A new mouse model of spontaneous diabetes derived from ddY strain

Hypofibrinolytic phenotype in Tsumura Suzuki Obese Diabetes (TSOD) mice unrelated to hyperglycemia

Obesity and diabetes mellitus are associated with increased risk of arterial thrombosis and venous thromboembolism. Tsumura Suzuki Obese Diabetes (TSOD) mice are useful models for elucidating the molecular mechanisms of these diseases. We investigated normoglycemic [Ng]-TSOD mice with a metabolic abnormality that was accompanied by a coagulative and fibrinolytic state with a phenotype that distinctly differed from that of standard TSOD mice. As in TSOD mice, plasminogen activation inhibitor-1 (PAI-1) that inhibits fibrinolysis was substantially augmented in Ng-TSOD mice, suggesting that they are hypofibrinolytic. However, blood clotting parameters were within the normal range in Ng-TSOD mice. These findings indicated that Ng-TSOD mice are novel models with a hypofibrinolytic phenotype that is not associated with hyperglycemia.

Animal Models in Diabetic Research-History, Presence, and Future Perspectives

Diabetes mellitus (DM) is a very serious disease, the incidence of which has been increasing worldwide. The beginning of diabetic research can be traced back to the 17th century. Since then, animals have been experimented on for diabetic research. However, the greatest development of diabetes research occurred in the second half of the last century, along with the development of laboratory techniques. Information obtained by monitoring patients and animal models led to the finding that there are several types of DM that differ significantly from each other in the causes of the onset and course of the disease. Through different types of animal models, researchers have studied the pathophysiology of all types of diabetic conditions and discovered suitable methods for therapy. Interestingly, despite the unquestionable success in understanding DM through animal models, we did not fully succeed in transferring the data obtained from animal models to human clinical research. On the contrary, we have observed that the chances of drug failure in human clinical trials are very high. In this review, we will summarize the history and presence of animal models in the research of DM over the last hundred years. Furthermore, we have summarized the new methodological approaches, such as "organ-on-chip," that have the potential to screen the newly discovered drugs for human clinical trials and advance the level of knowledge about diabetes, as well as its therapy, towards a personalized approach.

Multifaceted effects of obesity on cancer immunotherapies: Bridging preclinical models and clinical data

Obesity, defined by excessive body fat, is a highly complex condition affecting numerous physiological processes, such as metabolism, proliferation, and cellular homeostasis. These multifaceted effects impact cells and tissues throughout the host, including immune cells as well as cancer biology. Because of the multifaceted nature of obesity, common parameters used to define it (such as body mass index in humans) can be problematic, and more nuanced methods are needed to characterize the pleiotropic metabolic effects of obesity. Obesity is well-accepted as an overall negative prognostic factor for cancer incidence, progression, and outcome. This is in part due to the meta-inflammatory and immunosuppressive effects of obesity. Immunotherapy is increasingly used in cancer therapy, and there are many different types of immunotherapy approaches. The effects of obesity on immunotherapy have only recently been studied with the demonstration of an "obesity paradox", in which some immune therapies have been demonstrated to result in greater efficacy in obese subjects despite the direct adverse effects of obesity and excess body fat acting on the cancer itself. The multifactorial characteristics that influence the effects of obesity (age, sex, lean muscle mass, underlying metabolic conditions and drugs) further confound interpretation of clinical data and necessitate the use of more relevant preclinical models mirroring these variables in the human scenario. Such models will allow for more nuanced mechanistic assessment of how obesity can impact, both positively and negatively, cancer biology, host metabolism, immune regulation, and how these intersecting processes impact the delivery and outcome of cancer immunotherapy.

New Possibilities for Evaluating the Development of Age-Related Pathologies Using the Dynamical Network Biomarkers Theory

Aging is the slowest process in a living organism. During this process, mortality rate increases exponentially due to the accumulation of damage at the cellular level. Cellular senescence is a well-established hallmark of aging, as well as a promising target for preventing aging and age-related diseases. However, mapping the senescent cells in tissues is extremely challenging, as their low abundance, lack of specific markers, and variability arise from heterogeneity. Hence, methodologies for identifying or predicting the development of senescent cells are necessary for achieving healthy aging. A new wave of bioinformatic methodologies based on mathematics/physics theories have been proposed to be applied to aging biology, which is altering the way we approach our understand of aging. Here, we discuss the dynamical network biomarkers (DNB) theory, which allows for the prediction of state transition in complex systems such as living organisms, as well as usage of Raman spectroscopy that offers a non-invasive and label-free imaging, and provide a perspective on potential applications for the study of aging.

Contribution of animal models to diabetes research: Its history, significance, and translation to humans

Diabetes mellitus is still expanding globally and is epidemic in developing countries. The combat of this plague has caused enormous economic and social burdens related to a lowered quality of life in people with diabetes. Despite recent significant improvements of life expectancy in patients with diabetes, there is still a need for efforts to elucidate the complexities and mechanisms of the disease processes to overcome this difficult disorder. To this end, the use of appropriate animal models in diabetes studies is invaluable for translation to humans and for the development of effective treatment. In this review, a variety of animal models of diabetes with spontaneous onset in particular will be introduced and discussed for their implication in diabetes research.

Targeting activin receptor-like kinase 7 ameliorates adiposity and associated metabolic disorders

Activin receptor-like kinase 7 (ALK7) is a type I receptor in the TGF-β superfamily preferentially expressed in adipose tissue and associated with lipid metabolism. Inactivation of ALK7 signaling in mice results in increased lipolysis and resistance to both genetic and diet-induced obesity. Human genetic studies have recently revealed an association between ALK7 variants and both reduced waist to hip ratios and resistance to development of diabetes. In the present study, treatment with a neutralizing mAb against ALK7 caused a substantial loss of adipose mass and improved glucose intolerance and insulin resistance in both genetic and diet-induced mouse obesity models. The enhanced lipolysis increased fatty acid supply from adipocytes to promote fatty acid oxidation in muscle and oxygen consumption at the whole-body level. The treatment temporarily increased hepatic triglyceride levels, which resolved with long-term Ab treatment. Blocking of ALK7 signals also decreased production of its ligand, growth differentiation factor 3, by downregulating S100A8/A9 release from adipocytes and, subsequently, IL-1β release from adipose tissue macrophages. These findings support the feasibility of potential therapeutics targeting ALK7 as a treatment for obesity and diabetes.

Prevention of progressive hearing loss in a mouse model of diabetes by oral intake of eicosapentaenoic acid ethyl ester

BACKGROUND

The prevalence of hearing impairment in patients with diabetes was significantly higher, and the development of preventive methods is desirable.

AIMS/OBJECTIVES

This study examined the effects of eicosapentaenoic acid (EPA) administration on the prevention of early hearing loss in diabetic mice.

