Onset Of Diabetes In Rats Research Articles

Efficiency of a formulated condiment (duqqa) in mitigation of diabetes and its complications induced by streptozotocin-nicotinamide in rats

Introduction: Duqqa is a condiment, consisting of black pepper, cumin, sesame, coriander and high amount of salt. Reducing salt and adding other beneficial items to traditional duqqa can make it suitable dietary supplement for diabetes management. The current study aimed to assess the effect of a modified duqqa on diabetes and its complications in diabetic rats. Methods: The modified duqqa was formulated by mixing grounded fermented wheat, sesame, coriander, cumin, chicory leaves, cinnamon, turmeric and date seeds powder and studied in diabetic rats which were developed by streptozotocin-nicotinamide injection. Thirty-two rats were divided into four groups (n = 8) including non-diabetic, diabetic control and the other two groups fed on balanced diet supplemented with either 10 or 20% of duqqa prior the induction of diabetes (for one week) to the end of the experiment (8 weeks). Results: The dietary supplementation with 10 and 20% of the formulated duqqa prior the induction of diabetes did not delay the onset of diabetes in rats but produced reduction (32.56% and 50.47%, respectively) in the glucose levels of diabetic rats. Also, diabetic rats fed on the formulated duqqa showed insulin concentrations higher than that of diabetic control rats. Feeding diabetic rats on the formulated duqqa reversed the elevation of kidney lipid peroxidation and nitric oxide, limited the disturbance in the lipid profile as well as liver and kidney functions and elevated both serum and femur magnesium concentrations. Conclusion: The results indicated the hypoglycemic effect of the formulated duqqa and its efficiency in delaying diabetes complications.

Overexpression of renal proapoptotic factors is attenuated subsequent to endurance exercise in Type I diabetes: An immunohistochemistry study

Background: Upregulation of Apoptotic markers (p53 and active caspase-3) is reported in diabetic nephropathy. Exercise training is reported to exert renoprotective effects in diabetes. This study correlated the effects of endurance exercise training on the renal expression of p53 and active caspase-3 in a rat model of Type 1 diabetes. Materials and methods: Thirty healthy Sprague-Dawley rats were randomly divided into the following three groups: sedentary control (SC), sedentary diabetic (SD) rats, and exercised diabetic (ED) rats. The drug alloxan was administered to SD and ED groups of rats in order to induce diabetes mellitus. Expression of p53 and active caspase-3 in the renal tissue from each of the three different groups was investigated by immunohistochemistry. Increased blood levels compared to control group of rats validated the onset of diabetes in rats from SD and ED groups. Results: Significantly (P

Methods for exploring the morpho-functional relations of the aortic depressor nerve in experimental diabetes

The present study investigated morpho-functional relations of the aortic depressor nerve (ADN) 5, 15 and 120 days after the onset of streptozotocin-induced diabetes in rats. Time control animals received vehicle. Under pentobarbital anesthesia, ADN activity was recorded simultaneously with arterial pressure. After the recordings, nerves were prepared for light microscopy study and morphometry. ADN function was accessed by means of pressure-nerve activity curve (fitted by sigmoidal regression) and cross-spectral analysis between mean arterial pressure (MAP) and ADN activity. The relation between morphological (myelinated fibers number and density, total myelin area, total fiber area and percentage of occupancy) and functional (gain, signal/noise relation, frequency) parameters were accessed by linear regression analysis and correlation coefficient calculations. Functional parameters obtained by means of the sigmoidal regression curve as well as by cross-spectral analysis were similar in diabetic and control rats. Morphometric parameters of the ADN were similar between groups 5 days after the onset of diabetes. Average myelin area and myelinated fiber area were significantly smaller on diabetic rats 15 and 120 days after the onset of diabetes, being the myelinated fiber and respective axons area and diameter also smaller on 120 days group. Nevertheless, G ratio (ratio between axon and fiber diameter) was nearly 0.6 and not different between groups or experimental times. No significant relationship between morphological and functional parameters was detected in all experimental groups. The present study suggests that ADN diabetic neuropathy was time-dependent, with damage to myelinated fibers to be the primary event, not evidenced by physiological methods.

Nitric oxide may prevent hypertension early in diabetes by counteracting renal actions of superoxide.

