the levels of TNFα and HSL (hormone sensitive lipase) play an important role whereas in HFD-fed mice, ATGL (adipose triglyceride lipase) plays a major role in regulating adipocyte lipolysis and apoptosis during Mtb infection in adult mice. We also showed that Mtb infected adult mice that were fed an RD developed insulin resistance similar to infected adult mice that were overweight due to a HFD diet. Importantly, we found that a consequence of Mtb infection was increased lipid accumulation in the lungs, which altered cellular energy metabolism by inhibiting major energy signaling pathways such as insulin, AMPK and mToR. Thus, an altered balance between lipid metabolism and glucose metabolism in adipose tissue and other organs including the lungs may be an important component of the link between Mtb infection and subsequent metabolic syndrome.

An enriched environment reestablishes metabolic homeostasis by reducing obesity-induced inflammation

Obesity can lead to chronic inflammation in different tissues, generating insulin and leptin resistance and alterations in glucose and lipid metabolism, favoring the development of degenerative diseases, including type II diabetes. Congruently, the inflammatory signaling inhibition prevents the development of obesity and restores insulin sensitivity. Via the enhancement of central nervous system activity, an enriched environment (EE) has beneficial effects on learning and memory as well as on immune cell functions and inflammation in different disease models. Here, we explored whether an EE can restore energy balance in obese mice that previously presented metabolic alterations. We discovered that an EE improved glucose metabolism, increased insulin signaling in liver, and reduced hepatic steatosis and inflammation, and increased lipolysis and browning in the white adipose tissue of high-fat diet (HFD)-fed mice. Finally, we found reduced inflammatory signaling and increased anorexigenic signaling in the hypothalamus of HFD-fed mice exposed to an EE. These data indicate that an EE is able to restore the metabolic imbalance caused by HFD feeding. Thus, we propose EE as a novel therapeutic approach for treating obesity-related metabolic alterations.

This article has an associated First Person interview with the first author of the paper.

Summary: A series of physiological, histochemical and molecular analyses reveal that enriched environment decreases inflammation in adipose tissue and in hypothalamus, re-establishing glucose metabolism in metabolically compromised mice.

The effect of a low carbohydrate ketogenic diet with or without exercise on postpartum weight retention, metabolic profile and physical activity performance in postpartum mice

OBJECTIVE

the present study examined the effect of the isocaloric low-carbohydrate ketogenic diet (LCKD) with or without exercise training for 6 weeks on postpartum weight retention (PPWR), body composition, metabolic profile and physical activity performance in postpartum mice.

METHODS

postpartum mice were assigned to 4 groups (n=8/group) as follows: (1) those on a control diet without aerobic exercise (CN); (2) those on a control diet with aerobic exercise (CN+EX), (3); those on a LCKD without aerobic exercise (LCKD); (4) those on a LCKD with aerobic exercise (LCKD+EX). CN+EX and LCKD+EX mice performed 6 weeks of exercise training on a treadmill. After the 6-week intervention, physical activity performance was determined.

RESULTS

postpartum mice in all groups experienced progressive reductions in body weight over the study period. The LCKD group had the smallest reduction in PPWR (p<0.05). The LCKD group had significantly higher total cholesterol, low-density lipoprotein cholesterol and lactate dehydrogenase levels, and liver lipid concentrations with a worsened glucose tolerance, compared to the CN group (p<0.05). The LCKD group showed significant reductions in physical activity performance, whilst the LCKD+EX group showed significantly improvement in endurance performance, and paralleled the concomitant elevation in blood ketone levels.

CONCLUSIONS

6-week LCKD feeding on its own was less effective for reducing PPWR, and more detrimental to postpartum metabolic outcomes and physical activity performance of the postpartum mice. The feasibility of a LCKD with or without exercise during the postpartum period as a strategy for managing PPWR and improving postpartum metabolic profiles should be carefully considered.

