Temporal relationship between diet-induced steatosis and onset of insulin/leptin resistance in male Wistar rats

Mechanisms of Non-alcoholic Fatty Liver Disease and Beneficial Effects of Semaglutide: A Review

Non-alcoholic fatty liver disease stands as the predominant cause of chronic liver disease, with its prevalence and morbidity expected to escalate significantly, leading to substantial healthcare costs and diminished health-related quality of life. It comprises a range of disease manifestations that commence with basic steatosis, involving the accumulation of lipids in hepatocytes, a distinctive histological feature. If left untreated, it often advances to non-alcoholic steatohepatitis, marked by inflammatory and/or fibrotic hepatic changes, leading to the eventual development of non-alcoholic fatty liver disease-related cirrhosis and hepatocellular carcinoma. Because of the liver's vital role in body metabolism, non-alcoholic fatty liver disease is considered both a consequence and a contributor to the metabolic abnormalities observed in the metabolic syndrome. As of date, there are no authorized pharmacological agents for non-alcoholic fatty liver disease or non-alcoholic steatohepatitis. Semaglutide, with its glycemic and weight loss advantages, could potentially offer benefits for individuals with non-alcoholic fatty liver disease. This review aims to investigate the impact of semaglutide on non-alcoholic fatty liver disease.

Circadian rhythm in hypothalamic leptin receptor (Ob-Rb) mRNA expressions and cerebrospinal fluid and circulating glucose and leptin levels in lactating rats

In lactating animals, the food consumption increases several-fold for milk supply to the pups. The present study was conducted to clarify the relationship between the hyperphagia during lactation and hypothalamic leptin receptor (Ob-Rb) mRNA expression, cerebrospinal fluid (CSF) and circulating leptin and glucose levels. Food intakes significantly higher in lactation than in non-lactation at all time points (3 points: light phase, 4 points: dark phase) of the day. However, the expression of the hypothalamic Ob-Rb mRNA showed similar circadian rhythms in both the non-lactation and lactation, with only slight differences between the two groups. CSF leptin and glucose levels were constant throughout the day in both non-lactation and lactation, and there was almost no difference between the two groups at each time point. Circulating leptin and glucose levels showed circadian rhythms only in the non-lactating period, and were lower in lactation than in non-lactation, especially in the dark phase. In conclusion, the present study provides evidence that Ob-Rb mRNA expression fluctuates in the lactation period as well as in the non-lactation period, suggesting that the expression profile of whole hypothalamic Ob-Rb may not contribute to the difference in food consumption between lactation and non-lactation, and that chronic decrease in blood glucose levels may be associated with the increase in food consumption during lactation.

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There was no difference in CSF leptin levels between lactating and non-lactating rats.

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Hypothalamic Ob-Rb mRNA expressions showed different circadian rhythms between non-lactation and lactation.

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Chronic decrease in blood glucose levels may be associated with the elevation of food consumption in lactating rats.

Hyperleptinaemia and its Association with Postprandial Hypertriglyceridemia and Glucose Intolerance

INTRODUCTION

Leptin resistance is believed to cause insulin resistance though the exact mechanism is not fully understood. The present study aims to investigate the temporal profile of postprandial triglyceride (PPTG) and leptin levels, and their association with each other as well as with markers of metabolic syndrome.

MATERIALS AND METHODS

Serum leptin and PPTG levels were measured longitudinally till 26 weeks in Wistar rats fed on controlled diet (group 1) and high sucrose diet (HSD) (group 2). Two additional groups fed on HSD were taken and treated with pioglitazone (group 3) and atorvastatin (group 4). Body weight, homeostasis model assessment of insulin resistance (HOMA-IR), and glucose intolerance were also measured during this period. Comparison of the groups were done and Pearson's correlation coefficient was used to ascertain the association.

RESULTS

Leptin levels were significantly higher in all three groups receiving HSD compared to controlled diet group from week 2 to week 26 (P < 0.01). The postprandial triglyceride area under the curve (PPTG AUCs) were significantly higher in group 2 than controls during this period (P < 0.001). Body weight, HOMA-IR and glucose AUC were found to be significantly higher in group 2 rats than controls only from week 6, 8, and 12 respectively. In HSD-fed rats, but not in control, mean serum leptin levels from 2-26 weeks as well as peak (10^th week) and 26^th week were strongly associated with corresponding as well as preceding PPTG levels. Leptin levels significantly predicted HOMA-IR and prediabetes in group 2.

