Long-term high-fat high-fructose diet induces type 2 diabetes in rats through oxidative stress
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ABSTRACT: Long-term consumption of a western diet is a major cause of type 2 diabetes mellitus (T2DM). However, the effects of diet on pancreatic structure and function remain unclear. Rats fed a high-fat, high-fructose (HFHF) diet were compared with rats fed a normal diet for 3 and 18 months. Plasma biochemical parameters and inflammatory factors were used to reflect metabolic profile and in-flammatory status. The rats developed metabolic disorders, and the size of the islets in the pancreas increased after three months of HFHF treatment but decreased and became irregular after 18 months. Fasting insulin, C-peptide, proinsulin, and intact proinsulin levels were significantly higher in the HFHF group than those in the age-matched controls. Plasma oxidative parameters and nucleic acid oxidation markers (8-oxo-Gsn and 8-oxo-dGsn) elevated before inflammatory factors, suggesting that the HFHF diet increased the degree of oxidative stress before affecting in-flammation. Single-cell RNA sequencing also verified that the transcriptional level of oxidoreduc-tase changed differently in islet sub-populations with aging and long-term HFHF diet. We demonstrated that long-term HFHF diet and aging-associated structural and transcriptomic changes that underlie pancreatic islet functional decay is a possible underlying mechanism of T2DM, and our study could provide new insights to prevent the development of diet-induced T2DM
Project description:Intake of high-protein (HP) diets has increased over the last years, mainly due to their popularity for body weight control. Liver is the main organ handling ingested macronutrients and it is associated with the beginning of different pathologies. We aimed to deepen our knowledge on molecular pathways affected by long-term intake of an HP diet. We performed a transcriptome analysis on liver of rats chronically fed with a casein-rich HP diet and analyzed molecular parameters related to liver injury. Chronic increase in the dietary protein/carbohydrate ratio up-regulated processes related with amino acid uptake/metabolism and lipid synthesis, promoting a molecular environment indicative of hepatic triacylglycerol (TG) deposition. Moreover, changes in expression of genes involved in acidâbase maintenance and oxidative stress indicate alterations in the pH balance due to the high acid load of the diet, which has been linked to liver/health damage. Up-regulation of immune-related genes was also observed. In concordance with changes at gene expression level, we observed increased liver TG content and increased serum markers of hepatic injury/inflammation (aspartate transaminase, C-reactive protein and TNF-alpha). Moreover, the HP diet strongly increased hepatic mRNA and protein levels of HSP90, a marker of liver injury. Thus, we show for the first time that long-term consumption of an HP diet, resulting in a high acid load, results in a hepatic transcriptome signature reflecting increased TG deposition and increased signs of health risk (increased inflammation, alterations in the acidâbase equilibrium and oxidative stress). Persistence of this altered metabolic status could have unhealthy consequences. Wistar wildtype male rats, aged 8 weeks, received a low fat diet, high protein or high fat diet for 4 months. After sacrification, livers were dissected, and immediately snap frozen in liquid nitrogen. Total RNA was isolated, quantified and qualified, and subsequently used for global gene expression profiling using Agilent 4x44K microarrays.
