Animal Models Of Diabetes Mellitus Research Articles

Stem-cell based organ-on-a-chip models for diabetes research

Diabetes mellitus (DM) ranks among the severest global health concerns of the 21st century. It encompasses a group of chronic disorders characterized by a dysregulated glucose metabolism, which arises as a consequence of progressive autoimmune destruction of pancreatic beta-cells (type 1 DM), or as a result of beta-cell dysfunction combined with systemic insulin resistance (type 2 DM). Human cohort studies have provided evidence of genetic and environmental contributions to DM; yet, these studies are mostly restricted to investigating statistical correlations between DM and certain risk factors. Mechanistic studies, on the other hand, aimed at re-creating the clinical picture of human DM in animal models. A translation to human biology is, however, often inadequate owing to significant differences between animal and human physiology, including the species-specific glucose regulation. Thus, there is an urgent need for the development of advanced human in vitro models with the potential to identify novel treatment options for DM. This review provides an overview of the technological advances in research on DM-relevant stem cells and their integration into microphysiological environments as provided by the organ-on-a-chip technology.

HOXA11-AS regulates diabetic arteriosclerosis-related inflammation via PI3K/AKT pathway.

This study aims to explore whether homeobox A11 antisense RNA (HOXA11-AS) could regulate inflammation induced by diabetic arteriosclerosis (DAA) via PI3K/AKT pathway. Quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) was used to detect expressions of HOXA11-AS and proinflammatory genes in carotid endarterectomy samples of symptomatic and asymptomatic atherosclerosis (AS) patients, diabetes mellitus (DM), and non-DM patients. The above-mentioned genes in DM animal model and non-DM animal model were also detected. We detected the expression of HOXA11-AS in vascular smooth muscle cells (VSMCs) treated with platelet-derived growth factor (PDGF) or PDGF inhibitor imatinib, respectively. Subsequently, we applied cell transfection technology to interfere with the expression of HOXA11-AS in VSMCs. In vascular endothelial cells (VECs) and VSMCs, we detected the effect of HOXA11-AS on the expressions of genes related to the proliferation, migration, and cell cycle. Then, VSMCs were treated with tumor necrosis factor-α (TNF-α), and the expression of HOXA11-AS was examined in VSMCs. The effect of HOXA11-AS on TNF-α-induced inflammation in VSMCs was detected as well. Finally, we analyzed the effect of HOXA11-AS on PDGF-induced activation of PI3K/AKT pathway in VSMCs and VECs. HOXA11-AS expression was markedly increased in carotid endarterectomy specimens of symptomatic AS patients compared to that of asymptomatic AS patients. Expression levels of HOXA11-AS and pro-inflammatory genes were significantly elevated in carotid endarterectomy specimens of DM patients. Similarly, HOXA11-AS expression was also significantly increased in carotid arteries of DM mice compared with that of non-DM mice. PDGF could upregulate HOXA11-AS expression in VSMCs, which was reversed by PDGF inhibitor imatinib. HOXA11-AS knockdown could reduce the expressions of the proliferation-associated gene (PCNA) and the cycle-related genes (p21, p53), and also inhibited the proliferation and migration of VSMCs induced by PDGF. HOXA11-AS was upregulated by TNF-α. HOXA11-AS knockdown remarkably downregulated expressions of inflammation-related genes in VSMCs induced by TNF-α. In VECs, low expression of HOXA11-AS can inhibit the expression of TNF-α-induced pro-inflammatory genes and PDGF-induced vascular inflammation-related genes. Low expression of HOXA11-AS inhibited PDGF-induced activation of PI3K/AKT pathway in VSMCs and VECs. HOXA11-AS may participate in DAA by activating the PI3K/AKT pathway to regulate inflammation in VSMCs and VECs.

