Novel molecular aspects of ghrelin and leptin in the control of adipobiology and the cardiovascular system

Sex-Specific Effects of Long-Term Antipsychotic Drug Treatment on Adipocyte Tissue and the Crosstalk to Liver and Brain in Rats

Antipsychotic drug (APD) medication can lead to metabolic dysfunctions and weight gain, which together increase morbidity and mortality. Metabolically active visceral adipose tissue (VAT) in particular plays a crucial role in the etiopathology of these metabolic dysregulations. Here, we studied the effect of 12 weeks of drug medication by daily oral feeding of clozapine and haloperidol on the perirenal fat tissue as part of VAT of male and female Sprague Dawley rats in the context of complex former investigations on brain, liver, and blood. Adipocyte area values were determined, as well as triglycerides, non-esterified fatty acids (NEFAs), glucose, glycogen, lactate, malondialdehyde equivalents, ferric iron and protein levels of Perilipin-A, hormone-sensitive-lipase (HSL), hepcidin, glucose transporter-4 (Glut-4) and insulin receptor-ß (IR-ß). We found increased adipocyte mass in males, with slightly higher adipocyte area values in both males and females under clozapine treatment. Triglycerides, NEFAs, glucose and oxidative stress in the medicated groups were unchanged or slightly decreased. In contrast to controls and haloperidol-medicated rats, perirenal adipocyte mass and serum leptin levels were not correlated under clozapine. Protein expressions of perilipin-A, Glut-4 and HSL were decreased under clozapine treatment. IR-ß expression changed sex-specifically in the clozapine-medicated groups associated with higher hepcidin levels in the perirenal adipose tissue of clozapine-treated females. Taken together, clozapine and haloperidol had a smaller effect than expected on perirenal adipose tissue. The perirenal adipose tissue shows only weak changes in lipid and glucose metabolism. The main changes can be seen in the proteins examined, and probably in their effect on liver metabolism.

The effects of bariatric surgery on cardiac function: a systematic review and meta-analysis

INTRODUCTION

Obesity is associated with alterations in cardiac structure and haemodynamics leading to cardiovascular mortality and morbidity. Culminating evidence suggests improvement of cardiac structure and function following bariatric surgery.

OBJECTIVE

To evaluate the effect of bariatric surgery on cardiac structure and function in patients before and after bariatric surgery.

METHODS

Systematic review and meta-analysis of studies reporting pre- and postoperative cardiac structure and function parameters on cardiac imaging in patients undergoing bariatric surgery.

RESULTS

Eighty studies of 3332 patients were included. Bariatric surgery is associated with a statistically significant improvement in cardiac geometry and function including a decrease of 12.2% (95% CI 0.096-0.149; p < 0.001) in left ventricular (LV) mass index, an increase of 0.155 (95% CI 0.106-0.205; p < 0.001) in E/A ratio, a decrease of 2.012 mm (95% CI 1.356-2.699; p < 0.001) in left atrial diameter, a decrease of 1.16 mm (95% CI 0.62-1.69; p < 0.001) in LV diastolic dimension, and an increase of 1.636% (95% CI 0.706-2.566; p < 0.001) in LV ejection fraction after surgery.

CONCLUSION

Bariatric surgery led to reverse remodelling and improvement in cardiac geometry and function driven by metabolic and haemodynamic factors.

Association of sleep characteristics with cardiovascular disease risk in adults over 40 years of age: a cross-sectional survey

Background

The relationship between sleep characteristics and cardiovascular disease (CVD) risk has yet to reach a consistent conclusion, and more research needs to be carried out. This study aimed to explore the relationship between snoring, daytime sleepiness, bedtime, sleep duration, and high-risk sleep patterns with CVD risk.

Methods

Data from the National Health and Nutrition Examination Survey (NHANES) 2015-2018 were collected and analyzed. Multivariable logistic regression was used to evaluate the relationship between snoring, daytime sleepiness, bedtime, sleep duration, high-risk sleep patterns, and CVD risk. Stratified analysis and interaction tests were carried out according to hypertension, diabetes and age.

Results

The final analysis contained 6,830 participants, including 1,001 with CVD. Multivariable logistic regression suggested that the relationship between snoring [OR = 7.37,95%CI = (6.06,8.96)], daytime sleepiness [OR = 11.21,95%CI = (9.60,13.08)], sleep duration shorter than 7 h [OR = 9.50,95%CI = (7.65,11.79)] or longer than 8 h [OR = 6.61,95%CI = (5.33,8.19)], bedtime after 0:00 [OR = 13.20,95%CI = (9.78,17.80)] compared to 22:00-22:59, high-risk sleep patterns [OR = 47.73,95%CI = (36.73,62.04)] and CVD risk were statistically significant. Hypertension and diabetes interacted with high-risk sleep patterns, but age did not.

Conclusions

Snoring, daytime sleepiness, excessive or short sleep duration, inappropriate bedtime, and high-risk sleep patterns composed of these factors are associated with the CVD risk. High-risk sleep patterns have a more significant impact on patients with hypertension and diabetes.

Molecular and cellular mechanisms underlying the hepatoprotective role of ghrelin against NAFLD progression

The underlying mechanisms for the development and progression of nonalcoholic fatty liver disease (NAFLD) are complex and multifactorial. Within the last years, experimental and clinical evidences support the role of ghrelin in the development of NAFLD. Ghrelin is a gut hormone that plays a major role in the short-term regulation of appetite and long-term regulation of adiposity. The liver constitutes a target for ghrelin, where this gut-derived peptide triggers intracellular pathways regulating lipid metabolism, inflammation, and fibrosis. Interestingly, circulating ghrelin levels are altered in patients with metabolic diseases, such as obesity, type 2 diabetes, and metabolic syndrome, which, in turn, are well-known risk factors for the pathogenesis of NAFLD. This review summarizes the molecular and cellular mechanisms involved in the hepatoprotective action of ghrelin, including the reduction of hepatocyte lipotoxicity via autophagy and fatty acid β-oxidation, mitochondrial dysfunction, endoplasmic reticulum stress and programmed cell death, the reversibility of the proinflammatory phenotype in Kupffer cells, and the inactivation of hepatic stellate cells. Together, the metabolic and inflammatory pathways regulated by ghrelin in the liver support its potential as a therapeutic target to prevent NAFLD in patients with metabolic disorders.

Association of 3-year change in sleep duration with risk of all-cause mortality in Chinese older population: A national cohort study

BACKGROUND

Existing evidence on the association of dynamic change in sleep duration with risk of all-cause mortality in Chinese older population is limited. We aimed to explore the association of 3-year change in sleep duration with risk of all-cause mortality in a Chinese older population.