MATERIALS AND METHODS

Tsumura, Suzuki, Obese Diabetes (TSOD) mice were used as a model of diabetes and Tsumura, Suzuki, Non Obesity (TSNO) mice were used as controls. The animals were divided into three groups: the TSNO group and the TSOD (EPA-) group (provided sunflower oil), and the TSOD (EPA+) group (provided EPA). Auditory brainstem responses (ABRs) were measured and the cochlea was evaluated histologically.

RESULTS

The TSOD (EPA+) group showed a lower tendency to increase thresholds than the TSOD (EPA-) group. The TSOD (EPA+) group had a significantly lower ABR threshold than the TSOD (EPA-) group from 11 to 14 months of age at 4 kHz. Narrowing of the capillary lumens in the stria vascularis and thickening of the vessel wall in the modiolus were observed in the TSOD (EPA-) group.

CONCLUSIONS AND SIGNIFICANCE

It was suggested that the suppression of cochlear vascular atherosclerosis by EPA administration in TSOD mice suppressed early age-related hearing loss.

Roles of Macrophages in Advanced Liver Fibrosis, Identified Using a Newly Established Mouse Model of Diet-Induced Non-Alcoholic Steatohepatitis

Macrophages play critical roles in the pathogenesis of non-alcoholic steatohepatitis (NASH). However, it is unclear which macrophage subsets are critically involved in the development of inflammation and fibrosis in NASH. In TSNO mice fed a high-fat/cholesterol/cholate-based diet, which exhibit advanced liver fibrosis that mimics human NASH, we found that Kupffer cells (KCs) were less abundant and recruited macrophages were more abundant, forming hepatic crown-like structures (hCLS) in the liver. The recruited macrophages comprised two subsets: CD11c+/Ly6C- and CD11c-/Ly6C+ cells. CD11c+ cells were present in a mesh-like pattern around the lipid droplets, constituting the hCLS. In addition, CD11c+ cells colocalized with collagen fibers, suggesting that this subset of recruited macrophages might promote advanced liver fibrosis. In contrast, Ly6C+ cells were present in doughnut-like inflammatory lesions, with a lipid droplet in the center. Finally, RNA sequence analysis indicates that CD11c+/Ly6C- cells promote liver fibrosis and hepatic stellate cell (HSC) activation, whereas CD11c-/Ly6C+ cells are a macrophage subset that play an anti-inflammatory role and promote tissue repair in NASH. Taken together, our data revealed changes in liver macrophage subsets during the development of NASH and shed light on the roles of the recruited macrophages in the pathogenesis of advanced fibrosis in NASH.

Dynamical network biomarkers: Theory and applications

This paper reviews theory of DNB (Dynamical Network Biomarkers) and its applications including both modern medicine and traditional medicine. We show that omics data such as gene/protein expression profiles can be effectively used to detect pre-disease states before critical transitions from healthy states to disease states by using the DNB theory. The DNB theory with big biological data is expected to lead to ultra-early precision and preventive medicine.

Effect of Continuous Feeding of Ayu-Narezushi on Lipid Metabolism in a Mouse Model of Metabolic Syndrome

Ayu-narezushi, a traditional Japanese fermented food, comprises abundant levels of lactic acid bacteria (LAB) and free amino acids. This study aimed to examine the potential beneficial effects of ayu-narezushi and investigated whether ayu-narezushi led to improvements in the Tsumura Suzuki obese diabetes (TSOD) mice model of spontaneous metabolic syndrome because useful LAB are known as probiotics that regulate intestinal function. In the present study, the increased body weight of the TSOD mice was attenuated in those fed the ayu-narezushi-comprised chow (ayu-narezushi group) compared with those fed the normal rodent chow (control group). Serum triglyceride and cholesterol levels were significantly lower in the Ayu-narezushi group than in the control group at 24 weeks of age. Furthermore, hepatic mRNA levels of carnitine-palmitoyl transferase 1 and acyl-CoA oxidase, which related to fatty acid oxidation, were significantly increased in the ayu-narezushi group than in the control group at 24 weeks of age. In conclusion, these results suggested that continuous feeding with ayu-narezushi improved obesity and dyslipidemia in the TSOD mice and that the activation of fatty acid oxidation in the liver might contribute to these improvements.

Development of a novel mouse model of diet-induced nonalcoholic steatohepatitis-related progressive bridging fibrosis

Nonalcoholic steatohepatitis (NASH) progresses to liver fibrosis and cirrhosis. Existing mouse models of NASH rarely develop diet-induced severe fibrosis. We aimed to establish a dietary model of NASH with rapid progression to fibrosis. Six-week-old male Tsumura-Suzuki obese diabetes (TSOD) mice (a model of spontaneous metabolic syndrome) and corresponding control Tsumura-Suzuki nonobese (TSNO) mice were fed a novel diet high in fat, cholesterol, and cholate (iHFC). Histologic steatohepatitis, including steatosis, inflammation, and fibrosis, were observed in both TSNO and TSOD iHFC diet-fed mice at 20 weeks of age. As compared with TSOD mice, TSNO mice developed much more severe fibrosis and reached stage 3 of bridging fibrosis within 14 weeks under the iHFC diet feeding. Perivenular/perisinusoidal pattern of fibrosis in TSNO mice resembled human NASH. Our model of NASH with advanced fibrosis by simple diet offers many advantages useful in studying the mechanism of liver fibrosis and preclinical drug testing.

Butyrate modulates adipose-derived stem cells isolated from polygenic obese and diabetic mice to drive enhanced immunosuppression

BACKGROUND AIMS

Adipose-derived stem cells (ASCs) offer promising therapeutic possibilities for immunomodulation. Butyrate (BA) exerts potent anti-inflammatory effects and exhibits multiple regulatory functionalities in adipose tissue (AT). The authors aimed to explore whether BA modulates ASCs to augment their immunosuppressive capabilities.

METHODS

The authors examined the potency of BA and ASCs for controlling anti-CD3 plus CD28-stimulated splenocyte proliferation in vitro, both in combination and with pre-treatment. Further, the authors investigated genes specifically upregulated by BA-treated ASCs, which were harvested from ASC-splenocyte co-culture after the removal of floating splenocytes. In addition, the authors investigated the influence of oral BA supplementation on the ex vivo immunosuppressive potency of ASCs from BALB/c and Tsumura, Suzuki, obese, diabetes (TSOD) mice.

RESULTS

BA enhanced the immunosuppressive potency of ASCs when directly added to ASC-splenocyte co-cultures or via pre-conditioning treatment. The percentages of ASC-induced Foxp3⁺ regulatory T cells increased, whereas the numbers of ASC-suppressed T helper 17 cells further decreased after BA exposure. The messenger RNA expression levels of inducible nitric oxide (NO) synthase (iNOS), chemokines, IL-10 and amphiregulin in ASCs co-cultured with activated splenocytes were upregulated after incubation with BA. This was accompanied by an amplification of iNOS-inducing cytokines, interferon gamma and tumor necrosis factor alpha in the ASC-splenocyte co-culture, triggering ASCs to produce high NO levels under the influence of BA. Mechanistically, the authors detected BA-mediated acetylated histone H3 in ASCs. BA treatment consistently improved the immunosuppressive potency of ASCs derived from both BALB/c and TSOD mice.

