Glucose tolerance tests for systematic screening of glucose homeostasis in mice

Transplantation of Exercise-Enhanced Mesenchymal Stem Cells Improves Obesity and Glucose Tolerance via Immune Modulation in Adipose Tissue

Exercise-conditioned mesenchymal stem cells (MSCs) may modulate immune responses and improve white adipose tissue (WAT) function. While MSCs are known to reduce inflammation, it remains unclear if exercise-stimulated MSCs can improve obesity-related dysfunctions. This study is the first to explore how exercise-conditioned MSCs may influence adipose tissue inflammation and remodeling in the context of obesity. MSCs were isolated from exercised- and sedentary donor mice, then cultured in vitro. After culture, MSCs were assessed for differentiation capacity and cytokine gene expression, including Il10, as indicators of immune modulation. Exercise-conditioned MSCs were then transplanted into obese recipient mice. Following transplantation, immune cell profiles, inflammatory markers, and adipocyte morphology in recipient WAT were analyzed. Flow cytometry was used to quantify macrophage subtypes (pro-inflammatory and anti-inflammatory), and histological analysis was performed to measure changes in adipocyte size. Exercise-activated MSCs showed a ± 35% increase in Il10 expression and a ± 20% enhancement in differentiation capacity compared to controls, indicating improved immunomodulatory potential. In recipient mice, transplantation led to a ± 25% reduction in pro-inflammatory macrophages (CD86+ CD206-) and a 15% decrease in adipocyte size within WAT. Additionally, WAT in treated mice showed balanced inflammatory profiles and reduced adipose hypertrophy, suggesting restored immune balance and metabolic health. These findings suggest that exercise-modified MSCs exhibit enhanced immunomodulatory and metabolic regulatory properties. This study provides evidence that exercise enhances MSC characteristics, potentially improving their capacity to modulate adipose tissue immune balance and metabolic function in obesity. Exercise-conditioned MSCs may serve as a foundation for future strategies that integrate exercise-induced stem cell modifications to modulate obesity-related metabolic dysfunction.

Optimizing expression, purification, structural and functional assessments of a novel dimeric incretin (GLP-1cpGLP-1)

Glucagon-like peptide-1 (GLP-1) is an incretin hormone that reduces postprandial glycemic excursions by enhancing insulin secretion. In this study, a new dimeric GLP-1 analogue (GLP-1cpGLP-1) was designed by inserting human insulin C-peptide (CP) in the middle of a dimer of [Gly8] GLP-1 (7-36). Then, the dimeric incretin (GLP-1cpGLP-1) was ligated to human αB-crystallin (αB-Cry) to create a hybrid protein, abbreviated as αB-GLP-1cpGLP-1. The constructed gene was well expressed in the bacterial host system. After specific chemical release from the hybrid protein, the dimeric incretin was purified by size exclusion chromatography (SEC). Finally, the RP-HPLC analysis indicated a purity of >99 % for the dimeric incretin. The secondary structure assessments by various spectroscopic methods, and in silico analysis suggested that the dimeric incretin has α-helical rich structure. The dynamic light scattering (DLS) analysis indicates that our dimeric incretin forms large oligomeric structures. This incretin analogue significantly reduced blood glucose levels in both healthy and diabetic mice while effectively triggering insulin release. The size exclusion HPLC also indicates the interaction of the new incretin analogue with human serum albumin, the main carrier protein in the bloodstream. Consistent with the results obtained from the biological activity assessments, this significant interaction indicates its potential as a viable therapeutic agent with a long-lasting effect. The results of our research represent a significant breakthrough in the successful design of an active incretin dimer capable of effectively controlling blood sugar levels and inducing insulin secretion in the realm of diabetes treatment.

Power-Doppler Ultrasonic Imaging of Peripheral Perfusion in Diabetic Mice

OBJECTIVE

We explored the capabilities of power-Doppler ultrasonic (PD-US) imaging without contrast enhancement for monitoring changes in muscle perfusion over time.