Spontaneously Diabetic Torii (SDT) Fatty Rat, a Novel Animal Model of Type 2 Diabetes Mellitus, Shows Blunted Circadian Rhythms and Melatonin Secretion

In patients with diabetes mellitus (DM), impairments of circadian rhythms, including the sleep–wake cycle, blood pressure, and plasma melatonin concentrations, are frequently observed. Animal models of DM are also reported to show aberrant circadian rhythms. However, the changes in the circadian rhythms of plasma soluble substances, including melatonin, in diabetic animals are controversial. In the present study, we investigated the circadian rhythms of spontaneous locomotor activity, metabolic parameters (plasma glucose, triglyceride, and total cholesterol), and plasma melatonin concentrations in Spontaneously Diabetic Torii (SDT) fatty rats, a novel animal model of type 2 DM. Although SDT fatty rats exhibited low locomotor activity in the dark phase, no phase shifts were observed. The circadian variations of plasma metabolic parameters were more apparent in the SDT fatty rats compared with control Sprague–Dawley (SD) rats. The circadian rhythms of plasma melatonin concentrations were significantly impaired in SDT fatty rats. To get an insight into the mechanism underlying the impaired melatonin secretion in SDT fatty rats, the expression of arylalkylamine N-acetyltransferase (Aanat) and acetylserotonin O-methyltransferase (Asmt) mRNA, which encode the rate-limiting enzymes for melatonin synthesis, was investigated in the pineal gland. There were no significant differences in Aanat and Asmt expression between the control SD and SDT fatty rats. These results suggest that SDT fatty rats show impaired circadian rhythms and dysregulated melatonin secretion.

Identification of therapeutic effect of glucagon-like peptide 1 in the treatment of STZ-induced diabetes mellitus in rats by restoring the balance of intestinal flora.

The objective of this study was to identify the therapeutic effect and the underlying mechanism of glucagon-like peptide 1 (GLP-1) in the treatment of STZ-induced diabetes mellitus (DM). Mice were treated with STZ to establish an animal model of DM, which was further treated with a GLP-1 receptor agonist. Subsequently, the status of glucose, insulin, nitric oxide, inflammatory and oxidative factors was evaluated and compared among Sham, STZ, and STZ + GLP-1 groups. In addition, the intestinal flora spectrum in each group was also evaluated. In this study, it was found that the administration of STZ increased the level of glucose and glycosylated hemoglobin but reduced the level of insulin. It was also found that the levels of inflammation and oxidative stress in STZ-induced DM were both enhanced, as evidenced by a decreased level of catalase, superoxide dismutase, glutathione peroxidase, as well as increased levels of malonyldialdehyde, interleukin-1β (IL-1β), and IL-6. Meanwhile, the expression of nitric oxide, a factor associated with both oxidative stress and inflammation, was also suppressed in STZ-induced DM. More importantly, the imbalance of intestinal flora was observed in STZ-induced DM, as shown by a decreased level of both total bacteria and that of some strains including Clostridium, Bacteroides, Lactobacilli, and Bifidobacteria. In summary, the findings of this study confirmed the antihyperglycemic effect of GLP-1 and demonstrated that the therapeutic effect of GLP-1 in the treatment of STZ-induced DM was mediated, at least partially, by its ability to restore the balance of intestinal flora.

Deficient Activity of Mitochondrial Flavine Adenine Dinucleotide-Linked Glycerophosphate Dehydrogenase in Pancreatic Islet Beta Cells as a Determinant of Non-Insulin-Dependent Diabetes Mellitus

Extensive experimental investigations in animal models of diabetes mellitus have led to the proposal that a deficient activity of mitochondrial flavine adenine dinucleotide (FAD)-linked glycerophosphate dehydrogenase represents a far-from-uncommon, albeit not invariable, determinant of pancreatic islet B-cell insulin secretory dysfunction. The major aim of the present review is to summarize the results of these investigations and, hence, to encourage further work on the prevalence of this enzymatic defect in the islet B cell of human subjects, especially non-insulin-dependent diabetic patients. J Endocrinol Metab. 2018;8(2-3):16-26 doi: https://doi.org/10.14740/jem496w

Lipid accelerating the fibril of islet amyloid polypeptide aggravated the pancreatic islet injury in vitro and in vivo

