Single Low Dose Of Streptozotocin Research Articles

Protective and curative effects of unconjugated bilirubin on gene expression of LOX-1 and iNOS in the heart of rats receiving high-fat diet and low dose streptozotocin: a histomorphometric approach

BackgroundAtherosclerosis is a chronic inflammatory condition affecting the large arteries and is a major cause of cardiovascular diseases (CVDs) globally. Increased levels of adhesion molecules in cardiac tissue serve as prognostic markers for coronary artery occlusion risk. Given the antioxidant properties of bilirubin and its inverse correlation with atherosclerosis, this study aimed to assess the beneficial effects of bilirubin on atherosclerotic indices and heart structure in high-fat diet-fed diabetic rats with atherosclerosis.MethodsAtherosclerosis was induced in three out of five groups of adult male Sprague Dawley rats through a 14-week period of high-fat diet (HFD) consumption and a single low dose of streptozotocin (STZ) (35 mg/kg). The atherosclerotic rats were then treated with intraperitoneal administration of 10 mg/kg/day bilirubin for either 6 or 14 weeks (treated and protected groups, respectively), or the vehicle. Two additional groups served as the control and bilirubin-treated rats. Subsequently, the mRNA expression levels of vascular cell adhesion molecule 1 (VCAM-1), intercellular adhesion molecule 1 (ICAM-1), lectin-like LDL receptor 1 (LOX-1), and the inducible nitric oxide synthase (iNOS) were analyzed using quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). Histopathological and stereological analyses were performed to assess changes in the heart structure.ResultsBilirubin significantly decreased the expression of VCAM-1, ICAM-1, LOX-1, and iNOS genes in the treated group. Moreover, bilirubin mitigated pathological damage in the left ventricle of the heart. Stereological analysis revealed a decrease in the left ventricle and myocardium volume, accompanied by an increase in vessel volume in rats treated with bilirubin.ConclusionThese findings demonstrate that mild hyperbilirubinemia can protect against the progression of atherosclerosis and heart failure by improving lipid profile, modulating adhesion molecules, LOX-1, and iNOS gene expression levels.

The Effects of Alpha Lipoic Acid on Oxidative Stress, Lipid Profile, and Blood Glucose Levels in Type 2 Diabetic Male Sprague Dawley Rats

Objective: To determine the effect of Alpha Lipoic Acid (ALA) on blood glucose, lipid profile, and oxidative stress in streptozotocin-induced type II diabetic male Sprague Dawley rats.Study Design: Laboratory-based experimental study.Place and Duration of the Study: The study was carried out at the Physiology Research Lab, Army Medical College, Rawalpindi, Pakistan, from 20th January 2021 to 24th June 2021.Methods: Thirty Sprague Dawley (SD) rats were divided into three equal groups. Group I was given a normal standard rat diet. In Groups II and III after feeding a diet rich in fat and calories for 2 weeks, after feeding a diet rich in fat and calories for 2 weeks, a single low dose of streptozotocin was injected for Type 2 Diabetes Mellitus (T2DM) induction. Alpha Lipoic Acid 30 mg/kg body weight/day was administered intraperitoneally in Group III for 01 weeks after the development of T2DM.Results: The blood glucose, lipid profile, and serum Malondialdehyde levels were deranged in the diabetic group. After Alpha Lipoic Acid supplementation, the blood glucose levels, Serum MDA, and levels of triglycerides, cholesterol, and Low Density Lipoproteins decreased, whereas High Density Lipoproteins level were significantly raised (p <0.001) in group III as compared to the diabetic group II. Conclusion: Treatment with Alpha Lipoic Acid reduces oxidative stress and improve reduces oxidative stress and improves glycemic and lipid profiles in T2DM rats.
 How to cite this: khan BU, Arshad S, Ikram F, Yousef I, Naizi I, Ismaeel M. The Effects of Alpha Lipoic Acid on Oxidative Stress, Lipid Profile and Blood Glucose Levels in Type 2 Diabetic Male Sprague Dawley Rats. Life and Science. 2024; 5(1): 89-94. doi: http://doi.org/10.37185/LnS.1.1.405

Alpha lipoic acid improves memory and antioxidant enzymes activity in diabetic Wistar rats

