Histopathological changes in rat pancreas and skeletal muscle associated with high fat diet induced insulin resistance

Reduced Branched-Chain Amino Acid Intake Improved High-Fat Diet-Induced Nonalcoholic Fatty Pancreas Disease in Mice

OBJECTIVE

To explore the effects of branched-chain amino acids (BCAAs) on nonalcoholic fatty pancreas disease (NAFPD) and its possible mechanism in high-fat diet (HFD) induced mice.

MATERIALS AND METHODS

Pancreatic morphology and lipid infiltration was assessed by hematoxylin-eosin staining and immunohistochemistry, and lipid levels in the pancreas were determined using colorimetric enzymatic method. Relevant mechanism was investigated using western blotting and biochemical test.

RESULTS

In HFD-fed mice, dietary BCAAs restriction could attenuate body weight increase, improve glucose metabolism, and reduce excessive lipid accumulation in the pancreas. Furthermore, expression of AMPKα and downstream uncoupling protein 1 were upregulated, while genes related to mammalian target of rapamycin complex 1 (mTORC1) signal pathway and lipid de novo synthesis were suppressed in HFD-BCAA restriction group compared with HFD and HFD-high BCAAs fed mice. In addition, BCAA restriction upregulated expression of BCAAs related metabolic enzymes including PPM1K and BCKDHA, and decreased the levels of BCAAs and branched chain keto acid in the pancreas. However, there was no difference in levels of lipid content in the pancreas and gene expression of AMPKα and mTORC1 between HFD and HFD-high BCAAs groups.

CONCLUSIONS

Branched-chain amino acid restriction ameliorated HFD-induced NAFPD in mice by activation of AMPKα pathway and suppression of mTORC1 pathway.

Intrapancreatic fat deposition and nutritional treatment: the role of various dietary approaches

Ectopic fat accumulation in various organs and tissues, such as the liver, muscle, kidney, heart, and pancreas, is related to impaired capacity of adipose tissue to accumulate triglycerides, as a consequence of overnutrition and an unhealthy lifestyle. Ectopic fat promotes organ dysfunction and is a key factor in the development and progression of cardiometabolic diseases. Interest in intrapancreatic fat deposition (IPFD) has developed in the last few years, particularly in relation to improvement in methodological techniques for detection of fat in the pancreas, and to growing evidence for the role that IPFD might have in glucose metabolism disorders and cardiometabolic disease. Body weight reduction represents the main option for reducing fat, and the evidence consistently shows that hypocaloric diets are effective in reducing IPFD. Changes in diet composition, independently of changes in energy intake, might offer a more feasible and safe alternative treatment to energy restriction. This current narrative review focused particularly on the possible beneficial role of the diet and its nutrient content, in hypocaloric and isocaloric conditions, in reducing IPFD in individuals with high cardiometabolic risk, highlighting the possible effects of differences in calorie quantity and calorie quality. This review also describes plausible mechanisms by which the various dietary approaches could modulate IPFD.

Pancreatic GLUT2 protein expression and isolated islets insulin secretion decreased in high-fat fed rat dams

Purpose

Chronic consumption of high-fat foods during the reproductive period may endanger the dams' metabolic homeostasis and might adversely affect pregnancy outcome. In this regard the present study aimed to investigate the effect of long-term high-fat feeding on pancreatic glucose transporter-2 (GLUT2) protein expression and isolated islets glucose-stimulated insulin secretion in Wistar rat dams.

Materials and methods

Female rats were randomly divided into normal (N) and high-fat (HF; containing cow butter) diet groups and consumed their respective diets for 10 weeks (from prepregnancy to the end of lactation). After lactation, fasting plasma concentrations of glucose and insulin were measured to calculate HOMA-IR index, then intraperitoneal glucose tolerance test (IPGTT) was performed. Moreover, the pancreatic GLUT2 protein expression and insulin secretion from isolated islets at basal (5.6 mM) and stimulated (16.7 mM) glucose concentrations were assessed.

Results

In HF group compared to N group, the plasma insulin level increased, whereas the plasma glucose level did not change in fasting state. Accordingly, the HOMA-IR index increased in HF fed animals. Furthermore, the IPGTT revealed glucose intolerance based on the plasma glucose and insulin results. Also, the pancreatic GLUT2 expression and isolated islets insulin secretion, in response to high glucose concentration, were decreased.