BackgroundThe fibrillation of islet amyloid polypeptide (IAPP) triggered the amyloid deposition, then enhanced the loss of the pancreatic islet mass. However, it is not clear what factor is the determinant in development of the fibril formation. The aim of this study is to investigate the effects of lipid on IAPP fibril and its injury on pancreatic islet.MethodsThe fibril form of human IAPP (hIAPP) was tested using thioflavin-T fluorescence assay and transmission electron microscope technology after incubated with palmitate for 5 h at 25 °C. The cytotoxicity of fibril hIAPP was evaluated in INS-1 cells through analyzing the leakage of cell membrane and cell apoptosis. Type 2 diabetes mellitus (T2DM) animal model was induced with low dose streptozotocin combined the high-fat diet feeding for two months in rats. Plasma biochemistry parameters were measured before sacrificed. Pancreatic islet was isolated to evaluate their function.ResultsThe results showed that co-incubation of hIAPP and palmitate induced more fibril form. Fibril hIAPP induced cell lesions including cell membrane leakage and cell apoptosis accompanied insulin mRNA decrease in INS-1 cell lines. In vivo, Plasma glucose, triglyceride, rIAPP and insulin increased in T2DM rats compared with the control group. In addition, IAPP and insulin mRNA increased in pancreatic islet of T2DM rats. Furthermore, T2DM induced the reduction of insulin receptor expression and cleaved caspase-3 overexpression in pancreatic islet.ConclusionsResults in vivo and in vitro suggested that lipid and IAPP plays a synergistic effect on pancreatic islet cell damage, which implicated in enhancing the IAPP expression and accelerating the fibril formation of IAPP.

Evaluation of Polyphenol and Flavonoid Profiles and the Antioxidant Effect of Carduus Acanthoides Hydroalcoholic Extract Compared with Vaccinium Myrtillus in an Animal Model of Diabetes Mellitus

This study was aimed to evaluate in vitro total content of polyphenols and flavonoids and in vivo antioxidant effect of the hydroalcoholic extract of Carduus acanthoides L. as compared to that of Vaccinium myrtillus L. The total content of polyphenols and flavonoids was evaluated by a spectrophotometric method. The chemical composition of plant extracts was determined using thin-layer chromatography, HPLC, and GC-MS techniques. Tests for the antioxidant activity were performed using streptozotocin-diabetic adult Swiss albino mice distributed in four groups, including three control groups – mice with normal pancreatic function (group I), diabetic mice (group II), and diabetic mice treated with V. myrtillus extract recognized for its antioxidant effect (group IV) – and the test group of diabetic mice treated with C. acanthoides extract at 150 mg/kg b.w. (group III). At the end of experiments, the animals were sacrificed and the activities of superoxide dismutase, glutathione peroxidase, and glutathione reductase were tested, the level of lipid peroxides was determined, and a histological analysis of the pancreas was performed. Both plant extracts contain polyphenols and flavonoids in significant amounts due to which they have antioxidant properties. The antioxidant enzymes exhibited higher activities in mice treated with C. acanthoides extract, but the level of lipid peroxides was significantly lower in mice treated with V. myrtillus extract.

Impaired permeability and antimicrobial barriers in type 2 diabetes skin are linked to increased serum levels of advanced glycation end-product.