CONCLUSION

This study found significant hyperleptinemia associated with postprandial hypertriglyceridemia that predicted insulin resistance and prediabetes in high sucrose diet-fed rats.

Association between Single Nucleotide Polymorphism rs9891119 of STAT3 Gene and the Genetic Susceptibility to Type 2 Diabetes in Chinese Han Population from Guangdong

Background

The aim of this study was to investigate the association between single nucleotide polymorphism (SNP) rs9891119 of the signal transducer and activator of the transcription 3 (STAT3) gene and genetic susceptibility to type 2 diabetes in Chinese Han population from the Guangdong province.

Objective

The aim of the present study was to explore the relationship between single nucleotide polymorphism rs9891119 of STAT3 gene and type 2 diabetes mellitus (T2DM), which provides a basis for molecular genetic research on the pathogenesis of T2DM in Chinese Han population.

Methods

In our case-control study, the SNP rs9891119 was picked out from the STAT3 gene and the SNP genotyping was performed by using the SNPscan^™ kit in 1092 patients with type 2 diabetes as cases and 1092 normal persons as controls. The distributions of genotype and allele frequencies in two groups were analyzed by SPSS 20.0 software.

Results

Our results showed that the alleles of A and C of rs9891119 of the STAT3 gene were 54.3 and 45.7% in patients with type 2 diabetes, while 55.5% and 44.5% in the normal persons, which have no statistical significance (P > 0.05). There were also no significant differences in AA, AC, and CC genotype frequencies between type 2 diabetes patients and normal persons. There were no significant differences in codominant, dominant, recessive, and overdominant genetic models of SNP rs9891119 before and after adjusting the covariant factors (P > 0.05).

Conclusions

Therefore, genetic susceptibility to type 2 diabetes may be not associated with SNP rs9891119 of the STAT3 gene in Chinese Han population from the Guangdong province.

Diet-induced rodent models of obesity-related metabolic disorders-A guide to a translational perspective

Diet is a critical element determining human health and diseases, and unbalanced food habits are major risk factors for the development of obesity and related metabolic disorders. Despite technological and pharmacological advances, as well as intensification of awareness campaigns, the prevalence of metabolic disorders worldwide is still increasing. Thus, novel therapeutic approaches with increased efficacy are urgently required, which often depends on cellular and molecular investigations using robust animal models. In the absence of perfect rodent models, those induced by excessive consumption of fat and sugars better replicate the key aspects that are the root causes of human metabolic diseases. However, the results obtained using these models cannot be directly compared, particularly because of the use of different dietary protocols, and animal species and strains, among other confounding factors. This review article revisits diet-induced models of obesity and related metabolic disorders, namely, metabolic syndrome, prediabetes, diabetes and nonalcoholic fatty liver disease. A critical analysis focused on the main pathophysiological features of rodent models, as opposed to the criteria defined for humans, is provided as a practical guide with a translational perspective for the establishment of animal models of obesity-related metabolic diseases.

Is "Leptin Resistance" Another Key Resistance to Manage Type 2 Diabetes?

Although novel pharmacological options for the treatment of type 2 diabetes mellitus (DM2) have been observed to modulate the functionality of several key organs in glucose homeostasis, successful regulation of insulin resistance (IR), body weight management, and pharmacological treatment of obesity remain notable problems in endocrinology. Leptin may be a pivotal player in this scenario, as an adipokine which centrally regulates appetite and energy balance. In obesity, excessive caloric intake promotes a low-grade inflammatory response, which leads to dysregulations in lipid storage and adipokine secretion. In turn, these entail alterations in leptin sensitivity, leptin transport across the blood-brain barrier and defects in post-receptor signaling. Furthermore, hypothalamic inflammation and endoplasmic reticulum stress may increase the expression of molecules which may disrupt leptin signaling. Abundant evidence has linked obesity and leptin resistance, which may precede or occur simultaneously to IR and DM2. Thus, leptin sensitivity may be a potential early therapeutic target that demands further preclinical and clinical research. Modulators of insulin sensitivity have been tested in animal models and small clinical trials with promising results, especially in combination with agents such as amylin and GLP-1 analogs, in particular, due to their central activity in the hypothalamus.