Alterations in Lysosome Homeostasis in Lipid-Related Disorders: Impact on Metabolic Tissues and Immune Cells

Lipid-related disorders, which primarily affect metabolic tissues, including adipose tissue and the liver are associated with alterations in lysosome homeostasis. Obesity is one of the more prevalent diseases, which results in energy imbalance within metabolic tissues and lysosome dysfunction. Less frequent diseases include Niemann-Pick type C (NPC) and Gaucher diseases, both of which are known as Lysosomal Storage Diseases (LSDs), where lysosomal dysfunction within metabolic tissues remains to be fully characterized. Adipocytes and hepatocytes share common pathways involved in the lysosome-autophagic axis, which are regulated by the function of cathepsins and CD36, an immuno-metabolic receptor and display alterations in lipid diseases, and thereby impacting metabolic functions. In addition to intrinsic defects observed in metabolic tissues, cells of the immune system, such as B cells can infiltrate adipose and liver tissues, during metabolic imbalance favoring inflammation. Moreover, B cells rely on lysosomes to promote the processing and presentation of extracellular antigens and thus could also present lysosome dysfunction, consequently affecting such functions. On the other hand, growing evidence suggests that cells accumulating lipids display defective inter-organelle membrane contact sites (MCSs) established by lysosomes and other compartments, which contribute to metabolic dysfunctions at the cellular level. Overall, in this review we will discuss recent findings addressing common mechanisms that are involved in lysosome dysregulation in adipocytes and hepatocytes during obesity, NPC, and Gaucher diseases. We will discuss whether these mechanisms may modulate the function of B cells and how inter-organelle contacts, emerging as relevant cellular mechanisms in the control of lipid homeostasis, have an impact on these diseases.

Deficiency of Cathelicidin Attenuates High-Fat Diet Plus Alcohol-Induced Liver Injury through FGF21/Adiponectin Regulation

Alcohol consumption and obesity are known risk factors of steatohepatitis. Here, we report that the deficiency of CRAMP (cathelicidin-related antimicrobial peptide—gene name: Camp) is protective against a high-fat diet (HFD) plus acute alcohol (HFDE)-induced liver injury. HFDE markedly induced liver injury and steatosis in WT mice, which were attenuated in Camp^–/– mice. Neutrophil infiltration was lessened in the liver of Camp^–/– mice. HFDE feeding dramatically increased epididymal white adipose tissue (eWAT) mass and induced adipocyte hypertrophy in WT mice, whereas these effects were attenuated by the deletion of Camp. Furthermore, Camp^–/– mice had significantly increased eWAT lipolysis, evidenced by up-regulated expression of lipolytic enzymes, adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL). The depletion of Camp also increased uncoupling protein 1 (UCP1)-dependent thermogenesis in the brown adipose tissue (BAT) of mice. HFDE fed Camp^–/– mice had elevated protein levels of fibroblast growth factor 21 (FGF21) in the eWAT, with an increased adiponectin production, which had been shown to alleviate hepatic fat deposition and inflammation. Collectively, we have demonstrated that Camp^–/– mice are protected against HFD plus alcohol-induced liver injury and steatosis through FGF21/adiponectin regulation. Targeting CRAMP could be an effective approach for prevention/treatment of high-fat diet plus alcohol consumption-induced steatohepatitis.

Brain insulin signalling in metabolic homeostasis and disease

Insulin signalling in the central nervous system regulates energy homeostasis by controlling metabolism in several organs and by coordinating organ crosstalk. Studies performed in rodents, non-human primates and humans over more than five decades using intracerebroventricular, direct hypothalamic or intranasal application of insulin provide evidence that brain insulin action might reduce food intake and, more importantly, regulates energy homeostasis by orchestrating nutrient partitioning. This Review discusses the metabolic pathways that are under the control of brain insulin action and explains how brain insulin resistance contributes to metabolic disease in obesity, the metabolic syndrome and type 2 diabetes mellitus.

Modulatory role of atorvastatin against high-fat diet and zymosan-induced activation of TLR2/NF-ƙB signaling pathway in C57BL/6 mice

OBJECTIVES

Accumulated evidence provides a strong connection between the immune system and vascular inflammation. The innate immune system's main sensors are toll-like receptors (TLRs). Zymosan (Zym), a fungal product, induces an inflammatory response via activating TLR2 of the immune system. Atorvastatin, a potent statin, possesses pleiotropic effects including immunomodulatory, lipid-lowering, and anti-inflammatory. Therefore, the current study aimed to evaluate the protective role of atorvastatin against a high-fat diet (HFD) and Zym-induced vascular inflammation in C57BL/6 mice via modulation of TLR2/NF-ƙB signaling pathway.