Conclusion

The chronic consumption of high-fat foods during prepregnancy, pregnancy, and lactation periods can lead to glucose intolerance, insulin resistance, and inhibition of pancreatic GLUT2 expression, which impairs glucose homeostasis. Therefore, it is crucial to carefully monitor the diet composition of dams during this critical period.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-023-01274-6.

Pancreatic steatosis and metabolic pancreatic disease: a new entity?

Overweight and obesity are some of the most important health challenges. Many diseases are related to these metabolic disorders, and, among them, the pancreatic fat accumulation, also called "pancreatic steatosis" or "nonalcoholic fatty pancreas", seems to have an emerging role in different conditions. There are different method to evaluate the fat content in the pancreas, such as histology, different imaging techniques and endoscopic ultrasound, but there is no gold standard for the correct diagnosis and for the identification of "inter/intralobular" and "intra-acinar" pancreatic fat. However, the fat storage in the pancreas is linked to chronic inflammation and to several conditions, such as acute and chronic pancreatitis, type 2 diabetes mellitus and pancreatic cancer. In addition, pancreatic fat accumulation has also been demonstrated to play a role in surgical outcome after pancreatectomy, in particular for the development of postoperative pancreatic fistula. Different possible therapeutic approaches have been proposed, but there is still a lack of evidence. The aim of this review is to report the current evidence about the relationship between the obesity, the pancreatic fat accumulation and its potential role in pancreatic diseases.

Fatty infiltration of the pancreas: a systematic concept analysis

Fatty infiltration of the pancreas (FIP) has been recognized for nearly a century, yet many aspects of this condition remain unclear. Regular literature reviews on the diagnosis, consequences, and management of FIP are crucial. This review article highlights the various disorders for which FIP has been established as a risk factor, including type 2 diabetes mellitus (T2DM), pancreatitis, pancreatic fistula (PF), metabolic syndrome (MS), polycystic ovary syndrome (PCOS), and pancreatic duct adenocarcinoma (PDAC), as well as the new investigation tools. Given the interdisciplinary nature of FIP research, a broad range of healthcare specialists are involved. This review article covers key aspects of FIP, including nomenclature and definition of pancreatic fat infiltration, history and epidemiology, etiology and pathophysiology, clinical presentation and diagnosis, clinical consequences, and treatment. This review is presented in a detailed narrative format for accessibility to clinicians and medical students.

Anti-Diabetic and Anti-Adipogenic Effect of Harmine in High-Fat-Diet-Induced Diabetes in Mice

One of the most important health issues facing the world today is obesity. It is an important independent risk factor for developing type 2 diabetes. Harmine offers various pharmacological effects, such as anti-inflammatory and anti-tumor effects. The current study aims to investigate Harmine's anti-diabetic and anti-adipogenic properties in albino mice after inducing low-grade inflammation with a high-fat diet (HFD). About forty-eight male albino mice were divided into four groups. Group 1: control mice were injected with daily saline and fed a normal chow diet of 21% protein for 5 months. Group 2: mice were treated daily with IP-injected Harmine (30 mg/kg body weight) and were fed a normal chow diet for 5 months. Group 3: mice were fed HFD to induce type 2 Diabetes Mellitus (T2DM) for 5 months. Group 4: mice were fed HFD for 14 weeks and treated with Harmine for the last 6 weeks. A figh-fat diet caused a significant increase in body and organ weight, lipid profiles, and destructive changes within the pancreas, kidney, and liver tissue. The administration of Harmine led to a remarkable improvement in the histological and ultrastructural changes induced by HFD. The findings indicate that mice cured using Harmine had lower oxidative stress, a higher total antioxidant capacity, and a reduced lipid profile compared to HFD mice. Harmine led to the hepatocytes partly restoring their ordinary configuration. Furthermore, it was noticed that the pathological incidence of damage in the structure of both the kidney and pancreas sections reduced in comparison with the diabetic group. Additional research will be required to fully understand Harmine and its preventive effects on the two forms of diabetes.