Maternal cinnamon intake during lactation led to visceral obesity and hepatic metabolic dysfunction in the adult male offspring

PURPOSE

Studies with foods, known to promote health benefits in addition to the nutritive value, show that their consumption by pregnant and/or lactating females could induce negative outcomes to the offspring. It is well characterized that cinnamon intake promotes benefits to energy homeostasis. The present study aimed to analyze the effects of the consumption of an aqueous extract of cinnamon by lactating female rats on the endocrine-metabolic outcomes in the adult offspring.

METHODS

Lactating dams (Wistar rats) were supplemented with cinnamon aqueous extract (400 mg/kg body weight/day) for the entire lactating period. The male adult offspring were evaluated at 180 days old (CinLac).

RESULTS

The offspring presented visceral obesity (P = 0.001), hyperleptinemia (P = 0.002), and hyperinsulinemia (P = 0.016). In the liver, CinLac exhibited reduced p-IRβ (P = 0.018) suggesting insulin resistance. However, phosphorylation of IRS1 (P = 0.041) and AKT (P = 0.050) were increased. JAK2 (P = 0.030) and p-STAT3 (P = 0.015) expressions were higher, suggesting that the activation of IRS1/AKT in the CinLac group could have resulted from the increased activation of leptin signaling. Although we observed no changes in the gluconeogenic pathway, the CinLac group exhibited lower hepatic glycogen content (P = 0.005) accompanied by increased p-GSK3β (P = 0.011). In addition, the CinLac group showed increased hepatic triacylglycerol content (P = 0.049) and a mild steatosis (P = 0.001), accompanied by reduced PPARα mRNA expression (P = 0.005).

CONCLUSION

We conclude that maternal intake of aqueous extract of cinnamon induces long-term molecular, metabolic, and hormonal changes in the adult progeny, including visceral obesity, higher lipid accumulation, and lower glycogen content in the liver.

The traditional Chinese formulae Ling-gui-zhu-gan decoction alleviated non-alcoholic fatty liver disease via inhibiting PPP1R3C mediated molecules

BACKGROUND

Ling-gui-zhu-gan decoction (LGZG), a classic traditional Chinese medicine formula, has been confirmed to be effective in improving steatosis in non-alcoholic fatty liver disease (NAFLD). However, the mechanism under the efficacy remains unclear. Hence, this study was designed to investigate the mechanisms of LGZG on alleviating steatosis.

METHODS

Twenty four rats were randomly divided into three groups: normal group, NAFLD group, fed with high fat diet (HFD) and LGZG group (fed with HFD and supplemented with LGZG). After 4 weeks intervention, blood and liver were collected. Liver steatosis was detected by Oil Red O staining, and blood lipids were biochemically determined. Whole genome genes were detected by RNA-Seq and the significant different genes were verified by RT-qPCR. The protein expression of Protein phosphatase 1 regulatory subunit 3C (PPP1R3C) and key molecules of glycogen and lipid metabolism were measured by western blot. Chromophore substrate methods measured glycogen phosphorylase (GPa) activity and glycogen content.

RESULTS

HFD can markedly induce hepatic steatosis and promote liver triglyceride (TG) and serum cholesterol (CHOL) contents, while liver TG and serum CHOL were both markedly decreased by LGZG treatment for 4 weeks. By RNA sequencing, we found that NAFLD rats showed significantly increase of PPP1R3C expression and LGZG reduced its expression. RT-qPCR and Western blot both verified the alteration of PPP1R3C upon LGZG intervention. LGZG also promoted the activity of glycogen phosphorylase liver type (PYGL) and inhibited the activity of glycogen synthase (GS) in NAFLD rats, resulting in glycogenolysis increase and glycogen synthesis decrease in the liver. By detecting glycogen content, we also found that LGZG reduced hepatic glycogen in NAFLD rats. In addition, we analyzed the key molecules in hepatic de novo lipogenesis and cholesterol synthesis, and indicated that LGZG markedly inhibited the activity of acetyl-CoA carboxylase (ACC), sterol receptor element-binding protein-1c (SREBP-1c) and 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), resulting in lipid synthesis decrease in the liver.

CONCLUSION

Our data highlighted the role of PPP1R3C targeting pathways, and found that hepatic glycogen metabolism might be the potential target of LGZG in preventing NAFLD.