MATERIALS AND METHODS

In silico study was conducted to confirm the binding affinity of atorvastatin against TLR2. Under in vivo study, mice were divided into four groups: Normal control: normal standard chow-diet fed for 30 days + Zym vehicle (sterile PBS, 5 mg/ml on 8th day); HFD (30 days) + Zym (80 mg/kg, IP, on 8th day); HFD/Zym + atorvastatin vehicle (0.5% CMC, p.o., from 10th to 30th day); HFD/Zym + atorvastatin (3.6 mg/kg, p.o., from 10th to 30th day).

RESULTS

Atorvastatin treatment along with HFD and Zym inhibited vascular inflammation by suppressing the levels of aortic TLR2, cardiac NF-ƙB and decrease in serum TNF-α and IL-6. Further, there was an increase in hepatic LDLR levels, resulting in a decrease in serum LDL-C and an increase in HDL-C levels. Histopathological examination of the aorta showed a reduction in plaque accumulation with the atorvastatin-treated group as compared with HFD and Zym-treated group.

CONCLUSION

Atorvastatin attenuates vascular inflammation mediated by HFD and Zym through suppression of TLR2, NF-ƙB, TNF-α, IL-6, and upregulation of LDLR levels.

Nutrient regulation of inflammatory signalling in obesity and vascular disease

Despite obesity and diabetes markedly increasing the risk of developing cardiovascular diseases, the molecular and cellular mechanisms that underlie this association remain poorly characterised. In the last 20 years it has become apparent that chronic, low-grade inflammation in obese adipose tissue may contribute to the risk of developing insulin resistance and type 2 diabetes. Furthermore, increased vascular pro-inflammatory signalling is a key event in the development of cardiovascular diseases. Overnutrition exacerbates pro-inflammatory signalling in vascular and adipose tissues, with several mechanisms proposed to mediate this. In this article, we review the molecular and cellular mechanisms by which nutrients are proposed to regulate pro-inflammatory signalling in adipose and vascular tissues. In addition, we examine the potential therapeutic opportunities that these mechanisms provide for suppression of inappropriate inflammation in obesity and vascular disease.

Insulin Sensitivity After Living Donor Nephrectomy

BACKGROUND

The kidney is essential for glucose and insulin metabolism. Living kidney donors (LKDs) experience a reduction in glomerular filtration rate of 25 to 30 mL/min after donor nephrectomy. Little is known about the effect of glomerular filtration rate decline on insulin sensitivity in LKDs.

METHODS

We conducted a prospective pilot study on 9 LKDs (N = 9) who underwent dynamic metabolic testing (mixed meal tolerance test) to measure proxies of insulin sensitivity (homeostatic model assessment of insulin resistance, the area under curve [AUC] for insulin/glucose ratio, and Matsuda insulin sensitivity index) before and 3 months after donor nephrectomy. The primary outcome was the change in insulin sensitivity indices (delta [post-nephrectomy - pre-nephrectomy]).

RESULTS

Four of the donors had a body mass index (BMI) between 32.0 and 36.7 predonation. Post-donor nephrectomy, compared with prenephrectomy values, median insulin AUC increased from 60.7 to 101.7 hr*mU/mL (delta median 33.3, P = .04) without significant change in median glucose AUC levels from 228.9 to 209.3 hr*mg/dL (delta median 3.2, P = .77). There was an increase in the median homeostatic model assessment of insulin resistance from 2 to 2.9 (delta median 0.8, P = .03) and the AUC insulin/glucose ratio from 30.9 to 62.1 pmol/mmol (delta median 17.5, P = .001), whereas the median Matsuda insulin sensitivity index decreased from 5.9 to 2.9 (delta median -2, P = .05). The changes were more pronounced in obese (BMI >32) donors.

