Tsumura Suzuki Non-obesity Mice Research Articles

Impacts of liver macrophages, gut microbiota, and bile acid metabolism on the differences in iHFC diet-induced MASH progression between TSNO and TSOD mice.

Tsumura-Suzuki non-obese (TSNO) mice exhibit a severe form of metabolic dysfunction-associated steatohepatitis (MASH) with advanced liver fibrosis upon feeding a high-fat/cholesterol/cholate-based (iHFC) diet. Another ddY strain, Tsumura-Suzuki diabetes obese (TSOD) mice, are impaired in the progression of iHFC diet-induced MASH. To elucidate the underlying mechanisms contributing to the differences in MASH progression between TSNO and TSOD mice. We analyzed differences in the immune system, gut microbiota, and bile acid metabolism in TSNO and TSOD mice fed with a normal diet (ND) or an iHFC diet. TSOD mice had more anti-inflammatory macrophages in the liver than TSNO mice under ND feeding, and were impaired in the iHFC diet-induced accumulation of fibrosis-associated macrophages and formation of histological hepatic crown-like structures in the liver. The gut microbiota of TSOD mice also exhibited a distinct community composition with lower diversity and higher abundance of Akkermansia muciniphila compared with that in TSNO mice. Finally, TSOD mice had lower levels of bile acids linked to intestinal barrier disruption under iHFC feeding. The dynamics of liver macrophage subsets, and the compositions of the gut microbiota and bile acids at steady state and post-onset of MASH, had major impacts on MASH development.

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.

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

ObjectiveType 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. MethodsWe 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. ResultsBone 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. ConclusionsBone 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.

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

ABSTRACTAngelica 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.

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

BackgroundObesity 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.MethodsWe 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.Results4-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.ConclusionOur 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.

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.

Switching from singlet-oxygen-mediated oxidation to free-radical-mediated oxidation in the pathogenesis of type 2 diabetes in model mouse

Oxidative stress plays a key role in the development of type 2 diabetes. However, it is still unknown what kind of oxidative stress underlies the development of type 2 diabetes. We investigated hydroxyoctadecadienoic acid (HODE) isomers, which have been proposed as a biomarker for evaluating oxidative stress in vivo, during the development of diabetes in Tsumura Suzuki Obese Diabetes (TSOD) mouse, a type 2 diabetes model. It was revealed that glucose tolerance and insulin resistance index HOMA-IR in TSOD mice at 5 weeks of age were approximately normal, namely, the mice were in the prediabetic state, but these levels were significantly exacerbated from 8 weeks of age compared with those in Tsumura Suzuki Non Obesity (TSNO) mice (control). Concomitantly, the plasma levels of free-radical-mediated oxidation products, 9- and 13-(E,E)-HODE and 7β-hydroxycholesterol, in TSOD mice were significantly higher than those in TSNO mice at 8, and 8 and 11 weeks of age, respectively. Interestingly, the plasma levels of 10- and 12-(Z,E)-HODE, which are produced specifically by singlet-oxygen-mediated oxidation, in TSOD mice were higher than those in TSNO mice only at 5 weeks of age, and not at 8, 11, and 13 weeks of age. We demonstrated that singlet-oxygen-mediated oxidation occurred in TSOD mice before development of the diabetic phenotypes, including impaired glucose tolerance and insulin resistance. These results suggest that excessive singlet-oxygen-mediated oxidation plays an important role in the pathogenesis of type 2 diabetes.

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.

Possible Involvement of Hypothalamic Nucleobindin-2 in Hyperphagic Feeding in Tsumura Suzuki Obese Diabetes Mice

