Induction Of Experimental Diabetes Mellitus Research Articles

Модель диет-индуцированного экспериментального сахарного диабета у лабораторных песчанок и дегу

According to the latest data from the International Diabetes Federation (IDF), the number of patients with diabetes has outpaced previously predicted growth rates and is expected to increase by 51% by 2045. Thus, the development and evaluation of the effectiveness and safety of hypoglycemic agents is an urgent task due to the high social significance of the problem. In preclinical studies there are many models of experimental diabetes mellitus in animals, both with the use of chemical inducers that cause damage to the islet apparatus of the pancreas, and with the use of diets. Accor­ding to the literature data, gerbils and degus are prone to hyperglycemia and insulin resistance when fed on standard laboratory diets, which are relatively high in calories compared to the food obtained by these animals in their natural habitat. Due to this feature the experimental induction of diabetes mellitus in these animal species can be modeled only through the use of a high-calorie diet. The purpose of this study was to test this hypothesis. Male and female gerbils of two age categories (14–20 and 40–41 weeks), as well as male and female degus, whose age was 65–70 weeks, were used as experimental animals. During the experiment the following indicators were evaluated: the concentration of glucose, cholesterol, triglycerides, creatinine, urea in blood plasma, the activity of dipeptidyl peptidase type 4 (DPP-4) and the parameters of the glucose tolerance test. Based on the totality of all experimental data a state close to pre-diabetic was established in male and female degus fed on a high-carbohydrate diet. This conclusion was made due to an increase in the activity of the DPP-4 enzyme and the presence of glucose tolerance by the 12th week of the experiment. The induction of experimental diabetes mellitus or latent diabetes mellitus using high-calorie diets failed in the majority of experimental animals (gerbils and degus) regardless of age. The obtained results are suggestive of the motivation for the use of these experimental models for the creation of experimental diabetes.

In Situ Neutral System Synthesis, Spectroscopic, and Biological Interpretations of Magnesium(II), Calcium(II), Chromium(III), Zinc(II), Copper(II) and Selenium(IV) Sitagliptin Complexes.

Magnesium(II), calcium(II), chromium(III), zinc(II), copper(II), and selenium(IV) sitagliptin (STG) complexes—with the general formulas [Mg(STG)2(Cl)2]·6H2O, [Ca(STG)2(Cl)2], [Cr(STG)2(Cl)2]Cl.6H2O, [Zn(STG)2(Cl)2], [Cu(STG)2(Cl)2]·2H2O, and [Se(STG)2(Cl)2]Cl2, respectively—were designed and synthesized by the chemical reactions between metal(II, III, and IV) chloride salts with an STG ligand in situ methanol solvent in a 1:2 stoichiometric ratio (metal:ligand). Tentative structures of the complexes were proposed based on elemental analysis, molar conductance, magnetic moments, thermogravimetric analysis, and spectral (infrared, electronic, and 1H NMR) data. The particle size and morphological investigation were checked on the bases of scanning electron microscopy, transmission electron microscopy, and X-ray powder diffraction analyses. All the Mg2+, Ca2+, Cr3+, Zn2+, Cu2+, and Se4+ complexes were found to be six-coordinated, wherein the STG ligands act as bidentate chelating agents. This study demonstrates that pancreatic tissues are affected by the induction of experimental diabetes mellitus and clarifies the potential of the synthesized STG complexes, which was found to more significantly improve insulin secretion and the pancreatic and glycometabolic complications of diabetic rats than STG alone.

Role of endocannabinoid CB1 receptors in Streptozotocin-induced uninephrectomised Wistar rats in diabetic nephropathy