Project description:Skeletal muscle mitochondrial dysfunction is secondary to T2DM and can be improved by long-term regular exercise training Mitochondrial dysfunction has long been implicated to play a causative role in development of type 2 diabetes (T2DM). However, a growing number of recent studies provide data that mitochondrial dysfunction is a consequence of T2DM development. The aim of our study is to clarify in further detail the causal role of mitochondrial dysfunction in T2DM by a comprehensive ex vivo analysis of mitochondrial function combined with global gene expression analysis in muscle of pre-diabetic newly diagnosed untreated T2DM subjects and long-standing insulin treated T2DM subjects compared with age- and BMI-matched controls. In addition, we assessed the impact of long-term interval exercise training on physical activity performance, mitochondrial function and glycemic control in long-standing insulin-treated T2DM subjects. Ex vivo mitochondrial density, quality and functioning was comparable between pre-diabetic subjects and matched controls, however, gene expression analysis showed a switch from carbohydrate toward lipids as energy source in pre-diabetes subjects. In contrast, long-term insulin treated T2DM subjects had slightly decreased mitochondrial density and ex vivo function. Expression of Krebs cycle and OXPHOS related genes were decreased, indicating a decreased capacity to use lipids as an energy source. The insulin-treated T2DM subjects had a lower physical activity level than pre-diabetic and normoglycemic subjects. A 52 weeks exercise training of these subjects increased submaximal oxidative efficiency, increased in vivo PCr recovery rate, as well as mildly increased in vitro mitochondrial function. Gene expression of β-oxidation, Krebs cycle and OXPHOS-related genes was increased. Our data demonstrate that mitochondrial dysfunction is rather a consequence than a causative factor in T2DM development as it was only detected in overt diabetes and not in early diabetes. Regular exercise training stabilized exogenous insulin requirement and improved mitochondrial functioning, fatty acid oxidation and general physical work load capacity in long-standing insulin-treated T2DM subjects. As such, the present study shows for the first time that long-term exercise interventions are beneficial in this group of complex diabetes patient and may prevent further metabolic deterioration. Insulin-treated T2DM subjects before and after 52 weeks of exercise training (T2DM_0 and T2DM_52), normoglycemic controls (NGT) and pre-diabetes subjects (IGT) and were selected. RNA was extracted from skeletal muscle biopsies and hybridized on Affymetrix microarrays.
Project description:The ZDF rat, with spontaneous homozygous mutation of the leptin receptor gene (fa/fa), is one of the widely used animal model for studying the human type 2 diabetes mellitus (T2DM). Male ZDF rats have the symptoms of obesity and insulin resistance at a young age, accompanying with impaired islet function. However, their hepatic pathogenesis is still unclear. Based on the successive observations and the transcriptomic analyses of the liver tissue at 22 weeks old, we detected the typical clinical indications of T2DM, severe hepatic metabolic remodeling and the inflammatory liver injury in the ZDF rats. The integrin linked kinase signaling, as well as the endoplasmic reticulum stress and its downstream p38 MAPK signaling, seemed to play crucial roles in it. We have proved the ZDF rats could better simulate the pathogenesis of the human T2DM associated nonalcoholic fatty liver disease (NAFLD), and provided targets and reference for future T2DM studies.
Project description:Vascular endothelial growth factor B (VEGFB) plays a crucial role in glucolipid metabolism and is highly associated with type 2 diabetes mellitus (T2DM). The role of VEGFB in the insulin secretion of β cells remains unverified. Thus, this study aims to discuss the effect of VEGFB on regulating insulin secretion in T2DM development, and its underlying mechanism. A high-fat diet and streptozocin were used for inducing T2DM in mice model, and VEGFB gene in islet cells of T2DM mice was knocked out by CRISPR Cas9 and overexpressed by Adeno-Associated Virus (AAV) injection. The effect of VEGFB and its underlying mechanism was assessed by light microscope, electron microscope, fluorescence confocal microscope, enzyme-linked immunosorbent assay, mass spectrometer, and western blot. The decrement of insulin secretion in islet β cell of T2DM mice are aggravated and blood glucose remains at a high level after VEGFB deletion. However, glucose tolerance and insulin sensitivity of T2DM mice were improved after the AAV-VEGFB186 injection. VEGFB knockout or overexpression can inhibit or activate PLCγ/IP3R in a VEGFR1-dependent manner. Then, the change of PLCγ/IP3R caused by VEGFB/VEGFR1 will alter the expression of key factors on the Ca2+/CaMK2 signal pathway such as PPP3CA. Moreover, VEGFB can cause altered insulin secretion by changing the calcium concentration in β cells of T2DM mice. These findings indicated that VEGFB activated the Ca2+/CaMK2 pathway via VEGFR1-PLCγ and IP3R pathway to regulate insulin secretion, which provides new insight into the regulatory mechanism of abnormal insulin secretion in T2DM.