The aim of this study was to clarify the hypothalamic neuropeptides that are associated with hyperphagic feeding in Tsumura Suzuki Obese Diabetes (TSOD) mice, a model of type 2 diabetes with polygenic abnormalities. TSOD mice showed an increase in body weight and hyperleptinemia from 1 month of age and hyperphagic feeding, hyperglycemia, hyperlipidemia and hyperinsulinemia from 3 to 12 months of age compared with age-matched non-diabetic control Tsumura Suzuki Non Obesity (TSNO) mice. The mRNA level of nucleobindin-2 (NUCB2), the precursor of the anorexigenic neuropeptide nesfatin-1, was significantly decreased in the hypothalamus of TSOD mice compared with that in TSNO mice from 3 to 12 months of age. The protein level of NUCB2 was significantly decreased in the hypothalamus of TSOD mice compared with that in TSNO mice at 3 months of age. The mRNA levels of galanin, melanin-concentrating hormone, neuropeptide Y, and pro-opiomelanocortin were significantly changed in the hypothalamus in TSOD mice at several time points. Another model of type 2 diabetes, db/db mice, which is a mutant mouse that lacks a functional leptin receptor, showed hyperphagic feeding but no change in hypothalamic NUCB2 mRNA compared with non-diabetic control db/+ mice. The results suggest that the disrupted control of hypothalamic NUCB2-mediated signaling may contribute to hyperphagic feeding in TSOD mice. In addition, the mechanism for the development of hyperphagic feeding in TSOD mice is different than that in db/db mice.

Aging-Like Skin Changes Induced by Ultraviolet Irradiation in an Animal Model of Metabolic Syndrome

Both physiological skin aging and pathologic photo-aging caused by ultraviolet (UV) irradiation are mediated by latent inflammation and oxidative stress. Although numerous animal skin-aging models have used UV irradiation, most require massive doses or long-term irradiation. To establish a more refined skin-aging model, we focused on an animal model of metabolic syndrome (MS) because MS involves damage to various organs via oxidative stress or inflammation, similar to the changes associated with aging. We hypothesized that MS skin might exhibit more aging-like changes after milder, shorter-term UV irradiation than would normal animal skin under similar conditions, thus providing a useful model for skin aging. The authors therefore examined the skin from Tsumura Suzuki obese diabetic (TSOD) mice (MS model) and control Tsumura Suzuki non-obese (TSNO) mice before and after UV irradiation. Skin from TSOD mice had a thinner epidermis and dermis, a thicker fatty layer, reduced density and convolution of the fragmented collagen fibers, and upregulated expression of tumor necrosis factor (TNF)-α, a dual marker for inflammation and aging, compared to the skin from TSNO mice. UV irradiation affected TSOD skin more severely than TSNO skin, resulting in various changes resembling those in aged human skin, including damage to the dermis and subcutaneous fatty tissue, infiltration of inflammatory cells, and further upregulation of TNF-α expression. These results suggest that UV-irradiated TSOD mice may provide a new model of skin aging and imply that skin from humans with MS is more susceptible to UV- or aging-related damage than normal human skin.

Preventive Effect of Boiogito on Metabolic Disorders in the TSOD Mouse, a Model of Spontaneous Obese Type II Diabetes Mellitus

“Boiogito” is a Kampo preparation which has been used since ancient times in patients with obesity of the “asthenic constitution” type, so-called “watery obesity”, and its effect has been recognized clinically. In this study, we investigated the anti-obesity effect of Boiogito in the TSOD (Tsumura Suzuki Obese Diabetes) mouse, a model of spontaneous obese type II diabetes mellitus. Boiogito showed a significant anti-obesity effect in TSOD mice by suppressing body weight gain in a dosage-dependent manner. In addition, Boiogito showed significant ameliorative effects on features of metabolic syndrome such as hyperinsulinemia, fasting hyperglycemia and abnormal lipid metabolism. Regarding lipid accumulation in TSOD mice, Boiogito showed a significant suppressive effect on accumulation of subcutaneous fat, but the effect on the visceral fat accumulation that constitutes the basis of metabolic syndrome was weak, and the suppressive effect on insulin resistance was also weak. Furthermore, Boiogito did not alleviate the abnormal glucose tolerance, the hypertension or the peripheral neuropathy characteristically developed in the TSOD mice. In contrast, in the TSNO (Tsumura Suzuki Non-Obesity) mice used as controls, Boiogito suppressed body weight gain and accumulation of subcutaneous and visceral fat. The above results suggested that Boiogito is effective as an anti-obesity drug against obesity of the “asthenic constitution” type in which subcutaneous fat accumulates, but cannot be expected to exert a preventive effect against various symptoms of metabolic syndrome that are based on visceral fat accumulation.