CONCLUSIONS

The use of BA to counteract metaflammation by restoring the defective immunomodulation of ASCs from dysregulated AT in obese donors is recommended.

β-Cryptoxanthin from Satsuma Mandarin and Its Multiple Functions

Satsuma mandarin (Citrus unshiu Marc.), a unique Japanese citrus species, is one of the foods which have most abundant β-cryptoxanthin all over the world. In this study, β-cryptoxanthin has a variety of health-promoting functions such as the body fat reducing, cosmetic (whitening), and osteoporosis prevention. β-Cryptoxanthin has also been shown in human studies to have anti-exercise fatigue and diabetes prevention actions. These multiple functions further support that β-cryptoxanthin may play a role in vitamin A function.

Suppression of Dynamical Network Biomarker Signals at the Predisease State (Mibyou) before Metabolic Syndrome in Mice by a Traditional Japanese Medicine (Kampo Formula) Bofutsushosan

Due to the increasing incidence of metabolic syndrome, the development of new therapeutic strategies is urgently required. One promising approach is to focus on the predisease state (so-called Mibyou in traditional Japanese medicine) before metabolic syndrome as a preemptive medical target. We recently succeeded in detecting a predisease state before metabolic syndrome using a mathematical theory called the dynamical network biomarker (DNB) theory. The detected predisease state was characterized by 147 DNB genes among a total of 24,217 genes in TSOD (Tsumura-Suzuki Obese Diabetes) mice, a well-accepted model of metabolic syndrome, at 5 weeks of age. The timing of the predisease state was much earlier than the onset of metabolic syndrome in TSOD mice reported to be at approximately 8-12 weeks of age. In the present study, we investigated whether the predisease state in TSOD mice can be inhibited by the oral administration of a Kampo formula, bofutsushosan (BTS), which is usually used to treat obese patients with metabolic syndrome in Japan, from 3 to 7 weeks of age. We found the comprehensive suppression of the early warning signals of the DNB genes by BTS at 5 weeks of age and later. Specifically, the standard deviations of 134 genes among the 147 DNB genes decreased at 5 weeks of age as compared to the nontreatment control group, and 80 of them showed more than 50% reduction. In addition, at 7 weeks of age, the body weight and blood glucose level were significantly lower in the BTS-treated group than in the nontreatment control group. The results of our study suggest a novel mechanism of BTS; it suppressed fluctuations of the DNB genes at the predisease state before metabolic syndrome and thus prevented the subsequent transition to metabolic syndrome. In conclusion, this study demonstrated the preventive and preemptive effects of a Kampo formula on Mibyou before metabolic syndrome for the first time based on scientific evaluation.

Phenotypic characterization of a novel type 2 diabetes animal model in a SHANXI MU colony of Chinese hamsters

PURPOSE

Developing animal models for human diseases is critical for studying complex diseases such as type 2 diabetes mellitus (T2DM). Since inbred colonies of Chinese hamsters tend toward spontaneous development of diabetes, we investigated them as a possible model.

METHODS

We regarded individuals with fasting blood glucose (FBG) higher than 6.0 mmol/L and post-prandial blood glucose (PBG) higher than 7.0 mmol/L as diabetic based on the mean and 95% frequency distribution values of FBG and PBG. Diabetic hamsters were characterized based on metabolic profiles, histopathological features, and changes in the expression of genes involved in glucose and lipid metabolism.

RESULTS

Metabolic analyses showed that diabetic hamsters exhibited mild hyperglycemia, hypertriglyceridemia, glucose intolerance, and insulin resistance. Histopathological analysis revealed that cell nuclei migrated inward in skeletal muscle and obvious partial liver lipid deposition and focal necrosis was found. We additionally observed mild injury, atrophy, and occasional vacuolization in islet cells. Changes in the expression of several genes related to glucose and lipid metabolism were observed. Decreased expression of adiponectin and GLUT4 and increased expression of PPARγ, Akt, and leptin was observed in skeletal muscle. Decreased expression of adiponectin with increased expression of PPARγ and leptin was observed in the liver.

CONCLUSIONS

These results indicate that we have established a spontaneous diabetic hamster line that closely mimics human T2DM, which may hold potential for further research on the pathogenesis and treatment of this disease.

Identifying pre-disease signals before metabolic syndrome in mice by dynamical network biomarkers

The establishment of new therapeutic strategies for metabolic syndrome is urgently needed because metabolic syndrome, which is characterized by several disorders, such as hypertension, increases the risk of lifestyle-related diseases. One approach is to focus on the pre-disease state, a state with high susceptibility before the disease onset, which is considered as the best period for preventive treatment. In order to detect the pre-disease state, we recently proposed mathematical theory called the dynamical network biomarker (DNB) theory based on the critical transition paradigm. Here, we investigated time-course gene expression profiles of a mouse model of metabolic syndrome using 64 whole-genome microarrays based on the DNB theory, and showed the detection of a pre-disease state before metabolic syndrome defined by characteristic behavior of 147 DNB genes. The results of our study demonstrating the existence of a notable pre-disease state before metabolic syndrome may help to design novel and effective therapeutic strategies for preventing metabolic syndrome, enabling just-in-time preemptive interventions.

Oral administration of an herbal medicine to prevent progressive hearing loss in a mouse model of diabetes

OBJECTIVE

Tsumura Suzuki Obese Diabetes (TSOD) mice exhibit early age-associated hearing loss. Histopathological analysis of these mice shows narrowing of capillaries in the stria vascularis and chronic reduction of blood flow in the cochlea. In this study, we investigated the effect of oral administration of a herbal medicine or calorie restriction on hearing in TSOD mice.

METHODS

TSOD mice were divided into 4 groups: CR (calorie restriction), BF and DS (treated with the herbal medicines, Bofutsushosan and Daisaikoto, respectively), and the control group. Body weight, blood glucose levels, and auditory brainstem responses (ABRs) were measured. The cochleae were excised and evaluated histopathologically.

RESULTS

Blood glucose levels were suppressed in the CR, BF, and DS groups. In addition, the elevation of ABR thresholds was inhibited in the CR, BF, and DS groups. Cochlear blood vessels remained wide in the three treatment groups compared with the control group. These results suggested that the administration of these herbal medicines improved glucose tolerance and yielded results similar to those on calorie restriction.

CONCLUSION

Oral administration of 2 herbal medicines can prevent hearing function disorder in a model mouse of diabetes. The results may clarify the possibility of clinical application.