BackgroundThe endocannabinoid CB1 receptor is known to have protective effects in kidney disease. The aim of the present study is to evaluate the potential agonistic and antagonistic actions and to determine the renoprotective potential of CB1 receptors in diabetic nephropathy. The present work investigates the possible role of CB1 receptors in the pathogenesis of diabetes-induced nephropathy. Streptozotocin (STZ) (55 mg/kg, i.p., once) is administered to uninephrectomised rats for induction of experimental diabetes mellitus. The CB1 agonist (oleamide) and CB1 antagonist (AM6545) treatment were initiated in diabetic rats after 1 week of STZ administration and were given for 24 weeks.ResultsThe progress in diabetic nephropathy is estimated biochemically by measuring serum creatinine (1.28±0.03) (p < 0.005), blood urea nitrogen (67.6± 2.10) (p < 0.001), urinary microprotein (74.62± 3.47) (p < 0.005) and urinary albuminuria (28.31±1.17) (p < 0.0001). Renal inflammation was assessed by estimating serum levels of tumor necrosis factor alpha (75.69±1.51) (p < 0.001) and transforming growth factor beta (8.73±0.31) (p < 0.001). Renal morphological changes were assessed by estimating renal hypertrophy (7.38± 0.26) (p < 0.005) and renal collagen content (10.42± 0.48) (p < 0.001).ConclusionsFrom the above findings, it can be said that diabetes-induced nephropathy may be associated with overexpression of CB1 receptors and blockade of CB1 receptors might be beneficial in ameliorating the diabetes-induced nephropathy.Graphical abstract

Age Susceptibility of Wistar Rats to Alloxan-Induced Diabetes: A Paradox

Selection of appropriate ages of rats for experimental diabetes mellitus studies has been posing great challenges to researchers as the rats may either not come down with diabetes or may even die upon induction. This study investigated the influence of age as a possible factor affecting successful induction of diabetes mellitus in albino Wistar rats. One hundred male albino Wistar rats of varying ages weighing between 23.63 ± 0.46 g and 279.00 ± 27.00 g and assigned into ten (10) groups of ten rats per group were used for the study. Diabetes was induced in groups 1-9 consisting of rats aged 3, 5, 7, 9, 11, 13, 15, 17 and 19 weeks respectively by injecting 160 mg/kg of alloxan monohydrate intraperitoneally while group 10 rats (aged 12 weeks) served as normal control. Fasting blood glucose levels and the weights of the rats were determined on 0 h, 24 h, 48 h, 72 h and 96 h post alloxan monohydrate injection. Body conditions and behaviors of the rats were subjectively scored. Results showed that rats in groups 3-9 came down with hyperglycemia 48 h post-alloxan injection. The body conditions and behaviors of groups 3 (aged 7 weeks) and 4 (Aged 9 weeks) rats compared very well (p&lt;0.05) with those of the normal control rats. It was concluded that rats aged 7-9 weeks were most suitable for use in studies involving induction of experimental diabetes mellitus using alloxan monohydrate at the dose of 160 mg/kg intraperitoneally.

Ameliorating effect of betanin, a natural chromoalkaloid by modulating hepatic carbohydrate metabolic enzyme activities and glycogen content in streptozotocin – nicotinamide induced experimental rats

Betanin, a chromoalkaloid of beetroot, has shown significant biological effects of antioxidants, anti-inflammatory and anticarcinogenic activities. So, we attempted to determine whether betanin (a natural pigment) would be protective against hyperglycemia in streptozotocin (STZ) - nicotinamide (NA) induced diabetic rats. Rats were injected with STZ (40mg/kgb.w.) 15 mins after the administration of NA (110mg/kgb.w.) by intraperitonially (i.p.) 30days for the induction of experimental diabetes mellitus. After 72h diabetic rats were treated with betanin orally at a doses of 10, 20 and 40mg/kg b.w., respectively in a dose dependent manner and glibenclamide (600μg/kgb.w.). The promising character of betanin against diabetic rats was evaluated by performing the various biochemical parameters and histomorphological changes in liver and pancreas. Among the three doses, 20mg/kgb.w. of betanin was able to positively regulate plasma glucose, insulin, glycosylated hemoglobin (HbA1c) and hemoglobin (Hb) levels by significantly increasing the activity of glycolytic enzyme (glucokinase and pyruvate kinase), glucose-6-phosphate dehydrogenase and significantly decreasing the activity of gluconeogenic enzymes (glucose-6-phosphatase and fructose-1,6-bisphosphatase) thereby increasing the glycogen content in the liver. We put forward that betanin could significantly restore the levels of carbohydrate metabolic key enzymes to near normal in diabetic rat. Immunohistochemical observation of pancreas revealed that betanin treated diabetic rats showed increased insulin immunoreactive β-cells, which confirmed the biochemical findings. Taken together, present study suggests that betanin modulates the carbohydrate metabolism and has beneficial effects in glucose homeostasis.