Obesity, Nonalcoholic Fatty Liver Disease and Adipocytokines Network in Promotion of Cancer

Western populations are becoming increasingly sedentary and the incidence of nonalcoholic fatty liver disease (NAFLD) is increasing and becoming one of the most common causes of liver disease worldwide. Also, NAFLD is considered one the new emerging risk factors for development of tumors of the gastro-intestinal tract, particularly hepatocellular carcinoma (HCC). Visceral obesity is an important risk factor for the onset of NAFLD. An accumulation of ectopic fat, including visceral obesity and fatty liver leads to a dysfunction of the adipose tissue with impaired production of adipocytokines which, in turn, favor an increase in pro-inflammatory cytokines. In this review, we discuss how the obesity-related chronic state of low-grade inflammation and the presence of NAFLD lead to the emergence of a microenvironment favorable to the development of cancer.

Morphofunctional Changes After Sleeve Gastrectomy and Very Low Calorie Diet in an Animal Model of Non-Alcoholic Fatty Liver Disease

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease and is found in 70% of obese people. The evidence available to date suggests that bariatric surgery could be an effective treatment by reducing weight and also by improving metabolic complications in the long term. This work aimed to compare, in a diet-induced NAFLD animal model, the effect of both sleeve gastrectomy (SG) and very-low calorie diet (VLCD).

METHODS

Thirty-five Wistar rats were divided into control rats (n = 7) and obese rats fed a high-fat diet (HFD). After 10 weeks, the obese rats were subdivided into four groups: HFD (n = 7), VLCD (n = 7), and rats submitted to either a sham operation (n = 7) or SG (n = 7). Both liver tissue and blood samples were processed to evaluate steatosis and NASH changes in histology (Oil Red, Sirius Red and H&E); presence of endothelial damage (CD31, Moesin/p-Moesin, Akt/p-Akt, eNOS/p-eNOS), oxidative stress (iNOS) and fibrosis (αSMA, Col1, PDGF, VEGF) proteins in liver tissue; and inflammatory (IL6, IL10, MCP-1, IL17α, TNFα), liver biochemical function, and hormonal (leptin, ghrelin, visfatin and insulin) alterations in plasma.

RESULTS

Both VLCD and SG improved histology, but only SG induced a significant weight loss, improved endothelial damage, and a decreased cardiovascular risk by reducing insulin resistance (IR), leptin, total cholesterol, and triglyceride levels. There were no relevant variations in the inflammatory and fibrosis markers.

CONCLUSION

Our study suggests a slight superiority of SG over VLCD by improving not only the histology but also the IR and cardiovascular risk markers related to NAFLD.

Altered Feeding Behaviors and Adiposity Precede Observable Weight Gain in Young Rats Submitted to a Short-Term High-Fat Diet

Information regarding the early effects of obesogenic diets on feeding patterns and behaviors is limited. To improve knowledge regarding the etiology of obesity, young male Wistar rats were submitted to high-fat (HFD) or regular chow diets (RCDs) for 14 days. Various metabolic parameters were continuously measured using metabolic chambers. Total weight gain was similar between groups, but heavier visceral fat depots and reduced weight of livers were found in HFD rats. Total calorie intake was increased while individual feeding bouts were shorter and of higher calorie intake in response to HFD. Ambulatory activity and sleep duration were decreased in HFD rats during passive and active phase, respectively. Acylated and unacylated ghrelin levels were unaltered by the increased calorie intake and the early changes in body composition. This indicates that at this early stage, the orexigenic signal did not adapt to the high-calorie content of HFD. We hereby demonstrate that, although total weight gain is not affected, a short-term obesogenic diet alters body composition, feeding patterns, satiation, ambulatory activity profiles, and behaviours in a young rat model. Moreover, this effect precedes changes in weight gain, obesity, and ensuing metabolic disorders.

Chronic Trypanosoma cruzi infection potentiates adipose tissue macrophage polarization toward an anti-inflammatory M2 phenotype and contributes to diabetes progression in a diet-induced obesity model