The dependence of blood pressure on a balance between superoxide and nitric oxide may be amplified in diabetes. We have shown that the first occurrence of sustained hyperglycemia in type I diabetes causes hypertension when induced in rats that have had nitric oxide synthesis blocked chronically (L-NAME, 10 microg/kg per minute IV). This study used tempol (18 micromol/kg per hour IV) to test the hypothesis that superoxide mediates that hypertensive response. Induction of diabetes in untreated rats had no significant effect on mean arterial pressure (MAP, measured 18 h/d), and glomerular filtration rate (GFR) increased significantly during the 2 weeks of diabetes. Chronic infusion of L-NAME in a separate group of rats increased baseline MAP from approximately 90 mm Hg to a stable level of approximately 120 mm Hg after 6 days of infusion, and induction of diabetes (streptozotocin, 40 mg/kg IV) in those rats caused a rapid, progressive increase in MAP that averaged 156+/-5 mm Hg by day 14 of diabetes that was associated with a decrease in GFR and 4-fold increase in isoprostane excretion. Tempol infusion was begun on day 2 of diabetes in a subgroup of those rats, and the progressive hypertensive response was prevented, with MAP averaging 134+/-10 mm Hg by day 14. In addition, the normal renal hyperfiltration response was restored by tempol and the increase in isoprostane did not occur. Thus, the hypertension and decrease in GFR caused by onset of diabetes in rats without a functioning nitric oxide system was prevented by chronic administration of the superoxide dismutase mimetic tempol.

Ramipril and aminoguanidine restore renal lysosomal processing in streptozotocin diabetic rats.

We aimed to examine the time course for the diabetes-related changes in renal lysosomal processing and to determine whether these changes can be prevented by aminoguanidine or ramipril treatment. The percentage desulphation of intravenously injected tritium labelled dextran sulphate ([3H]DSO4) in the urine, as determined by ion-exchange chromatography, was used as a marker of lysosomal sulphatase activity. Sulphatase activity was determined 1, 2, 3 and 4 weeks after the onset of diabetes in rats as well as in rats treated with either aminoguanidine or ramipril for twelve weeks. The amount of totally desulphated [3H]DSO4 in urine collected from control rats was 65.6 +/- 0.8%. This was significantly reduced in diabetic rats two (57.4 +/- 1.4% desulphated), three (56.8 +/- 1.3 % desulphated) and four (52.9 +/- 2.2% desulphated) weeks after the onset of diabetes. The significant decrease in the amount of totally desulphated [3H]DSO4 in the urine also found at 12 weeks after the onset of diabetes was not affected by drug treatment. There was no significant difference in the amount of partially desulphated [3H]DSO4 in the urine between all the study groups. However, the increase in totally sulphated [3H]DSO4 in the urine collected from diabetic rats (8.7 +/- 1.7 % sulphated) compared with that of control rats (2.2 +/- 0.5% sulphated) was normalised by treatment with both aminoguanidine (4.8 +/- 1.6% sulphated) or ramipril (4.5 +/- 0.8% sulphated). These results raise the possibility that the diabetes-induced changes in renal lysosomal processing may be one of the initial events in the development of diabetic nephropathy. Aminoguanidine and ramipril, known for their different mechanism of action, seem to prevent diabetes-induced changes in lysosomal processing either through their effects on enzyme activity within the lysosome or through their effects on the trafficking of molecules to and from the lysosome.

Streptozotocin- and alloxan-induced diabetes modifies total plasma and lipoprotein lipid concentration and composition without altering cholesteryl ester transfer activity.

The objectives of this study were to determine the total plasma and lipoprotein lipid concentration and composition and cholesteryl ester transfer activity in two diabetic animal models (alloxan-induced diabetes in rabbits and streptozotocin-induced diabetes in rats). Furthermore, we wanted to determine if the severity of diabetes influences lipoprotein lipid profiles and cholesteryl ester transfer activity. Rats and rabbits were randomly divided into non-diabetic and diabetic groups. Rats were administered either 55 mg/kg or 100 mg/kg of streptozotocin intravenously through the tail vein, while rabbits were administered 100 mg/kg or 200 mg/kg of alloxan intravenously through the marginal ear vein under light anesthesia. Hyperglycaemia was tested for at 48 hr following the doses. Total and lipoprotein cholesterol and triglyceride concentrations using enzymatic kits and cholesteryl ester transfer activity from low-density lipoproteins to high-density lipoproteins using 3H-cholesteryl ester incorporated into low-density lipoproteins were determined. Elevations in both total and lipoprotein cholesterol and triglyceride concentrations and alterations in lipoprotein lipid composition are observed following the onset of drug-induced diabetes in rats and rabbits compared to non-diabetics. However, these findings were observed only in animals administered the higher streptozotocin and alloxan dose. Furthermore, cholesteryl ester transfer from low-density lipoproteins to high-density lipoproteins is not significantly different in drug-induced diabetic compared to non-diabetic rats and rabbits, regardless of which streptozotocin and alloxan dose was used. These findings suggest that difference in lipoprotein lipid concentration and composition as a result of drug-induced diabetes is independent of cholesteryl ester transfer activity in both rats and rabbits. Furthermore, diabetic severity may influence lipoprotein metabolism in these animal models.

Changes in the redox state in the retina and brain during the onset of diabetes in rats.