Diabetes mellitus (DM) and oxidative stress are among the leading causes of memory loss and dementia. Dietary supplements have been used to manage many disorders. This research aimed to determine the effect of alpha lipoic acid (ALA) on memory and oxidative stress in diabetic Wistar rats. 30 rats were grouped into six (5 in each). Diabetes was induced using a high-fat diet followed by a single low dose of streptozotocin (40 mg/kg) intraperitoneally. Group I served as normoglycemic control (1 mL/kg normal saline), while groups II, III, IV, V, and VI were diabetic and received 1 mL/kg at normal saline, glibenclamide at 1 mg/kg, ALA at 100 mg/kg, 200 mg/kg and 400 mg/kg respectively for 21 days. Blood glucose level was determined before and after treatment. Long-term and recognition memory were determined using novel object recognition tasks (NORT). Brain tissues were used for antioxidant enzymes. The result obtained showed that at 400 mg/kg after 21 days of administration of ALA, long-term memory and recognition ability were increased significantly (45.65±3.43s and 83.77±1.49%) compared to the diabetic control (26.24 ± 3.81s and 65.09 ± 2.52%) respectively. Antioxidant enzymes’ levels were increased significantly in the group VI including catalase (1.76±0.02 IU/mg) superoxide dismutase (1.02±0.71 IU/mg) and reduced glutathione (91.08±3.49 µg/mL) compared to the diabetic control group (0.84±0.03 IU/mg, 0.49±0.03 IU/mg and 51.64±0.87 µg/mL) respectively. The findings suggest that ALA has antioxidant activity and improves memory in diabetic Wistar rats.

Alpha lipoic acid improved blood glucose level and lipid profile in type-2 diabetic Wistar rats

Diabetes mellitus is one of the most common metabolic disorders that is associated with many complications such as dyslipidemia and cardiovascular disease. This study aimed to evaluate the effects of alpha lipoic acid (ALA) on blood glucose levels and lipid profile in type-2 diabetic male Wistar rats. Thirty (30) Wistar rats weighing between 200 – 250 grams were distributed into six groups of five each (n=5). Diabetes was induced using a high-fat diet for eight weeks with a single low dose of streptozotocin (40 mg/kg) intraperitoneally at the end of the sixth week. Group I served as normoglycemic control and received 1 ml/kg normal saline; groups II, III, IV, V, and VI were diabetic and received 1 ml/kg normal saline; glibenclamide 1 mg/kg; ALA 100 mg/kg, ALA 200 mg/kg and ALA 400 mg/kg; respectively. All administrations were done orally for a duration of 21 days. Blood glucose level was determined using the glucose oxidase method. Serum was collected for lipid profile determination. The results obtained from this study showed that ALA across all doses (100 mg/kg, 200 mg/kg, and 400 mg/kg) decreased significantly (p < 0.05) the fasting blood glucose level (10.02 ± 0.71 mmol/L, 8.78 ± 0.94 mmol/L and 8.6 ± 0.68 mmol/L, respectively) when compared to the diabetic control group (20.06 ± 0.70 mmol/L). Lipid profiles were improved with HDL- and LDL- cholesterols increasing and decreasing significantly (42.60 ± 1.66 mg/dL and 1.12 ± 3.68 mg/dL) in the 400 mg/kg ALA group compared to the diabetic untreated group (37.00 ± 2.55 mg/dL and 26.31 ± 2.95 mg/dL, respectively). Therefore, the study demonstrated that ALA has both antihyperglycemic and antilipidemic in type-2 diabetic Wistar rats.

Dapagliflozin prevents abdominal visceral and subcutaneous adipose tissue dysfunction in the insulin-resistant canine model.

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) promote urinary glucose excretion, induce weight loss, and reduce fat accumulation. The effects of the SGLT2i dapagliflozin (DAPA) on subcutaneous (SC) and visceral (VIS) adipose tissue function remain unclear. The objective of this study is to evaluate SC and VIS adipose tissue function in an insulin-resistant canine model. A total of 12 dogs were fed a high-fat diet (HFD) for 6 weeks and thenwere given a single low dose of streptozotocin (18.5 mg/kg) to induce insulin resistance. Animals were then randomized and exposed to DAPA (n = 6, 1.25 mg/kg) or placebo (n = 6) once per day for 6 weeks while remaining on the HFD. DAPA prevented further weight gain induced by the HFD and normalized fat mass. DAPA reduced fasting glucose and increased free fatty acids, adiponectin, and β-hydroxybutyrate. DAPA reduced adipocyte diameter and cell distribution. Furthermore, DAPA increased genes associated with beiging, lipolysis, and adiponectin secretion and the expression of the adiponectin receptor ADR2, in SC and VIS adipose tissue. DAPA increased AMP-activated protein kinase activity and maximal mitochondrial respiratory function, especially in the SC depot. Furthermore, DAPA reduced cytokines and ceramide synthesis enzymes in SC and VIS depots. For the first time, to our knowledge, we identify mechanisms by which DAPA enhances adipose tissue function in regulating energy homeostasis in an insulin-resistant canine model.