Obesity-Linked Cancers: Current Knowledge, Challenges and Limitations in Mechanistic Studies and Rodent Models

The worldwide prevalence of obesity has doubled during the last 50 years, and according to the World Obesity Federation, one third of the people on Earth will be obese by the year 2025. Obesity is described as a chronic, relapsing and multifactorial disease that causes metabolic, biomechanical, and psychosocial health consequences. Growing evidence suggests that obesity is a risk factor for multiple cancer types and rivals smoking as the leading preventable cause for cancer incidence and mortality. The epidemic of obesity will likely generate a new wave of obesity-related cancers with high aggressiveness and shortened latency. Observational studies have shown that from cancer risk to disease prognosis, an individual with obesity is consistently ranked worse compared to their lean counterpart. Mechanistic studies identified similar sets of abnormalities under obesity that may lead to cancer development, including ectopic fat storage, altered adipokine profiles, hormone fluctuations and meta-inflammation, but could not explain how these common mechanisms produce over 13 different cancer types. A major hurdle in the mechanistic underpinning of obesity-related cancer is the lack of suitable pre-clinical models that spontaneously develop obesity-linked cancers like humans. Current approaches and animal models fall short when discerning the confounders that often coexist in obesity. In this mini-review, we will briefly survey advances in the different obesity-linked cancers and discuss the challenges and limitations in the rodent models employed to study their relationship. We will also provide our perspectives on the future of obesity-linked cancer research.

Characteristics of bone strength and metabolism in type 2 diabetic model Tsumura, Suzuki, Obese Diabetes mice

OBJECTIVE

Type 2 diabetes mellitus (T2DM) is a metabolic disease characterized by hyperglycemia, hyperinsulinemia, and complications such as obesity and osteoporosis. The Tsumura, Suzuki, Obese Diabetes (TSOD) mouse is an animal model of spontaneous obese T2DM. However, bone metabolism in TSOD mice is yet to be investigated. The objective of the present study was to investigate the effects of T2DM on bone mass, metabolism, microstructure, and strength in TSOD mice.

METHODS

We determined the following parameters in TSOD mice and Tsumura, Suzuki, Non-obesity (TSNO) mice (as controls): serum glucose levels; serum insulin levels; bone mass; bone microstructure; bone metabolic markers; and bone strength. We also performed the oral glucose tolerance test and examined histological sections of the femur. We compared these data between both groups at pre-diabetic (10 weeks) and established (20 weeks) diabetic conditions.

RESULTS

Bone strength, such as extrinsic mechanical properties, increased with age in the TSOD mice and intrinsic material properties decreased at both 10 weeks and 20 weeks. Bone resorption marker levels in TSOD mice were significantly higher than those in the control mice at both ages, but there was no significant difference in bone formation markers between the groups. Bone mass in TSOD mice was lower than that in controls at both ages. The trabecular bone volume at the femoral greater trochanter increased with age in the TSOD mice. The femoral mid-diaphysis in TSOD mice was more slender and thicker than that in TSNO mice at both ages.

CONCLUSIONS

Bone mass of the femur was lower in TSOD mice than in TSNO mice because hyperinsulinemia during pre-diabetic and established diabetic conditions enhanced bone resorption due to high bone turnover. In addition, our data suggest that the bone mass of the femur was significantly reduced as a result of chronic hyperglycemia during established diabetic conditions in TSOD mice. We suggest that bone strength in the femur deteriorated due to the reduction of bone mass and because the femoral mid-diaphysis was more slender in TSOD mice.

Insulin Regulates Lipolysis and Fat Mass by Upregulating Growth/Differentiation Factor 3 in Adipose Tissue Macrophages

Previous genetic studies in mice have shown that functional loss of activin receptor-like kinase 7 (ALK7), a type I transforming growth factor-β receptor, increases lipolysis to resist fat accumulation in adipocytes. Although growth/differentiation factor 3 (GDF3) has been suggested to function as a ligand of ALK7 under nutrient-excess conditions, it is unknown how GDF3 production is regulated. Here, we show that a physiologically low level of insulin converts CD11c^- adipose tissue macrophages (ATMs) into GDF3-producing CD11c⁺ macrophages ex vivo and directs ALK7-dependent accumulation of fat in vivo. Depletion of ATMs by clodronate upregulates adipose lipases and reduces fat mass in ALK7-intact obese mice, but not in their ALK7-deficient counterparts. Furthermore, depletion of ATMs or transplantation of GDF3-deficient bone marrow negates the in vivo effects of insulin on both lipolysis and fat accumulation in ALK7-intact mice. The GDF3-ALK7 axis between ATMs and adipocytes represents a previously unrecognized mechanism by which insulin regulates both fat metabolism and mass.

Ashitaba (Angelica Keiskei) Exudate Prevents Increases in Plasminogen Activator Inhibitor-1 Induced by Obesity in Tsumura Suzuki Obese Diabetic Mice

Angelica keiskei koidzumi (ashitaba) is consumed as a traditional folk medicine and health food in Japan. Ashitaba extract contains abundant flavonoids containing chalcones. Plasminogen activator inhibitor-1 (PAI-1) is the primary physiological inhibitor of tissue plasminogen activator. Excessive amounts of PAI-1 in plasma disrupt the fibrinolytic balance and promote a prothrombotic state with which thrombosis and cardiovascular diseases are associated. In the present study, we investigated the effects of ashitaba yellow exudate (AE) on enhanced PAI-1 levels in Tsumura Suzuki obese diabetic (TSOD) mice. AE significantly decreased food efficiency and plasma PAI-1 in TSOD mice but did not affect lean control Tsumura Suzuki nonobese (TSNO) mice. AE also decreased some parameters in the plasma, such as glucose, insulin, tumor necrosis factor alpha (TNF-α) and gains in body weight, subcutaneous, mesenteric fat weight in TSOD mice but had little effect on these parameters in TSNO mice. Levels of adipose PAI-1 were significantly higher in TSOD than in TSNO mice. Major sources of plasma PAI-1 are thought to be adipose tissue and liver. AE significantly suppressed PAI-1 protein levels in the livers of both TSOD and TSNO mice. These results suggest that AE decreased plasma PAI-1 levels by suppressing both the adipose tissue retention of PAI-1 protein and liver PAI-1 production in TSOD mice. Supplementing the diet with AE might help to prevent thrombotic diseases or alleviate the risk of thrombotic diseases as well as to suppress metabolic state in obese individuals.

Tsumura-Suzuki obese diabetic mice-derived hepatic tumors closely resemble human hepatocellular carcinomas in metabolism-related genes expression and bile acid accumulation

BACKGROUND AND AIMS

Tsumura-Suzuki obese diabetic (TSOD) is a good model of metabolic syndrome showing typical lesions found in nonalcoholic fatty liver disease and nonalcoholic steatohepatitis, and develops spontaneous hepatic tumors with a high frequency. Majority of the developing tumors overexpress glutamine synthetase (GS), which is used as a marker of hepatocellular carcinoma (HCC). The aim of this study is to assess the status of expression of metabolism-related genes and the level of bile acids in the TSOD mice-derived tumors and to determine the association with metabolic dysregulation between human HCC and TSOD mice-derived tumors.

