Effect Of Alloxan-induced Diabetes Research Articles

Protective effect of grape seed and skin extract against diabetes-induced oxidative stress and renal dysfunction in virgin and pregnant rat.

The present work deal with the effect of alloxan-induced diabetes on kidney oxidative stress and dysfunction of virgin and pregnant rat as well as the protection that may be afforded by high dosage GSSE (4g/kg) treatment. Diabetes affected negatively several kidney function parameters as creatinemia, uremia, uricemia and proteinuria without affecting kidney index. Diabetes also induced an oxidative stress characterized by increased lipid and protein oxidation, a drop in antioxidant enzyme defenses as catalase, superoxide-dismutase, glutathione-peroxidase, an alteration in transition metals as free iron, copper, selenium and associated enzymes and an increase in calpain and acetyl-cholinesterase activities. Tremendously, GSSE treatment protected efficiently against all the deleterious effects of diabetes-induced kidney dysfunction in both virgin and pregnant animals. High dosage GSSE is a safe and potent anti-oxidant that may be further tested in clinical trials for the long-term preservation of kidney function especially in multiple pregnancies.

Effect of alloxan-induced diabetes on implantation sites of pregnant rats with special emphasis on angiogenesis

Background Diabetes is relatively common worldwide. According to the reports of the WHO, more than 150 million people suffer from diabetes across the world. A primary negative effect of a diabetic environment on the developing embryo is impaired vascularization of the yolk sac. Angiogenesis at the sites of blastocyst implantation is associated with increased vascular permeability. Aim The present study aimed to investigate the effect of diabetes on the implantation site and intersite in albino rats during the early period of pregnancy, with special emphasis on angiogenesis, by studying vascular endothelial growth factor expression. Materials and method Forty adult female albino rats aged 4–6 months were used in this study. Rats were divided into two groups (20 rats each). Group I constituted the control group and group II constituted the alloxan-induced diabetic group. Diabetes was induced in rats by intravenous injection of alloxan monohydrate dissolved in normal saline into the dorsal tail vein at a dose of 40 mg/kg body weight. Vaginal smears were collected from each animal; the presence of sperm in the smear was designated as day 1 of pregnancy. Pregnant rats from the control and diabetic groups were sacrificed at days 4, 5, 6, and 7 of pregnancy (n=5). Examination of the uterine horn sections showed occurrence of implantation on day 6 in the control group, whereas implantation in the diabetic group occurred only on day 7. Granulated metrial glandular cells were clearly seen in the control group, whereas lymphocytic infiltration was obvious in the diabetic group. The expression of vascular endothelial growth factor was stronger in the diabetic group.

Histochemical and ultrastructural analysis of hepatic glycogen and collagen fibers in alloxan-induced diabetic rats submitted to long-term physical training

Alterations in liver functions are common among diabetic patients, and many symptoms in the liver have been reported, including changes in glycogen stores and in the amount of collagen fibers. The practice of physical training and its morphological effects in this organ, however, are scarcely studied. In order to observe the morphological effects of alloxan-induced diabetes and the alterations arising from the practice of long-term chronic physical training in the liver, samples were collected and processed, and then analyzed by means of the histochemical techniques Periodic Acid-Schiff and Picrosirius-Hematoxylin, and ultrastructural cytochemical test of Afzelius. Through evaluation of the tissue, it was observed a drastic reduction in hepatic glycogen stores of sedentary diabetics, recovered in trained diabetic rats. Furthermore, it was detected a decrease in the content of perisinusoidal collagen fibers in the diabetic liver, also recovered due to the development of a training protocol. On ultrastructural level, cytochemical analysis confirmed the loss of glycogen and the recovery obtained by training. In conclusion, the practice of a long-term chronic physical training protocol may be considered an important assistant in the treatment of diabetes, mitigating the occurrence of possible damages to liver tissue.

Effects of alloxan-induced diabetes on the expression of insulin signal transmission molecules

The mRNA of insulin receptor (IR), the insulin receptor substrates (IRSs), glucose transporter 2 (GLUT2) and glucokinase (GK) in alloxan-induced diabetic rat livers were amplified by RT-PCR. The protein of the insulin receptor in rat livers was determined by western-blotting. The results show that IR expression level decreased at the level of mRNA and protein. The gene expressions of IRSs, GLUT2 and GK changed significantly. The hepatic glycogen content in alloxan-diabetic rats treated with insulin ((13.2 ± 0.4) mg · g−1) did not restore to normal level ((17.0 ± 0.4) mg · g−1) by means of anthrone-H2SO4 methods. The results imply that insulin resistance is developed during inchoate phase of alloxan-induced diabetic rats.