Regulation of PKC/TLR-4/NF-kB signaling by sulbutiamine improves diabetic nephropathy in rats

One of the serious complications of diabetes mellitus is diabetic nephropathy (DN) which may finally lead to renal failure. The current study aimed to explore the effect of sulbutiamine, a synthetic derivative of vitamin B1, in streptozotocin (STZ)-induced DN and related pathways. Experimental DN was successfully induced 8 weeks after a single low dose of STZ (45 mg/kg, I.P.). Four groups of rats were used in this study and divided randomly into: control group, diabetic group, sulbutiamine control (control + sulbutiamine) group, and sulbutiamine-treated (60 mg/kg) (diabetic + sulbutiamine) group. The fasting blood glucose level (BGL), the levels of kidney injury molecule-1 (Kim-1), urea and creatinine in serum, as well as the renal content of malondialdehyde (MDA), protein kinase C (PKC), toll-like receptor-4 (TLR-4) and nuclear factor kappa B (NF-κB) were determined. Additionally, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and transforming growth factor-β1 (TGF-β1) contents were evaluated immunohistochemically. Sulbutiamine treatment decreased fasting BGL and improved the kidney function tests compared to diabetic rats. Moreover, TLR-4, NF-κB, MDA and PKC contents were substantially reduced following sulbutiamine treatment compared to the diabetic group. Sulbutiamine managed to obstruct the production of the pro-inflammatory TNF-α and IL-1β and suppressed TGF-β1 level, in addition to attenuating the histopathological changes associated with DN. This study revealed, for the first time, the ability of sulbutiamine to ameliorate STZ-induced diabetic nephropathy in rats. This nephroprotective outcome of sulbutiamine against DN may be attributed to glycemic control in addition to its anti-oxidative, anti-inflammatory and anti-fibrotic effects.

Biochanin A Attenuates Cardiomyopathy in Type 2 Diabetic Rats by Increasing SIRT1 Expression and Reducing Oxidative Stress.

Diabetic cardiomyopathy is one of the major complications in type 2 diabetes associated with myocardial structure abnormality and major cause of morbidity in type 2 diabetic patients. Biochanin A is a methylated isoflavone present in flowering tops of Trifolium pratense reported for anti-inflammatory, anti-oxidant, anti-infective, anti-cancer and anti-diabetic activity. The study was designed to assess the efficacy of Biochanin A in type 2 diabetic cardiomyopathy. Type 2 diabetes was induced in rats feeding high fat diet for two weeks and administration of single low dose of streptozotocin. Biochanin A was administered for 16 weeks orally once in a day (10, 20 and 40 mg/kg of body weight). Various parameters such as blood glucose, cardiac markers, oxidative stress and hemodynamic parameters, immunohistochemical, histopathological investigation and SIRT1 expression were measured at the end of the study. Biochanin A treatment resulted into reduction in plasma concentration of cardiac markers along with reduction in hyperglycemia, hyperlipidemia and oxidative stress in cardiac tissue. Biochanin A treated animals also demonstrated improvement in hemodynamic parameters. Diabetic animals treated with different doses of Biochanin A shown increased SIRT1 expression in cardiac tissue, and also confirmed reduced cardiac hypertrophy and cardiac protection in histopathological study. Outcome of the study indicates that Biochanin A is the potential candidate to control hyperglycemia, oxidative stress and improve SIRT1 expression in cardiac tissue. Biochanin A might be considered as potential candidate to control progression of cardiomyopathy in type 2 diabetes mellitus.