Antidiabetic and antihyperlipidemic activity of p-coumaric acid in diabetic rats, role of pancreatic GLUT 2: In vivo approach.

P-coumaric acid (p-CA, 3-[4-hydroxyphenyl]-2-propenoic acid), the major component widely found in nutritious plant foods, has various antioxidant, antiinflammatory and anticancer property. To evaluate the antidiabetic and antihyperlipidemic mechanisms, via the effects on carbohydrate, lipids and lipoproteins responses in adult male albino Wistar rats were examined by treated with p-CA. Rats were injected with streptozotocin (STZ, 40mg/kg b.w.) by intraperitonially (i.p.) 30days for the induction of experimental diabetes mellitus. Diabetic rats were treated with p-CA orally at a dose of 100mg/kg b.w. The potential defending character of p-CA against diabetic rats was evaluated by performing the various biochemical parameters and glucose transporter such as GLUT2 mRNA expression of pancreas. Administration of p-CA significantly lowers the blood glucose level, gluconeogenic enzymes such as glucose-6-phosphatase and fructose-1,6-bisphosphatase whereas increases the activities of hexokinase, glucose-6 phosphatase dehydrogenase and GSH via by increasing level of insulin. p-CA reduces the total cholesterol and triglycerides in both plasma and tissues i.e. liver and kidney. p-CA also decreases the LDL-C, VLDL-C and it considerably increase the level of HDL-C. A significant decreased expression of GLUT 2 mRNA in the pancreas was recorded in the supplementation of p-CA treated groups. Taken together, these results suggest that p-CA modulates glucose and lipid metabolism via GLUT 2 activation in the pancreatic and has potentially beneficial effects in improving or treating metabolic disorders.

EFFECT OF CAMELS MILK FEEDING ON OXIDATIVE STRESSES IN EXPERIMENTALLY INDUCED DIABETIC RABBITS

Diabetes mellitus is a multi-factorial disorder that CHARacterized by hyperglycemia, lipoprotein abnormalities resulting from malfunction in insulin secretion and/or insulin action causing impaired metabolism of glucose, lipids and protein. In addition, generation of free radicals often worsen the complications of diabetes mellitus such as hypertension, atherosclerosis and microcirculatory disorders. A group of scientists reported the effect of camel milk on diabetes, referring to its importance in treatment of diabetes and patients who drink camel milk daily, their need to insulin decrease. Therefore, this study aimed to throw light on the effect of camel milk in comparison to insulin treatment. This study was carried out on forty male New Zealand rabbits, divided into four equal groups each group contained ten rabbits. The first group (G1) was considered as control non diabetic group injected with normal saline solution. The other animals were injected intravenously with alloxan for induction of experimental diabetes mellitus and then divided into three equal groups ten rabbits each as the follows: (G2) considered as control diabetic left untreated, (G3) was considered as diabetic insulin treated group, (G4) was considered as diabetic camel milk treated group. After the end of the experiment (4 weeks), blood (whole blood & serum) in addition to tissue samples (liver, kidney and pancreas) were collected from all the animals for analysis of: enzymatic SOD and catalase, non-enzymatic GSH antioxidant enzyme activities. Serum malondialdeyde, glucose, insulin and lipid profile.It was observed that the effect of camel milk containing insulin like peptides, vitamin C and zinc in addition to other minerals and vitamins that are effective in the treatment of diabetes in comparison to insulin treatment alone. In addition to its hypoglycemic effect and improvement of oxidative stress accompanied with diabetes mellitus.It was observed that there is regeneration in  cells and S.Sherbini. et.al., 76 high number of islets of Langerhans among the pancreatic acini in rabbits receiving camel milk. There is a wide similarity between camel milk and goat milk. So, from this study, camel milk administration in case of insulin dependant diabetes mellitus is recommended as oral anti diabetic drug. ,