MATERIALS AND METHODS

A total of 5772 Chinese older participants (median age 82 years) were enrolled in the current study. Cox proportional-hazard models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association of 3-year change in sleep duration with risk of all-cause mortality. Subgroup analyses of the association between 3-year change in sleep duration and risk of all-cause mortality were conducted by age, sex and residence.

RESULTS

During a median of 4.08 years of follow-up, death developed in 1762 participants. Compared with -1 to <1 h/day change in sleep duration, the adjusted risk of all-cause mortality with < -3 h/day change in sleep duration may increase 26% (HR = 1.26, 95% CI: 1.05-1.52); the risk of all-cause mortality with 3-year change from short to long sleep duration, or long to short sleep duration versus stable normal sleep duration status was increased about 28% and 52%, respectively (HR = 1.28, 95% CI: 1.00-1.64 and HR = 1.52, 95% CI: 1.21-1.92). Subgroup analyses demonstrated that similar significant associations were observed among participants with 65 to <85 years, men and living in city and town.

CONCLUSIONS

Dynamic sleep duration change was significantly associated with risk of all-cause mortality. The current study suggests that sleep duration may be a non-invasive indicator for interventions aiming to reduction risk of all-cause mortality in Chinese older population.

AMP-activated protein kinase is a key regulator of obesity-associated factors

An imbalance between caloric intake and energy expenditure leads to obesity. Obesity is an important risk factor for the development of several metabolic diseases including insulin resistance, metabolic syndrome, type 2 diabetes mellitus, and cardiovascular disease. So, controlling obesity could be effective in the improvement of obesity-related diseases. Various factors are involved in obesity, such as AMP-activated protein kinases (AMPK), silent information regulators, inflammatory mediators, oxidative stress parameters, gastrointestinal hormones, adipokines, angiopoietin-like proteins, and microRNAs. These factors play an important role in obesity by controlling fat metabolism, energy homeostasis, food intake, and insulin sensitivity. AMPK is a heterotrimeric serine/threonine protein kinase known as a fuel-sensing enzyme. The central role of AMPK in obesity makes it an attractive molecule to target obesity and related metabolic diseases. In this review, the critical role of AMPK in obesity and the interplay between AMPK and obesity-associated factors were elaborated.

Intracerebroventricular injection of ghrelin receptor antagonist alleviated NAFLD via improving hypothalamic insulin resistance

OBJECTIVES

Non-alcoholic fatty liver disease (NAFLD) is a hepatic manifestation of clinical metabolic syndrome. Insulin resistance is an important factor in the pathogenesis of NAFLD. Ghrelin, widely distributed in peripheral tissues and the central nervous system, plays a vital role in regulating food intake, energy balance, and substance metabolism. In this study, the effect of intracerebroventricular (ICV) injection of ghrelin receptor antagonist on NAFLD was explored.

MATERIALS AND METHODS

A rat model of NAFLD was established by feeding a high-fat diet, and a selective ghrelin receptor antagonist [D-Lys-3]-GHRP-6 was injected via ventricular intubation implantation. The serum total cholesterol (TC), triglycerides (TGs), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and hepatic TGs were measured using the colorimetric method. Fasting plasma glucose (FPG) and fasting plasma insulin (FPI) were determined to calculate homeostatic model assessment insulin resistance (HOMA-IR). Hematoxylin-eosin (HE) and Oil Red O staining were conducted to observe the pathological changes and lipid accumulation in the liver. Hosphatidylinositide3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling pathway protein expressions were measured using western blot analysis.

RESULTS

ICV injection of [D-Lys-3]-GHRP-6 significantly reduced serum lipids, transaminase, and HOMA-IR, improved liver injury, and inhibited lipid accumulation in the liver of NAFLD rats. Moreover, ICV injection of [D-Lys-3]-GHRP-6 significantly up-regulated the phosphorylation levels of PI3K/Akt/mTOR signaling protein expressions in the hypothalamus, indicating a significant improvement in hypothalamic insulin resistance.

CONCLUSION

Blockade of central ghrelin receptor can treat NAFLD possibly via the hypothalamic PI3K/Akt/mTOR signaling pathway to improve insulin resistance.

Association of Sleep Duration With All-Cause and Cardiovascular Mortality: A Prospective Cohort Study

To clarify the association of sleep duration with all-cause and cardiovascular mortality, and further estimate the population attributable fraction (PAF) for the 10-year risk of cardiovascular disease (CVD) due to inappropriate sleep duration among US adults, we included data of the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2014 by linkage to the National Death Index until December 31, 2015 in a prospective design. Cox proportional hazards models were used for multivariate longitudinal analyses. The Pooled Cohort Equations methods was adopted to calculate the predicted 10-year CVD risk. In the current study, sleep <5 h or longer than 9 h per day were significantly associated with elevated risks of all-cause mortality, and the multivariable-adjusted HRs across categories were 1.40 (95% CI, 1.14–1.71), 1.12 (95% CI, 0.91–1.38), 1 (reference), 1.35 (95% CI, 1.12–1.63), and 1.74 (95% CI, 1.42–2.12). Similarly, the HRs of cardiovascular mortality across categories were 1.66 (95% CI, 1.02–2.72), 1.15 (95% CI, 0.77–1.73), 1 (reference), 1.55 (95% CI, 1.05–2.29), and 1.81 (95% CI, 1.09–3.02). Under a causal–effect assumption, we estimated that 187 000 CVD events (PAF 1.8%, 0.9% to 2.3%) were attributable to short sleep duration and 947 000 CVD events (PAF 9.2%, 6.4% to 11.6%) were attributable to long sleep duration from 2018 to 2028. This study informed the potential benefit of optimizing the sleep duration for the primary prevention of CVD in a contemporary population.

Role of the Ghrelin System in Colorectal Cancer

The ghrelin system contains several components (e.g., ghrelin with growing number of alternative peptides, growth hormone secretagogue receptors (GHS-Rs), and ghrelin-O-acyl-transferase (GOAT) and participates in regulation of a number of key processes of gastrointestinal (GI) tract cancer progression, including cell proliferation, migration, invasion, apoptosis, inflammation, and angiogenesis. However, its exact role in promoting or inhibiting cancer progression is still unclear. Colorectal cancer (CRC) is one of the most common human malignancies worldwide. Molecular studies suggest an autocrine/paracrine mechanism for the secretion of ghrelin in colorectal carcinogenesis and its contribution to its initial stages. However, the signalling pathways of CRC development involving the ghrelin system are poorly understood. Potential mechanisms of colon carcinogenesis involving components of the ghrelin system were previously described in an animal model and in in vitro studies. However, the diagnostic–prognostic role of serum ghrelin concentrations, tissue expression, or genetic changes of this system in various stages of CRC progression remains an open case. Thus, the aim of this study is to discuss the role of the ghrelin system in colon carcinogenesis, diagnostics and CRC prognostics, as well as the results of studies on the use of ghrelin and its analogues in the therapy of CRC-related syndromes (e.g., cachexia and sarcopenia).