Diabetic retinopathy is thought to result from chronic changes in the metabolic pathways of the retina. Hyperglycemia leads to increased intracellular glucose concentrations, alterations in glucose degradation and an increase in lactate/pyruvate ratio. We measured lactate content in retina and other ocular and non-ocular tissues from normal and diabetic rats in the early stages of streptozotocin-induced diabetes. The intracellular redox state was calculated from the cytoplasmic [lactate]/[pyruvate] ratio. Elevated lactate concentration were found in retina and cerebral cortex from diabetic rats. These concentrations led to a significant and progressive decrease in the NAD+/NADH ratio, suggesting that altered glucose metabolism is an initial step of retinopathy. It is thus possible that tissues such as cerebral cortex have mechanisms that prevent the damaging effect of lactate produced by hyperglycemia and/or alterations of the intracellular redox state.

Local anesthetic-induced conduction block and nerve fiber injury in streptozotocin-diabetic rats.

Patients with diabetes may have peripheral neuropathy, which may have clinical implications for the use of regional nerve block. The effects of local anesthetics on nerve conduction and nerve fiber injury were tested in control rats and at 4 weeks after the onset of diabetes in rats injected with streptozotocin (50 mg/kg intraperitoneally). Nerve conduction was assessed by recording evoked electrical activity in hindpaw muscles following ipsilateral electrical stimulation of the sciatic nerve near the hip. Block of motor nerve conduction was quantified by recording the amplitude of the evoked response at 1-min intervals for up to 15 min after the injection of 500 microliters 1% lidocaine HCl or procaine HCl into the midthigh next to the sciatic nerve. In control animals, procaine was much less effective than lidocaine in producing conduction block. The rate and magnitude of lidocaine-induced conduction block were not significantly different between control and diabetic groups. However, conduction block due to procaine was sufficiently enhanced in diabetic rats to become comparable to that of lidocaine-treated control nerves. Long-lasting injury was assessed in sciatic nerve harvested 2 days after the extraneural injection of saline or 2 or 4% lidocaine HCl. Using a light microscope with a superimposed grid, nerve edema was quantified as the proportion of intersection points falling on extracellular space. Lidocaine induced edema in both control and diabetic nerves, but 4% lidocaine induced significantly more edema in diabetic nerves than in controls. Nerve fiber injury, based on light microscopic scoring of axonal degeneration and demyelination, was not observed in saline-treated nerves.(ABSTRACT TRUNCATED AT 250 WORDS)

In situ analysis of pancreatic islets in rats developing diabetes. Appearance of nonendocrine cells with surface MHC class II antigens and cytoplasmic insulin immunoreactivity.

Aberrant expression of MHC class II molecules on endocrine cells has been proposed to induce autoimmune reactions in thyroid and endocrine pancreas. The present study examines whether MHC class II positive insulin-containing islet cells occur at the onset of diabetes in rats, in analogy to the findings in man. At the onset of diabetes, both streptozotocin-treated and diabetes-prone BB rats exhibited numerous class II positive islet cells that presented ultrastructural features of monocytes and were surrounded by class II negative islet B cells. These class II positive cells were characterized by vacuoles that contained insulin immunoreactive granules and disrupted membranes. Similar cells also appeared positive for the monocyte marker OX-42. The presence of class II positive monocytes with insulin-containing vacuoles may indicate a removal of damage B cells by infiltrating leukocytes. A similar electron microscopical study in man will be necessary to distinguish the putative endocrine pancreatic B cells with aberrant class II expression from infiltrating nonendocrine class II positive cells with insulin-containing phagosomes.

Relationship Between Renal Function and Metabolic Alterations in Early Streptozocin-Induced Diabetes in Rats

To investigate the temporal relationship of diabetes-induced renal growth and its associated metabolic alterations to the early development of renal hyperfunction, parallel functional and metabolic studies were performed shortly after the onset of diabetes in rats. Hyperglycemia and hypoinsulinemia were evident 18 h after streptozocin injection, and significant hyperglucagonemia and acidosis were present at 36-48 h. Glomerular filtration rate (GFR), expressed per unit of body weight, first increased at 3 days of diabetes [1.35 +/- 0.07 (SE) (N = 14)] and was 18% greater than in controls [1.14 +/- 0.03 ml X min-1 X 100 g-1 (SE) (N = 38)] (P less than .005). Renal enlargement preceded GFR changes, so that GFR per unit of kidney weight was lower at 48 h in diabetics [1.31 +/- 0.06 (SE) (N = 16)] than in controls [1.54 +/- 0.04 ml X min-1 X g-1 (SE) (N = 38)] (P less than .01). Nucleotide and RNA metabolism was studied in the renal cortex after infusion of radio-labeled orotate or adenine. Rate of RNA synthesis, total cellular RNA, and the pools of ATP, UTP, and uridine 5'-diphospho-N-acetyl glucosamine were significantly increased 13-51% in 48-h diabetics. Nucleotide precursor incorporation was significantly increased only in uracil ribonucleotides. The increase in uracil ribonucleotide pool exceeded the degree of cell hypertrophy. Our studies indicate that renal hypertrophy and specific increases in uracil ribonucleotide synthesis precede functional changes in early diabetes. Renal metabolic changes may be the critical primary factors in diabetic nephropathy.