Antiobesity effects of Kaempferia parviflora in spontaneously obese type II diabetic mice

Kaempferia parviflora Wall. Ex Baker (KP) has been used as a folk medicine in Laos and Thailand to lower blood glucose levels, improve blood flow, and increase vitality. This study investigated the preventive effects of KP on obesity and its downstream symptoms (various metabolic disorders) using Tsumura, Suzuki, Obese Diabetes (TSOD) mice, a multifactorial genetic disease animal model in which metabolic diseases develop spontaneously, similar to metabolic syndrome in humans, and Tsumura, Suzuki, Non-Obesity (TSNO) mice as the corresponding control mice. When feed that was mixed with KP (1 or 3%) was given ad libitum to TSOD and TSNO mice for 8weeks, body weight increase, visceral fat accumulation, lipid metabolism abnormalities, hyperinsulinemia, glucose intolerance, insulin resistance, hypertension, and peripheral neuropathy were suppressed in TSOD mice, but no marked differences were observed in TSNO mice. Because KP had preventive effects on metabolic diseases, including antiobesity effects, only in obese animals, we propose that KP will be extremely valuable as a medicine or component of food in alternative health care.

Differences in the pharmacokinetics of Cyp3a substrates in TSOD and streptozotocin-induced diabetic mice

The pharmacokinetics of drugs can change in diabetes mellitus and even among diabetics. They may differ between type I diabetes (T1DM) and type 2 diabetes (T2DM).As triazolam was administered orally to Tsumura, Suzuki, obese, diabetes (TSOD) mice and streptozotocin (STZ) mice, clearance per body (CL/F) in TSOD mice did not differ compared with Tsumura, Suzuki, non-obesity (TSNO) mice. In STZ mice, CL/F was greater than in control mice. Small intestinal cytochrome P450 (Cyp) 3a expression in TSOD mice was significantly lower than in TSNO mice. No significant difference existed in small intestinal Cyp3a expression between STZ mice and control mice. In insulin-treated mice, small intestinal Cyp3a expression was significantly lower than in control mice.These results suggested that the differences in changes in small intestinal Cyp3a expression between T1DM and T2DM may be due to differences in plasma insulin concentrations. This may be a factor in the difference in the drug pharmacokinetics between T2DM and T1DM patients.

Preventive Effects of Bofutsushosan on Obesity and Various Metabolic Disorders

Visceral fat accumulation has been reported as the most important risk factor for the development of various metabolic disorders. In this study, the preventive effects of Bofutsushosan, a Japanese Kampo preparation, on obesity and various metabolic disorders were investigated focusing on visceral fat accumulation using Tsumura, Suzuki, Obese, Diabetes (TSOD) mice, which showed significant accumulation of visceral fat, and developed metabolic disorders including glucose intolerance, hyperlipidemia, hypertension and hyperinsulinemia. At 2 months after initiation of the study, the control TSOD mice developed various metabolic disorders such as marked obesity and visceral fat accumulation, increases in the levels of blood glucose, insulin, total-cholesterol (TC) and triglyceride (TG), and abnormal glucose tolerance, hypertension and peripheral neuropathy as distinct from the control Tsumura, Suzuki, Non-Obesity (TSNO) mice, which do not develop obesity and various metabolic disorders. In the TSOD mice treated with Bofutsushosan, body weight gain and visceral/subcutaneous fat accumulation were significantly suppressed. Biochemical parameters in plasma (glucose, TC, insulin and tumor necrosis factor-alpha (TNF-alpha) level) were significantly suppressed, and abnormal glucose tolerance, elevation of blood pressure and peripheral neuropathy accompanying progression of metabolic disorders were also significantly suppressed. On the other hand, in TSNO mice, Bofutsushosan showed no noteworthy impacts on most parameters except for an improvement of the lipid plasma level. The above results suggested that Bofutsushosan could be effective in preventing obesity and various metabolic disorders.