Exercise improves testicular morphology and oxidative stress parameters in rats with testicular damage induced by a high-fat diet

Obesity and male infertility are problems that affect population. Exercise is a nonpharmacological way to reduce the negative health effects of obesity. The purpose of this study was to examine the effects of exercise on hormone levels, blood-testis barrier, and inflammatory and oxidative biomarkers in rats that became obese due to a high-fat diet (HFD). Male rats received a standard diet (STD group) or a HFD (HFD group) for 18 weeks. During the final 6 weeks of the experiment, swimming exercises (1 h/5 days/week) were given to half of these animals (STD + EXC and HFD + EXC groups). Finally, blood and testicular tissues were analysed by biochemical and histological methods. Body weight, leptin, malondialdehyde, interleukin-6, TNF-alpha and myeloperoxidase levels, apoptotic cells and DNA fragmentation were increased, and testis weight, insulin, FSH, LH, testosterone, glutathione and superoxide dysmutase levels, proliferative cells, ZO-1, occludin, and gap junction protein Cx43 immunoreactivity were decreased in the HFD group. All these hormonal, morphological, oxidative and inflammatory biomarkers were enhanced in the HFD + EXC group. It is thought that exercise protected testicular cytotoxicity by regulating hormonal and oxidant/antioxidant balances and testicular function, inhibiting inflammation and apoptosis, as well as preserving blood-testis barrier.

Amelioration of the Abnormalities Associated with Metabolic Syndrome by L-Norvaline in Hyperlipidemic Diabetic Rats

The present study was designed to assess the treatment effect of arginase inhibitor, L-Norvaline in abnormalities associated with high fat diet (HFD) and fructose-induced metabolic syndrome. The HFD and fructose was fed to the rats for a period of 45 days. Animals having body weight of 350 g and fasting blood sugar level of more than 250 mg/dl were considered as hyperlipidemic diabetic rats (HDR) and selected for the study. The HDR were divided into three groups having six animals each. The HDR received L–Norvaline (10 mg/kg/day, i.p.) and standard drug, gemfibrozil (60 mg/kg/day, p.o.), for a period of 30 days. Various hormonal, biochemical and tissue parameters were evaluated at the end of the study. Both treatments significantly decreased body weight, BMI, fasting blood sugar and insulin level and improved insulin resistance in HDR as compared to the toxicant control group. A significant improvement was observed in the lipid profile, levels of nitrate, leptin, C-reactive protein and adiponectin in HDR. L-Norvaline also caused slight decrease in the malondialdehyde level, though, no prominent effect was observed on the level of superoxide dismutase and reduced glutathione in the pancreas of HDR, as compared to the toxicant control group. L-Norvaline treatment also improved the histo-architecture of pancreatic cells. Results of the present study concludes that L-Norvaline caused significant alleviation of the abnormalities of MetS indicating that it can be used as potential treatment strategy for managing the symptoms of metabolic syndrome.

Synbiotic goat milk kefir improves health status in rats fed a high-fat and high-fructose diet

Background and Aim:

Kefir, a natural probiotic containing bacteria and yeast, is a fermented milk product, whereas glucomannan from porang tuber (Amorphophallus oncophyllus) is prebiotic in vivo. Simvastatin is a potent lipid-lowering statin that can be utilized for pharmacological therapy in obesity. This study aimed to determine the effect of goat milk kefir supplemented with porang glucomannan (synbiotic kefir) and goat milk kefir without glucomannan (probiotic kefir) on blood glucose, hemoglobin A1c (HbA1c), free fatty acids (FFAs), tumor necrosis factor-alpha (TNF-α), gene expression of peroxisome proliferator-activated receptor gamma (PPARg), and insulin-producing cells in rats fed a high-fat and high-fructose (HFHF) diet.

Materials and Methods:

Male Sprague-Dawley rats were divided into five dietary groups: (1) Normal control, (2) rats fed HFHF, (3) rats fed HFHF+probiotic kefir, (4) rats fed HFHF+synbiotic kefir, and (5) rats fed HFHF+simvastatin. All of these treatments were administered for 4 weeks.

Results:

There were no significant differences in plasma glucose levels in HFHF diet-fed rats before and after treatment. However, plasma HbA1c and TNF-α decreased, and FFAs were inhibited in rats after treatment with synbiotic kefir. Synbiotic kefir decreased the gene expression of PPARγ2 in HFHF diet-fed rats but did not affect the total number of islets of Langerhans and insulin-producing cells.