Usefulness of Breath Test for Evaluating Pancreatic Exocrine Function Using N-Benzoyl-L-tyrosyl-1-13C-L-alanine Sodium in Non-invasive and Conscious Rats

N-Benzoyl-L-tyrosyl-1-13C-L-alanine sodium is a dipeptide used for evaluating pancreatic exocrine function. The method of evaluation, however, is not yet satisfactory, especially in experimental animals. The relation between diabetes and pancreatic exocrine function also is not clear. Therefore, this study sought to establish a method for evaluating pancreatic exocrine function and to validate the method by determining non-invasively the effect of alloxan-induced diabetes in conscious rats. After fasting, rats were orally administered Racol containing N-benzoyl-L-tyrosyl-1-13C-L-alanine sodium or 1-13C-L-alanine and housed in desiccators. The expired air in the desiccator was collected in a breath-sampling bag using a tube and aspiration pump, and the level of 13CO2 in this air was measured using an infrared spectrometer at appropriate intervals over a 120 min period. The rate of 13CO2 excretion increased, peaked and then decreased in a dose-dependent manner. The maximum concentration and area under the curve of 13CO2 excretion significantly and positively correlated with the doses of N-benzoyl-L-tyrosyl-1-13C-L-alanine sodium. In the rats made diabetes by the administration of alloxan, the level of expired 13CO2 air changed at significantly lower levels as compared with that of the control rats on day 3, although the level of expired 13CO2 air from 1-13C-L-alanine was also markedly lower than that of the control rats. These results showed that pancreatic exocrine function can be evaluated using this breath test system and that alloxan-induced diabetes affects this function.

Effect of experimental diabetes on monoamine oxidase activity from discrete areas of rat brain: relationship with diabetes associated reproductive failure.

The effect of alloxan-induced diabetes was studied on the activity of monoamine oxidase (MAO), the oxidative deaminating enzyme of monoamine neurotransmitters. MAO was assayed from discrete brain regions like medial preoptic area and median eminence--arcuate region of hypothalamus, septum, amygdala, thalamus, hippocampus, pons and medulla. In all these areas studied, the induction of diabetes resulted in significant increase in MAO activity at 3, 8, 15 and 28 day intervals, whereas, the treatment of diabetic rats with insulin led to recovery in the enzyme activity. Blood glucose levels increased significantly after induction of diabetes and the recovery was seen after insulin treatment. These data suggest the involvement of MAO in diabetes associated alterations in physiological and endocrinological disorders.

Effect of alloxan-induced diabetes on acetylcholinesterase activity from discrete areas of rat brain

The effect of experimental diabetes induced in rats was examined in brain areas like the septum, medial preoptic area, median eminence-arcuate region, amygdala, thalamus, hippocampus, pons and medulla. In all the areas studied, acute hyperglycemia caused an increase in the activity of acetylcholinesterase, the degradative enzyme of cholinergic system, whereas insulin administration reversed this effect. These findings suggest that the dysfunction of cholinergic system may also be involved in the diabetes associated CNS complications.

Basal and histamine-induced gastric acid secretion in alloxan diabetic rats

1. 1. Effects of alloxan-induced diabetes on the rat gastric acid secretion were investigated using a number of biostatistical models described earlier. 2. 2. Histamine-induced gastric acid secretion was found to be decreased in alloxan-diabetic rats when compared with their age-matched controls. 3. 3. Basal acid secretion was also decreased depending on experimentally-induced diabetes. 4. 4. The above results strongly suggest that alloxan-induced diabetes depresses vagal activity and H 2-receptor activity in the stomach.

Diabetes Mellitus Impairs Neurogenic and Endothelium-Dependent Relaxation of Rabbit Corpus Cavernosum Smooth Muscle