The incidence of type 2 diabetes mellitus (DM) has been increasing rapidly, and the disease has become a serious sociomedical problem. Many skin problems, such as xerosis, pruritus, skin infections and delayed wound healing, that might be related to chronic impairment of skin barrier function decrease the quality of life in patients with DM. However, the status of the permeability and antimicrobial barrier of the skin in DM remains unknown. This study aimed to elucidate skin barrier impairment in patients with type 2 DM and its pathomechanisms using classic animal models of type 2 DM. Functional studies of the skin barrier and an analysis of stratum corneum (SC) lipids were compared between patients with type 2 DM and age- and sex-matched non-diabetes controls. Also, functional studies on the skin barrier, epidermal lipid analyses, and electron microscopy and biomolecular studies were performed using type 2 DM animal models, db/db and ob/ob mice. Patients with type 2 DM presented with epidermal barrier impairments, including SC hydration, which was influenced by blood glucose control (HbA1c level). In the lipid analysis of SC, ceramides, fatty acids and cholesterol were significantly decreased in patients with type 2 DM compared with controls. Type 2 DM murine models presented with severe hyperglycaemia, impairment of skin barrier homeostasis, decreases in epidermal proliferation and epidermal lipid synthesis, decreases in lamellar body (LB) and epidermal antimicrobial peptides (AMPs), an increase in receptors for advanced glycation end-product (AGE) in the epidermis and an increase in serum AGE. Impairment of the skin barrier was observed in type 2 DM, which results in part from a decrease in epidermal proliferation. Serum AGE and its epidermal receptors were increased in type 2 diabetic mice which display impaired skin barrier parameters such as epidermal lipid synthesis, LB production, epidermal AMP and SC lipids.

Animal models of obesity and diabetes mellitus.

More than one-third of the worldwide population is overweight or obese and therefore at risk of developing type 2 diabetes mellitus. In order to mitigate this pandemic, safer and more potent therapeutics are urgently required. This necessitates the continued use of animal models to discover, validate and optimize novel therapeutics for their safe use in humans. In order to improve the transition from bench to bedside, researchers must not only carefully select the appropriate model but also draw the right conclusions. In this Review, we consolidate the key information on the currently available animal models of obesity and diabetes and highlight the advantages, limitations and important caveats of each of these models.

Multi-Omics Insights into Functional Alterations of the Liver in Insulin-Deficient Diabetes Mellitus

The liver regulates the availability of insulin to other tissues and is the first line insulin response organ being physiologically exposed to higher insulin concentrations than the periphery. Basal insulin during fasting inhibits hepatic gluconeogenesis and glycogenolysis, whereas postprandial insulin peaks stimulate glycogen synthesis. The molecular consequences of chronic insulin deficiency for the liver have not been studied systematically. We analyzed liver samples of a genetically diabetic pig model (MIDY) and of wild-type (WT) littermate controls by RNA sequencing, proteomics and targeted metabolomics/lipidomics. Cross-omics analyses revealed increased activity in gluconeogenesis, ketogenesis, amino acid metabolism and oxidation of fatty acids in the MIDY samples, whereas pathways related to extracellular matrix and inflammation/pathogen defense response were less active than in the WT samples. Our study identified key drivers of these alterations, such as RDH16 and HMGCS2 for stimulated gluconeogenesis and ketogenesis, in a clinically relevant large animal model for insulin-deficient diabetes mellitus.

High glucose enhances the metastatic potential of tongue squamous cell carcinoma via the PKM2 pathway.

Previous evidence has indicated an increased cancer risk in individuals with diabetes mellitus (DM). The aim of this study was to investigate the relationship between DM (high glucose) and tongue squamous cell carcinoma (TSCC) and how high glucose mediated the metastatic potential of TSCC. The relationship between DM and TSCC was assessed in a retrospective study. The role and its mechanism of high glucose on the proliferation, metastatic potential of TSCC were investigated in vitro and in vivo. The prevalence rate of DM in patients with TSCC was 12.84%, which was significantly higher than that (9.7%) in the general population in China. Although no significant difference was observed in the overall survival (OS) rate, TSCC patients with DM have a 1.38-fold increase in relative risk affecting 5-year OS compared to patients without DM. High glucose enhanced the TSCC cell proliferation, migration, invasion and upregulated PKM2 (pyruvate kinase M2) expression. Whereas, these effect was abolished after knockdown of PKM2 in TSCC cells. High glucose promoted tumour growth and lung metastasis of TSCC in a DM animal model. Our results confirm DM as a risk factor for the development of TSCC. High glucose enhances the metastatic potential of TSCC through stimulation of the PKM2 pathway.