Metabolic and Pancreatic Derangement in type 2 Diabetic Rat

Introduction: The prevalence of diabetes mellitus is increasing globally, despite the best current therapies available. A large diversity of animal models has been developed for better understanding the pathogenesis of diabetes mellitus. This study aimed to develop a rat model that mimics the metabolic characteristics of human type 2 diabetes mellitus. Methods: Twenty-four male Sprague–Dawley rats (200–250 g) were divided into two groups and fed either a commercially available standard pellet diet (n=8) or a self-prepared high-fat diet (HFD) (n=16) for 6 weeks. HFD-fed rats were significantly obese compared to standard-fed rats. Eight of the obese rats were injected a single low dose of streptozotocin (STZ) at 35 mg/kg intraperitoneally to induce type 2 diabetic rat (T2DR) and were monitored for 6 weeks. Results: The weekly fasting blood glucose levels (FBG) in T2DR remained consistently high throughout the 6 weeks. The T2DR group exhibits decreased body weight, increased water intake, increased 24-hour urine volume with microalbuminuria, hyperlipidemia, altered liver and kidney functions, and structural changes of the islet of Langerhans. Conclusion: This model simulates the natural disease progression and metabolic characteristics of type 2 diabetic patients. This model mimics the human syndrome that can be maintained at a reasonable cost, and easy to develop.

Effect of Agmatine on Non-Alcoholic Fatty Liver Disease Induced by Type 2 Diabetes in Rats

Aim: To determine the potential hepatoprotective effect of Agmatine (AGM) on NAFLD-induced by Type 2 diabetes mellitus (T2DM) in rats.
 Study design: Forty male Wistar rats weighing from (200 -250 g) were distributed at random into five groups (8 rats per group): group 1 as control; group 2 as untreated-T2DM; groups 3 & 4 as T2DM cotreated with AGM (40 & 80 mg/kg/d), while group 5 T2DM cotreated with Silymarin (100 mg/kg/d).
 Place and duration of study: Department of Pharmacology, Faculty of Medicine, king Abdul-Aziz University; between October 2020 and January 2021.
 Methodology: A rat model of T2DM with NAFLD complication was established by feeding rats with 10% fructose in drinking water and intraperitoneally injecting them with a single low dose of streptozotocin (STZ) (45mg/kg). The fasting blood glucose was detected, serum levels of hepatic biomarkers were all assessed. Moreover, histopathological examination was performed by hematoxylin and eosin (H&E) staining.
 Results: STZ induced T2DM in rats causes a significant (p<0.05, n=8) rise in serum levels of FBG, ALT, AST, TB, TC, TG, and LDL in comparison with the corresponding control group. Co-treatment with AGM (40 & 80 mg/kg) and silymarin significantly alleviated hyperglycemia and amended hepatic biomarkers that was reflected on improved histopathological changes.
 Conclusion: The current data suggest that oral AGM co-treatment could have a hepatoprotective effect against T2DM associated with NAFLD in rats. Further investigations are recommended to elucidate molecular mechanisms accountable for the useful effects of AGM on hepatocytes.

120-OR: Dapagliflozin Increases Adiponectin and Its Receptors, and Reduces Inflammation and Ceramide Synthesis Enzymes in the Obese Prediabetic Dog

Sodium glucose cotransporter-2 (SGLT2) inhibitors promote urinary glucose excretion, consequently reducing blood glucose. Previously we showed that 6 weeks of Dapagliflozin (Dapa) treatment improved insulin sensitivity and prevented weight gain. In addition, Dapa promoted adipose tissue (AT) beiging, lipolysis and decreased adipocyte size primarily in the visceral (VIS) depot in a canine model of mild type 2 diabetes. Little is known about the effects of Dapa on AT inflammation and ceramide synthesis in both the subcutaneous (SC) and VIS fat depots. Twelve dogs were fed a high fat diet for 6 weeks, then received a single low dose of streptozotocin (18.5mg/kg) to induce mild type 2 diabetes. Animals were then exposed to Dapa (n=6, 1.25mg/kg) or placebo (n=6) once per day for 6 weeks, while remaining on the high fat diet. At the end of the treatment, fasting plasma parameters were measured, and SC and VIS fat biopsies were obtained for molecular studies. Dapa increased adiponectin, adiponectin receptors 1 and 2 gene expression by 90%, 74% and 69% (<0.001) in VIS depot respectively. Adiponectin gene expression was upregulated by 85% in the SC (P<0.05). Inflammation markers such as TNFα and IL-6 are downregulated by 74% (P<0.05) and 86% (P<0.001) in the VIS depot respectively. In addition, genes involved in ceramide synthesis, toll like receptor 4 (TLR4) and serine palmitoyl-CoA transferase (SPTLC2) decreased by 77% and 73 % respectively (P<0.05) in the VIS depot. In conclusion, Dapa promoted adiponectin and its receptors, decreased inflammation and enzymes involved in ceramide synthesis mainly in the VIS depot. These changes were independent of fasting glucose and insulin. Thus, for the first time we are beginning to identify mechanisms by which Dapa enhances AT function in regulating energy homeostasis and improving AT inflammation in mild type 2 diabetes canine model. Disclosure M. Kabir: None. R. N. Bergman: None. V. Gopaul: None. H. Yang: Employee; Self; AstraZeneca. C. M. Kolka: Research Support; Self; AstraZeneca. Funding National Institutes of Health

Antidiabetic and Renoprotective Effects of Coffea arabica Pulp Aqueous Extract through Preserving Organic Cation Transport System Mediated Oxidative Stress Pathway in Experimental Type 2 Diabetic Rats.