METHODS

Ischemic recovery was observed in healthy and type II diabetic male and female mice with and without exercise. In separate studies, perfusion was measured during and after 5-min ischemic periods and during four-week recovery periods following irreversible femoral ligation. A goal was to assess how well PD-US estimates tracked the diabetic-related changes in endothelial function that influenced perfusion.

RESULTS

The average perfusion recovery time following femoral ligation increased 47% in diabetic males and 74% in diabetic females compared with non-diabetic mice. Flow-mediated dilation in conduit arteries and the reactive hyperemia index in resistive vessels each declined by one half in sedentary diabetic mice compared with sedentary non-diabetic mice. We found that exercise reduced the loss of endothelial function from diabetes in both sexes. The reproducibility of perfusion measurements was limited primarily by our ability to select the same region in muscle and to effectively filter tissue clutter.

CONCLUSIONS/SIGNIFICANCE

PD-US measurements can precisely follow site-specific changes in skeletal muscle perfusion related to diabetes over time, which fills the need for techniques capable of regularly monitoring atherosclerotic changes leading to ischemic vascular pathologies.

Comparative Phenotyping of Mice Reveals Canonical and Noncanonical Physiological Functions of TRα and TRβ

Thyroid hormone (TH) effects are mediated through TH receptors (TRs), TRα1, TRβ1, and TRβ2. The TRs bind to the DNA and regulate expression of TH target genes (canonical signaling). In addition, they mediate activation of signaling pathways (noncanonical signaling). Whether noncanonical TR action contributes to the spectrum of TH effects is largely unknown. The aim of this study was to attribute physiological effects to the TR isoforms and their canonical and noncanonical signaling. We conducted multiparameter phenotyping in male and female TR knockout mice (TRαKO, TRβKO), mice with disrupted canonical signaling due to mutations in the TR DNA binding domain (TRαGS, TRβGS), and their wild-type littermates. Perturbations in senses, especially hearing (mainly TRβ with a lesser impact of TRα), visual acuity, retinal thickness (TRα and TRβ), and in muscle metabolism (TRα) highlighted the role of canonical TR action. Strikingly, selective abrogation of canonical TR action often had little phenotypic consequence, suggesting that noncanonical TR action sufficed to maintain the wild-type phenotype for specific effects. For instance, macrocytic anemia, reduced retinal vascularization, or increased anxiety-related behavior were only observed in TRαKO but not TRαGS mice. Noncanonical TRα action improved energy utilization and prevented hyperphagia observed in female TRαKO mice. In summary, by examining the phenotypes of TRα and TRβ knockout models alongside their DNA binding-deficient mutants and wild-type counterparts, we could establish that the noncanonical actions of TRα and TRβ play a crucial role in modulating sensory, behavioral, and metabolic functions and, thus, contribute to the spectrum of physiological TH effects.

Antidiabetic Activities of 80% Methanol Extract and Solvent Fractions of Verbascum Sinaiticum Benth (Scrophulariaceae) Leaves in Mice

Background

Because of the scarcity, high cost, and severe side effects of current medications, it is necessary to discover novel, safe, and affordable anti-diabetic drugs. The current study was conducted to evaluate the antidiabetic activities of Verbascum sinaiticum Benth leaves in mice.

Methods

Leaf coarse powder was extracted with 80% methanol and then fractionated with n-hexane, ethyl acetate, and distilled water. The glucose-lowering effects of V. sinaiticum at 100, 200, and 400mg/kg were then studied. Glibenclamide was used as a positive control at a dose of 5 mg/kg. For oral glucose tolerance tests and hypoglycemia tests, Tween 2% was used as a negative control, while citrate buffer was used as a negative control for antihyperglycemic investigations. The results from the study were evaluated using one-way ANOVA, and then Tukey's post hoc multiple comparison test was performed.