Diet-induced insulin resistance state disturbs brain clock processes and alters tuning of clock outputs in the Sand rat, Psammomys obesus

Reciprocal interactions closely connect energy metabolism with circadian rhythmicity. Altered clockwork and circadian desynchronization are often linked with impaired energy regulation. Conversely, metabolic disturbances have been associated with altered autonomic and hormonal rhythms. The effects of high-energy (HE) diet on the master clock in the suprachiasmatic nuclei (SCN) remain unclear.This question was addressed in the Sand rat (Psammomys obesus), a non-insulin-dependent diabetes mellitus (NIDDM) animal model. The aim of this work was to determine whether enriched diet in Psammomys affects locomotor activity rhythm, as well as daily oscillations in the master clock of the SCN and in an extra-SCN brain oscillator, the piriform cortex. Sand rats were fed during 3 months with either low or HE diet. Vasoactive intestinal peptide (VIP), vasopressin (AVP) and CLOCK protein cycling were studied by immunohistochemistry and running wheel protocol was used for behavioral analysis. High energy feeding dietary triggered hyperinsulinemia, impaired insulin/glucose ratio and disruption in pancreatic hormonal rhythms. Circadian disturbances in hyper-insulinemic animals include a lengthened rest/activity rhythm in constant darkness, as well as disappearance of daily rhythmicity of VIP, AVP and the circadian transcription factor CLOCK within the suprachiasmatic clock. In addition, daily rhythmicity of VIP and CLOCK was abolished by HE diet in a secondary brain oscillator, the piriform cortex. Our findings highlight a major impact of diabetogenic diet on central and peripheral rhythmicity. The Psammomys model will be instrumental to better understand the functional links between circadian clocks, glucose intolerance and insulin resistance state.

Overexpression of acetyl CoA carboxylase β exacerbates podocyte injury in the kidney of streptozotocin-induced diabetic mice

A single nucleotide polymorphism (SNP) within the acetyl CoA carboxylase (ACC) β gene (ACACB), rs2268388, has been shown to be associated with susceptibility to development of proteinuria in patients with type 2 diabetes. To investigate the biological roles of ACCβ in the pathogenesis of diabetic nephropathy, we examined the effects of overexpression of ACACB using podocyte-specific ACACB-transgenic mice or ACACB-overexpressing murine podocytes. Podocyte-specific ACACB-transgenic mice or littermate mice were treated with streptozotocin (STZ) to induce diabetes, and 12 weeks after induction of diabetes, we examined the expression of podocyte markers to evaluate the degree of podocyte injury in these mice. We also examined the effects of ACCβ on podocyte injury in ACACB- or LacZ-overexpressing murine podocytes. Podocyte-specific ACACB overexpression did not cause visible podocyte injury in non-diabetic mice. In STZ-induced diabetic mice, ACACB-transgenic mice showed a significant increase in urinary albumin excretion, accompanied by decreased synaptopodin expression and podocin mislocalization in podocytes, compared with wild-type mice. In cultured murine podocytes, overexpression of ACACB significantly decreased synaptopodin expression and reorganized stress fibers under high glucose conditions, but not in normal glucose conditions. The decrease of synaptopodin expression and reorganized stress fibers observed in ACACB overexpressing cells cultured under high glucose conditions was reversed by a treatment of 5-aminoimidazole-4-carboxamide-1-beta-4-ribofuranoside (AICAR), activator of AMP-activated protein kinase (AMPK). The excess of ACCβ might contribute to exacerbation of podocyte injury in the kidney of an animal model for diabetes mellitus, and the AMPK/ACCβ pathway may be a novel therapeutic target for the prevention of diabetes-related podocyte injury.

22016 ATVB Plenary Lecture: Receptor for Advanced Glycation Endproducts and Implications for the Pathogenesis and Treatment of Cardiometabolic Disorders: Spotlight on the Macrophage.