Induction of diabetes by Streptozotocin in rats

The objective of this study is to induce experimental diabetes mellitus by Streptozotocin in normal adult Wistar rats via comparison of changes in body weight, consumption of food and water, volume of urine and levels of glucose, insulin and C-peptide in serum, between normal and diabetic rats. Intra-venous injection of 60mg/kg dose of Streptozotocin in adult wistar rats, makes pancreas swell and at last causes degeneration in Langerhans islet beta cells and induces experimental diabetes mellitus in the 2-4 days. Induction of experimental diabetes mellitus is indeed the first step in the plan of purification of pancreatic Langerhans islet cells of normal rats for transplanting under the testis subcutaneous of experimentally induced diabetic rats. Streptozotocin induces one type of diabetes which is similar to diabetes mellitus with non-ketosis hyperglycemia in some animal species. For induction of experimental diabetes in male adult rats weighted 250-300 grams (75-90 days), 60mg/kg of Streptozotocin was injected intravenously. Three days after degeneration of beta cells, diabetes was induced in all animals. The diabetic and normal animals were kept in the metabolic cages separately and their body weight, consumption of food and water, urine volume, the levels of serum glucose, insulin and C-peptide quantities in all animals were measured and then these quantities were compared. For a microscopic study of degeneration of Langerhans islet beta cells of diabetic rats, sampling from pancreas tissue of diabetic and normal rats, staining and comparison between them, were done. Induction of diabetes with Streptozotocin decreases Nicotinamide-adenine dinucleotide (NAD) in pancreas islet beta cells and causes histopathological effects in beta cells which probably intermediates induction of diabetes. In this study, we used Streptozotocin for our experiments in induction of experimental diabetes mellitus. After Induction of diabetes, consumption of food and water, volume of urine and glucose increased in the diabetic animals in comparison with normal animals, but the weight of body and the volume of insulin and C-peptide decreased in the diabetic animals. Sampling and staining of pancreas tissue of diabetic and normal rats showed that the Langerhans islet beta cells of diabetic rats have been clearly degenerated. In three days, Streptozotocin makes pancreas swell and at last causes degeneration in Langerhans islet beta cells and induces experimental diabetes. It also changes normal metabolism in diabetic rats in comparison with normal rats. Consumption of water and food, volume of urine, serum glucose increases in diabetic animals in comparison with normal rats but the levels of serum insulin, C-peptide and body weight decreases.

Terminal ileum submucous plexus: Study of the VIP-ergic neurons of diabetic rats treated with ascorbic acid.

The aim of this study was to evaluate the effect of the ascorbic acid (AA) supplementation on the neurons that produce the vasoactive intestinal peptide (VIP) in the submucous plexus of the ileum of rat, four months after the induction of experimental diabetes mellitus with streptozotocin. Three groups of rats were used: C - control, D - diabetic, DA - diabetic receiving AA. We have measured the immunoreactivity and area of 80 cellular bodies of VIP-ergic neurons from each studied group. In the diabetic animals, we have observed hyperphagia, polydipsia, and an increase of glycemia and glycated hemoglobin. The VIP-ergic neurons have presented an increase of their immunoreactivity and the highest profiles when compared to the other groups. In the diabetic animals supplemented with AA it has been observed a small reduction in the glycemia and the water and food intake. We have also noticed smaller immunoreactivity in their VIP-ergic neurons, similar to what we have observed in the control group animals (group C).

Autoradiographic thyroid evaluation in short-term experimental diabetes mellitus.

Previous studies have shown that in vitro thyroid peroxidase (TPO) iodide oxidation activity is decreased and thyroid T4-5'-deiodinase activity is increased 15 days after induction of experimental diabetes mellitus (DM). In the present study we used thyroid histoautoradiography, an indirect assay of in vivo TPO activity, to determine the possible parallelism between the in vitro and in vivo changes induced by experimental DM. DM was induced in male Wistar rats (about 250 g body weight) by a single i.p. streptozotocin injection (45 mg/kg), while control (C) animals received a single injection of the vehicle. Seven and 30 days after diabetes induction, each diabetic and control animal was given i.p. a tracer dose of 125I (2 microCi), 2.5 h before thyroid excision. The glands were counted, weighted, fixed in Bouin's solution, embedded in paraffin and cut. The sections were stained with HE and exposed to NTB-2 emulsion (Kodak). The autohistograms were developed and the quantitative distribution of silver grains was evaluated with a computerized image analyzer system. Thyroid radioiodine uptake was significantly decreased only after 30 days of DM (C: 0.38 +/- 0.05 vs DM: 0.20 +/- 0.04%/mg thyroid, P < 0.05) while in vivo TPO activity was significantly decreased 7 and 30 days after DM induction (C: 5.3 and 4.5 grains/100 micron 2 vs DM: 2.9 and 1.6 grains/100 micron 2, respectively, P < 0.05). These data suggest that insulin deficiency first reduces in vivo TPO activity during short-term experimental diabetes mellitus.