Project description:Obesity has become a global health concern. A molecule that safely prevents and/or treats obesity is urgently needed. Here, we show that long-term diet supplementation of disulfiram (DSF, Antabuse®), an FDA-approved drug, abrogated the adverse impact of an obesogenic diet on insulin responsiveness, while mitigating liver steatosis, cardiovascular remodeling, and pancreatic islet hypertrophy in mice. Additionally, DSF treatment of already obese male and female mice reversed weight gain and alleviated metabolic dysfunctions. Loss of fat tissue and increase in liver fenestrations were also observed in rats on DSF. Transcriptomics and proteomics analyses of mouse and rat livers unveiled comparable signatures, as revealed by pathways associated with lipid and energy metabolism, redox, and detoxification. Mechanistically, markers of hepatic oxidative stress were abrogated in DSF-treated mice through activation of ALDH2 and GST activities in vivo and stimulation of autophagic flux in vitro. Thus, repurposing DSF may represent a new strategy to combat obesity and reverse the associated metabolic disorders in human.
Project description:The effect of a long-term calorie restricted diet was evaluated in kidney of male mice The dietary intervention was initiated at 14 months of age and continued until 30 months of age
Project description:The effect of a long-term calorie restricted diet was evaluated in hippocampus of male mice The dietary intervention was initiated at 14 months of age and continued until 30 months of age
Project description:Direct lineage conversion is a promising approach to generate therapeutically important cell types for disease modeling and tissue repair. However, it is often unclear whether lineage-reprogrammed cells remain stable long-term and whether the properties of the reprogrammed cells evolve over time. Here, using an improved method of converting pancreatic acinar cells to beta-cells, we show that induced beta-cells persist in the adult pancreas for up to 14 months and form islet-like structures. Detailed analyses of induced cells over 7 months reveal that global DNA methylation changes occur rapidly whereas transcription network remodeling evolves over two months to resemble that of endogenous beta-cells and then stabilizes thereafter. Progressive gain of beta-cell function by converted cells during the 7 month period coincides with both transcriptional changes and the formation of islet-like structures. These studies demonstrate the ability of lineage-reprogrammed cells to achieve a stable state and identify key cellular and molecular milestones during their long-term evolution. Acinar cells and beta cells were collected as control, as well as induced beta cell samples at day 10, day 30, day 60, and 7 months
Project description:Direct lineage conversion is a promising approach to generate therapeutically important cell types for disease modeling and tissue repair. However, it is often unclear whether lineage-reprogrammed cells remain stable long-term and whether the properties of the reprogrammed cells evolve over time. Here, using an improved method of converting pancreatic acinar cells to beta-cells, we show that induced beta-cells persist in the adult pancreas for up to 14 months and form islet-like structures. Detailed analyses of induced cells over 7 months reveal that global DNA methylation changes occur rapidly whereas transcription network remodeling evolves over two months to resemble that of endogenous beta-cells and then stabilizes thereafter. Progressive gain of beta-cell function by converted cells during the 7 month period coincides with both transcriptional changes and the formation of islet-like structures. These studies demonstrate the ability of lineage-reprogrammed cells to achieve a stable state and identify key cellular and molecular milestones during their long-term evolution.
Project description:Direct lineage conversion is a promising approach to generate therapeutically important cell types for disease modeling and tissue repair. However, it is often unclear whether lineage-reprogrammed cells remain stable long-term and whether the properties of the reprogrammed cells evolve over time. Here, using an improved method of converting pancreatic acinar cells to beta-cells, we show that induced beta-cells persist in the adult pancreas for up to 14 months and form islet-like structures. Detailed analyses of induced cells over 7 months reveal that global DNA methylation changes occur rapidly whereas transcription network remodeling evolves over two months to resemble that of endogenous beta-cells and then stabilizes thereafter. Progressive gain of beta-cell function by converted cells during the 7 month period coincides with both transcriptional changes and the formation of islet-like structures. These studies demonstrate the ability of lineage-reprogrammed cells to achieve a stable state and identify key cellular and molecular milestones during their long-term evolution.