CONCLUSION

LKDs appear to have a trend toward a decline in insulin sensitivity post-donor nephrectomy in the short term, especially in obese donors (BMI >32). Further investigation with a larger sample size and longer follow-up is needed.

Selective Inhibition of 11β-Hydroxysteroid Dehydrogenase Type 1 Attenuates High-Fat Diet-Induced Hepatic Steatosis in Mice

Introduction

The effect of 11β-hydroxysteroid dehydrogenase type1 (11β-HSD1) inhibition on hepatic steatosis is incompletely understood. Here, we aimed to determine the therapeutic effect of BVT.2733, a selective 11β-HSD1 inhibitor, on hepatic steatosis.

Materials and Methods

C57B/6J mice were randomly divided into a low-fat diet (LFD) fed group and a high-fat diet (HFD) fed group. Mice were fed with HFD for 28 weeks which induced obesity and severe hepatic steatosis. The two groups were further divided into four groups as follows: LFD, LFD with BVT.2733, HFD, and HFD with BVT.2733. Mice in LFD+BVT and HFD+BVT groups were intraperitoneally injected with BVT.2733 daily for 30 days. Effects of BVT.2733 on mice body weight, serum lipid profile, serum free fatty acids (FFAs), glucocorticoid levels, gene expression in adipose and liver tissues were assessed.

Results

Injection of a low dose of BVT.2733 (50 mg/kg/day) reduced body weight and hyperlipidemia, but did not improve glucose tolerance and insulin resistance in diet-induced obese mice. The low dose of BVT.2733 attenuated hepatic steatosis, liver injury, and liver lipolytic gene expression in diet-induced obese mice. Besides, the low dose of BVT.2733 reduced fat mass and lipolysis in visceral adipose tissues, hepatic FFAs, and serum corticosterone levels in diet-induced obese mice.

Conclusion

Our study shows that moderate inhibition of 11β-HSD1 by BVT.2733 reduces FFAs and corticosterone synthesis in fatty tissues, thereby attenuates the delivery of corticosterone and FFAs to the liver. Collectively, this prevents high-fat diet-induced hepatic steatosis.

Thermogenic Fat: Development, Physiological Function, and Therapeutic Potential

The concerning worldwide increase of obesity and chronic metabolic diseases, such as T2D, dyslipidemia, and cardiovascular disease, motivates further investigations into preventive and alternative therapeutic approaches. Over the past decade, there has been growing evidence that the formation and activation of thermogenic adipocytes (brown and beige) may serve as therapy to treat obesity and its associated diseases owing to its capacity to increase energy expenditure and to modulate circulating lipids and glucose levels. Thus, understanding the molecular mechanism of brown and beige adipocytes formation and activation will facilitate the development of strategies to combat metabolic disorders. Here, we provide a comprehensive overview of pathways and players involved in the development of brown and beige fat, as well as the role of thermogenic adipocytes in energy homeostasis and metabolism. Furthermore, we discuss the alterations in brown and beige adipose tissue function during obesity and explore the therapeutic potential of thermogenic activation to treat metabolic syndrome.

Heat stress promotes lipid accumulation by inhibiting the AMPK-PGC-1α signaling pathway in 3T3-L1 preadipocytes

Heat stress (HS) results in health problems in animals. This study was conducted to investigate the effect and the underlying mechanism of HS on the proliferation and differentiation process of 3T3-L1 preadipocytes. 3T3-L1 preadipocytes were treated at 37 °C or 41.5 °C. HS up-regulated the mRNA and protein expression level of heat shock protein 70 (HSP70). Furthermore, the proliferation of 3T3-L1 preadipocytes were significantly inhibited after HS treatment for 2 days. A large number of accumulated lipid droplets were observed under the microscope after HS treatment for 8 days. Notably, the result of oil red O staining showed that the number of lipid droplets increased significantly and the differentiation ability of the cells was enhanced after HS. Moreover, after 2 and 8 d of differentiation, HS increased the transcription levels of fat synthesis genes including peroxisome proliferators activated receptor γ (PPARγ), fatty acid binding protein 2 (AP2), fatty acid synthase (FAS) and CCAAT enhancer binding protein α (CEBPα) genes, while decreasing the transcription levels of lipid decomposition genes including ATGL and HSL genes. In addition, HS reduced the expression of AMPK and PGC-1α, as well as the dephosphorylation of AMPK. 5-Aminoimidazole-4-carboxamide ribonucleotide (AICAR) can eliminate HS induced lipogenesis by activating AMPK. These results indicated that HS inhibited the proliferation of 3T3-L1 preadipocytes and promoted lipid accumulation by inhibiting the AMPK-PGC-1α signaling pathway in 3T3-L1 preadipocytes. This work lays a theoretical foundation for improving the effect of HS on meat quality of livestock and provides a new direction for the prevention of obesity caused by HS.