The receptor for advanced glycation endproducts (RAGE) interacts with a unique repertoire of ligands that form and collect in the tissues and circulation in diabetes mellitus, aging, inflammation, renal failure, and obesity. RAGE is expressed on multiple cell types linked to tissue perturbation in these settings. This brief review focuses on the role of RAGE in monocytes/macrophages and how RAGE ligand engagement on these cells mediates seminal changes in monocyte/macrophage migration, oxidative stress, cholesterol efflux, and pro- versus anti-inflammatory cues that signal to tissue damage. Studies using mice devoid of Ager (gene encoding RAGE) or pharmacological antagonists of RAGE are protective in animal models of diabetes mellitus, atherosclerosis, and high-fat diet-induced obesity, in least in part through key roles in monocytes/macrophages. RAGE signal transduction requires the interaction of RAGE cytoplasmic domain with the formin, DIAPH1 (diaphanous 1) and novel antagonists of this interaction show significant promise in attenuation of the maladaptive effects of RAGE ligands in cellular and in vivo models. Finally, this brief review discusses evidence for RAGE axis perturbation in human monocytes/macrophages and how tracing RAGE activity in these cells may identify target engagement biomarkers of RAGE antagonism for future clinical trials.

제2형 당뇨 마우스에서 십조탕(十棗湯)에 의한 혈당 및 신기능 부전 개선효과

Objectives : It is well known that Sibjotang (Shizaotang), traditional herbal medicine formula, regulates the body fluid blood pressure homeostasis. This study is to investigate whether Sibjotang improves diabetic renal dysfunction in type II diabetes mellitus animal model, db/db mice. Methods : The animals model were divided into three groups at the age of 8 weeks; control group (C57BLKS/J-db/m mice), diabetic group [(C57BLKS/J+Lepr)-db/db mice], and Sibjotang group [(C57BLKS/J+Lepr)-db/db mice + Sibjotang 100 mg/kg/day]. During 8 weeks of treatment, blood glucose and urinary albumin excretion were checked in metabolic chamber at 8, 12, and 16 weeks of age, respectively. Results : Body weight and food intake of diabetic group were significantly higher than control group after 8 weeks administration. However, there were not significant different between the diabetic group and Sibjotang group. Urinary albumin excretion was significantly decreased in the Sibjotang group than the diabetic group. In addition, supplementation with Sibjotang significantly lowered levels of blood glucose, insulin, and homeostatic model assessment-insulin resistance (HOMA-IR), suggesting reduced insulin resistance. The ratio of mesangial matrix/glomerular area was markedly larger in diabetic group than control group, whereas Sibjotang significantly reduced this expansion. Moreover, immunohistological study revealed that Sibjotang attenuated the increase of transforming growth <TEX>$factor(TGF)-{\beta}$</TEX> expression in kidney. Conclusion : Sibjotang ameliorates diabetes-associated renal injury through the improvement of the blood glucose and insulin sensitivity, and inhibiting the <TEX>$TGF-{\beta}1$</TEX> expression. Therefore, Sibjotang may be a new therapeutic formula for the treatment of diabetic-associated renal dysfunction.

Hyperglycemia simultaneously induces initial caries development and enhances spontaneous occlusal surface wear in molar teeth related to parotid gland disorder in alloxan-induced diabetic rats.

Diabetes and salivary gland dysfunction are major factors that induce dental caries in experimental animals, but there are no reports analyzing the association of dental caries and salivary glands in an animal model of diabetes mellitus (DM). To clarify the initial development of dental caries and preceding salivary gland disorder, we performed a histopathological analysis on teeth and salivary glands in diabetic Wistar rats 7 weeks after alloxan treatment (DM group) in comparison with nondiabetic rats (Non-DM group) and functional analysis on saliva secretion during the experimental period. Pilocarpine-induced salivary fluid secretion in diabetic rats gradually decreased with continuous hyperglycemia from immediately after alloxan treatment to the time of autopsy. Histopathologically, Oil Red O-positive lipid droplets accumulated in the acinar cells of the parotid gland. No tooth was stereoscopically defined as having dental caries in any of the rats in either group; however, the external appearance remarkably changed owing to occlusal wear in almost all molars in the DM group. The initial lesions of dental caries, appearing as micro-defects in dentin with bacterial colonization on the molar surface, were identified using histopathological analysis, and the incidence in the DM group was more than twice that in the Non-DM group. In conclusion, hyperglycemia simultaneously induces initial caries development and enhances spontaneous occlusal wear in molar teeth of Wistar rats 7 weeks after alloxan treatment. The parotid gland dysfunction caused by hyperglycemia may be mostly involved in the pathogenesis of occlusal wear as well as in dental caries in this diabetic model.