Shared postulations between bipolar disorder and polycystic ovary syndrome pathologies

INTRODUCTION

Women with bipolar disorder (BD) present a high prevalence of polycystic ovary syndrome (PCOS) and other reproductive disorders even before diagnosis or treatment of the disease. Postulations on the potential molecular mechanisms of comorbid PCOS in women with BD remain limited to influence of medications and need further extension.

OBJECTIVES

This review focuses on evidence suggesting that common metabolic and immune disorders may play an important role in the development of BD and PCOS.

RESULTS

The literature covered in this review suggests that metabolic and immune disorders, including the dysfunction of the hypothalamic-pituitary-adrenal axis, chronic inflammatory state, gut microbial alterations, adipokine alterations and circadian rhythm disturbance, are observed in patients with BD and PCOS. Such disorders may be responsible for the increased prevalence of PCOS in the BD population and indicate a susceptibility gene overlap between the two diseases. Current evidence supports postulations of common metabolic and immune disorders as endophenotype in BD as well as in PCOS.

CONCLUSIONS

Metabolic and immune disorders may be responsible for the comorbid PCOS in the BD population. The identification of hallmark metabolic and immune features common to these two diseases will contribute to the clarification of the effect of BD on the reproductive endocrine function and development of symptomatic treatments targeting the biomarkers of the two diseases.

Perivascular Adipose Tissue Inflammation: The Anti-Inflammatory Role of Ghrelin in Atherosclerosis Progression

Perivascular adipose tissue (PVAT) and its adipokines engage in bidirectional crosstalk with the vascular wall. Atherosclerosis disrupts this interaction through inflammation, rupture-prone plaques, and subsequent thrombosis. The cardioprotective effects of ghrelin are in contradiction to its adipogenic properties. The concurrent research of anti-/pro-atherogenic mechanisms of ghrelin and PVAT-derived adipokines provides a better understanding of atherosclerosis progression in metabolic disorders. In-depth coverage of the characteristic features of PVAT concerning vascular dysfunction, with a survey of ghrelin-induced anti-inflammatory effects on adipose tissue macrophage infiltration and the inhibitory activity of ghrelin on the proinflammatory adipokine secretion, show that the impact of ghrelin on the endothelial function should be studied in relation to PVAT.

The impact of a novel Chinese yam-derived polysaccharide on blood glucose control in HFD and STZ-induced diabetic C57BL/6 mice

Chinese yam, as a kind of traditional “medicine and food homologous food” in Asia, could assistance to digestion, nourish the lungs and relieve cough. Some research also suggested that Chinese...

New Insights on the Relationship between Leptin, Ghrelin, and Leptin/Ghrelin Ratio Enforced by Body Mass Index in Obesity and Diabetes

Currently, adipose tissue is considered an endocrine organ, however, there are still many questions regarding the roles of adipokines—leptin and ghrelin being two adipokines. The purpose of the study was to assess the relationship between the adipokines and their ratio with obesity and diabetes. Methods: Sixty patients (mean age 61.88 ± 10.08) were evaluated. Cardiovascular risk factors, leptin, ghrelin, and insulin resistance score values were assessed. The patients were classified according to their body mass index (BMI) as normal weight, overweight, and obese. Results: 20% normal weight, 51.7% overweight, 28.3% obese, and 23.3% diabetic. Obese patients had higher leptin values (in obese 34,360 pg/mL vs. overweight 18,000 pg/mL vs. normal weight 14,350 pg/mL, p = 0.0049) and leptin/ghrelin ratio (1055 ± 641 vs. 771.36 ± 921 vs. 370.7 ± 257, p = 0.0228). Stratifying the analyses according to the presence of obesity and patients’ gender, differences were found for leptin (p = 0.0020 in women, p = 0.0055 in men) and leptin/ghrelin ratio (p = 0.048 in women, p = 0.004 in men). Mean leptin/BMI and leptin/ghrelin/BMI ratios were significantly higher, and the ghrelin/BMI ratio was significantly lower in obese and diabetic patients. In conclusion, obesity and diabetes are associated with changes not only in the total amount but also in the level of adipokines/kg/m². Changes appear even in overweight subjects, offering a basis for early intervention in diabetic and obese patients.

Puerarin suppresses the hepatic gluconeogenesis via activation of PI3K/Akt signaling pathway in diabetic rats and HepG2 cells

Pueraria, a Chinese herbal medicine, plays an important role in many classic prescriptions for the treatment of diabetes. Puerarin is the main component of pueraria. The current in vivo and in vitro research mainly focus on exploring the potential mechanism of puerarin in inhibiting hepatic gluconeogenesis. The type 2 diabetic rats were established by a combination of small dosage of streptozotocin (STZ) injection with high-fat diet. After the administration of puerarin 4 weeks, the parameters of the glucose and lipid metabolism were determined. HepG2 cells were treated by palmitic acid (PA) to induce the insulin resistance in vitro model. After the treatment of puerarin, the glucose consumption and cell viability were examined. Then, the protein expression of PI3K, Akt, pAkt, pFOXO1, FOXO1, PEPCK and G6pase in liver tissue and HepG2 cells were evaluated by western blot. RT-PCR was used to measure the content of PEPCK, G6pase mRNA in liver tissue. The results showed that puerarin administration significantly decrease the level of FBG, HbA1C and triglycerides in diabetic rats. Mechanistic research showed that puerarin activating PI3K/Akt is puerarin-mediated beneficial effects and can be reversed by inhibitor of PI3K or Akt. In conclusion, puerarin inhibits hepatic gluconeogenesis by activating PI3K/Akt signaling pathway.