METHODS

GS-positive hepatic tumors or adjacent normal tissues from 71-week-old male TSOD mice were subjected to immunohistochemical staining, quantitative RT-PCR (qRT-PCR), quantitation of cholic acid and taurocholic acid.

RESULTS

We found that downregulation of the rate-limiting enzyme for betaine synthesis (BADH), at both mRNA and protein levels in GS-positive TSOD mice-derived tumors. Furthermore, the bile acid receptor FXR and the bile acid excretion pump BSEP (Abcb11) were found to be downregulated, whereas BAAT and Akr1c14, involved in primary bile acid synthesis and bile acid conjugation, were found to be upregulated at mRNA level in GS-positive TSOD mice-derived tumors. BAAT and Akr1c14 were also overexpressed at protein levels. Total cholic acid was found to be increased in GS-positive TSOD mice-derived tumors.

CONCLUSION

Our results strongly support the significance of TSOD mice as a model of spontaneously developing HCC.

From mice to men – mouse models in obesity research: What can we learn?

Obesity has become a world-wide epidemic and is associated with diseases such as diabetes, dyslipidaemia, cardiovascular disease and certain types of cancers. Understanding the adipose tissue developmental process, involving adipogenesis, angiogenesis and extracellular matrix remodelling, is therefore crucial to reveal the pathobiology of obesity. Experimental mouse models are extensively used to gain new insights into these processes and to evaluate the role of new key players, in particular proteolytic system components, in adipose tissue development and obesity. In this paper, we will review available in vitro and in vivo murine models of obesity and discuss their value in understanding the mechanisms contributing to obesity.

Animal models for analyzing metabolic syndrome-associated liver diseases

Metabolic syndrome (MS) is a worldwide healthcare issue and a dominant risk factor for the development of incurable diseases affecting the entire body. The hepatic manifestations of MS include nonalcoholic fatty liver disease (NAFLD) and its progressive variant, nonalcoholic steatohepatitis (NASH). NASH is known to progress to liver cirrhosis and hepatocellular carcinoma (HCC). Excellent animal models for determining the mechanism of pathogenesis and establishing therapeutic treatment of NASH/HCC are strongly required worldwide. We recently reported that two previously established mouse models of obesity and diabetes mellitus, namely, Tsumura-Suzuki Obese Diabetes (TSOD) mice and MSG mice, developed MS-associated NASH and that their clinical course and pathological characteristics closely mimicked those of human MS-NASH patients. Interestingly, most of the mice developed HCC with advancing age, and the pathological and functional characteristics of this condition were identical to those of human HCC. We further established a novel mouse model of HCC based on type 1 diabetes (DIAR-nSTZ mice) and reported its histopathological features. By comparing various aspects of these mouse models, specific and useful characteristics in a suitable model of MS-associated liver diseases, including hepato-carcinogenesis, can be highlighted.

Reduction and fragmentation of elastic fibers in the skin of obese mice is associated with altered mRNA expression levels of fibrillin-1 and neprilysin

AIM OF THE STUDY

Our previous research suggested that obesity induces structural fragility in the skin. Elastic fibers impart strength and elasticity. In this study, we determined whether elastic fibers decrease in the skin of obese mice.

MATERIALS AND METHODS

To confirm alterations in elastic fiber content due to obesity, we used spontaneously obese model mice (TSOD) and control mice (TSNO). Furthermore, to evaluate the elastin structure and gene expression dependent on the severity of obesity, an obesity-enhanced mouse model was developed by feeding a high fat diet to TSOD (TSOD-HF). Back skin samples were stained with hematoxylin and eosin and Elastica van Gieson for microscopic examination, and the samples were stained for immunohistochemical analysis of neprilysin. Gene expression levels were determined using a real-time PCR system.

RESULTS

The abundance of elastic fibers beneath the epidermis was remarkably reduced and fragmented in TSOD as compared with TSNO. Fibrillin-1 mRNA levels in TSOD were significantly suppressed compared with those in TSNO, whereas neprilysin mRNA levels and immunohistochemical expression in TSOD were significantly increased, as compared with those in TSNO. The reduction of elastic fibers was enhanced and the expression levels of elastic fiber formed factors were significantly suppressed in TSOD-HF, as compared with those in the TSOD.

CONCLUSIONS

The abundance of elastic fibers was reduced and fragmented in obesity, suggesting that the reduction in elastic fibers is initially caused by increased neprilysin and decreased fibrillin-1 expression, which may inhibit formation and stabilization of elastic fibers, resulting in skin fragility in obesity.

4-Nitroquinoline 1-Oxide-Induced Tongue and Esophagus Carcinogenesis in Obese and Diabetic TSOD Mice

Background

Obesity and diabetes mellitus are associated with lifestyle-related carcinogenesis. They are also risk factors of esophageal adenocarcinoma, but there are only a few reports on association between obesity/diabetes and development of squamous cell carcinoma in the oral cavity and esophagus. In this study, we therefore aimed to determine whether obesity and diabetes affect oral and esophageal carcinogenesis using model mice of obesity and diabetes, the Tsumura Suzuki obese diabetes (TSOD) and Tsumura Suzuki non-obesity (TSNO) control mice, which were treated with 4-nitroquinoline 1-oxide (4-NQO) to produce tongue and esophageal carcinomas.

Methods

We used 28 each of the male TSOD and TSNO mice of 8 weeks of age. They were divided into the 4-NQO-treated group (n = 20) and untreated group (n = 8). 4-NQO was administered to mice in drinking water at a dose level of 20 ppm for 8 weeks. The untreated group was given distilled water without 4-NQO. At 28 experimental weeks, histopathological examination was performed on all organs including tongue and esophagus. We performed analysis of histopathology of all organs which included buccal capsule (a tongue)/esophagus after an experiment start in 28 weeks. Fasting plasma glucose (FPG) and lipid parameters including total cholesterol (T-Cho), triglyceride (TG), high-density lipoprotein (HDL)-cholesterol and low-density lipoprotein (LDL)-cholesterol were measured and all these parameters were compared between the two genotypes. Also, mRNA expression of eight cytokines including interleukin (IL)-1β, IL-6, IL-17, interferon (IFN)-γ, keratinocyte-derived cytokine (KC), macrophage inflammatory protein (MIP)-1α, MIP-2, and tumor necrosis factor (TNF)-α in the esophageal mucosa was assayed.

Results

4-NQO treatment produced proliferative squamous cell lesions (dysplasia, papilloma and carcinoma) in the tongue and esophagus of both the TSOD and TSNO mice. The incidence and multiplicity of tongue tumors were 30% and 0.45 ± 0.83 in the TSOD mice and 30% and 0.40 ± 0.68 in the TSNO mice. The incidence and multiplicity of esophageal tumors were 70% and 2.25 ± 2.29 in the TSOD mice and 30% and 0.60 ± 1.14 (P < 0.01) in the TSNO mice.