Emblica officinalis and Hordeum vulgare L. Mixture Regulates Lipolytic Activity in Differentiated 3T3-L1 Cells

In this study, we investigated the lipolytic effects of an Emblica officinalis (Indian gooseberry [IG]) and Hordeum vulgare L. (barley sprout [BP]) mixture on differentiated 3T3-L1 cells. On the ninth day of differentiation, Oil red O staining and Western blotting were performed; additionally, glycerol release and triglyceride (TG), fatty acid (FA), and cyclic adenosine monophosphate (cAMP) levels were measured. Compared to the differentiation-induced control (C) group, the IG and BP mixture inhibited intracellular TG and FA levels by 61.7% and 48.9%, respectively, at a concentration of 200 μg/mL. Moreover, the mixture increased glycerol release and cAMP levels by more than twofold more than those in the C group. Western blotting was performed to confirm the protein expression involved in lipolysis, and the IG and BP mixture was found to significantly increase the protein activities of AMP-activated protein kinase, protein kinase A, and hormone-sensitive lipase compared to those of the C group. Furthermore, the mixture significantly inhibited the protein activities of phosphodiesterase 3B, adipose TG lipase, and perilipin compared to those of the C group at a concentration of 200 μg/mL. We found that the IG and BP mixture activates the cAMP pathway and regulates lipolytic enzymes, which are necessary for lipolysis. In conclusion, our findings suggest that the IG and BP mixture can be potentially developed as a new material for targeting mechanisms underlying lipolysis.

Ferulic Acid Stimulates Adipocyte-Specific Secretory Proteins to Regulate Adipose Homeostasis in 3T3-L1 Adipocytes

Obesity has recently emerged as a public health issue facing developing countries in the world. It is caused by the accumulation of fat in adipose, characterized by insulin resistance, excessive lipid accumulation, inflammation, and oxidative stress, leading to an increase in adipokine levels. Herein, we investigated the capacity of a bioactive polyphenolic compound (ferulic acid (FA)) to control adipocyte dysfunction in 3T3-L1 adipocytes (in vitro). Key adipocyte differentiation markers, glycerol content, lipolysis-associated mRNA, and proteins were measured in experimental adipocytes. FA-treated adipocytes exhibited downregulated key adipocyte differentiation factors peroxisome proliferator-activated receptor-γ (PPAR-γ), CCAT enhancer binding-proteins-α (C/EBP-α) and its downstream targets in a time-dependent manner. The FA-treated 3T3-L1 adipocytes showed an increased release of glycerol content compared with non-treated adipocytes. Also, FA treatment significantly up-regulated the lipolysis-related factors, including p-HSL, and p-perilipin, and down-regulated ApoD, Sema3C, Cxcl12, Sfrp2, p-stearoyl-CoA desaturase 1 (SCD1), adiponectin, and Grk5. Also, the FA treatment showed significantly down-regulated adipokines leptin, chemerin, and irisin than the non-treated cells. The present findings indicated that FA showed significant anti-adipogenic and lipogenic activities by regulating key adipocyte factors and enzyme, enhanced lipolysis by HSL/perilipin cascade. FA is considered a potent molecule to prevent obesity and its associated metabolic changes in the future.