Coffea arabica pulp (CP) is a by-product of coffee processing. CP contains polyphenols that have exhibited beneficial effects, including antioxidant and lipid-lowering effects, as well as enhanced insulin sensitivity, in in vitro and in vivo models. How polyphenols, as found in CP aqueous extract (CPE), affect type 2 diabetes (T2D) has not been investigated. Thus, the present study examined the potential antidiabetic, antioxidant, and renoprotective effects of CPE-rich polyphenols, using an experimental model of T2D in rats induced by a high-fat diet and a single low dose of streptozotocin. The T2D rats received either 1000 mg/kg body weight (BW) of CPE, 30 mg/kg BW of metformin (Met), or a combination treatment (CPE + Met) for 3 months. Plasma parameters, kidney morphology and function, and renal organic transport were determined. Significant hyperglycemia, hypertriglyceridemia, insulin resistance, increased renal lipid content and lipid peroxidation, and morphological kidney changes related to T2D were restored by both CPE and CPE + Met treatments. Additionally, the renal uptake of organic cation, 3H-1-methyl-4-phenylpyridinium (MPP+), was reduced in T2D, while transport was restored by CPE and CPE + Met, through an up-regulation of antioxidant genes and protein kinase Cα deactivation. Thus, CPE has antidiabetic and antioxidant effects that potentially ameliorate kidney function in T2D by preserving renal organic cation transport through an oxidative stress pathway.

EXPERIMENTAL INDUCTION OF TYPE 2 DIABETES MELLITUS AND THE EFFICIENCY OF BARIATRIC SURGERY IN ITS REVERSAL IN RATS.

Following recent years, there is an increased body of literature on the connections that might exist between type 2 diabetes mellitus and the efficiency of bariatric surgery in its reversal compared to other medical approaches such as dieting. To induce experimentally type 2 diabetes mellitus in rats in order to observe the effects of bariatric surgery in the recovery as well as the reestablishment of normal insulin levels in order to extend the findings in house animals. This study was conducted in three stages: the first consisted in inducing type 2 diabetes mellitus (T2DM) in 40 young Wistar male rats, by initially feeding them human food high in vegetal fats, oleaginous seeds, simple and complex carbohydrates, sugars, lipids, fats, proteins and fructose for a period of 8 weeks followed by a single low dose of streptozotocin (STZ), administered through intraperitoneal injection. The second stage of the study started when the rats became obese and therefore qualified for the bariatric procedure and the third stage consisted of post-operation supervision and care. The surgical procedure, performed on 10 obese rats, consisted in reducing the size of the stomach by partial gastrectomy of a 1.5 - 2.0 cm wide and 6.5 - 7.5 cm long area on the large curvature. Showed rapid improvements in body weight and blood sugar control after 9 days. After putting the rats on a diet high in carbohydrates, sugars, lipids and fats and administering them STZ, the induction of type 2 diabetes was successful and the partial gastrectomy led to a better blood sugar control. The bariatric procedure provides a faster therapeutic response than conventional diets.

Minocycline attenuates depressive-like behaviors in mice treated with the low dose of intracerebroventricular streptozotocin; the role of mitochondrial function and neuroinflammation.