The Association of Serum Levels of Leptin and Ghrelin with the Dietary Fat Content in Non-Obese Women with Polycystic Ovary Syndrome

Women with polycystic ovary syndrome (PCOS) are at an increased risk of developing insulin resistance and abdominal obesity in the state of an improper diet balance. Leptin is a peptide considered to be a satiety hormone that plays an important role in the long-term energy balance, whereas ghrelin is a hormone that controls short-term appetite regulation and is considered a hunger hormone. The aim of the present study was to assess the relationship between serum leptin and ghrelin concentrations and the dietary macronutrient content in PCOS women. We examined 73 subjects: 39 women diagnosed with PCOS by the Rotterdam criteria and 34 healthy controls, matched by the body mass index. The subjects completed a consecutive three-day dietary diary to identify the macronutrient and micronutrient intake. Serum concentrations of leptin and total ghrelin were measured and homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. The studied groups did not differ significantly in terms of the intake of macronutrients (proteins, fats, and carbohydrates) and serum concentrations of ghrelin and leptin (all p > 0.05). In the PCOS group, the serum leptin concentration positively correlated with the intake of total fat (r = 0.36, p = 0.02), total cholesterol (r = −0.36, p = 0.02), saturated fatty acids (r = 0.43, p < 0.01), and monounsaturated fatty acids (MUFA) (r = 0.37, p = 0.02), whereas the serum ghrelin concentration correlated in an inverse manner with the intake of total fat (r = −0.37, p = 0.02), MUFA (r = −0.37, p = 0.02), polyunsaturated fatty acids (r = −0.34, p = 0.03), and long chain polyunsaturated fatty acids (r = −0.38, p = 0.02). In this group, we also found a negative association of HOMA-IR with serum ghrelin levels (r = −0.4, p = 0.03) and a positive relationship with the serum leptin concentration (r = 0.5, p < 0.01) and relationships between HOMA-IR and total dietary fat (r = 0.38, p = 0.03) and MUFA (r = 0.35, p = 0.04) intake. In PCOS women, dietary components such as the total fat and type of dietary fat and HOMA-IR are positively connected to serum leptin concentrations and negatively connected to serum ghrelin concentrations, which may influence the energy balance.

The associations between some biological markers, obesity, and cardiovascular risk in Slovenian children and adolescents

INTRODUCTION

The occurrence of cardiovascular diseases and metabolic disorders steadily increases with the body mass index (BMI). Since the latter is not the best and earliest indicator of obesity and cardiovascular risk, the aim of the study was to evaluate some potential biological markers that would allow us to detect children and adolescents at higher risk at an early stage.

METHODS

A sample of 330 children and adolescents were included in the study and divided into four groups: obese patients with hypertension, normal-weight patients with hypertension, patients with mildly elevated lipids and a control group of healthy children and adolescents. Some clinical parameters (age, body weight, body height, BMI, waist circumference, hip circumference, blood pressure), biochemical parameters (glucose, total cholesterol, triglycerides, HDL, LDL, apolipoprotein A1, homocysteine) and biological markers of obesity (ghrelin, adiponectin, leptin) were evaluated.

RESULTS

Ghrelin and adiponectin were found to have a strong negative statistically significant correlation with BMI in all three observed groups (p < 0.001), but not in the control group (p = 0.053 and p = 0.316, respectively). In addition, leptin had a strong positive statistically significant correlation with BMI in all four groups (p < 0.001 for the research groups, p = 0.009 for the controls). In the group of obese patients with hypertension, statistically significant differences in all three markers of obesity were found in comparison to the control group (p < 0.001 for all markers). In the group of patients with mildly elevated lipids, ghrelin and leptin were significantly different (p = 0.002 and p < 0.001, respectively). In the group of normal-weight hypertensive patients, only values of ghrelin were different compared to the control group (p = 0.001).

CONCLUSION

In the research groups, significant differences were found in clinical, biochemical and biological parameters compared to the control group. The observed biological markers of obesity are useful early markers for identifying groups of patients that are at cardiovascular risk.

Relationships between Body Composition and Plasma Levels of Pancreatic, Gut, and Adipose Tissue Hormones in db/db Mice, a Model of Type 2 Diabetes Mellitus

We studied the relationships between body composition parameters and plasma levels of pancreatic, gut, and adipose tissue hormones regulating energy balance and glucose metabolism in diabetic db/db mice (BKS.Cg-Dock7^m+/+Lepr^db/J). The body composition parameters in mice aged 8, 12, and 16 weeks were assessed by magnetic resonance imaging. The concentrations of insulin, glucagon, ghrelin, glucagon-like peptide-1, glucose-dependent immunotropic peptide, leptin, resistin, and plasminogen activator-1 were measured by multiplex analysis at the age of 8 and 16 weeks. In comparison with non-diabetic control (db/+), db/db mice demonstrated high fat mass and reduced lean body mass and water content. In 8- and 16-week-old db/db mice, the levels of leptin (p<0.001), insulin (p<0.01), and glucagon-like peptide-1 (p<0.05) were elevated and the concentration of ghrelin (p<0.05) was reduced. The body weight and fat mass positively correlated with the levels of leptin, insulin, plasminogen activator-1, and glucagon-like peptide-1 and negatively correlated with ghrelin concentration. The results provide further details for characteristics of db/db mice, a widely used model of obesity and type 2 diabetes mellitus.

The role of ghrelin and tumor necrosis factor alpha in diazinon-induced dyslipidemia: insights into energy balance regulation

The evidence shows that organophosphate compounds (OPCs), as toxic agents that stimulate the cholinergic system, can increase the incidence of metabolic disorders such as dyslipidemia. In the present study, we focused on the role of tumor necrosis factor alpha (TNF-α) and serum leptin and ghrelin in Diazinon (DZN)-induced dyslipidemia. The rats were randomly divided into five groups comprising eight animals, and all were treated via oral gavage for 28 consecutive days as follows: group one received only corn oil daily, while groups two through five received different doses of DZN dissolved in corn oil equal to 1/40, 1/20, 1/10 and 1/5 of the LD50 daily, respectively. The alteration of the serum lipid profile, such as triglycerides, high-density lipoprotein (HDL) and very-low-density lipoprotein (VLDL), was confirmed the occurrence of dyslipidemia in the range of doses 1/20-1/5 LD50 of DZN. Although no changes were found in the serum leptin levels, a significant increase was observed in the size of adipocytes, as well as in the TNF-α and ghrelin serum levels, and in the accumulation of epididymal fat, especially at a dose of 1/5 LD50 of DZN. It seems that interactions among the inflammatory reaction, cholinergic pathways and ghrelin secretion may be effective causes of DZN-induced dyslipidemia.

Metabolic Effects of Testosterone Hormone Therapy in Normal and Orchiectomized Male Rats: From Indirect Calorimetry to Lipolytic Enzymes

BACKGROUND AND AIM

Changes in total energy expenditure (TEE) and substrate metabolism may help explain the metabolic actions of testosterone (T). This study measured respiratory quotient (RQ), TEE, ghrelin, insulin, and key lipolysis enzyme concentrations in relation to body weight (wt) and food intake (FI) in both normal and bilaterally orchiectomized rats with/without T treatment.