Oxidative Stress, Plant Natural Antioxidants, and Obesity

Oxidative stress is important in the pathophysiology of obesity, altering regulatory factors of mitochondrial activity, modifying the concentration of inflammation mediators associated with a large number and size of adipocytes, promoting lipogenesis, stimulating differentiation of preadipocytes to mature adipocytes, and regulating the energy balance in hypothalamic neurons that control appetite. This review discusses the participation of oxidative stress in obesity and the important groups of compounds found in plants with antioxidant properties, which include (a) polyphenols such as phenolic acids, stilbenes, flavonoids (flavonols, flavanols, anthocyanins, flavanones, flavones, flavanonols, and isoflavones), and curcuminoids (b) carotenoids, (c) capsaicinoids and casinoids, (d) isothiocyanates, (e) catechins, and (f) vitamins. Examples are analyzed, such as resveratrol, quercetin, curcumin, ferulic acid, phloretin, green tea, Hibiscus Sabdariffa, and garlic. The antioxidant activities of these compounds depend on their activities as reactive oxygen species (ROS) scavengers and on their capacity to prevent the activation of NF-κB (nuclear factor κ-light-chain-enhancer of activated B cells), and reduce the expression of target genes, including those participating in inflammation. We conclude that natural compounds have therapeutic potential for diseases mediated by oxidative stress, particularly obesity. Controlled and well-designed clinical trials are still necessary to better know the effects of these compounds.

Dietary fat content and adipose triglyceride lipase and hormone-sensitive lipase gene expressions in adults' subcutaneous and visceral fat tissues

INTRODUCTION

We examined the association of adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL) gene expressions, as the key regulators of lipolysis, with dietary fat quantity and composition in subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT).

METHODS

In this observational study, samples were collected from patients undergoing elective abdominal surgery. Participants were categorized into two groups based on their body mass index (BMI) status. Dietary, anthropometric, and biochemical data were collected before surgery. Linear regression was performed to determine the association of dietary fat content with ATGL and HSL gene expressions in SAT and VAT.

RESULTS

152 individuals with a mean ± SD age of 40.7 ± 13.2 years and a median (inter-quartile range) BMI of 39.4 (26.5-45.3 kg/m²) participated in this study, of whom 54 were non-obese (BMI<30 kg/m²), and 98 were obese (BMI≥30 kg/m²). Among non-obese participants, positive associations were observed between ATGL mRNA expression and reported intakes of total fatty acids (TFA) (β=0.306, P = 0.025), myristic (β=0.285, P = 0.038), palmitic (β=0.417, P = 0.002), oleic (β=0.333, P = 0.017), dairy trans (β=0.374, P = 0.006), and other trans FAs (β=0.369, P = 0.006) in SAT. In contrast, inverse associations between HSL mRNA expression and reported intakes of TFAs (β=-0.377, P = 0.005), myristic (β=-0.282, P = 0.039), palmitic (β=-0.372, P = 0.006), stearic (β=-0.314, P = 0.020), and oleic acid (β=-0.372, P = 0.007) were observed in SAT. No associations were observed among obese participants, nor in VAT among non-obese individuals.

CONCLUSION

ATGL and HSL mRNA expressions in SAT were associated with dietary fat quantity and composition among non-obese adults.

Salvia hispanica L. (chia) seed promotes body fat depletion and modulates adipocyte lipid handling in sucrose-rich diet-fed rats

The aim of this study was to analyze the effects of Salvia hispanica L. (chia) seed upon metabolic pathways that play a key role in adipose tissue lipid handling which could be involved in visceral adiposity reduction developed in rats fed a sucrose-rich diet (SRD). Male Wistar rats were fed with a reference diet (RD) -6 months- or SRD-3 months. Then, the last group was randomly divided into two subgroups. One subgroup continued receiving the SRD up to 6 months and the other was fed with a SRD where whole chia seed was incorporated as the source of dietary fat for the next 3 months (SRD + CHIA). Results showed that chia seed in the SRD-fed rat reduced the abdominal and thoracic circumferences, carcass fat content, adipose tissue weights, and visceral adiposity index. This was accompanied by an improvement in insulin sensitivity and plasma lipid profile. In epididymal adipose tissue, the decreased fat cell triglyceride content was associated with a reduction in both, FAT/CD 36 plasma membrane levels and the fat synthesis enzyme activities. There were not changes in oxidative CPT enzyme activities. PKCβ and the precursor and mature forms of SREBP-1 protein levels were decreased, while pAMPK was increased. Our findings suggest that chia seed supplementation can modulate essential pathways of lipid metabolism in adipose tissue, contributing to reduced visceral fat accumulation in SRD-fed rats.