Results

Blood glucose levels were significantly reduced by the V. sinaiticum 80% methanol extract at 400 mg/kg (p<0.05). The blood glucose levels were significantly lowered by the aqueous residue at 400 mg/kg (p<0.05) and the ethyl acetate fractions at 200 mg/kg (p<0.01) and 400 mg/kg (p<0.001); however, none of the fraction extracts resulted in hypoglycemic shock in healthy mice. Higher glucose tolerance was seen in orally glucose-loaded mice after exposure to 80% methanol extracts at 200 and 400 mg/kg (p<0.05), the aqueous residual fraction at 200 mg/kg (p<0.01), and the ethyl acetate fraction at 200 and 400 mg/kg (p<0.05). The ethyl acetate fraction at 200 and 400 mg/kg (p<0.01), the 80% methanol extract at 400 mg/kg (p<0.05) and the aqueous residue at 400 mg/kg (p 0.01) significantly lowered blood glucose levels in streptozotocin-induced diabetic mice.

Conclusion

The results of this study revealed that the 80% methanol extract and solvent fractions of V. sinaiticum Benth leaves are endowed with antidiabetic activity.

Anti-Hyperglycemic and Hypoglycemic Activities of 80% Methanol Extract and Solvent Fractions of Ocimum lamiifolium Hochst Ex Benth. (Lamiaceae) Leaves in Mice

Background

Globally, the prevalence of diabetes mellitus is rising. Due to the scarcity, high cost, and many adverse effects of modern treatments, traditional medicine is commonly used in rural areas to treat a variety of illnesses, including diabetes mellitus. The aim of this study was to assess the antihyperglycemic and hypoglycemic effects of Ocimum lamiifolium Hochst ex Benth leaves.

Methods

A crude methanol 80% extract's and its solvent fractions' effects on healthy, oral glucose-given, and STZ-induced diabetic mice were examined. Swiss albino mice of either sex were assigned into sixteen groups, each containing six mice, for the OGTT and hypoglycemia tests. Male mice were used in the study, and they were divided into groups for the negative control (citrate buffer for diabetic mice), the normal control (Tween 2%), the test groups, and a positive control (glibenclamide) for the antihyperglycemic test in STZ (200 mg/kg body weight)-induced diabetic mice.

Results

A crude 80% methanol extract of 200 mg/kg effectively lowered blood glucose levels (p <0.05) and none of the fractions extracts caused hypoglycemia shock in norma mice. The aqueous residue at 100, 200, and 400 mg/kg, the n-butanol fraction at 100 and 200 mg/kg, and the chloroform fraction at 200 mg/kg demonstrated higher glucose tolerance in orally glucose-loaded mice (p <0.05). The crude 400 mg/kg of an 80% methanol extract, 100 and 200 mg/kg of the n-butanol fraction, 200 and 400 mg/kg of the chloroform fraction, and 5 mg/kg of glibenclamide significantly reduced blood glucose levels in STZ-induced diabetic mice (p <0.05).

Conclusion

The current research demonstrates that a crude 80% methanol extract of Ocimum lamiifolium Hochst ex Benth leaves, as well as its solvent fractions, significantly reduce blood sugar levels in mice that are healthy, loaded with glucose, and streptozotocin induced diabetic mice.

Dietary intervention improves health metrics and life expectancy of the genetically obese Titan mouse

Suitable animal models are essential for translational research, especially in the case of complex, multifactorial conditions, such as obesity. The non-inbred mouse (Mus musculus) line Titan, also known as DU6, is one of the world’s longest selection experiments for high body mass and was previously described as a model for metabolic healthy (benign) obesity. The present study further characterizes the geno- and phenotypes of this non-inbred mouse line and tests its suitability as an interventional obesity model. In contrast to previous findings, our data suggest that Titan mice are metabolically unhealthy obese and short-lived. Line-specific patterns of genetic invariability are in accordance with observed phenotypic traits. Titan mice also show modifications in the liver transcriptome, proteome, and epigenome linked to metabolic (dys)regulations. Importantly, dietary intervention partially reversed the metabolic phenotype in Titan mice and significantly extended their life expectancy. Therefore, the Titan mouse line is a valuable resource for translational and interventional obesity research.

This study further characterizes the non-inbred Titan (also known as DU6) mouse line, which could be a useful model for obesity research.