Conclusion

Our findings indicate that the obese and diabetic TSOD mice were susceptible to 4-NQO-induced esophageal carcinogenesis, suggesting risk factors of obese and diabetes for esophageal squamous cell carcinoma. Additionally, the TSOD mice were useful as esophagus carcinogenic model. Our study first reported that 4-NQO induced esophageal cancer in mice.

Comparative analysis of the intestinal flora in type 2 diabetes and nondiabetic mice

A relationship between type 2 diabetes mellitus (T2DM) and intestinal flora has been suggested since development of analysis technology for intestinal flora. An animal model of T2DM is important for investigation of T2DM. Although there are some animal models of T2DM, a comparison of the intestinal flora of healthy animals with that of T2DM animals has not yet been reported. The intestinal flora of Tsumura Suzuki Obese Diabetes (TSOD) mice was compared with that of Tsumura, Suzuki, Non Obesity (TSNO) mice in the present study. The TSOD mice showed typical type 2 diabetes symptoms, which were high-fat diet-independent. The TSOD and the TSNO mouse models were derived from the same strain, ddY. In this study, we compared the intestinal flora of TSOD mice with that if TSNO mice at 5 and 12 weeks of age. We determined that that the number of operational taxonomic units (OTUs) was significantly higher in the cecum of TSOD mice than in that of TSNO mice. The intestinal flora of the cecum and that of the feces were similar between the TSNO and the TSOD strains. The dominant bacteria in the cecum and feces were of the phyla Firmicutes and Bacteroidetes. However, the content of some bacterial species varied between the two strains. The percentage of Lactobacillus spp. within the general intestinal flora was higher in TSOD mice than in TSNO mice. In contrast, the percentages of order Bacteroidales and family Lachnospiraceae were higher in TSNO mice than in TSOD mice. Some species were observed only in TSOD mice, such as genera Turicibacter and SMB53 (family Clostridiaceae), the percentage of which were 3.8% and 2.0%, respectively. Although further analysis of the metabolism of the individual bacteria in the intestinal flora is essential, genera Turicibacter and SMB53 may be important for the abnormal metabolism of type 2 diabetes.

Daily Coffee Intake Inhibits Pancreatic Beta Cell Damage and Nonalcoholic Steatohepatitis in a Mouse Model of Spontaneous Metabolic Syndrome, Tsumura-Suzuki Obese Diabetic Mice

BACKGROUND

Metabolic syndrome is one of the most important health issues worldwide. Obesity causes insulin resistance, hyperlipidemia, diabetes, and various diseases throughout the body. The liver phenotype, which is called nonalcoholic steatohepatitis (NASH), frequently progresses to hepatocellular carcinoma. We recently established a new animal model, Tsumura-Suzuki obese diabetic (TSOD) mice, which spontaneously exhibit obesity, diabetes, hyperlipidemia, and NASH with liver nodules.

METHODS

We examined the effects of coffee intake on various conditions of the metabolic syndrome using TSOD mice. The daily volume of coffee administered was limited so that it reflected the appropriate quantities consumed in humans. To clarify the effects of the specific components, animals were divided into two coffee-intake groups that included with and without caffeine.

RESULTS

Coffee intake did not significantly affect obesity and hyperlipidemia in TSOD mice. In contrast, coffee intake caused various degrees of improvement in the pancreatic beta cell damage and steatohepatitis with liver carcinogenesis. Most of the effects were believed to be caused by a synergistic effect of caffeine with other components such as polyphenols. However, the antifibrotic effects of coffee appeared to be due to the polyphenols rather than the caffeine.

CONCLUSIONS

A daily habit of drinking coffee could possibly play a role in the prevention of metabolic syndrome.

Animal models for assessing the impact of natural products on the aetiology and metabolic pathophysiology of Type 2 diabetes

Type 2 diabetes mellitus is a complex and heterogeneous disorder which in its most common manifestation arises from insulin resistance and later insulin insufficiency. Type 2 diabetes is characterised by impaired insulin sensitivity and diagnosed as hyperglycaemia. Because of its cardiovascular consequences, Type 2 diabetes represents one of the world's leading causes of mortality and morbidity. Drug discovery and development are required to produce better ways to prevent, treat and manage diabetes and its complications. Diabetes is a human, not an animal disease, so animals do not get Type 2 diabetes. However there are animal models which are variously suitable for the investigation of new agents for the treatment of Type 2 diabetes. In this Review we have examined the various models that are available for the study of natural products with a focus on models (genetic, nutritional and spontaneous) for the metabolic abnormities of diabetes. These models are also relevant to the investigation of Western medicines for the treatment of diabetes. A suitable experimental model plays an important role in drug discovery for translational studies leading to increased understanding of the molecular basis and management of diabetes.

A study of hearing function and histopathologic changes in the cochlea of the type 2 diabetes model Tsumura Suzuki obese diabetes mouse

OBJECTIVES

This study used Tsumura Suzuki Obese Diabetes (TSOD) mice as a spontaneous type 2 diabetes model and Tsumura Suzuki Non-obesity (TSNO) mice as controls to investigate factors involved in the onset of hearing impairment.

METHOD

Body weight, blood glucose levels, and auditory brainstem responses (ABRs) were measured. The cochleae were excised and evaluated histopathologically.

RESULTS

The TSOD mice showed significant hyperglycemia at 2-7 months and severe obesity at 5-10 months; significantly elevated ABR thresholds at 8-10 months; and the capillary lumens in the cochlea stria vascularis were narrower in the TSOD mice than in the TSNO mice. At 17 months, India ink vascular staining of the TSOD mice's cochleae revealed decreased capillary density in the stria vascularis. The vascular area of capillaries in the stria vascularis and the vascular area were significantly smaller in TSOD mice. Histopathological analysis showed vessel wall thickening in the modiolus and narrowed capillaries in the stria vascularis, suggesting reduced blood flow to the inner ear.

CONCLUSION

The diabetes mice model used in our study showed early age-associated hearing loss, and histopathology showed findings of vessel wall thickening in the modiolus, narrowing of capillaries in the stria vascularis, and chronically reduced blood flow in the cochlea.

Animal models of insulin resistance: A review

Insulin resistance can be seen as a molecular and genetic mystery, with a role in the pathophysiology of type 2 diabetes mellitus. It is a basis for a number of chronic diseases like hypertension, dyslipidemia, glucose intolerance, coronary heart disease, cerebral vascular disease along with T2DM, thus the key is to cure and prevent insulin resistance. Critical perspicacity into the etiology of insulin resistance have been gained by the use of animal models where insulin action has been modulated by various transgenic and non-transgenic models which is not possible in human studies. The following review comprises the pathophysiology involved in insulin resistance, various factors causing insulin resistance, their screening and various genetic and non-genetic animal models highlighting the pathological and metabolic characteristics of each.