The effect of alloxan-induced diabetes on the reactivity of corporeal nerves, endothelium and smooth muscle was studied in the New Zealand white rabbit. Fifteen rabbits were randomly divided into treated (n = 6) and control (n = 9) groups. The treated group was maintained for 6 weeks. Two control groups were studied. One control group (n = 3) was maintained for 6 weeks as littermate controls for diabetic group. The second control group (n = 6) was not maintained but was weight matched with the 6 week diabetic group. The reactivity of corpus cavernosum tissue from the diabetic animals and the control animals was studied in organ chambers. When tissue contraction was produced with phenylephrine for the study of relaxation to various stimuli, the tension induced was similar in the diabetic and the control groups. Relaxation of corpus cavernosum tissue to electrical stimulation of autonomic nerves as well as relaxation to the endothelium-dependent vasodilator acetylcholine were comparably unaffected in the weight matched and littermate control groups while significantly inhibited in the diabetic group. Treatment of the corporeal tissue with the cyclooxygenase inhibitor indomethacin enhanced the relaxation to electrical stimulation and to acetylcholine in the control and in the diabetic groups but did not improve the significant difference in relaxation between the two groups. Relaxation of corporeal tissue to endothelium-independent vasodilators, papaverine and nitroprusside was similar in the control groups and the diabetic groups. It is concluded that diabetes impairs neurogenic and endothelium-mediated relaxation of rabbit corpus cavernosum smooth muscle. These findings are comparable to those described in corpus cavernosum tissue from diabetic men, showing the validity of this experimental animal model. The mechanism for the nerve or endothelial dysfunction does not appear to involve alteration in cyclooxygenase products of arachidonate or the ability of the corporeal smooth muscle to relax via a cGMP-dependent mechanism. Since nitric oxide has been shown to act as the nonadrenergic noncholinergic neurotransmitter as well as endothelium-derived relaxing factor (EDRF) of the trabecular smooth muscle, it is possible that impairment of neurogenic and endothelium-dependent relaxation due to diabetes is mediated by alteration in the synthesis or availability of nitric oxide in corporeal tissue.

Effects of alloxan-induced diabetes on hemorheology in rabbits.

Plasma viscosity (PV), apparent whole blood viscosity (WBV), relative blood viscosity (RV) and erythrocyte deformability (filterability) (EDF) were determined in 13 New Zealand White (NZW) rabbits with alloxan induced-diabetes (AID) and 8 normal NZW rabbits, matched for age, sex and weight. AID rabbits were divided into two groups depending on the duration of hyperglycemia (long-term, greater than 6.0 months (n = 7), and short-term, less than or equal to 3.0 months of hyperglycemia, n = 6). Comparing long-term AID rabbits to normal animals, we found significant increases in WBV (P less than 0.001, 0.005 for high and low rates of shear, respectively), and a marked reduction in EDF (P less than 0.001). There was no significant difference in PV between long-term AID and normal rabbits. Conversely, PV was significantly increased in rabbits with short-term diabetes (P less than 0.01) while there was a concurrent significant increase in WBV measured at high and low rates of shear (P less than 0.001, 0.001, respectively). No difference was detected in EDF between normal and short-term AID rabbits. Furthermore, in long-term AID rabbits there was a strongly positive correlation between RV and reduced erythrocyte deformability (r = 0.94, P = 0.006) while WBV strongly correlated with PV (r = 0.92, P = 0.004) in the short-term AID subgroup. We conclude from these data: (1) elevated blood viscosity in long term AID rabbits is associated with reduced erythrocyte filterability; and (2) elevated WBV in short-term AID rabbits is associated with increased PV.

Long-term effects of alloxan-induced diabetes on the nucleus ventralis posterolateralis in the thalamus of the rat.

The present paper describes the long-term ultrastructural changes in the nucleus ventralis posterolateralis of the thalamus of male Wistar rats after alloxan-induced diabetes. Degenerating dendrites were characterized by an electron-dense cytoplasm with scattered endoplasmic reticulum and ribosomes. Degenerating axon terminals were characterized by an electron-dense cytoplasm and clustering of small spherical agranular vesicles. Degenerating axon terminals formed axosomatic synapses with seemingly normal cell bodies and axodendritic synapses with normal as well as degenerating dendrites. Degenerating axons (both myelinated and unmyelinated) were readily encountered in the neuropil. Activated microglial and astrocytic cells in the neuropil were in the process of phagocytosis or had residua in their cytoplasm.

Effects of alloxan-induced diabetes on somatostatin binding to cytosolic components of rabbit gastric fundic mucosa.

Diabetes was induced by administration of alloxan (150 mg/Kg) to 24 h-fasted rabbits. Somatostatin-like immunoreactivity (SLI) and cytosolic binding sites for somatostatin in gastric fundic mucosa were studied using radiolabelled Tyr11-somatostatin. Three months after the onset of the disease, the specific binding of somatostatin to these sites was seen to be significantly lower, due to a reduction in the number (but not the affinity) of specific somatostatin binding sites of high-affinity and a disappearance of the specific somatostatin binding sites of low-affinity. These changes were associated with an increase in the SLI concentration in both gastric fundic mucosa and plasma.

Effects of alloxan-induced diabetes on ischemia-reperfusion injury in rabbit hearts.