The effect of hyperglycaemia on osseointegration: a review of animal models of diabetes mellitus and titanium implant placement.

Patients with type 2 diabetes mellitus have a higher risk of dental and/or orthopaedic implant failure. However, the mechanism behind this phenomenon is unclear, and animal studies may prove useful in shedding light on the processes involved. This review considers the available literature on rat models of diabetes and titanium implantation. The process of osseointegration whereby direct contact is achieved between bone and an implant surface depends on healthy bone metabolism. Collective evidence suggests that hyperglycaemia adversely affects bone turnover and the quality of the organic matrix resulting in an overall deterioration in the quality, resilience and structure of the bone tissue. This in turn results in compromised osseointegration in patients receiving dental and orthopaedic implants. The incidence of diabetes mellitus (DM), which is a chronic metabolic disorder resulting in hyperglycaemia, is rising. Of particular significance is the rising incidence of adult onset type 2 diabetes mellitus (T2DM) in an ageing population. Understanding the effects of hyperglycaemia on osseointegration will enable clinicians to manage health outcomes for patients receiving implants. Much of our understanding of how hyperglycaemia affects osseointegration comes from animal studies. In this review, we critically analyse the current animal studies. Our review has found that most studies used a type 1 diabetes mellitus (T1DM) rodent model and looked at a young male population of rodents. The pathophysiology of T1DM is however very different to that of T2DM and is not representative of T2DM, the incidence of which is rising in the ageing adult population. Genetically modified rats have been used to model T2DM, but none of these studies have included female rats and the metabolic changes in bone for some of these models used are not adequately characterized. Therefore, the review suggests that the study population needs to be broadened to include both T1DM and T2DM models, older rats as well as young rats, and importantly animals from both sexes to reflect more accurately clinical practice.

Urea transport and clinical potential of urearetics.

Urea is transported by urea transporter proteins in kidney, erythrocytes, and other tissues. Mice in which different urea transporters have been knocked out have urine-concentrating defects, which has led to the development and testing of urea transporters Slc14A2 (UT-A) and Slc14A1 (UT-B) inhibitors as urearetics. This review summarizes the knowledge gained during the past year on urea transporter regulation and investigations into the clinical potential of urearetics. UT-A1 undergoes several posttranslational modifications that increase its function by increasing UT-A1 accumulation in the apical plasma membrane. UT-A1 is phosphorylated by protein kinase A, exchange protein activated by cyclic AMP, protein kinase Cα, and AMP-activated protein kinase, all at different serine residues. UT-A1 is also regulated by 14-3-3, which contributes to UT-A1 removal from the membrane. UT-A1 is glycosylated with various glycan moieties in animal models of diabetes mellitus. Transgenic expression of UT-A1 into UT-A1/UT-A3 knockout mice restores urine-concentrating ability. UT-B is present in descending vasa recta and urinary bladder, and is linked to bladder cancer. Inhibitors of UT-A and UT-B have been developed that result in diuresis with fewer abnormalities in serum electrolytes than conventional diuretics. Urea transporters play critical roles in the urine-concentrating mechanism. Urea transport inhibitors are a promising new class of diuretic agent.

107 - Experimental Model of Type 2 Diabetic Cardiomyopathy: A State of cGMP Deficiency