Supplier-origin mouse microbiomes significantly influence locomotor and anxiety-related behavior, body morphology, and metabolism

The mouse is the most commonly used model species in biomedical research. Just as human physical and mental health are influenced by the commensal gut bacteria, mouse models of disease are influenced by the fecal microbiome (FM). The source of mice represents one of the strongest influences on the FM and can influence the phenotype of disease models. The FM influences behavior in mice leading to the hypothesis that mice of the same genetic background from different vendors, will have different behavioral phenotypes. To test this hypothesis, colonies of CD-1 mice, rederived via embryo transfer into surrogate dams from four different suppliers, were subjected to phenotyping assays assessing behavior and physiological parameters. Significant differences in behavior, growth rate, metabolism, and hematological parameters were observed. Collectively, these findings show the profound influence of supplier-origin FMs on host behavior and physiology in healthy, genetically similar, wild-type mice maintained in identical environments.

Systematic Investigation of the Effects of Long-Term Administration of a High-Fat Diet on Drug Transporters in the Mouse Liver, Kidney and Intestine

BACKGROUND

Long-term intake of a high-fat diet is a crucial factor contributing to obesity, which has become a global public health problem. Progressive obesity subsequently leads to hepatic injury, renal damage and intestinal atrophy. Transporters expressed in the liver, kidney and intestine play important roles in the deposition of nutrients and drugs, but researchers have not clearly determined whether/how the expression of transporters changes after long-term administration of a High-Fat Diet (HFD). This study aims to explore the effects of the long-term administration of a HFD on the expression of drug transporters in the liver, kidney and intestine in mice and to provide useful information for medical applications in the clinic.

METHODS

Male C57BL/6J mice were fed either a basal diet or HFD for 24 weeks, and oral glucose tolerance tests were performed after 3, 11 and 23 weeks. Serum was obtained to measure lipid metabolism, inflammatory mediators, renal function and hepatic function. Adipose tissues, kidney, pancreas and liver were collected for hematoxylin and eosin (H&E) staining after 4, 12 and 24 weeks. The mRNA and proteins expression of drug transporters in the liver, kidney and intestine were detected using real-time PCR and western blot, respectively.

RESULTS

Compared with the control group, long-term HFD administration significantly increased the adipose index. The serum lipid levels, including Total Cholesterol (TC), Triglyceride (TG), and Low-Density Lipoprotein Cholesterol (LDL-C), as well as the levels of the inflammatory cytokines Interleukin-10 (IL-10) and tumor necrosis factor-α (TNF-α) were significantly elevated in HFD-induced obese mice. H&E staining revealed pathological changes in the adipose cells, liver, kidney and pancreas from the obese group following the long-term administration of the HFD. The liver of the obese group presented increased mRNA expression of the efflux transporter Mrp2 and uptake transporter Oat2 at 24 weeks. The relative expression of Oat2 increased 4.08-fold and the protein expression of Oat2 was upregulated at 24 weeks in HFD-fed mice, while the mRNA expression of the uptake transporters Oct1, Oatp1b2 and Oatp1a4 decreased by 79%, 61% and 19%, respectively. The protein expression of Oct1 was significantly downregulated in obese mice at 12 weeks. The mRNA expression of the efflux transporter Mdr1a was significantly reduced in HFD-fed mice compared with the control group at 24 weeks. Western blot showed that the trend of protein level of Mdr1 was consistent with the mRNA expression. In the kidney, the level of the Oct2 mRNA increased 1.92- and 2.46-fold at 4 and 12 weeks in HFD-fed mice, respectively. The expression of the Oat1 and Oat3 mRNAs was markedly downregulated in the kidneys of mice with HFD-induced obesity at 4 weeks. The decrease of 72% and 21% in Mdr1a mRNA expression was observed in the obese model at 4 weeks and 12 weeks, respectively. Western blot showed that the protein levels of Mdr1 and Oat1 were consistent with the mRNA expression. The qPCR experiments showed a 2.87-fold increase in Bcrp mRNA expression at 24 weeks, and the expression of the Pept1 mRNA increased 2.84-fold in intestines of obese mice subjected to long-term administration of the HFD compared with control mice at 12 weeks. Western blot showed that the trend of protein levels of Mdr1 and Mrp2 were consistent with the mRNA expression.