Conclusion:

Synbiotic kefir improved the health of rats fed an HFHF diet by decreasing HbA1c, TNF-α, and PPARγ2 gene expression and preventing an increase in FFAs.

Nonalcoholic Fatty Pancreas Disease: Role in Metabolic Syndrome, "Prediabetes," Diabetes and Atherosclerosis

Fat accumulation in the pancreas associated with obesity and the metabolic syndrome (MetS) has been defined as "non-alcoholic fatty pancreas disease" (NAFPD). The aim of this review is to describe the association of NAFPD with obesity, MetS, type 2 diabetes mellitus (T2DM) and atherosclerosis and also increase awareness regarding NAFPD. Various methods are used for the detection and quantification of pancreatic fat accumulation that may play a significant role in the differences that have been observed in the prevalence of NAFPD. Endoscopic ultrasound provides detailed images of the pancreas and its use is expected to increase in the future. Obesity and MetS have been recognized as NAFPD risk factors. NAFPD is strongly associated with non-alcoholic fatty liver disease (NAFLD) and it seems that the presence of both may be related with aggravation of NAFLD. A role of NAFPD in the development of "prediabetes" and T2DM has also been suggested by most human studies. Accumulation of fat in pancreatic tissue possibly initiates a vicious cycle of beta-cell deterioration and further pancreatic fat accumulation. Additionally, some evidence indicates a correlation between NAFPD and atherosclerotic markers (e.g., carotid intima-media thickness). Weight loss and bariatric surgery decreases pancreatic triglyceride content but pharmacologic treatments for NAFPD have not been evaluated in specifically designed studies. Hence, NAFPD is a marker of local fat accumulation possibly associated with beta-cell function impairment, carbohydrate metabolism disorders and atherosclerosis.

Subcutaneous Adipose Tissue Browning, Serum Orexin-A, and Insulin Resistance Following Aerobic Exercise in High-Fat Diet Obesity Male Wistar Rats

Background

Subcutaneous adipose tissue (SAT) relative to the other adipose tissues may have different roles in health and insulin resistance. The purpose of this study was to investigate the effectiveness of aerobic exercise on SAT thermogenesis indices, serum orexin-A (OXA), and insulin resistance in high-fat diet-induced obesity male Wistar rats.

Methods

Thirty-two male Wistar rats with an average weight of 180-200 g were randomly assigned into 4 equal groups: normal fat diet (NFD), high-fat diet obesity (HFDO), normal fat diet after high-fat diet obesity (HFDO-NFD), and aerobic exercise group with normal fat diet after high-fat diet obesity (HFDO-AEX). Fasting levels of serum OXA, insulin, FBS, high-density lipoproteins, low-density lipoproteins, cholesterol and gene expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and UCP1 in SAT were evaluated. Samples were taken in the HFDO group after obesity-induced and in other groups 48 h after 8 weeks of aerobic exercise.

Results

The results showed that HFD significantly decreased serum levels of OXA, HDL-c and gene expression of PGC1α and UCP1 in SAT. In addition, it caused a significant increase in Lee index, FBS, insulin resistance, and serum lipid profile in comparison with the NFD group (P ≤ 0.001). Aerobic exercise significantly modified the changes caused by HFD to the normal levels (P ≤ 0.001).

Conclusions

These data suggest that aerobic exercise caused an improvement in insulin resistance and blood lipid profiles through an increase in the serum level of OXA and alteration in the SAT phenotype from white to brown or beige.

Dapagliflozin ameliorates pancreatic injury and activates kidney autophagy by modulating the AMPK/mTOR signaling pathway in obese rats