Neuroinflammation and mitochondrial dysfunction are suggested as mechanisms which are implicated in the pathophysiology of depression. Streptozotocin (STZ) is known to produce immune-inflammatory responses and mitochondrial dysfunction in different types of animal models of disease (e.g. type-1 diabetes and Alzheimer's disease). Therefore, a single low dose of Streptozotocin (STZ; intracerebroventricular, i.c.v, 0.2mg/mouse) was used to induce an animal model of depression. The present study aims to investigate the effects of short (24h) and long (14days) exposure to minocycline on STZ-induced depressive-like behaviors (n = 6-8), hippocampal oxidative state biomarkers (n = 4), and the expression of hippocampal genes related to innate immunity (n = 3) in the hippocampus of male adult mice. In addition, the protective effects of different modes of minocycline (acute pretreatment (20mg/kg, 1h before STZ), acute post-treatment (20mg/kg, 24h after STZ), chronic pretreatment (5mg/kg/day for 14days before STZ), and chronic post-treatment (5mg/kg/day for 14days after STZ) were compared with the STZ effects. As the data showed, both short and long effects of STZ were associated with the depressive-like behaviors, abnormal mitochondrial function, and upregulation of neuroinflammatory genes in the hippocampus. Different modes of minocycline treatment could attenuate the negative impact of STZ on animals. The data suggested that minocycline at a human therapeutic dose (5mg/kg) had protective effects against acute cellular damage induced by oxidation and the consequent inflammatory responses.

1711-P: Dapagliflozin Promotes Adipose Beiging and Lipolysis and Reduces Adipocyte Size in the Obese Prediabetic Dog

Selective sodium glucose cotransporter-2 inhibition promotes urinary glucose excretion, thus reducing blood glucose. Previously we showed that 6 weeks of Dapagliflozin (Dapa) treatment improved insulin sensitivity and prevented weight gain in a canine model of mild type 2 diabetes. Little is known about the effects of Dapa on adipose tissue (AT) function. Eleven dogs were fed a high fat diet for 6 weeks, then received a single low dose of streptozotocin (18.5mg/kg) to induce mild type 2 diabetes. Animals were then exposed to Dapa (n=5, 1.25mg/kg) or placebo (n=6) once per day for 6 weeks, while remaining on the high fat diet. At the end of the study, subcutaneous (SC) and visceral (VIS) fat depots were obtained for adipocytes isolation and molecular studies and fasting plasma parameters were measured. Fasting plasma glucose and insulin levels were unaffected by Dapa treatment. Finite mixture modeling linear regression was used for adipocyte distributions. Dapa decreased adipocyte size and bimodal distributions in both SC and VIS by 10% (P<0.001). Dapa increased UCP1, PGC1α and Prdm16 gene expression by 2.68, 2.34 and 2.16 folds (<0.05) in SC and 2.5, 3.6 and 1.6 folds (<0.05) in VIS depots respectively. Immunostaining of UCP1 in SC and VIS tissues confirmed beiging process. Primary adipocytes were cultured for 4 and 24h. Lipolysis, indicated by glycerol release into the media increased by 40% in SC and 43% in vis after 24h (P<0.05). Adiponectin levels increased only in the SC adipocytes by 80% (P<0.05) after 4 and 24h cultures. Leptin levels increased in SC (by 3 folds P<0.05) and VIS by 2.6 P<0.05) after 24h adipocyte cultures. In conclusion, Dapa promotes AT beiging, lipolysis, adiponectin and leptin release by adipocytes and decreased adipocyte size and distributions. These changes were independent of glucose and insulin. Thus, for the first time we are beginning to identify mechanisms by which Dapa enhances AT function and improves energy homeostasis in mild type 2 diabetes canine model. Disclosure M. Kabir: None. R.N. Bergman: None. F. Piccinini: Employee; Self; Medtronic. D. Stefanovski: None. V. Gopaul: None. H. Yang: Employee; Self; AstraZeneca. C.M. Kolka: Research Support; Self; AstraZeneca. Funding AstraZeneca (D1690L00045-CSR212966)

Zinc deficient diet exacerbates the testicular and epididymal damage in type 2 diabetic rat: Studies on oxidative stress-related mechanisms

Zinc (Zn) is one of the most important trace elements in the body and is required for insulin secretion and release. Zn is also required for the growth and development of the reproductive system. Alteration in the Zn levels can cause moderate to severe damage to various organs, including the reproductive system. Most of type 2 diabetic patients have altered Zn levels/signaling. So, here we investigated the role of Zn-deficient diet (ZDD) in type 2 diabetes. Type 2 diabetes in the rat was induced by the combination of high-fat diet (HFD) and a single low dose of streptozotocin (STZ, 35 mg/kg, i.p.). Control animals were fed normal pellet diet throughout the study, while ZDD was given for four consecutive weeks to the diabetic rats, which were earlier kept on HFD for 16 weeks. The present findings showed that ZDD further decreased the serum Zn, plasma insulin and serum testosterone levels, whereas it increased cholesterol, triglycerides, BUN, %HbA1c in diabetic rats. Oxidative stress in testes was increased by ZDD as evidenced by decreased glutathione, catalase and SOD1 levels. ZDD-induced several abnormalities in sperm head morphology, altered sperm decondensation, sperm chromatin and protamine content, along with significant histopathological alterations in testes and epididymis. Further, ZDD altered protein levels of MT, MTF-1, Keap1, Nrf2, Nf-κB, GPX4 and GPX5 levels in the testes and epididymis of diabetic rat. The present results demonstrated that dietary Zn deficiency could exacerbate type 2 diabetes-induced germ cell damage.