Chronic obesity and Chagas disease (caused by the protozoan Trypanosoma cruzi) represent serious public health concerns. The interrelation between parasite infection, adipose tissue, immune system and metabolism in an obesogenic context, has not been entirely explored. A novel diet-induced obesity model (DIO) was developed in C57BL/6 wild type mice to examine the effect of chronic infection (DIO+I) on metabolic parameters and on obesity-related disorders. Dyslipidemia, hyperleptinemia, and cardiac/hepatic steatosis were strongly developed in DIO mice. Strikingly, although these metabolic alterations were collectively improved by infection, plasmatic apoB100 levels remain significantly increased in DIO+I, suggesting the presence of pro-atherogenic small and dense LDL particles. Moreover, acute insulin resistance followed by chronic hyperglycemia with hypoinsulinemia was found, evidencing an infection-related-diabetes progression. These lipid and glucose metabolic changes seemed to be highly dependent on TLR4 expression since TLR4-/- mice were protected from obesity and its complications. Notably, chronic infection promoted a strong increase in MCP-1 producing macrophages with a M2 (F4/80+CD11c-CD206+) phenotype associated to oxidative stress in visceral adipose tissue of DIO+I mice. Importantly, infection reduced lipid content but intensified inflammatory infiltrates in target tissues. Thus, parasite persistence in an obesogenic environment and the resulting host immunometabolic dysregulation may contribute to diabetes/atherosclerosis progression.

Hepatic lipid metabolism and non-alcoholic fatty liver disease in aging

Aging is associated with dysregulation of glucose and lipid metabolism. Various factors that contribute to the dysregulation include both modifiable (e.g. obesity, insulin resistance) and non-modifiable risk factors (age-associated physiologic changes). Although there is no linear relationship between aging and prevalence of non-alcoholic fatty liver disease, current data strongly suggests that advanced age leads to more severe histological changes and poorer clinical outcomes. Hepatic lipid accumulation could lead to significant hepatic and systemic consequences including steatohepatitis, cirrhosis, impairment of systemic glucose metabolism and metabolic syndrome, thereby contributing to age-related diseases. Insulin, leptin and adiponectin are key regulators of the various physiologic processes that regulate hepatic lipid metabolism. Recent advances have expanded our understanding in this field, highlighting the role of novel mediators such as FGF 21, and mitochondria derived peptides. In this review, we will summarize the mediators of hepatic lipid metabolism and how they are altered in aging.

A Western-style obesogenic diet alters maternal metabolic physiology with consequences for fetal nutrient acquisition in mice

KEY POINTS

In the Western world, obesogenic diets containing high fat and high sugar (HFHS) are commonly consumed during pregnancy, although their effects on the metabolism of the mother, in relation to feto-placental glucose utilization and growth, are unknown. In the present study, the consumption of an obesogenic HFHS diet compromised maternal glucose tolerance and insulin sensitivity in late pregnancy in association with dysregulated lipid and glucose handling by the dam. These maternal metabolic changes induced by HFHS feeding were related to altered feto-placental glucose metabolism and growth. A HFHS diet during pregnancy therefore causes maternal metabolic dysfunction with consequences for maternal nutrient allocation for fetal growth. These findings have implications for the health of women and their infants, who consume obesogenic diets during pregnancy.

ABSTRACT

In the Western world, obesogenic diets containing high fat and high sugar (HFHS) are commonly consumed during pregnancy. However, the impacts of a HFHS diet during pregnancy on maternal insulin sensitivity and signalling in relation to feto-placental growth and glucose utilization are unknown. The present study examined the effects of a HFHS diet during mouse pregnancy on maternal glucose tolerance and insulin resistance, as well as, on feto-placental glucose metabolism. Female mice were fed a control or HFHS diet from day (D) 1 of pregnancy (term = D20.5). At D16 or D19, dams were assessed for body composition, metabolite and hormone concentrations, tissue abundance of growth and metabolic signalling pathways, glucose tolerance and utilization and insulin sensitivity. HFHS feeding perturbed maternal insulin sensitivity in late pregnancy; hepatic insulin sensitivity was higher, whereas sensitivity of the skeletal muscle and white adipose tissue was lower in HFHS than control dams. These changes were accompanied by increased adiposity and reduced glucose production and glucose tolerance of HFHS dams. The HFHS diet also disturbed the hormone and metabolite milieu and altered expression of growth and metabolic signalling pathways in maternal tissues. Furthermore, HFHS feeding was associated with impaired feto-placental glucose metabolism and growth. A HFHS diet during pregnancy therefore causes maternal metabolic dysfunction with consequences for maternal nutrient allocation for fetal growth. These findings have implications for the health of women and their infants, who consume HFHS diets during pregnancy.

Effect of Octreotide on Hepatic Steatosis in Diet-Induced Obesity in Rats

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) caused by liver lipid dysregulation is linked to obesity. Somatostatin (SST) and its analogs have been used to treat pediatric hypothalamic obesity. However, the application of such drugs for the treatment of NAFLD has not been evaluated.