Hearts from rabbits with 8-16 weeks of alloxan-diabetes were compared with hearts from normal rabbits to determine whether diabetic myocardium is more sensitive to ischemic injury. In isolated buffer-perfused hearts, left ventricular developed pressure, diastolic pressure, time to peak pressure (TTPP), time to half-maximal relaxation (RT1/2), and positive and negative dP/dt were measured during generation of left ventricular filling curves before and after 90 minutes of low-flow ischemia. Hearts from diabetic rabbits (blood glucose, 384 +/- 28 mg/dl, mean +/- 95% confidence limits) had left ventricular developed and diastolic pressures similar to normal hearts but exhibited significant increases in TTPP and RT1/2 with decreased positive and negative dP/dt. Left ventricular chamber volume relative to heart mass was greater in diabetic than in normal hearts. Recovery of developed pressure after ischemia was similar in normal (41 +/- 16%) and diabetic hearts (47 +/- 13%). In diabetic hearts during recovery from ischemia, TTPP and R1/2 remained increased compared with normal hearts, with positive and negative dP/dt decreased compared with normal hearts, in proportion to the preischemic differences. After ischemia, high-energy phosphates were depleted to the same extent in normal and diabetic rabbits. In coronary ligation experiments, histochemically determined infarct size in diabetic rabbits after 30 minutes occlusion and 24 hours reperfusion was similar to that in normal rabbits when adjusted for a significantly smaller heart weight and a correspondingly smaller anatomic risk region in the diabetic animals. Thus, despite characteristic abnormalities of mechanical function in diabetic hearts, the severity of injury after ischemia with reperfusion was normal for diabetic hearts.

Effects of diabetes on uterine condition, decidualization, vascularization, and corpus luteum function in the pseudopregnant rat.

The effects of alloxan-induced diabetes on uterine decidualization and the associated changes in uterine blood flow (UBF) and corpus luteum activity were evaluated in rats between days 4-9 of pseudopregnancy (day 0 = ovulation). Rats were made diabetic (D) with a 40 mg/kg injection (iv) of alloxan on day 1 of pseudopregnancy. Saline-treated rats served as controls (C). Uterine weights were depressed in D rats between days 6-7 of pseudopregnancy in association with elevated blood glucose levels (greater than 300 mg/dl) relative to control values. UBF rates were also depressed in D rats between days 6-7 of pseudopregnancy compared with control values. Insulin replacement therapy (6 IU bovine/day) effectively normalized both uterine weight and UBF in diabetic rats. Decidual tissue (DT) growth was impaired in D rats between days 7 and 9 of pseudopregnancy (DT induction on day 4 of pseudopregnancy) compared with controls. Tissue blood flow rates were severely depressed throughout pseudopregnancy in D rats, but insulin treatment normalized both uterine parameters to control levels. Serum progesterone levels were lower in D rats than in controls between days 7 and 9 of pseudopregnancy. Daily insulin treatment normalized luteal function to control levels. The depressed DT weights in D rats were mimicked by the experimental reduction of DT blood flow in control rats. These results indicate that the uterine atrophy and poor endometrial decidualization that characterized the D rat are accompanied by impaired UBF and luteal activity. These findings suggest that the D-associated depression in female reproductive performance is related to the lack of proper hormone support of tissue vascular dynamics.

Changes in intestinal mucosal permeability caused by nonprotein thiol loss in rats.

The barrier selectivity of the intestinal mucosal membrane permeability may be impaired in certain disease conditions. Membrane permeability was previously shown to be correlated with changes in nonprotein thiol in rat intestinal tissue by the everted sac method. In the present study, the mucosal effects of alloxan-induced diabetes and chronic alcohol administration to intact rats, as well as pre-treatment with diethyl maleate, ethanol, and salicylate, were investigated. In each case, a drop of mucosal nonprotein thiol was associated with an increased absorption of cefoxitin, cefmetazole, and phenol red, hydrophilic compounds that are poorly absorbed through intact membrane, and with a decreased absorption of L-phenylalanine. The effect of nonprotein thiol loss on rectal absorption of cefoxitin, cefmetazole, and phenol red was greater than that on the small intestinal absorption. The increase in phenol red absorption by diethyl maleate in the in vitro everted sac method correlated with Ca(2+) release from the intestinal mucosa, which was induced by nonprotein thiol loss. Resistance to the effect of nonprotein thiol loss on Ca(2+) homeostasis was greater in rat ileum than in rat colon (including rectum). The administration of cysteamine as an exogenous nonprotein thiol restored non-protein thiol levels in the mucosa along with the barrier function of the intestinal mucosa to the absorption of cefoxitin, cefmetazole, and phenol red. In contrast, the transport of L-phenylalanine in the small intestinal mucosa was not restored by cysteamine treatment.