Impact of Ginkgo biloba extract and magnetized water on the survival rate and functional capabilities of pancreatic β-cells in type 2 diabetic rat model.

IntroductionType 2 diabetes (T2D) is a widely distributed disease that affects large population worldwide. This study aimed to verify the role of Ginkgo biloba (GB) extract and magnetized water (MW) on the survival rate and functional capabilities of pancreatic β-cells in type 2 diabetic rats.Materials and methodsT2D was induced by feeding the rats on a high-fat diet (20% fat, 45% carbohydrate, 22% protein) for eight weeks followed by intra-peritoneal injection of a single low dose of streptozotocin (25mg/Kg). Forty rats were randomly assigned to four groups (n=10 rats) as follows: non treated control and three diabetic groups. One diabetic group served as a positive control (diabetic), while the other two groups were orally administered with water extract of GB leaves (0.11 g/kg/day) and MW (600 gauss) for four weeks, respectively.ResultsThe β-cell mass and insulin expression in these cells increased markedly after both treatments, particularly in GB treated group. In addition, the immune-expression of the two antioxidant enzymes; glutathione and superoxide dismutase 2 (SOD2) in the pancreatic tissue demonstrated a down-regulation in GB and MW treated groups as compared with the diabetic group.ConclusionA four-week treatment of GB and MW protected pancreatic β-cell cells and improved their insulin expression and antioxidant status in type 2 diabetic rats.

Impact of coxsackievirus-B4E2 combined with a single low dose of streptozotocin on pancreas of outbred mice: investigation of viral load, pathology and inflammation

Coxsackieviruses B (CV-B) belong to the EV-B species. CV-B and particularly CV-B4 are thought to be involved in the development of chronic diseases like type 1 diabetes (T1D). The mechanisms of the enteroviral pathogenesis of T1D are not well known, yet. The in vitro studies are rich with information but in vivo infection models are needed to investigate the impact of viruses onto organs. Our objective was to study the impact of CV-B4E2 combined with a single sub-diabetogenic dose of streptozotocin (STZ) on the pancreas of mice. The infection with CV-B4E2 of CD1 outbred mice treated with a sub-diabetogenic dose of STZ induced hyperglycemia and hypoinsulinemia. Along with the chemokine IP-10, viral RNA and infectious particles were detected in the pancreas. The pancreas of these animals was also marked with insulitis and other histological alterations. The model combining STZ and CV-B4E2 opens the door to new perspectives to better understand the interactions between virus and host, and the role of environmental factors capable, like STZ, to predispose the host to the diabetogenic effects of enteroviruses.

The Effect of Different Types of Bariatric Surgery on Metabolic and Hormonal Parameters in Rats with a Decompensated Form of Type II Diabetes Mellitus

Bariatric surgery (BS), including sleeve gastrectomy (SG), gastric bypass (GB), and ileal transposition (IT), is one of the approaches currently used for the correction of metabolic disturbances in type 2 diabetes mellitus (DM2) with obesity. However, the efficiency of these approaches and their impact on hypothalamic signaling and hormonal status in severe forms of DM2 without obesity remain poorly characterized. The aim of this work is to study the effect of IT, SG, and GB on insulin, leptin, ghrelin, and glucagon-like peptide-1 (GLP-1) levels in the blood and on the expression of the genes encoding the main components of the hypothalamic signaling systems in rats with a decompensated form of DM2 induced by a high-fat diet (three months) and a single low dose of streptozotocin (25 mg/kg, two months after the start of the diet). Pronounced hyperglycemia, impaired glucose tolerance, a decrease in the glucose-stimulated GLP-1 level, a slight decrease in the insulin and leptin levels, and a slight increase in the ghrelin level are detected in diabetic rats. Expression of genes encoding the GLP-1 receptor, the orexigenic agouti-related peptide (AgRP), and phosphotyrosine phosphatase 1B and SOCS3, the negative regulators of the leptin and insulin pathways, is increased in the hypothalamus. IT in diabetic rats leads to a reduction of glucose levels 120 min after glucose loading, an increase of basal and glucose-stimulated GLP-1 levels, and normalization of the expression levels of the phosphotyrosine phosphatase 1B, SOCS3, AgRP, and GLP-1 receptor genes, which is indicative of restoration of the hypothalamic signaling responsible for the control of energy metabolism and insulin sensitivity. Glucose tolerance is improved in the case of SG and GB, and an increase in the basal and glucose-stimulated GLP-1 levels is demonstrated in the case of SG, but no significant effects on the expression of the hypothalamic genes are observed in SG and GB. Thus, IT is the most efficient bariatric surgical intervention among those studied for the treatment of severe DM2 forms without obesity.