The effect of leukocyte function of streptozotocin-induced diabetes in naturally occurring gingivitis rat.

Although diabetes mellitus is known to aggravate periodontal disease, the precise relationship between these two entities is far from being completely understood. Further study of this relationship was therefore undertaken in the form of observation of both naturally occurring gingivitis in rats (ODUS/Odu) and effects produced by induction of experimental diabetes mellitus by injection of streptozotocin (STZ: 65 mg/kg, i.v.). At one and 3 mon after STZ injection, liquid paraffin was injected intraperitoneally. Four days thereafter, pocket probing depths of rats were measured and blood samples as well as peritoneal macrophages were collected from both experimental animals and non diabetic controls. Both chemotaxis and phagocytosis of macrophages were studied. At one and 3 mon after STZ injection, pocket probing depths of diabetic animals were significantly deeper than those of controls (p < 0.001). Pocket probing depths were deeper at 3 mon after STZ injection than after 1 mon in diabetic animals. At three months after STZ injection, there was a high degree of positive correlation between pocket probing depths, blood glucose levels, triglyceride, and hemoglobin A1c levels (p < 0.01). Also, macrophage chemotaxis was more suppressed in diabetic rats than it was in controls. Additionally, both phagocytosis ratios and phagocytosis indices of macrophages in the diabetes group were significantly more suppressed than those in controls in both experimental periods (p < 0.001). Findings suggest that both chemotaxis and phagocytosis are compromised in macrophages from rats rendered diabetic by STZ injection. Thus as host defense mechanisms become weakened, there is a corresponding progression of periodontal disease.

Presynaptic deficit of sympathetic nerves: a cause for disturbed sciatic nerve blood flow responsiveness in diabetic rats

Reduced nerve blood flow is thought to play an important role in the pathogenesis of diabetic neuropathy. This disturbance in nerve blood flow might be the consequence of either microangiopathy or an impaired autonomic innervation of the vasa nervorum. In order to differentiate between a vascular or an adrenergic-autonomic defect as the underlying cause of the disturbed nerve blood flow, we investigated the effects of the adrenocorticotropic hormone [ACTH]-(4–9) analogue Org 2766 on sciatic nerve blood flow under basal and adrenergic-stimulated conditions. Org 2766 has neuroprotective effects without cardiovascular effects. Treatment with Org 2766 was started 6 weeks after the induction of experimental diabetes mellitus. At week 12 the sciatic nerve blood flow, measured by laser-Doppler flowmetry, was reduced to 60% of the non-diabetic level; blood pressure was unchanged in diabetic rats compared to non-diabetic rats. Basal haemodynamic values were not affected by Org 2766 treatment. Vasa nervorum adrenergic responsiveness to tyramine (presynaptic) and phenylephrine (postsynaptic) was investigated. Diabetic rats showed adrenergic hyporesponsiveness. Treatment with Org 2766 restored the reduced presynaptic response to tyramine without affecting the reduced postsynaptic response to phenylephrine. It is concluded that a presynaptic-sympathetic deficit of nervi vasorum causes a disturbed flow responsiveness in diabetic rat sciatic nerve and that adrenergic autonomic disturbances in the vasa nervorum have only a small role in the reduced basal nerve blood flow of diabetic rats.

Streptozocin- and Alloxan-Induced H2O2 Generation and DNA Fragmentation in Pancreatic Islets: H2O2 as Mediator for DNA Fragmentation