Introduction: Patients with type 2 diabetes mellitus (DM) are predisposed to long term cardiovascular complications, including development of myocardial dysfunction and heart failure. Despite the high prevalence of diabetic cardiomyopathy, characterized by diastolic dysfunction independent of coronary artery disease and thought to be related to metabolic derangements and protein alterations, not much is known regarding the genesis and treatment of this condition. The development of an experimental type 2 diabetes mellitus animal model can help to better understand pathophysiology and mechanisms of diabetic cardiomyopathy. Methods: Genetically designated Zucker diabetic ZDFO rats and Zucker lean non-diabetic ZDFL rats (ten each) were maintained on Purina 5008 diet from 13 to 32 weeks of age. Echocardiography with strain imaging was performed, and vital signs and blood work were obtained from the rats at the beginning and end of the study. Echocardiography was used to assess left ventricular (LV) structure and function. At the end of 32 weeks, rats were anesthetized and arterial blood was collected from carotid artery. Cardiac tissues were harvested for histological analysis and sections stained with Picrosirius Red to assess for fibrosis. Results: The development of diabetes was confirmed by HbA1c measurements (diabetic rats 12.7 ± 0.2 vs nondiabetic rats 5.1 ± 0.1%, P < .01). There was no difference in LV ejection fraction between the diabetic rats as compared to nondiabetic controls (78.1 ± 0.6 vs 78.0 ± 0.7%, P = .87). However, there was evidence of diastolic dysfunction with longitudinal strain imaging. Early diastolic strain demonstrated a trend for difference in the diabetic group from 13 to 32 weeks (−10.9 ± 0.6 to −9.6 ± 0.7, P = .16) that is not seen in the nondiabetic group (−11.1 ± 0.5 to −11.6 ± 0.9, P = .98). The diabetic vs nondiabetic rats had increased mean arterial pressures at 32 weeks (106 ± 4 vs 95 ± 2 mmHg, P = .01). LV mass indexed to rat body weight was increased in the diabetic vs nondiabetic rats (2.34 ± 0.36 vs 2.06 ± 0.03 mg/g, P < .01). Upon tissue histological examination, there was greater LV interstitial (21.6 ± 3 vs 10.8 ± 1%, P = .01) and perivascular (25.8 ± 3 vs 14.8 ± 1%, P < .01) fibrosis. The diabetic vs nondiabetic rats had decreased plasma cGMP at 32 weeks (2.8 ± 0.7 vs 8.9 ± 1.7 pmol/ml, P = .01) and no difference in plasma BNP (24.6 ± 5.5 vs 18.4 ± 2.6 pg/ml, P = .76). Conclusion: In this genetically designated Zucker type 2 diabetes mellitus rat model, we demonstrated that there is development of cardiac hypertrophy, fibrosis and diastolic dysfunction, along with a cGMP deficiency state. Future studies using these diabetic animal models can help better elucidate the pathophysiology of diabetic cardiomyopathy and development of novel therapeutic options.

ANTIDIABETIC ACTIVITY OF ETHANOLIC EXTRACT OF KALANCHOE PINNATA LEAVES IN ALLOXAN INDUCED HYPERGLYCAEMIC RATS.

Diabetes remains a major burden in health care both in developed and developing countries. Kalanchoe pinnata has been used as a traditional medicine to treat diabetes. We try to find scientific evidence of antidiabetic activity of Kalanchoe pinnata extract (KPE) through hypoglycemic effect using animal model of diabetes mellitus. Hyperglycaemia was developed in rats using alloxan 150 mg/kgBW. Three days after alloxan injection, rats having fasting blood glucose (FBG) >200 mg/dL were divided into six groups, namely HG (hyperglycaemia), HG+KPE high-dose (hyperglycaemia+KPE 33.2 mg/kg), HG+ KPE medium-dose (hyperglycaemia+KPE 11.6 mg/kg), HG+KPE low-dose (hyperglycaemia+ KPE 5.8 mg/kg), standard drug 1 (hyperglycaemia+glibenclamidee 1.35 mg/kg), standard drug 2 (hyperglycaemia+acarbose 13.5 mg/kg). Then, FBG was measured every 5 days recorded as t1, t2, and t3 to determine fluctuations in blood glucose. At the end of the study, rats were sacrified, pancreas was collected and number of pancreatic beta cell langerhans was determined. KPE 11.6 mg/kg showed best hypoglycemic effect and improvement of the number of pancreatic beta cell langerhans. KPE has hypoglycemic effect through improvement of the number of pancreatic beta cell langerhans but not in dose dependent manner.