CONCLUSION

The expression of uptake and efflux transporters mRNAs and protein levels were altered in obese mice compared with control mice, providing scientific evidence for future medical applications in the clinic.

Combination of honey with metformin enhances glucose metabolism and ameliorates hepatic and nephritic dysfunction in STZ-induced diabetic mice

Honey is a natural sweetener that contains a large amount of monosaccharides such as glucose and fructose, as well as small amounts of disaccharides and trisaccharides such as sucrose and pine trisaccharides. In addition to carbohydrates, honey also contains vitamins, minerals, enzymes, amino acids, and polyphenols including phenolic acids and flavonoids. The polyphenols in honey have been proved to have great antioxidant activity, besides inhibiting α-glycosidase activity and improving blood-lipid metabolism. However, whether it is safe for diabetic patients to consume honey remains controversial. This study investigated the effects of honey, metformin and their combination on the characteristic pathological changes and glucose metabolism in STZ-induced diabetic mice over five weeks. Our results showed that honey and its combination with metformin could prevent hyperglycemia, stimulate insulin secretion, reduce liver fat accumulation, attenuate liver injury and kidney damage in STZ-induced diabetic mice. Moreover, treatment with honey or combination of honey and metformin significantly enhanced glucokinase (GK) activity (p < 0.05), and meanwhile suppressed the activities of glucose-6-phosphatase (G6Pase), phosphoenolpyruvate carboxykinase (PEPCK), pyruvate carboxylase (PC) and pyruvate dehydrogenase kinases (PDK) (p < 0.05) in diabetic mice.

Estradiol and NADPH oxidase crosstalk regulates responses to high fat feeding in female mice

We previously demonstrated protection against high fat-induced obesity in female but not male p47phox−/− mice lacking NADPH oxidase NOX1/2 activity. To test the role of estradiol (E2)-NOX crosstalk in development of this sexually dimorphic phenotype, we fed diets containing 42% fat/0.5% cholesterol to intact and ovariectomized wild type female C57BL/6 mice and female p47phox−/− mice and to ovariectomized mice where the diet was supplemented with an 1 mg/kg 17β estradiol (E2) for 12 weeks from PND28. Weight gain, gonadal fat pad weight, serum leptin and adiponectin, and adipose tissue inflammation were greater in intact wild type vs. p47 mice ( P < 0.05). Genotype effects on body weight/fat mass were abolished after ovariectomized and restored in OVX + E2 mice ( P < 0.05). The mRNA of downstream PPARγ targets CD36, lipoprotein lipase, and leptin was higher in intact wild type vs. p47phox−/− mice mice ( P < 0.05). Likewise, intact high fat-fed wild type mice had higher expression of the cytokine Mcp1; the pyroptosis marker Nirp3 and matrix remodeling and fibrosis markers Mmp2, Col1A1, and Col6a3 mRNAs ( P < 0.05). These genotype effects were reversed and restored by ovariectomized and OVX + E2, respectively ( P < 0.05). These data suggest that triglyceride accumulation in adipose tissue and development of adipose tissue injury in response to feeding diets high in fat and cholesterol is regulated by the balance between NOX-dependent reactive oxygen species signaling and E2-signaling during development. Loss of estrogens post menopause may increase the risk of obesity and metabolic syndrome as the result disinhibition of reactive oxygen species signaling.

Impact statement

Estrogens are known to regulate body composition. In addition, reactive oxygen species (ROS) produced by the action of NADPH oxidase (NOX) enzymes have been linked to obesity development. We examined development of obesity and adipose tissue injury in response to feeding “Western” diets high in fat and cholesterol in intact, ovariectomized (OVX), and estrogen-replaced (OVX + E2) wild type and p47phox−/− female mice where NOX2 activity is inhibited. Weight gain, gonadal fat pad weight, and adipose tissue inflammation were greater in intact WT vs. p47phox−/− mice. Genotype effects on body weight/fat mass were abolished after OVX and restored in OVX + E2 mice. These data indicate adipose tissue responses to feeding the “Western” diet is regulated by negative cross-talk between NOX-dependent ROS signaling and E2-signaling during development. Loss of estrogens post menopause may increase the risk of obesity and metabolic syndrome as the result disinhibition of ROS signaling.