New insights into the digestion and bioavailability of a high-melting-temperature solid triacylglycerol fraction in bovine milk fat

Clarifying the health risks associated with the consumption of high-melting-temperature solid triacylglycerol (TAG) from milk fat has profound significance for the nutritional evaluation and development of new dairy products. Our previous work effectively separated butterfat into solid/liquid fractions (30S and 30L) at 30 °C and successfully reconstituted milk fat globules (MFGs) with these fractions. The current study examined the postprandial digestive and daily metabolic properties of a high-melting-temperature solid TAG fraction by performing animal experiments (rats) with 30S-reconstituted MFG emulsion gavage for 240 min and 30S-containing diet administration for 4 weeks. Compared to the consumption of whole butterfat, 30S consumption altered apolipoprotein levels and did not lead to dyslipidaemia in the rats. Conversely, 30S administration induced significant body weight loss by enhancing satiety signals (glucagon-like peptide 1, GLP-1; cholecystokinin, CCK; and peptide YY, PYY), increasing faecal losses, and upregulating the level of hepatic lipolysis-associated enzymes (hormone-sensitive lipase, HSL; adipose triglyceride lipase, ATGL; and protein kinase A, PKA). The 30S diet efficiently improved adipocyte hypertrophy and reduced fat accumulation by downregulating the level of acetyl-CoA carboxylase (ACC) in adipose tissue. This study is of relevance to nutrition science and the dairy industry.

Post-exercise Effects and Long-Term Training Adaptations of Hormone Sensitive Lipase Lipolysis Induced by High-Intensity Interval Training in Adipose Tissue of Mice

Although studies have proven that high-intensity interval training (HIIT) shows a comparable effect to moderate-intensity continuous training (MICT) on reducing body fat, especially visceral fat, the mechanism is still unclear. Since MICT consumes more fat during exercise, the mechanism of HIIT weight loss may be related to post-exercise effects, long-term adaptive changes, and hormone sensitive lipase (HSL). The objective of this study was to compare the post-effects of acute exercise, long-term adaptive changes on HSL activity, and catecholamine-induced lipolysis between HIIT and MICT. Following a 14-week high-fat diet (HFD), obese female C57Bl/6 mice were divided into acute exercise groups (one time training, sacrificed at rest and 0, 1, and 12 h after exercise, n = 49), -L groups (12-week long-term training, 12-h fasting, n = 21), and -C groups (12-week training, primary adipocytes were isolated and stimulated by catecholamine in vitro, n = 18). MICT or HIIT treadmill protocols (running distance matched) were carried out during training. Comparison of acute exercise effects by two-way ANOVA showed no time × group interaction effect, however, a significant increase in HSL-Ser563 (at 0 and 1 h) and Ser660 phosphorylation (at 0, 1, and 12 h) in inguinal (subcutaneous) fat was only observed in HIIT mice (p < 0.05 vs. rest), but not in MICT mice. The periuterine (visceral) fat HSL expression and phosphorylation of HIIT mice was similar to or lower than MICT mice. After long-term training, 12-h fasting significantly increased periuterine fat Ser563 phosphorylation in HIIT mice (p < 0.05), but there was no change in MICT mice. Under stimulation of catecholamine in vitro, isolated primary adipocytes from periuterine fat of long-term HIIT mice showed a higher Ser563 increase than that found in MICT mice (p < 0.05). The quantity of triglyceride (TG) lipid bonds (representing lipolysis level) was significantly lower after HIIT than MICT (p < 0.05). The results indicate that (1) acute HIIT can induce an increase of HSL phosphorylation in subcutaneous fat lasting at least 12 h, implying longer post-exercise lipolysis than MICT and (2) long-time HIIT has a better effect on improving catecholamine resistance of visceral adipocytes caused by a HFD, which allows fat to be mobilized more easily when stimulated.