Galangin ameliorates changes of membrane–bound enzymes in rats with streptozotocin–induced hyperglycemia

Objective: To assess the protective effect of galangin on membrane bound enzymes in rats with streptozotocin-induced diabetes. Methods: A single low dose of streptozotocin was injected to adult male albino rats to induce hyperglycemia. Galangin (8 mg/kg) or glibenclamide 600 μg/kg as a standard drug was given orally once daily for 45 days by gavage. Membrane-bound adenosine triphosphatases were determined including total ATPase, sodium-potassium-ATPase, calcium-ATPase and magnesium-ATPase in erythrocytes and tissues (kidney, liver, and heart). Results: The levels of total ATPases, sodium-potassium-ATPase, calcium-ATPase and magnesium-ATPase in erythrocytes and tissues were significantly altered in diabetic rats as compared to that in normal rats. After 45 days of treatment with galangin or glibenclamide, the levels of these enzymes were similar to that of normal control rats. Conclusions: Oral administration of galangin or glibenclamide can improve activities of these membrane-bound ATPases towards normal levels. Mechanism of galangin needs to be further explored in future.

Dapagliflozin Improves Insulin Sensitivity in the Obese Prediabetic Canine

SGLT2 inhibition has positive effects on glucose balance, reducing fasting and postprandial glucose levels, however little is known about the effects of SGLT2 inhibitors on lipid levels. PKPD simulation for this canine model was applied for dose selection of dapagliflozin (dapa). Seven dogs were fed a high fat diet for 6 weeks, then received a single low dose of streptozotocin (18.5mg/kg) to induce mild type 2 diabetes. Animals were exposed to dapa (n=4, 1.25mg/kg) or placebo (n=3) once per day for 6 weeks, while remaining on the high fat diet. Animals were then subjected to the intravenous glucose tolerance test (IVGTT) to assess glucose tolerance and insulin response to glucose, and the euglycemic hyperinsulinemic clamp protocol in conjunction with tracer infusions to evaluate adipose tissue, skeletal muscle and hepatic insulin sensitivity. In the IVGTT, modeling techniques are used to estimate the acute insulin response to a glucose bolus, which was not altered with dapa treatment, but insulin sensitivity was significantly improved compared to placebo-treated animals (dapa 0.54±0.22, control -0.95±0.51mU/l-1.minute-1, p=0.05). The glucose infusion required for euglycemia during steady state in the clamp was decreased with dapa (dapa -3.0±1.05, control 1.53±1.28 mg/minute/kg, change from pre-drug timepoint, P=0.038), supporting the IVGTT results. Urinary glucose disposal rate during the clamp was inconsistent. There is a trend towards higher FFA levels in dapa-treated animals under noninsulin stimulated conditions (P=0.054). These may be a regulator of hepatic glucose production, or reflect a switch towards lipid utilization. We conclude that 6 weeks of dapa treatment improves insulin sensitivity in a canine model of mild type 2 diabetes. Further studies on lipid metabolism, body fat deposition and insulin clearance are on-going. Disclosure R.L. Paszkiewicz: None. R.N. Bergman: Advisory Panel; Self; Ingredion, Inc.. Research Support; Self; AstraZeneca. Consultant; Self; GI Dynamics Inc.. Research Support; Self; National Institute of Diabetes and Digestive and Kidney Diseases. Consultant; Self; Novo Nordisk A/S. I. Asare Bediako: None. H.J. Mkrtchyan: None. V. Gopaul: Employee; Self; AstraZeneca. H. Yang: Employee; Self; AstraZeneca. E. Lundborg: Employee; Self; AstraZeneca. S. Kim: None. I. Formentini: Employee; Self; AstraZeneca. C.M. Kolka: Research Support; Self; AstraZeneca.