METHODS

In total, thirty-two male Wistar rats (300-400 g) were divided into four groups (n = 8/group), including (a) sham-operated and vehicle-injected group (Sham), (b) T-treated sham group (T-Sham) for which sham-operated rats were injected with IM testosterone undecanoate (100 mg/kg, for one week), (c) orchiectomy and vehicle-injected group (Orch), and (d) T-replaced orchiectomy group (T-Orch). After one week, FI and wt were automatically recorded, indirect calorimetry parameters were measured, and blood samples were collected to measure T, ghrelin, insulin, growth hormone (GH), glucose, hormone-sensitive lipase (HSL), adipocyte triglyceride lipase (ATGL), free fatty acids (FFA), and lipid profiles.

RESULTS

Orchiectomy decreased ghrelin, GH, and insulin levels, increased TEE and RQ, and lowered FI and wt. The T-Orch group exhibited increased levels of ghrelin (3-fold), insulin, GH, blood levels of lipolysis products, TEE, and FI in addition to reduced glucose levels (P < 0.05). This group demonstrated no significant changes in wt. In the T-Sham group, T increased ghrelin and insulin levels (P < 0.05) with strong positive correlations (r = 0.663 and 0.644, respectively, P < 0.05), increased ATGL levels, RQ toward carbohydrate utilization ranges, and TEE, and reduced HSL levels (P < 0.05) with insignificant changes in FI or wt.

CONCLUSIONS

T administration in orchiectomized rats significantly increased orexigenic mediators such as ghrelin and insulin without inducing any significant changes in wt. The mechanism for this finding might be the increased TEE and the stimulation of lipolysis through the ATGL enzyme. The associated rise of GH might help in interference with accumulation of lipid in adipose tissue. Apart from the effect on GH, T-Sham showed similar effects of T supplementation.

IgG Anti-ghrelin Immune Complexes Are Increased in Rheumatoid Arthritis Patients Under Biologic Therapy and Are Related to Clinical and Metabolic Markers

Rheumatoid arthritis (RA) is a systemic autoimmune disease associated with increased risk of cardiovascular disease and metabolic alterations. The mechanisms underlying these alterations remain unclear. Ghrelin is a gastrointestinal hormone with potent effects on food intake, body weight, metabolism, and immune response. Recent studies reported the presence of anti-ghrelin autoantibodies in healthy subjects and the levels and affinity of these autoantibodies were altered in anorectic and obese individuals. In this cross-sectional study we analyzed anti-ghrelin autoantibodies in RA patients and evaluated its relationship with clinical, body-composition and metabolic parameters. Clinical measurements of RA patients included the disease activity score-28 (DAS-28), inflammatory biomarkers, autoantibodies (RF and anti-CCP), body composition, glucose and lipid profile. Serum ghrelin levels were measured by enzyme-linked immunosorbent assay (ELISA). Free and total anti-ghrelin autoantibodies quantification (IgG and IgA isotypes) was performed by in-house ELISA. RA patients had lower IgG anti-ghrelin autoantibodies levels and higher immune complexes percentage (IgG+ghrelin) compared to the control group, while the IgA anti-ghrelin autoantibodies showed no significant differences. In the bivariate analysis, the percentage of IgG anti-ghrelin immune complexes positively correlated with BMI and ghrelin whereas in the multivariate regression model, the variables associated were DAS-28, body weight, visceral fat, LDL-C and TG (R ² = 0.72). The percentage of IgA anti-ghrelin immune complexes positively correlated with RF and anti-CCP and the multivariate regression model showed an association with RF and body fat percentage (R ² = 0.22). Our study shows an increased percentage of IgG anti-ghrelin immune complexes in RA patients despite ghrelin levels were similar in both groups, suggesting an increase in the affinity of these autoantibodies toward ghrelin. The associations found in the multiple regression analysis for anti-ghrelin immune complexes support the previously reported functions of these natural autoantibodies as carriers and modulators of the stability and physiological effect of the hormone. However, in RA both the disease activity and the RF appear to influence the formation of these anti-ghrelin immune complexes.

The relationship between the leptin/ghrelin ratio and meals with various macronutrient contents in men with different nutritional status: a randomized crossover study

BACKGROUND

Hormones, which influence satiety and hunger, play a significant role in body energy balance regulation. Ghrelin is a peptide that plays an important role in short-term appetite regulation, whereas leptin is a factor that controls long-term energy balance and is considered as a satiety hormone. The aim of this study was to evaluate the leptin/ghrelin ratio in a fasting state and after the intake of meals with varying macronutrient contents and to assess the possible differences between normal body weight and overweight/obese men.

METHODS

We examined 46 healthy adult men (23 with normal body weight and 23 overweight/obese) aged 21-58, who were divided into two groups. In the crossover study, participants received isocaloric (450 kcal) meals with different macronutrient contents: men from the first group received high-carbohydrate (HC) and normo-carbohydrate (NC) meals, and in the second group, participants received high-carbohydrate and high-fat (HF) meals. The ratio of leptin/ghrelin levels was calculated from leptin and total ghrelin serum concentrations in a fasting state and 30, 60, 120, 180 and 240 min after meal intake. One-way ANOVA and Wilcoxon signed-rank tests were carried out. The normality of the variable distribution was checked with the Shapiro-Wilk test, the homogeneity of variances was verified with the Levene test, and the false discovery rate p-value adjustment method was used.

RESULTS

The leptin/ghrelin ratio was significantly higher in overweight/obese men than individuals with normal body weight in a fasting state, as well as postprandially. We observed trends towards a higher leptin/ghrelin ratio values from the 60 min after HC-meal intake compared to the NC- and HF-meals in normal body weight participants, while in overweight/obese men, we did not note any significant differences dependent on the meal type.

CONCLUSIONS

We have observed a significantly different postprandial leptin/ghrelin ratio in normal body weight and overweight/obese men, and our results suggest that in men with normal body weight, a greater feeling of satiety may occur after high-carbohydrate meal intake, which was not noted in the overweight/obese individuals.

Ghrelin, a gastrointestinal hormone, regulates energy balance and lipid metabolism

Ghrelin, an acylated peptide hormone of 28 amino acids, is an endogenous ligand of the released growth hormone secretagogue receptor (GHSR). Ghrelin has been isolated from human and rat stomach and is also detected in the hypothalamic arcuate nucleus. Ghrelin receptor is primarily located in the neuropeptide Y and agouti-related protein neurons. Many previous studies have shown that ghrelin and GHSR are involved in the regulation of energy homeostasis, and its administration can increase food intake and body weight gain. AMP-activated protein kinase is activated by ghrelin in the hypothalamus, which contributes to lower intracellular long-chain fatty acid level. Ghrelin appears to modulate the response to food cues via a neural network involved in the regulation of feeding and in the appetitive response to food cues. It also increases the response of brain areas involved in visual processing, attention, and memory to food pictures. Ghrelin is also an important factor linking the central nervous system with peripheral tissues that regulate lipid metabolism. It promotes adiposity by the activation of hypothalamic orexigenic neurons and stimulates the expression of fat storage-related proteins in adipocytes. Meanwhile, ghrelin exerts direct peripheral effects on lipid metabolism, including increase in white adipose tissue mass, stimulation of lipogenesis in the liver, and taste sensitivity modulation.