Effects of alloxan-induced diabetes on dopaminergic receptors in rat striatum and anterior pituitary.

The binding of [3H]-spiroperidol after 4 weeks of hyperglycemia was determined in the rat striatum and anterior pituitary. Alloxan-induced diabetes increased the number of dopaminergic binding sites in the striatum but not in the anterior pituitary. The interaction of metoclopramide with striatal dopaminergic receptors was slightly modified, while that of dopamine, bromocriptine and haloperidol was unaffected. These results suggest that chronic hyperglycemia exerts selective effects on nigrostriatal dopaminergic system in the rat.

The effect of alloxan-induced diabetes on tissue plasminogen activator activity and plasmin inhibition in the rat

In alloxan-diabetic rats the plasminogen activator activity (PAA) showed a tissue- and time-dependent pattern of changes in key organs. In arteries of the lung, heart, and kidney, and in the intima of the aorta the PAA was markedly enhanced on the 4th day after the induction of diabetes. Thereafter, up to the 12th week post induction of diabetes, the PAA in arteries of the lung showed a gradual return to the normal, while the intima of the aorta at the nonbranching regions exhibited a fluctuation in the PAA; at the branching regions the PAA was constantly increased as it was also in the controls. In arteries of the myocardium and the kidney (particularly of the renal cortex) the PAA was impaired. In caudal vena cava the PAA was unchanged throughout experimentation. Also, no difference was noted between diabetic rats and control rats in the PAA of the epicardium, endocardium, serosa of the lung and kidney and adventitia of the aorta. Tissue plasmin inhibition showed no significant difference between diabetic rats and controls.

Diabetes alters the myocardial cAMP-protein kinase cascade system.

An isolated perfused working rat heart preparation was used to assess the effect of alloxan-induced diabetes on the cAMP cascade system. Diabetes did not alter basal cAMP, cGMP content, or protein kinase or phosphorylase activities, but depressed (50%) isoproterenol-induced changes in cAMP content and protein kinase activity ratios. In contrast, phosphorylase activation and increased left ventricular pressure (LVP) were unaltered by diabetes. The relationship between cAMP and protein kinase activation is linear in hearts from both normal and diabetic rats. Diabetes did not alter this relationship. The relationship between protein kinase and phosphorylase activation or increases in LVP is also linear. An increase in the slopes obtained with diabetic hearts (P less than 0.05) was observed, suggesting an increased gain in the amplification cascade to protein kinase. The in vivo administration of insulin diminished this response. Thus, diabetes alters the ability of heart to accumulate cAMP and alters the gain of the amplification cascade system subsequent to protein kinase activation. This second effect may indicate an unmasking of a parallel regulatory pathway and in the beta-adrenergic regulation of phosphorylase activity and LVP.

Performance of diabetic rat hearts: effects of anoxia and increased work.

An isolated perfused working rat heart preparation was used to assess the effect of alloxan-induced diabetes on myocardial performance. Ventricular performance was assessed under different aortic afterload, isoproterenol-stimulated and anoxic conditions. Basal left ventricular pressure development and rate of rise of ventricular pressure were depressed in hearts from diabetic animals. Neither coronary flow nor cardiac output were affected by diabetes. The dose and temporal responses to an infusion of isoproterenol were unaltered in diabetic hearts. Isoproterenol increased coronary flow by 50% and elevated ventricular pressure, dP/dt, and cardiac output by two- to threefold. Anoxia depressed ventricular pressure to below 20% of control within 5 min in both diabetic and normal hearts. Reoxygenation after 10 min of anoxia produced equivalent recovery in both groups working against a 52-mmHg aortic afterload, whereas recovery after 20 or 30 min of anoxia, was depressed in diabetic hearts. Elevating aortic afterload decreased performance of diabetic hearts and decreased their ability to recover from a 10-min anoxic exposure. Many of these observed differences in mechanical performance of diabetic hearts can be overcome by high glucose or insulin in the perfusion media.

Effect of alloxan-induced diabetes on the hypertrophic response of rat heart

Rats with alloxan-induced moderate and severe diabetes underwent banding of the ascending aorta. The increase in myocardial tissue and RNA was similar to controls in both groups of diabetic animals. This study indicates that the myocardial response to increased afterload is normal in the diabetic animal.