Beneficial Effects of Poplar Buds on Hyperglycemia, Dyslipidemia, Oxidative Stress, and Inflammation in Streptozotocin-Induced Type-2 Diabetes

The effects of propolis on blood glucose regulation and the alleviation of various complications caused by diabetes have been widely studied. The main source of propolis in the northern temperate zone is poplar buds. However, there is limited research on the antidiabetic activity of poplar buds. In order to evaluate the effect of poplar buds on type-2 diabetes, crude extract and 50% fraction of poplar buds were used to feed streptozotocin-induced type-2 diabetic mice. The results showed that 50% fraction could increase insulin sensitivity and reduce insulin resistance, as well as decrease the levels of fasting blood glucose, glycated hemoglobin, and glycosylated serum proteins in diabetic mice. Compared with the model control group, the 50% fraction-treated group showed significant decreases of malondialdehyde (MDA) and increases of superoxide dismutase (SOD) in serum and liver homogenate. Moreover, 50% fraction could significantly decrease total cholesterol (TC), alleviate abnormal lipid metabolism, and enhance antioxidant capacity in the serum. For inflammatory factors, feeding of 50% fraction could also reduce the levels of interleukin 6 (IL-6), tumor necrosis factor α (TNF-α), monocyte chemotactic protein 1 (MCP-1), and cyclooxygenase-2 (COX-2) in liver homogenate. Taken together, our results suggest that crude extract and 50% fraction of poplar buds, particularly the latter, can decrease blood glucose levels and insulin resistance, and 50% fraction can significantly relieve dyslipidemia, oxidative stress, and inflammation caused by type-2 diabetes.

Laboratory mouse housing conditions can be improved using common environmental enrichment without compromising data

Animal welfare requires the adequate housing of animals to ensure health and well-being. The application of environmental enrichment is a way to improve the well-being of laboratory animals. However, it is important to know whether these enrichment items can be incorporated in experimental mouse husbandry without creating a divide between past and future experimental results. Previous small-scale studies have been inconsistent throughout the literature, and it is not yet completely understood whether and how enrichment might endanger comparability of results of scientific experiments. Here, we measured the effect on means and variability of 164 physiological parameters in 3 conditions: with nesting material with or without a shelter, comparing these 2 conditions to a “barren” regime without any enrichments. We studied a total of 360 mice from each of 2 mouse strains (C57BL/6NTac and DBA/2NCrl) and both sexes for each of the 3 conditions. Our study indicates that enrichment affects the mean values of some of the 164 parameters with no consistent effects on variability. However, the influence of enrichment appears negligible compared to the effects of other influencing factors. Therefore, nesting material and shelters may be used to improve animal welfare without impairment of experimental outcome or loss of comparability to previous data collected under barren housing conditions.

Adequate housing of laboratory animals is essential to guarantee their well-being. From a scientific perspective, physically and mentally healthy animals also contribute to increased validity and reproducibility of experimental results. The choice of nesting material or shelter type, referred to as environmental enrichment, may influence how laboratory animals perform species-specific behaviors. Consequently, changes in these nesting and shelter materials could influence scientific results by, for example, increasing variability in measured characteristics. Whether studies using different environmental enrichment materials can be compared is currently questioned. Our study shows that simple, species-specific environmental enrichment in the form of nesting material alone or in combination with a shelter did not consistently increase variability of physiological parameters in mice. Differences in parameter average values appeared to be of minor biological relevance when compared to the effects of other environmental factors. These simple environmental enrichment devices may therefore be applied to improve the housing environment of laboratory mice without compromising data validity or comparability.