Sex-specific differences in hepatic steatosis in obese spontaneously hypertensive (SHROB) rats

Background

Patients with metabolic syndrome, who are characterized by co-existence of insulin resistance, hypertension, hyperlipidemia, and obesity, are also prone to develop non-alcoholic fatty liver disease (NAFLD). Although the prevalence and severity of NAFLD is significantly greater in men than women, the mechanisms by which gender modulates the pathogenesis of hepatic steatosis are poorly defined. The obese spontaneously hypertensive (SHROB) rats represent an attractive model of metabolic syndrome without overt type 2 diabetes. Although pathological manifestation caused by the absence of a functional leptin receptor has been extensively studied in SHROB rats, it is unknown whether these animals elicited sex-specific differences in the development of hepatic steatosis.

Methods

We compared hepatic pathology in male and female SHROB rats. Additionally, we examined key biochemical and molecular parameters of signaling pathways linked with hyperinsulinemia and hyperlipidemia. Finally, using methods of quantitative polymerase chain reaction (qPCR) and western blot analysis, we quantified expression of 45 genes related to lipid biosynthesis and metabolism in the livers of male and female SHROB rats.

Results

We show that all SHROB rats developed hepatic steatosis that was accompanied by enhanced expression of SREBP1, SREBP2, ACC1, and FASN proteins. The livers of male rats also elicited higher induction of Pparg, Ppara, Slc2a4, Atox1, Skp1, Angptl3, and Pnpla3 mRNAs. In contrast, the livers of female SHROB rats elicited constitutively higher levels of phosphorylated JNK and AMPK and enhanced expression of Cd36.

Conclusion

Based on these data, we conclude that the severity of hepatic steatosis in male and female SHROB rats was mainly driven by increased de novo lipogenesis. Moreover, male and female SHROB rats also elicited differential severity of hepatic steatosis that was coupled with sex-specific differences in fatty acid transport and esterification.

Electronic supplementary material

The online version of this article (10.1186/s13293-018-0202-x) contains supplementary material, which is available to authorized users.

Implication of the PI3K/Akt/mTOR Pathway in the Process of Incompetent Valves in Patients with Chronic Venous Insufficiency and the Relationship with Aging

Chronic venous insufficiency (CVI) is a multifactorial disease, commonly caused by valvular incompetence (clinically diagnosed by venous reflux) and venous hypertension. The incidence of these factors clearly increases with patient age, and aging is one of the risk factors involved. The activity of the PI3K/Akt/mTOR pathway is considered fundamental in vascular pathologies, and understanding its involvement would help in the development of possible therapeutic targets. This is an observational, analytical, and prospective cohort study that reviewed 110 patients with CVI scheduled to undergo stratified saphenectomy. They were distributed according to the presence (R = 81) or absence (NR = 29) of valvular incompetence (venous reflux) diagnosed clinically. Each of the groups was further divided according to age, with a cutoff point of 50 years (NR < 50 = 13, NR ≥ 50 = 16, R < 50 = 32, and R ≥ 50 = 49). The involvement of the PI3K/Akt/mTOR pathway, as well as that of HIF-1α and HIF-2α and of CD4+, CD8+, and CD19+ cells and mastocytes, was assessed. Saphenous vein tissue samples obtained during surgery were processed for RT-qPCR and immunohistochemistry. Patients with venous reflux showed a significant increase in mRNA and protein expression levels for PI3K/mTOR and HIF-1α/HIF-2α. The number of mast cells was significantly elevated in the R group. In distribution by age, PI3K/Akt/mTOR and HIF-1α were significantly higher in R < 50 patients. Furthermore, these patients had a significant increase in the number of CD4+, CD8+, and CD19+ cells and mastocytes in the saphenous vein wall. These findings provide a basis for the possible existence of changes in PI3K/Akt/mTOR pathway expression in young patients, with potential accelerated asynchronous aging that is enhanced by CVI.

Gastrointestinal Tract: a Promising Target for the Management of Hypertension

The pathogenesis of hypertension remains elusive. Current treatments on hypertension have only achieved modest reductions. Facilitating theoretical research and looking for new therapeutic strategy are urgently needed. Besides food digestion and nutrients absorption, the gastrointestinal tract (GI) has been shown to influence the status of the central nervous system, immune system, metabolism, and cardiovascular homeostasis. Emerging findings demonstrate that endogenous factors derived from GI including gut hormones, autonomic nerve, and gut microbiota play important roles in the regulation of vascular function and/or blood pressure. Meanwhile, evidences from clinical practice and experimental study have found that intervention in GI through metabolic surgery, probiotics consumption, and dietary modification can efficiently ameliorate or even remit hypertension and related cardiometabolic diseases. Thus, we propose that GI might be an initiating organ of hypertension and a promising target for the management of hypertension. Further, illuminating this concept may aid to understand the pathogenesis and control of hypertension.

Sleeve Gastrectomy Reduces Body Weight and Improves Metabolic Profile also in Obesity-Prone Rats

BACKGROUND

Susceptibility to obesity is associated with a notable inter-individual variation. The aim of the present study was to compare the effectiveness of sleeve gastrectomy (SG) on weight loss and metabolic profile in obesity-prone (OP) rats vs animals that are non-susceptible to obesity (NSO).

METHODS

Young male Wistar rats (n = 101) were put in a diet-induced obesity (DIO) programme with ad libitum access to a high-fed diet (HFD) during 12 months. Body weight and food intake were regularly registered. Thereafter, rats were ranked by final body weight to identify the obesity-prone (OP) (n = 13) and non-susceptible to obesity (NSO) (n = 14) animals. OP and NSO rats were submitted to surgical interventions (sham operation, SG and pair-fed to the amount of food eaten by sleeve-gastrectomized rats). Body weight, food intake, energy expenditure, body temperature, fat pads weight, and metabolic profiling were analysed 4 weeks after surgical or dietary interventions.

RESULTS

SG in both OP and NSO rats decreased body weight as compared to sham and pair-fed groups (P < 0.05), mainly due to reductions in subcutaneous and perirenal fat mass (P < 0.001). Total weight loss achieved in sleeve-gastrectomized OP and NSO rats was higher than that of pair-fed ones (P < 0.05), showing that the SG effect goes beyond caloric restriction. In this regard, sleeve-gastrectomized rats exhibited significantly (P < 0.05) increased basal rectal temperature together with upregulated brown adipose tissue Ucp-1 protein expression levels. A significant (P < 0.05) improvement in insulin sensitivity was also observed in both OP and NSO animals that underwent SG as compared with pair-fed counterparts.