Chronic consumption of a high-fat diet induces obesity and impairs the ultra-structure of organs and tissues. We examined the effect of sodium-glucose cotransporter 2 (SGLT2) inhibitor-dapagliflozin on renal and pancreatic injuries in obese condition. Rats were fed a high-fat diet for 16 weeks to induce obesity. After that, dapagliflozin or vildagliptin, 1.0 or 3.0 mg/kg/day, respectively, was administered by oral gavage for 4 weeks. The effects of dapagliflozin on insulin resistance, kidney autophagy, pancreatic oxidative stress, endoplasmic reticulum (ER) stress, inflammation, and apoptosis in high-fat diet-induced obese rats were elucidated. High-fat-diet fed rats demonstrated metabolic abnormalities including increased body weight, visceral fat weight, plasma insulin, plasma cholesterol, homeostasis model assessment (HOMA) index, and TAUCg, indicating the obese-insulin resistant and glucose intolerance conditions. Also, high-fat-diet fed rats exhibited significant pancreatic injury accompanied by decreased kidney autophagy. Dapagliflozin or vildagliptin treatment for 4 weeks ameliorated pancreatic oxidative stress, ER stress, inflammation, and apoptosis and restored kidney autophagy in obese rats. Moreover, the morphology changes of the pancreas and kidney were improved in the treated groups. Interestingly, dapagliflozin showed higher efficacy than vildagliptin in improving body weight, visceral fat weight, plasma cholesterol level, and pancreatic oxidative stress in our model. Taken together, the present study demonstrated that the therapeutic effects of dapagliflozin attenuated pancreatic injury, pancreatic oxidative stress, ER stress, inflammation, apoptosis, and exerted renoprotective effects by restoring autophagic signaling in obese rats.

Intra-pancreatic fat deposition as a modifier of the relationship between habitual dietary fat intake and insulin resistance

BACKGROUND

Insulin resistance is a well-known derangement after an attack of pancreatitis but the role of dietary fat intake and intra-pancreatic fat deposition (IPFD) in it is unknown. We aimed to investigate the relationship of dietary fat intake with markers of insulin resistance in individuals after acute pancreatitis, taking into account IPFD.

METHODS

This was a cross-sectional study. The EPIC-Norfolk food frequency questionnaire was used to determine the habitual intake of saturated, monounsaturated, polyunsaturated fatty acids. The studied markers of insulin resistance were fasting insulin, HOMA-IR, and METS-IR. 3 T magnetic resonance imaging was used to quantify IPFD. Linear regression analysis, with adjustment for possible confounders, was performed.

RESULTS

A total of 111 individuals after acute pancreatitis (33 low IPFD, 40 moderate IPFD, and 38 high IPFD) were included. In the high IPFD group, intake of monounsaturated fatty acids was inversely associated with both fasting insulin, and HOMA-IR, and METS-IR in the unadjusted (β = -65.405, p < 0.001; β = -15.762, p < 0.001; β = -0.760, p = 0.041, respectively) and fully adjusted models (β = -155.620, p < 0.001; β = -34.656, p < 0.001, β = -2.008, p = 0.018, respectively). Intake of polyunsaturated or saturated fatty acids did not have a consistently significant pattern of associations with the three markers of insulin resistance. None of the above associations was significant in the low IPFD and moderate IPFD groups.

CONCLUSIONS

Habitual dietary fat intake is associated with insulin resistance only in individuals after an attack of pancreatitis who have high IPFD. These indviduals may benefit from a calorically balanced diet that is rich in monounsaturated fatty acids.

High-fat diet-induced splenic, hepatic, and skeletal muscle architecture damage: cellular and molecular players

The trend of consuming food high in calories, fat, and sugar with little nutritional value and reduced physical exercise has resulted in an alarming ratio of overweight and obese subjects worldwide. Low-grade chronic inflammation is the key feature of obesity that causes an increase in pro-inflammatory cytokines and decrease in anti-inflammatory cytokines in circulation. The current study was aimed to investigate the effect of high-fat diet on the architecture of spleen, liver, and skeletal muscle and changes in the expression of hepatic cytokines. Two groups of experimental rats were established, against control that were given different percentage of fats in their diet. After a period of sixteen weeks, rats were dissected and their organs were excised out and processed accordingly. Spleen sections of experimental groups, revealed increased recruitment of lymphocytes, sinusoidal dilatations, necrotic lymphocytes, increased ratio of white-to-red pulp, and hemosiderin and iron deposits in red pulp indicating immune system activation. Hepatic sections showed enlarged sinusoidal spaces, disruptive hepatocytes, necrosis and dilation of portal veins. Sections of skeletal muscle showed degenerating fibers, increased fat accumulation, and recruitment of macrophages. Elevated expression of IFN-γ and decreased expression of IFN-α and IFN-β cytokines verified the adverse effect of high-fat diet on immune system as well. Fats tend to accumulate in organs due to increased intake of fat-rich diet disturbing their normal function and histology. In addition, gene expression analysis of cytokines confirmed the effect of high-fat diet as an inflammatory agent.