OBJECTIVE

This study aimed to investigate the expression levels of important regulators of hepatic lipid metabolism and the possible effect of the SST analog octreotide on these regulators.

METHODS

SD rats were assigned to a control group and a high-fat diet group. Obese rats from the high-fat diet group were further divided into the obese and octreotide-treated groups. The body weight, plasma SST, fasting plasma glucose (FPG), insulin, triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and free fatty acid (FFA) levels were measured. Hepatic steatosis was evaluated based on the liver TG content, HE staining and oil red O staining. The SREBP-1c, ACC1, FAS, MTP, apoB and ADRP expression levels in the liver were also determined by RT-PCR, qRT-PCR, western blot or ELISA.

RESULTS

The obese rats induced by high-fat diet expressed more SREBP-1c, FAS and ADRP but less MTP protein in the liver than those of control rats, whereas octreotide intervention reversed these changes and increased the level of apoB protein. Compared to the control group, obese rats showed increased liver ACC1, SREBP-1c and apoB mRNA levels, whereas octreotide-treated rats showed decreased mRNA levels of apoB and SREBP-1c. This was accompanied by increased body weight, liver TG contents, FPG, TG, TC, LDL-C, FFA, insulin and derived homeostatic model assessment (HOMA) values. Octreotide intervention significantly decreased these parameters. Compared to the control group, the obese group showed a decreasing trend on plasma SST levels, which were significantly increased by the octreotide intervention.

CONCLUSION

Octreotide can ameliorate hepatic steatosis in obese rats, possibly by decreasing hepatic lipogenesis and increasing TG export from hepatocytes.

Obesity-related known and candidate SNP markers can significantly change affinity of TATA-binding protein for human gene promoters

BACKGROUND

Obesity affects quality of life and life expectancy and is associated with cardiovascular disorders, cancer, diabetes, reproductive disorders in women, prostate diseases in men, and congenital anomalies in children. The use of single nucleotide polymorphism (SNP) markers of diseases and drug responses (i.e., significant differences of personal genomes of patients from the reference human genome) can help physicians to improve treatment. Clinical research can validate SNP markers via genotyping of patients and demonstration that SNP alleles are significantly more frequent in patients than in healthy people. The search for biomedical SNP markers of interest can be accelerated by computer-based analysis of hundreds of millions of SNPs in the 1000 Genomes project because of selection of the most meaningful candidate SNP markers and elimination of neutral SNPs.

RESULTS

We cross-validated the output of two computer-based methods: DNA sequence analysis using Web service SNP_TATA_Comparator and keyword search for articles on comorbidities of obesity. Near the sites binding to TATA-binding protein (TBP) in human gene promoters, we found 22 obesity-related candidate SNP markers, including rs10895068 (male breast cancer in obesity); rs35036378 (reduced risk of obesity after ovariectomy); rs201739205 (reduced risk of obesity-related cancers due to weight loss by diet/exercise in obese postmenopausal women); rs183433761 (obesity resistance during a high-fat diet); rs367732974 and rs549591993 (both: cardiovascular complications in obese patients with type 2 diabetes mellitus); rs200487063 and rs34104384 (both: obesity-caused hypertension); rs35518301, rs72661131, and rs562962093 (all: obesity); and rs397509430, rs33980857, rs34598529, rs33931746, rs33981098, rs34500389, rs63750953, rs281864525, rs35518301, and rs34166473 (all: chronic inflammation in comorbidities of obesity). Using an electrophoretic mobility shift assay under nonequilibrium conditions, we empirically validated the statistical significance (α < 0.00025) of the differences in TBP affinity values between the minor and ancestral alleles of 4 out of the 22 SNPs: rs200487063, rs201381696, rs34104384, and rs183433761. We also measured half-life (t1/2), Gibbs free energy change (ΔG), and the association and dissociation rate constants, ka and kd, of the TBP-DNA complex for these SNPs.

CONCLUSIONS

Validation of the 22 candidate SNP markers by proper clinical protocols appears to have a strong rationale and may advance postgenomic predictive preventive personalized medicine.