Histopathological characteristics of glutamine synthetase-positive hepatic tumor lesions in a mouse model of spontaneous metabolic syndrome (TSOD mouse)

We previously reported that Tsumura-Suzuki obese diabetic (TSOD) mice, a polygenic model of spontaneous type 2 diabetes, is a valuable model of hepatic carcinogenesis via non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH). One of the characteristics of tumors in these mice is the diffuse expression of glutamine synthetase (GS), which is a diagnostic marker for hepatocellular carcinoma (HCC). In this study, we performed detailed histopathological examinations and found that GS expression was diffusely positive in >70% of the hepatic tumors from 15-month-old male TSOD mice. Translocation of β-catenin into nuclei with enhanced membranous expression also occurred in GS-positive tumors. Small lesions (<1 mm) in GS-positive cases exhibited dysplastic nodules, with severe nuclear atypia, whereas large lesions (>3 mm) bore the characteristics of human HCC, exhibiting nuclear and structural atypia with invasive growth. By contrast, the majority of GS-negative tumors were hepatocellular adenomas with advanced fatty change and low nuclear grade. In GS-negative tumors, loss of liver fatty acid-binding protein expression was observed. These results suggest that the histological characteristics of GS-positive hepatic tumors in TSOD mice resemble human HCC; thus, this model may be a useful tool in translational research targeting the NAFLD/NASH-HCC sequence.

Pathophysiology and Mechanisms of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) encompasses a spectrum of liver disorders characterized by abnormal hepatic fat accumulation, inflammation, and hepatocyte dysfunction. Importantly, it is also closely linked to obesity and the metabolic syndrome. NAFLD predisposes susceptible individuals to cirrhosis, hepatocellular carcinoma, and cardiovascular disease. Although the precise signals remain poorly understood, NAFLD pathogenesis likely involves actions of the different hepatic cell types and multiple extrahepatic signals. The complexity of this disease has been a major impediment to the development of appropriate metrics of its progression and effective therapies. Recent clinical data place increasing importance on identifying fibrosis, as it is a strong indicator of hepatic disease-related mortality. Preclinical modeling of the fibrotic process remains challenging, particularly in the contexts of obesity and the metabolic syndrome. Future studies are needed to define the molecular pathways determining the natural progression of NAFLD, including key determinants of fibrosis and disease-related outcomes. This review covers the evolving concepts of NAFLD from both human and animal studies. We discuss recent clinical and diagnostic methods assessing NAFLD diagnosis, progression, and outcomes; compare the features of genetic and dietary animal models of NAFLD; and highlight pharmacological approaches for disease treatment.

Oleuropein-Rich Diet Attenuates Hyperglycemia and Impaired Glucose Tolerance in Type 2 Diabetes Model Mouse

Oleuropein, a phenolic compound found in abundance in olive leaves, has beneficial effects on various diseases. However, it is unknown whether an oleuropein-rich diet is efficacious against type 2 diabetic phenotypes. In this study, we investigated the effects of the oleuropein-containing supplement OPIACE, whose oleuropein content exceeds 35% (w/w), on the diabetic phenotypes in type 2 diabetes model Tsumura Suzuki Obese Diabetes (TSOD) mouse. TSOD mice were fed OPIACE at 4 weeks of age, i.e., before the TSOD mice exhibited diabetic phenotypes. We revealed that OPIACE attenuated hyperglycemia and impaired glucose tolerance in TSOD mice over the long-term (from 10 to 24 weeks of age) but had no effect on obesity. Furthermore, we demonstrated that OPIACE mildly reduced oxidative stress in TSOD mice by 26.2% and attenuated anxiety-like behavioral abnormality in aged TSOD mice. The results suggest that oleuropein suppresses the progression of type 2 diabetes and diabetes-related behavioral abnormality over the long-term.

Current status and patent prospective of animal models in diabetic research

Diabetes mellitus is a heterogeneous complex metabolic disorder with multiple etiology which characterized by chronic hyperglycemia resulting from defects in insulin secretion, insulin action or both. The widespread occurrence of diabetes throughout the world has increased dramatically over the past few years. For better understanding, appropriate animal models that closely mimic the changes in humans needed, as vital tool for understanding the etiology and pathogenesis of the disease at the cellular/molecular level and for preclinical testing of drugs. This review aims to describe the animal models of type-1 diabetes (T1Ds) and T2Ds to mimic the causes and progression of the disease in humans. And also we highlight patent applications published in the last few years related to animal models in diabetes as an important milestone for future therapies that are aim to treating diabetes with specific symptoms and complications.

Obesity genetics in mouse and human: back and forth, and back again

Obesity is a major public health concern. This condition results from a constant and complex interplay between predisposing genes and environmental stimuli. Current attempts to manage obesity have been moderately effective and a better understanding of the etiology of obesity is required for the development of more successful and personalized prevention and treatment options. To that effect, mouse models have been an essential tool in expanding our understanding of obesity, due to the availability of their complete genome sequence, genetically identified and defined strains, various tools for genetic manipulation and the accessibility of target tissues for obesity that are not easily attainable from humans. Our knowledge of monogenic obesity in humans greatly benefited from the mouse obesity genetics field. Genes underlying highly penetrant forms of monogenic obesity are part of the leptin-melanocortin pathway in the hypothalamus. Recently, hypothesis-generating genome-wide association studies for polygenic obesity traits in humans have led to the identification of 119 common gene variants with modest effect, most of them having an unknown function. These discoveries have led to novel animal models and have illuminated new biologic pathways. Integrated mouse-human genetic approaches have firmly established new obesity candidate genes. Innovative strategies recently developed by scientists are described in this review to accelerate the identification of causal genes and deepen our understanding of obesity etiology. An exhaustive dissection of the molecular roots of obesity may ultimately help to tackle the growing obesity epidemic worldwide.

Type 2 diabetes model TSOD mouse is exposed to oxidative stress at young age

Tsumura Suzuki Obese Diabetes (TSOD) mouse, a model of obese type 2 diabetes, older than around 11 weeks of age develops diabetic phenotypes. Previous studies have indicated that the development of diabetes is partly due to three loci associated with body weight and glucose homeostasis. However, little is known about the initial events triggering the development of the diabetic phenotypes in TSOD mouse. Here, we investigated the alteration of diabetes-related parameters, including the levels of blood glucose and inflammatory cytokines, and the oxidative stress status, in young TSOD mice. TSOD mice at 5 weeks of age showed increases in body weight and plasma total cholesterol level, but not hyperglycemia or impaired glucose tolerance, compared with age-matched control Tsumura Suzuki Non-Obese (TSNO) mice. Plasma tumor necrosis factor (TNF)-α and interleukin (IL)-6 were not detected in TSOD mice at 5 weeks of age. However, plasma total hydroxyoctadecadienoic acid (tHODE), a biomarker of oxidative stress, was increased in TSOD mice relative to TSNO mice at same age. The results demonstrated that young TSOD mice are exposed to oxidative stress before developing the diabetic phenotypes, and suggested that oxidative stress is an initial event triggering the development of diabetes in TSOD mice.