Lisofylline mitigates cardiac inflammation in a mouse model of obesity through improving insulin secretion and activating cardiac AMPK signaling pathway

Obesity has emerged as a leading cause of death in the last few decades, mainly due to associated cardiovascular diseases. Obesity, inflammation, and insulin resistance are strongly interlinked. Lisofylline (LSF), an anti-inflammatory agent, demonstrated protection against type 1 diabetes, as well as reduced obesity-induced insulin resistance and adipose tissue inflammation. However, its role in mitigating cardiac inflammation associated with obesity is not well studied. Mice were divided into 4 groups; the first group was fed regular chow diet, the second was fed regular chow diet and treated with LSF, the third was fed high fat diet (HFD), and the fourth was fed HFD and treated with LSF. Cardiac inflammation was interrogated via expression levels of TNF α, interleukins 6 and 10, phosphorylated STAT4 and lipoxygenases 12 and 12/15. Apoptosis and expression of the survival gene, AMPK, were also evaluated. We observed that LSF alleviated obesity-induced cardiac injury indirectly by improving both pancreatic β-cell function and insulin sensitivity, as well as, directly via upregulation of cardiac AMPK expression and downregulation of cardiac inflammation and apoptosis. LSF may represent an effective therapy targeting obesity-induced metabolic and cardiovascular complications.

Semi-modified okara whey diet increased insulin secretion in diabetic rats fed a basal or high fat diet

Lifestyle and diet preferences are primarily responsible for developing type 2 diabetes. In this study, okara was manufactured into okara whey crackers (OWC) to investigate its dietary role in controlling diabetes in streptozotocin-diabetic rats with and without a high-fat diet. Forty-eight rats were divided into eight groups. G1-G4 were nondiabetic and fed a basal diet, a basal diet with 30% crackers, high fat diet, and a high-fat diet with 30% crackers, respectively. G5-G8 were diabetic groups that received similar diets as previous groups. Blood glucose, liver function, lipid pattern, pancreas and liver histopathology, and insulin immunohistochemistry were performed. OWC improved measured parameters and histopathology of the liver and pancreas in diabetic rats. The area % of positive insulin cells was increased in G6 (5.20%) and G8 rats (2.83%) fed OWC compared to diabetic rats (1.17%). In conclusion, the use of 30% OWC in a semi-modified diet has controlled the hyperglycemia and hyperlipidemia associated with diabetes.

The Relationship between Abdominal Fat Phenotypes and Insulin Resistance in Non-Obese Individuals after Acute Pancreatitis

Both type 2 prediabetes/diabetes (T2DM) and new-onset prediabetes/diabetes after acute pancreatitis (NODAP) are characterized by impaired tissue sensitivity to insulin action. Although the outcomes of NODAP and T2DM are different, it is unknown whether drivers of insulin resistance are different in the two types of diabetes. This study aimed to investigate the associations between abdominal fat phenotypes and indices of insulin sensitivity in non-obese individuals with NODAP, T2DM, and healthy controls. Indices of insulin sensitivity (homeostasis model assessment of insulin sensitivity (HOMA-IS), Raynaud index, triglyceride and glucose (TyG) index, Matsuda index) were calculated in fasting and postprandial states. Fat phenotypes (intra-pancreatic fat, intra-hepatic fat, skeletal muscle fat, visceral fat, and subcutaneous fat) were determined using magnetic resonance imaging and spectroscopy. Linear regression and relative importance analyses were conducted. Age, sex, and glycated hemoglobin A1c were adjusted for. A total of 78 non-obese individuals (26 NODAP, 20 T2DM, and 32 healthy controls) were included. Intra-pancreatic fat was significantly associated with all the indices of insulin sensitivity in the NODAP group, consistently in both the unadjusted and adjusted models. Intra-pancreatic fat was not significantly associated with any index of insulin sensitivity in the T2DM and healthy controls groups. The variance in HOMA-IS was explained the most by intra-pancreatic fat (R² = 29%) in the NODAP group and by visceral fat (R² = 21%) in the T2DM group. The variance in the Raynaud index was explained the most by intra-pancreatic fat (R² = 18%) in the NODAP group and by visceral fat (R² = 15%) in the T2DM group. The variance in the TyG index was explained the most by visceral fat in both the NODAP group (R² = 49%) and in the T2DM group (R² = 25%). The variance in the Matsuda index was explained the most by intra-pancreatic fat (R² = 48%) in the NODAP group and by visceral fat (R² = 38%) in the T2DM group. The differing association between intra-pancreatic fat and insulin resistance can be used to differentiate NODAP from T2DM. Insulin resistance in NODAP appears to be predominantly driven by increased intra-pancreatic fat deposition.