Effects of 17β-estradiol on cardiac Na(+)/K(+)-ATPase in high fat diet fed rats

The aim of this study was to investigate in vivo effects of estradiol on Na(+)/K(+)-ATPase activity/expression in high fat (HF) diet fed rats. Adult male Wistar rats were fed normally (Control, n = 7) or with a HF diet (Obese, n = 14) for 10 weeks. After 10 weeks, half of the obese rats were treated with estradiol (Obese + Estradiol, n = 7, 40 μg/kg, i.p.) as a bolus injection and 24 h after treatment all the rats were sacrificed. Estradiol in vivo in obese rats in comparison with obese non-treated rats led to a statistically significant increase in concentration of serum Na(+) (p < 0.05), Na(+)/K(+)-ATPase activity (p < 0.01), expression of α1 (p < 0.01) and α2 (p < 0.05) subunit of Na(+)/K(+)-ATPase, both PI3K subunits p85 (p < 0.01), p110 (p < 0.05), and association of IRS-1 with p85 (p < 0.05), while significantly decrease expression of AT1 (p < 0.05) and Rho A (p < 0.01) proteins. Our results suggest that estradiol in vivo in pathophysiological conditions, such as obesity accompanied with insulin resistance stimulates activity and expression of Na(+)/K(+)-ATPase by a mechanism that involves the participation of IRS-1/PI3K/Akt signaling. In addition, the decreasing level of AT1 and Rho A proteins estradiol probably attenuates the detrimental effect of obesity to decreased IRS-1/PI3K association and consequently reduce Na(+)/K(+)-ATPase activity/expression.

Impairment of insulin receptor substrate 1 signaling by insulin resistance inhibits neurite outgrowth and aggravates neuronal cell death

In the central nervous system (CNS), insulin resistance (I/R) can cause defective neurite outgrowth and neuronal cell death, which can eventually lead to cognitive deficits. Recent research has focused on the relationship between I/R and the cognitive impairment caused by dementia, with the goal of developing treatments for dementia. Insulin signal transduction mediated by insulin receptor substrate (IRS-1) has been thoroughly studied in the CNS of patients with I/R. In the present study, we investigated whether the impairment of IRS-1-mediated insulin signaling contributes to neurite outgrowth and neuronal loss, both in mice fed a high-fat diet and in mouse neuroblastoma (Neuro2A) cells. To investigate the changes caused by the inhibition of IRS-1-mediated insulin signaling in the brain, we performed Cresyl Violet staining and immunochemical analysis. To investigate the changes caused by the inhibition of IRS-1-mediated insulin signaling in neuroblastoma cells, we performed Western blot analysis, reverse transcription-PCR, and immunochemical analysis. We show that the deactivation of IRS-1-mediated insulin signaling can inhibit neuronal outgrowth and aggravate neuronal cell death in the insulin-resistant CNS. Thus, IRS-1-mediated insulin signal transduction may be an important factor in the treatment of cognitive decline induced by I/R.

Liver delipidating effect of a combination of resveratrol and quercetin in rats fed an obesogenic diet

Liver steatosis is characterized by an abnormal accumulation of triacylglycerols in this organ. This metabolic disorder is closely associated with obesity. In the present study, we aimed to analyse the effect of a combination of resveratrol and quercetin on liver steatosis in an animal model of dietetic obesity, and to compare it with one induced by the administration of each polyphenol separately. Rats were divided into four dietary groups of nine animals each and fed a high-fat, high-sucrose diet: an untreated control group and three groups treated either with resveratrol (RSV; 15 mg/kg/day), with quercetin (Q; 30 mg/kg/day), or with both (RSV + Q; 15 mg resveratrol/kg/day and 30 mg quercetin/kg/day) for 6 weeks. Liver weight and triacylglycerol content decreased only in the RSV + Q group. A significant reduction in acetyl-CoA carboxylase activity was observed in RSV and RSV + Q groups, without changes in fatty acid synthase activity. A significant increase in carnitine palmitoyltransferase-1a activity was observed only in rats treated with the combination of resveratrol and quercetin, suggesting increased fatty acid oxidation. Citrate synthase, a marker of mitochondrial density, remained unchanged in all groups. No significant changes were observed in the expression of peroxisome proliferator-activated receptor α (PPARα), nuclear respiratory factor 1 (NRF-1) and transcription factor A mitochondrial (TFAM). In conclusion, resveratrol and quercetin together, combining two doses which were shown to be ineffective singly, is an interesting tool to prevent liver steatosis associated with high-fat high-sucrose feeding. The delipidating effect seems to be mediated by increased fatty acid oxidation not associated with increased mitochondriogenesis, and by reduced de novo lipogenesis.