Reduced mitochondrial mass and function add to age-related susceptibility toward diet-induced fatty liver in C57BL/6J mice

Nonalcoholic fatty liver disease (NAFLD) is a major health burden in the aging society with an urging medical need for a better understanding of the underlying mechanisms. Mitochondrial fatty acid oxidation and mitochondrial‐derived reactive oxygen species (ROS) are considered critical in the development of hepatic steatosis, the hallmark of NAFLD. Our study addressed in C57BL/6J mice the effect of high fat diet feeding and age on liver mitochondria at an early stage of NAFLD development. We therefore analyzed functional characteristics of hepatic mitochondria and associated alterations in the mitochondrial proteome in response to high fat feeding in adolescent, young adult, and middle‐aged mice. Susceptibility to diet‐induced obesity increased with age. Young adult and middle‐aged mice developed fatty liver, but not adolescent mice. Fat accumulation was negatively correlated with an age‐related reduction in mitochondrial mass and aggravated by a reduced capacity of fatty acid oxidation in high fat‐fed mice. Irrespective of age, high fat diet increased ROS production in hepatic mitochondria associated with a balanced nuclear factor erythroid‐derived 2 like 2 (NFE2L2) dependent antioxidative response, most likely triggered by reduced tethering of NFE2L2 to mitochondrial phosphoglycerate mutase 5. Age indirectly influenced mitochondrial function by reducing mitochondrial mass, thus exacerbating diet‐induced fat accumulation. Therefore, consideration of age in metabolic studies must be emphasized.

Cardioprotection and lifespan extension by the natural polyamine spermidine

Aging is associated with an increased risk of cardiovascular disease and death. Here we show that oral supplementation of the natural polyamine spermidine extends the lifespan of mice and exerts cardioprotective effects, reducing cardiac hypertrophy and preserving diastolic function in old mice. Spermidine feeding enhanced cardiac autophagy, mitophagy and mitochondrial respiration, and it also improved the mechano-elastical properties of cardiomyocytes in vivo, coinciding with increased titin phosphorylation and suppressed subclinical inflammation. Spermidine feeding failed to provide cardioprotection in mice that lack the autophagy-related protein Atg5 in cardiomyocytes. In Dahl salt-sensitive rats that were fed a high-salt diet, a model for hypertension-induced congestive heart failure, spermidine feeding reduced systemic blood pressure, increased titin phosphorylation and prevented cardiac hypertrophy and a decline in diastolic function, thus delaying the progression to heart failure. In humans, high levels of dietary spermidine, as assessed from food questionnaires, correlated with reduced blood pressure and a lower incidence of cardiovascular disease. Our results suggest a new and feasible strategy for protection against cardiovascular disease.

Islet Insulin Secretion Measurements in the Mouse

This article describes detailed protocols for in vitro measurements of insulin function and secretion in isolated mouse islets for the analysis of glucose homeostasis. We specify a method of enzyme digestion and hand picking to isolate and release the greatest number of high quality islets from the pancreas of the mouse. We describe an effective method for generating dynamic measurements of insulin secretion using a perifusion assay including a detailed protocol for constructing a peristaltic pump and tubing assembly. In addition we describe an alternative and simple technique for measuring insulin secretion using static incubation of isolated islets. © 2016 by John Wiley & Sons, Inc.

Comparative aspects of rodent and nonrodent animal models for mechanistic and translational diabetes research

The prevalence of diabetes mellitus, which currently affects 387 million people worldwide, is permanently rising in both adults and adolescents. Despite numerous treatment options, diabetes mellitus is a progressive disease with severe comorbidities, such as nephropathy, neuropathy, and retinopathy, as well as cardiovascular disease. Therefore, animal models predictive of the efficacy and safety of novel compounds in humans are of great value to address the unmet need for improved therapeutics. Although rodent models provide important mechanistic insights, their predictive value for therapeutic outcomes in humans is limited. In recent years, the pig has gained importance for biomedical research because of its close similarity to human anatomy, physiology, size, and, in contrast to non-human primates, better ethical acceptance. In this review, anatomic, biochemical, physiological, and morphologic aspects relevant to diabetes research will be compared between different animal species, that is, mouse, rat, rabbit, pig, and non-human primates. The value of the pig as a model organism for diabetes research will be highlighted, and (dis)advantages of the currently available approaches for the generation of pig models exhibiting characteristics of metabolic syndrome or type 2 diabetes mellitus will be discussed.