The nutraceutical potential of Lepidium sativum L. seed flavonoid-rich extract in managing metabolic syndrome components

The present study aimed to investigate the phytochemical and pharmacological identities of a Lepidium sativum L. (LS) flavonoid-rich extract and its beneficial effects on metabolic, hormonal, and histological status. Chemical screening, as well as high-performance liquid chromatography with diode-array detection (HPLC-DAD) identified high concentrations of the main flavonoid compounds in LS crude extract such as flavonols (quercetin, kaempferol), flavones (luteolin, apigenin), and especially flavanones (naringin, naringenin). Examinations of the biochemical and histopathological aspects showed the curative effects carried by LS flavonoid-rich extracts on high-fat diet-fed Wistar rats. In this study, we propose that these molecules probably exerted the bioactivity observed in the treated group through improving insulin sensitivity, dyslipidemia, inflammation, and pancreas β cell integrity. PRACTICAL APPLICATIONS: The LS seed is widely used in traditional medicine to treat hyperglycemia and inflammation. During the traditional mixture preparation, the thermal procedures could impair the bioactions of the most interesting group of LS phytoconstituants, flavonoids. In the present study, we propose an appropriate procedure to preserve those phytochemicals and suggest them as a substitute for the management of metabolic diseases. The dried LS extract showed an incredible set of effective flavonoids, which revealed hypoglycemic, hypolipidemic, anti-inflammatory, cytoprotective, and antidiabetic activities. Thus, LS flavonoids constitute a remarkable product to consider in pharmaceutical industry targeting diabetes and heart diseases. Due to their enormous antioxidant potential, the LS flavonoids could be also used in food engineering and cosmetic preparations. Their practical applications is however often limited by low solubility and stability in lipophilic media. Therefore, a modification of the flavonoid structure is possibly required.

Long-term treatment with nicotinamide induces glucose intolerance and skeletal muscle lipotoxicity in normal chow-fed mice: compared to diet-induced obesity

Nicotinamide (NAM), or vitamin B3, is an essential coenzyme for ATP synthesis and an inhibitor of sirtuin 1. Recently, conflicting results were reported regarding the treatment of NAM in type 2 diabetes and obesity. The aim of this study was to determine whether and how long-term treatment with NAM at lower dose would affect insulin sensitivity in mice fed chow diet. We treated mice with NAM (100 mg/kg/day) and normal chow for 8 weeks. Strikingly, NAM induced glucose intolerance and skeletal muscle lipid accumulation in nonobese mice. NAM impaired mitochondrial respiration capacity and energy production in skeletal muscle, in combination with increased expression of the mediators for mitophagy (p62, PINK1, PARK2 and NIX) and autophagy (FOXO3, Bnip3, CTSL, Beclin1 and LC-3b). Next, we treated mice with high-fat diet (HFD) and resveratrol (RSV; 100 mg/kg/day) for 8 weeks. RSV protected against HFD-induced insulin resistance and obesity. HFD increased skeletal muscle lipid content as well as NAM, but this increase was attenuated by RSV. In contrast to NAM, HFD enhanced fatty acid oxidative capacity. Muscle transcript levels of genes for mitophagy and autophagy were largely suppressed by HFD, whereas RSV did not rescue these effects. These differences suggest that skeletal muscle autophagy may represent adaptive response to NAM-induced lipotoxicity, whereas reduced autophagy in skeletal muscle may promote HFD-induced lipotoxicity. Our results demonstrate that chronic NAM supplementation in healthy individuals, although at lower dose than previously reported, is still detrimental to glucose homeostasis and skeletal muscle lipid metabolism.