The peroxisome proliferator-activated receptor (PPAR) α agonist fenofibrate suppresses chemically induced lung alveolar proliferative lesions in male obese hyperlipidemic mice

Activation of peroxisome proliferator-activated receptor (PPAR) α disrupts growth-related activities in a variety of human cancers. This study was designed to determine whether fenofibrate, a PPARα agonist, can suppress 4-nitroquinoline 1-oxide (4-NQO)-induced proliferative lesions in the lung of obese hyperlipidemic mice. Male Tsumura Suzuki Obese Diabetic mice were subcutaneously injected with 4-NQO to induce lung proliferative lesions, including adenocarcinomas. They were then fed a diet containing 0.01% or 0.05% fenofibrate for 29 weeks, starting 1 week after 4-NQO administration. At week 30, the incidence and multiplicity (number of lesions/mouse) of pulmonary proliferative lesions were lower in mice treated with 4-NQO and both doses of fenofibrate compared with those in mice treated with 4-NQO alone. The incidence and multiplicity of lesions were significantly lower in mice treated with 4-NQO and 0.05% fenofibrate compared with those in mice treated with 4-NQO alone (p<0.05). Both doses of fenofibrate significantly reduced the proliferative activity of the lesions in 4-NQO-treated mice (p<0.05). Fenofibrate also significantly reduced the serum insulin and insulin-like growth factor (IGF)-1 levels, and decreased the immunohistochemical expression of IGF-1 receptor (IGF-1R), phosphorylated Akt, and phosphorylated Erk1/2 in lung adenocarcinomas. Our results indicate that fenofibrate can prevent the development of 4-NQO-induced proliferative lesions in the lung by modulating the insulin-IGF axis.

Modeling progressive non-alcoholic fatty liver disease in the laboratory mouse

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease in the world and its prevalence is rising. In the absence of disease progression, fatty liver poses minimal risk of detrimental health outcomes. However, advancement to non-alcoholic steatohepatitis (NASH) confers a markedly increased likelihood of developing severe liver pathologies, including fibrosis, cirrhosis, organ failure, and cancer. Although a substantial percentage of NAFLD patients develop NASH, the genetic and molecular mechanisms driving this progression are poorly understood, making it difficult to predict which patients will ultimately develop advanced liver disease. Deficiencies in mechanistic understanding preclude the identification of beneficial prognostic indicators and the development of effective therapies. Mouse models of progressive NAFLD serve as a complementary approach to the direct analysis of human patients. By providing an easily manipulated experimental system that can be rigorously controlled, they facilitate an improved understanding of disease development and progression. In this review, we discuss genetically- and chemically-induced models of NAFLD that progress to NASH, fibrosis, and liver cancer in the context of the major signaling pathways whose disruption has been implicated as a driving force for their development. Additionally, an overview of nutritional models of progressive NAFLD is provided.

Pentraxin 3 production in the adipose tissue and the skeletal muscle in diabetic-obese mice

: Inflammation has been shown to promote obesity-induced insulin resistance. Although pentraxin (PTX) 3 is known as an anti-inflammatory factor, the effect of PTX3 on insulin sensitivity has not yet been elucidated. The aim of this study is to investigate a part of the role of PTX3 on insulin sensitivity. The authors studied the PTX3 and glucose transport protein expression levels in epididymal adipose tissue and soleus muscles of male diabetic-obese [Tsumura Suzuki obese-diabetic (TSOD)] and lean control mice. The levels of PTX3 in both skeletal muscle and adipose tissue were significantly lower in TSOD mice than in controls, and there was a significant positive correlation between them. They observed a significant positive correlation between PTX3 and glucose transport protein 4 levels in skeletal muscle. This study suggests that PTX3 may play a part of role as promoting insulin sensitivity of skeletal muscle in TSOD mice.

Gender differences in metabolic disorders and related diseases in Spontaneously Diabetic Torii-Lepr(fa) rats

The Spontaneously Diabetic Torii Lepr(fa) (SDT fatty) rat is a novel type 2 diabetic model wherein both male and female rats develop glucose and lipid abnormalities from a young age. In this study, we investigated gender differences in abnormalities and related complications in SDT fatty rats. Food intake was higher in males compared to female rats; however, body weight was not different between genders. Progression of diabetes, including increases in blood glucose and declines in blood insulin, was observed earlier in male rats than in females, and diabetic grade was more critical in male rats. Blood lipids tended to increase in female rats. Gonadal dysfunction was observed in both male and female rats with aging. Microangiopathies, such as nephropathy, retinopathy, neuropathy, and osteoporosis, were seen in both genders, and pathological grade and progression were more significant in males. Qualitative and quantitative changes were observed for metabolic disease gender differences in SDT fatty rats. The SDT fatty rat is a useful model for researching gender differences in metabolic disorders and related diseases in diabetes with obesity.

A review of rodent models of type 2 diabetic skeletal fragility

Evidence indicating that adult type 2 diabetes (T2D) is associated with increased fracture risk continues to mount. Unlike osteoporosis, diabetic fractures are associated with obesity and normal to high bone mineral density, two factors that are typically associated with reduced fracture risk. Animal models will likely play a critical role in efforts to identify the underlying mechanisms of skeletal fragility in T2D and to develop preventative treatments. In this review we critically examine the ability of current rodent models of T2D to mimic the skeletal characteristics of human T2D. We report that although there are numerous rodent models of T2D, few have undergone thorough assessments of bone metabolism and strength. Further, we find that many of the available rodent models of T2D have limitations for studies of skeletal fragility in T2D because the onset of diabetes is often prior to skeletal maturation and bone mass is low, in contrast to what is seen in adult humans. There is an urgent need to characterize the skeletal phenotype of existing models of T2D, and to develop new models that more closely mimic the skeletal effects seen in adult-onset T2D in humans.

Skin and diabetes mellitus: what do we know?

Diabetes mellitus (DM) is becoming increasingly prevalent worldwide. Although major complications of this condition involve kidney, retina and peripheral nerves, the skin of diabetic patients is also frequently injured. Hence, interest is mounting in the definition of the structural and molecular profile of non-complicated diabetic skin, i.e., before injuries occur. Most of the available knowledge in this area has been obtained relatively recently and, in part, derives from various diabetic animal models. These include both insulin-dependent and insulin-resistant models. Structural work in human diabetic skin has also been carried out by means of tissue samples or of non-invasive methods. Indications have indeed been found for molecular/structural changes in diabetic skin. However, the overall picture that emerges is heterogeneous, incomplete and often contradictory and many questions remain unanswered. This review aims to detail, as much as possible, the various pieces of current knowledge in a systematic and synoptic manner. This should aid the identification of areas in which key questions are still open and more research is needed. A comprehensive understanding of this field could help in determining molecular targets for the prevention and treatment of skin injuries in DM and markers for the monitoring of cutaneous and systemic aspects of the disease. Additionally, with the increasing development of non-invasive optics-based deep-tissue-imaging diagnostic technologies, precise knowledge of cutaneous texture and molecular structure becomes an important pre-requisite for the use of such methods in diabetic patients.