Streptozocin (STZ) and alloxan (ALX) exhibit the most potent diabetogenicity and are used for induction of experimental diabetes mellitus. An understanding of the mechanisms of action of the typical diabetogenic agents is important for elucidating the causes of diabetes. Okamoto proposed a model in which DNA fragmentation plays an important role in the development of diabetes. DNA fragmentation supposedly results from the accumulation of superoxide or hydroxyl radicals. However, direct evidence for this accumulation is lacking. With isolated rat pancreatic islets in vitro, we demonstrated that STZ and ALX stimulated H2O2 generation and caused DNA fragmentation. Addition of STZ or ALX resulted in an increase in H2O2 generation. On DNA analysis, when incubated without STZ or ALX, DNA sedimented as a single peak; when incubated with STZ or ALX, DNA sedimented slower as a broad peak and was fragmented. Graded doses of STZ and ALX stimulated H2O2 generation and induced DNA fragmentation; their effects on H2O2 generation and DNA fragmentation were evident at a concentration of 0.1 mM and were maximal at 1 mM. Administration of STX or ALX to rats in vivo stimulated H2O2 generation and caused DNA fragmentation in pancreatic islets. H2O2 itself also induced DNA fragmentation. These findings may support Okamoto's proposal that STZ and ALX induce diabetes through the following biochemical events: STZ and ALX----H2O2 generation----DNA fragmentation----beta-cell destruction. This study may constitute the first demonstration of STZ- and ALX-stimulated H2O2 generation, which probably acts as a mediator of STZ- and ALX-induced DNA fragmentation.

Alloxan-induced DNA strand breaks in pancreatic islets. Evidence for H2O2 as an intermediate

Alloxan exhibits the most potent diabetogenicity and has been used for induction of experimental diabetes mellitus. Understanding the mechanisms of action of the typical diabetogenic agent is important for elucidating the causes of diabetes. Okamoto (Okamoto, H. (1985) BioEssays 2, 15-21) proposed a model in which DNA fragmentation plays an important role for the development of diabetes. This DNA fragmentation is supposed to result from the accumulation of superoxide or hydroxyl radicals. However, direct evidence for this accumulation is lacking. Using rat pancreatic islets, we demonstrated that alloxan stimulated H2O2 generation, which induced DNA strand breaks. These findings support Okamoto's proposal that alloxan induces diabetes through the following biochemical events: alloxan----H2O2 generation----DNA strand breaks----diabetes mellitus. Perhaps this report constitutes the first demonstration of alloxan-stimulated H2O2 generation which could conceivably act as an intermediate for alloxan-induced DNA strand breaks.

Elevation rate of glycosylated hemoglobins in dogs after induction of experimental diabetes mellitus

The glycosylated hemoglobin, hemoglobin A 1c (HbA 1c), which reflects average plasma glucose of the previous few weeks, has recently been used to monitor humans with diabetes mellitus. Further understanding of the HbA 1c elevation rate would improve interpretation of HbA 1c. We determined glycosylated hemoglobin elevation rates in 5 dogs with induced diabetes. Hemoglobin A 1c was determined by an established column chromatographic technique; plasma glucose by glucose oxidase. Values were determined on 13 normal dogs and compared with values obtained weekly from surgically or chemically-induced diabetic dogs. Hemoglobin A 1c increased in a fashion that could be predicted by modelling. The model predicts that large changes in Hb A 1c will occur within the first few weeks of a sudden change in glucose and that a new plateau will be reached at a time equal to the erythrocyte life span. In the present experiment abnormally elevated HbA 1c occurred after 2 wk of hyperglycemia. The results should approximate the elevation rate after acute onset and sustained severe hyperglycemia in humans, because humans and canines are hematologically similar and thus extend previously reported studies on human out-patient diabetics.

Altered myocardial mechanics in diabetic rats.

Diabetes mellitus is associated frequently with congestive heart failure in humans, even in the absence of associated coronary disease or hypertension. Nevertheless, the effects of the diabetic state on myocardial mechanics have not been studied. Accordingly, diabetes was induced in female Wistar rats by injection of streptozotocin (60 mg/kg). Left ventricular papillary muscles were studied 5, 10, and 30 weeks later and compared with controls. Relaxation was delayed significantly and velocity of shortening was depressed at all loads. However, the passive and active force-length curves, as well as the series elastic properties, were not altered. The changes in cardiac performance were found over a range of muscle lengths, stimulus frequencies, and bath concentrations of calcium, glucose, and norepinephrine. The duration of diabetes had no major effect on the mechanical changes observed. The possible influences of drug-induced cardiac toxicity, malnutrition, and altered thyroid hormone levels have been considered; the latter two factors could not be excluded completely from having some influence on the mechanical properties of diabetic cardiac muscle. Evidence is cited showing abnormalities in calcium uptake by sarcoplasmic reticulum and depressed actomyosin ATPase activity. Thus a cardiomyopathic state has been produced in the rat consequent to the induction of experimental diabetes mellitus. Various mechanisms for this entity have been suggested.