CONCLUSION

Our findings provide the first evidence that obesity-prone rats also benefit from surgery responding effectively to SG, as evidenced by the significant body weight reduction and the metabolic profile improvement.

Sleeve Gastrectomy Decreases Body Weight, Whole-Body Adiposity, and Blood Pressure Even in Aged Diet-Induced Obese Rats

BACKGROUND

Aging and obesity are two conditions associated with increased risk of cardiovascular disease. Our aim was to analyze whether an advanced age affects the beneficial effects of sleeve gastrectomy on weight loss and blood pressure in an experimental model of diet-induced obesity (DIO).

METHODS

Young (6-month-old) and old (18-month-old) male Wistar DIO rats (n = 101) were subjected to surgical (sham operation and sleeve gastrectomy) or dietary interventions (pair-fed to the amount of food eaten by sleeve gastrectomized animals). Systolic (SBP), diastolic (DBP), and mean (MBP) blood pressure values and heart rate (HR) were recorded in conscious, resting animals by non-invasive tail-cuff plethysmography before and 4 weeks after surgical or dietary interventions.

RESULTS

Aging was associated with higher (P < 0.05) body weight and subcutaneous and perirenal fat mass as well as mild cardiac hypertrophy. Sleeve gastrectomy induced a reduction in body weight, whole-body adiposity, and serum total ghrelin in both young and old DIO rats. The younger group achieved a higher excess weight loss than the older group (164 ± 60 vs. 82 ± 17 %, P < 0.05). A significant (P < 0.05) decrease in insulin resistance, SBP, DBP, MBP, and HR without changes in heart weight was observed after sleeve gastrectomy independently of age.

CONCLUSION

Our results provide evidence for the effectiveness of sleeve gastrectomy without increased operative risk in body weight and blood pressure reduction even in aged animals via endocrine changes that go beyond the mere caloric restriction.

Relationship of Sleep Duration With All-Cause Mortality and Cardiovascular Events: A Systematic Review and Dose-Response Meta-Analysis of Prospective Cohort Studies

Background

Effects of extreme sleep duration on risk of mortality and cardiovascular outcomes remain controversial. We aimed to quantify the dose‐response relationships of sleep duration with risk of all‐cause mortality, total cardiovascular disease, coronary heart disease, and stroke.

Methods and Results

PubMed and Embase were systematically searched for prospective cohort studies published before December 1, 2016, that examined the associations between sleep duration and at least 1 of the 4 outcomes in generally healthy populations. U‐shaped associations were indicated between sleep duration and risk of all outcomes, with the lowest risk observed for ≈7‐hour sleep duration per day, which was varied little by sex. For all‐cause mortality, when sleep duration was <7 hours per day, the pooled relative risk (RR) was 1.06 (95% CI, 1.04–1.07) per 1‐hour reduction; when sleep duration was >7 hours per day, the pooled RR was 1.13 (95% CI, 1.11–1.15) per 1‐hour increment. For total cardiovascular disease, the pooled RR was 1.06 (95% CI, 1.03–1.08) per 1‐hour reduction and 1.12 (95% CI, 1.08–1.16) per 1‐hour increment of sleep duration. For coronary heart disease, the pooled RR was 1.07 (95% CI, 1.03–1.12) per 1‐hour reduction and 1.05 (95% CI, 1.00–1.10) per 1‐hour increment of sleep duration. For stroke, the pooled RR was 1.05 (95% CI, 1.01–1.09) per 1‐hour reduction and 1.18 (95% CI, 1.14–1.21) per 1‐hour increment of sleep duration.

Conclusions

Our findings indicate that both short and long sleep duration is associated with an increased risk of all‐cause mortality and cardiovascular events.

Ghrelin and autophagy

PURPOSE OF REVIEW

A compromised autophagy is associated with the onset of obesity, type 2 diabetes, nonalcoholic fatty liver disease, cardiovascular and neurodegenerative diseases. Our aim is to review the potential role of ghrelin, a gut hormone involved in energy homeostasis, in the regulation of autophagy.

RECENT FINDINGS

In the recent years, it has been demonstrated that autophagy constitutes an important mechanism by which ghrelin exerts a plethora of central and peripheral actions. Ghrelin enhances autophagy through the activation of AMP-activated protein kinase in different target organs to regulate lipid and glucose metabolism, the remodeling and protection of small intestine mucosa, protection against cardiac ischemia as well as higher brain functions such as learning and memory consolidation. Nonetheless, in inflammatory states, such as acute hepatitis, liver fibrosis or adipose tissue inflammation, ghrelin acts as an anti-inflammatory factor reducing the autophagic flux to prevent further cell injury. Interestingly, several cardiometabolic disorders, including obesity, type 2 diabetes, nonalcoholic fatty liver disease or chronic heart failure are accompanied by low ghrelin levels in addition to altered autophagy.

SUMMARY

Ghrelin represents an attractive target for development of therapeutics for prevention or treatment of metabolic, cardiac or neuronal disorders, in which autophagy is impaired.

Foxc2 coordinates inflammation and browning of white adipose by leptin-STAT3-PRDM16 signal in mice

AIMS

The objective of this study is to characterize the relationship between forkhead box C2 protein (Foxc2) and leptin under adipose inflammatory response.

METHODS

Lipopolysaccharide (LPS)-induced inflammatory model was conducted. Data from wild-type and ob/ob mice were used to compare the alternative role of leptin on Foxc2-mediated inflammation and browning. Transcriptional regulation and protein-protein interaction were analyzed by bioinformatics and proved by chromatin immunoprecipitation and co-immunoprecipitation experiment.

RESULTS

Foxc2 and leptin correlated with inflammation and browning of white adipose tissue (WAT) in LPS-treated mice. Moreover, Foxc2-mediated inhibition of inflammation involved downstream activation of leptin signal and promoted WAT browning. We then determined CREB, the potential transcriptional factor of leptin, was required for Foxc2-mediated inflammation in the regulation of WAT browning. Foxc2 alleviated adipocyte inflammation by reducing leptin-mediated Janus-activated kinase 2/signal transducer and activator of transcription 3 (STAT3) pathway. Importantly, STAT3 physically interacted with PRDM16 and formed a complex to promote WAT browning. Exogenous Foxc2 overexpression also ameliorated inflammation and promoted adipose browning in high fat diet (HFD)-induced obese mice.

CONCLUSIONS

Our results indicated that Foxc2 inhibited inflammation and promoted browning of WAT through positive regulation of leptin signal and the STAT3-PRDM16 complex. These findings identify a new potential means to prevent and treat obese caused metabolic syndrome of mammals.

Consuming Two Eggs per Day, as Compared to an Oatmeal Breakfast, Decreases Plasma Ghrelin while Maintaining the LDL/HDL Ratio

Eggs contain high quality protein, vitamins, minerals and antioxidants, yet regular consumption is still met with uncertainty. Therefore, the purpose of this study was to compare the effects of consuming two eggs per day or a heart-healthy oatmeal breakfast on biomarkers of cardiovascular disease (CVD) risk and satiety measures in a young, healthy population. Fifty subjects participated in a randomized crossover clinical intervention; subjects were randomly allocated to consume either two eggs or one packet of oatmeal per day for breakfast for four weeks. After a three-week washout period, participants were allocated to the alternative breakfast. Fasting blood samples were collected at the end of each intervention period to assess plasma lipids and plasma ghrelin. Subjects completed visual analog scales (VAS) concurrent to dietary records to assess satiety and hunger. Along with an increase in cholesterol intake, there were significant increases in both low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol following the egg consumption period (p < 0.01). However, there was no difference in the LDL/HDL ratio, a recognized biomarker of CVD risk, nor in the plasma glucose, triglycerides or liver enzymes, between diet periods. Several self-reported satiety measures were increased following the consumption of eggs, which were associated with lower plasma ghrelin concentrations (p < 0.05). These results demonstrate that compared to an oatmeal breakfast, two eggs per day do not adversely affect the biomarkers associated with CVD risk, but increase satiety throughout the day in a young healthy population.

Acylated and desacyl ghrelin are associated with hepatic lipogenesis, β-oxidation and autophagy: role in NAFLD amelioration after sleeve gastrectomy in obese rats

Bariatric surgery improves non-alcoholic fatty liver disease (NAFLD). Our aim was to investigate the potential role of ghrelin isoforms in the resolution of hepatic steatosis after sleeve gastrectomy, a restrictive bariatric surgery procedure, in diet-induced obese rats. Male Wistar rats (n = 161) were subjected to surgical (sham operation and sleeve gastrectomy) or dietary interventions [fed ad libitum a normal (ND) or a high-fat (HFD) diet or pair-fed]. Obese rats developed hepatosteatosis and showed decreased circulating desacyl ghrelin without changes in acylated ghrelin. Sleeve gastrectomy induced a dramatic decrease of desacyl ghrelin, but increased the acylated/desacyl ghrelin ratio. Moreover, sleeve gastrectomy reduced hepatic triglyceride content and lipogenic enzymes Mogat2 and Dgat1, increased mitochondrial DNA amount and induced AMPK-activated mitochondrial FFA β-oxidation and autophagy to a higher extent than caloric restriction. In primary rat hepatocytes, the incubation with both acylated and desacyl ghrelin (10, 100 and 1,000 pmol/L) significantly increased TG content, triggered AMPK-activated mitochondrial FFA β-oxidation and autophagy. Our data suggest that the decrease in the most abundant isoform, desacyl ghrelin, after sleeve gastrectomy contributes to the reduction of lipogenesis, whereas the increased relative acylated ghrelin levels activate factors involved in mitochondrial FFA β-oxidation and autophagy in obese rats, thereby ameliorating NAFLD.

Pathophysiology of Non Alcoholic Fatty Liver Disease

The physiopathology of fatty liver and metabolic syndrome are influenced by diet, life style and inflammation, which have a major impact on the severity of the clinicopathologic outcome of non-alcoholic fatty liver disease. A short comprehensive review is provided on current knowledge of the pathophysiological interplay among major circulating effectors/mediators of fatty liver, such as circulating lipids, mediators released by adipose, muscle and liver tissues and pancreatic and gut hormones in relation to diet, exercise and inflammation.

Leptin administration restores the altered adipose and hepatic expression of aquaglyceroporins improving the non-alcoholic fatty liver of ob/ob mice

Glycerol is an important metabolite for the control of lipid accumulation in white adipose tissue (WAT) and liver. We aimed to investigate whether exogenous administration of leptin improves features of non-alcoholic fatty liver disease (NAFLD) in leptin-deficient ob/ob mice via the regulation of AQP3 and AQP7 (glycerol channels mediating glycerol efflux in adipocytes) and AQP9 (aquaglyceroporin facilitating glycerol influx in hepatocytes). Twelve-week-old male wild type and ob/ob mice were divided in three groups as follows: control, leptin-treated (1 mg/kg/d) and pair-fed. Leptin deficiency was associated with obesity and NAFLD exhibiting an AQP3 and AQP7 increase in WAT, without changes in hepatic AQP9. Adipose Aqp3 and hepatic Aqp9 transcripts positively correlated with markers of adiposity and hepatic steatosis. Chronic leptin administration (4-weeks) was associated with improved body weight, whole-body adiposity, and hepatosteatosis of ob/ob mice and to a down-regulation of AQP3, AQP7 in WAT and an up-regulation of hepatic AQP9. Acute leptin stimulation in vitro (4-h) induced the mobilization of aquaglyceroporins towards lipid droplets (AQP3) and the plasma membrane (AQP7) in murine adipocytes. Our results show that leptin restores the coordinated regulation of fat-specific AQP7 and liver-specific AQP9, a step which might prevent lipid overaccumulation in WAT and liver in obesity.

Sparstolonin B suppresses rat vascular smooth muscle cell proliferation, migration, inflammatory response and lipid accumulation

Vascular smooth muscle cells (VSMCs) play a crucial role in atherosclerotic lesion formation. Sparstolonin B (SsnB) is a TLR2/TLR4 antagonist that inhibits inflammatory responses in multiple cell types. Herein, we investigated if SsnB inhibited VSMC proliferation, migration, inflammatory response and lipid accumulation. We found that SsnB suppressed VSMC proliferation and migration induced by PDGF. SsnB significantly suppressed the expression of MCP-1, TNFα and IL-6 in VSMCs stimulated by either lipopolysaccharide (LPS) or PDGF. Erk1/2 and Akt signaling pathways, which are responsible for the VSMC inflammatory response, were activated by LPS or PDGF stimulation, and SsnB significantly inhibited their activation. SsnB also substantially suppressed the intracellular cholesterol accumulation in VSMCs loaded with acetylated LDL. Mechanistically, SsnB remarkably repressed LPS-induced up-regulation of CD36, which is responsible for lipid uptake, and dramatically reversed LPS-induced inhibition of ABCA1, which promotes the efflux of intracellular free cholesterol. In conclusion, our results indicate that SsnB significantly inhibits VSMC proliferation, migration, inflammatory responses and lipid accumulation. Along with the previously reported anti-inflammatory activities of SsnB on macrophages and vascular endothelial cells, our data strongly suggest that SsnB may be developed as a new anti-atherogenic therapy.