Induction Of Alloxan Diabetes Research Articles

Antidiabetic effect of diasulin, a herbal drug, on blood glucose, plasma insulin and hepatic enzymes of glucose metabolism in hyperglycaemic rats.

The present study was designed to investigate the effect of diasulin, a polyherbal drug, on blood glucose, plasma insulin and the activities of hepatic glucose metabolic enzymes in alloxan-induced diabetic rats. Male Wistar rats, body weight of 180-200 g (12 normal and 30 diabetic rats), were used in this study. The rats were divided into seven groups after the induction of alloxan diabetes. In the experiment, six rats were used in each group. Group 1: normal rats given 2 ml of saline; group 2: normal rats given aqueous solution of diasulin (0.20 g/kg of body weight); group 3: diabetic control rats given 2 ml of saline; group 4: diabetic rats given aqueous solution of diasulin (0.05 g/kg of body weight); group 5: diabetic rats given aqueous solution of diasulin (0.10 g/kg of body weight); group 6: diabetic rats given aqueous solution of diasulin (0.20 g/kg of body weight) and group 7: diabetic rats given aqueous solution of glibenclamide (600 micro g/kg of body weight). The treatment was given for 30 days. After the treatment, fasting blood glucose, plasma insulin, urine sugar and the activities of hepatic glucose metabolic enzymes were determined in normal and experimental animals. Treatment with diasulin resulted in a significant reduction in blood glucose, glycosylated haemoglobin and an increase in plasma insulin and total haemoglobin and a significant improvement in glucose tolerance. Diasulin also resulted in a significant reduction in the activities of glucose-6-phosphatase and fructose-1,6-bisphosphatase in the liver, whereas the level of plasma insulin and hepatic hexokinase activity was significantly increased in alloxan diabetic rats. The present investigation suggests that diasulin, a polyherbal drug, controls the blood glucose level by increasing glycolysis and decreasing gluconeogenesis with a lower demand of pancreatic insulin than in untreated rats. This is possible, because it regulates the activities of hepatic glucose metabolic enzymes.

Effect of Cogent db, a herbal drug, on serum and tissue lipid metabolism in experimental hyperglycaemic rats.

We have previously reported the antidiabetic effect of Cogent db. The present study with alloxan-induced hyperglycaemic rats is focused on the mechanism of action, specifically on the activity of hepatic lipogenic enzymes, serum and tissue lipids. Male Wistar rats body weight of 180-200 g (six normal and 18 diabetic rats) were used in this study. The rats were divided into four groups after the induction of alloxan diabetes: normal rats; diabetic control; diabetic rats given Cogent db (0.45 g/kg body weight); diabetic rats given glibenclamide (600 micro g/kg body weight). After 40 days treatment, fasting blood glucose, plasma insulin, activities of hepatic lipogenic enzymes, serum and tissue lipids were determined in normal and experimental animals. Oral administration of Cogent db for 40 days resulted in significant reduction in blood glucose, serum and tissue (liver and kidney) lipids, whereas the level of plasma insulin and the activity of hepatic lipogenic enzymes were significantly increased in alloxan diabetic rats. Similar studies using glibenclamide have been conducted to compare the mode of action of these two drugs. Thus our study shows that Cogent db exhibits a strong antihyperlipidaemic effect, which could exert a beneficial action against macrovascular complications (cardiovascular disease) associated with diabetes mellitus.

Effect of cogent db, a herbal drug, on plasma insulin and hepatic enzymes of glucose metabolism in experimental diabetes.

The present study was designed to investigate the effect of cogent db, a polyherbal drug on blood glucose, plasma insulin and the activities of hepatic glucose metabolic enzymes in alloxan-induced diabetic rats. Male Wistar rats body weight of 180-200 g (six normal and 18 diabetic rats) were used in this study. The rats were divided into four groups after the induction of alloxan diabetes. In the experiment, six rats were used in each group: Group 1, normal rats given 2 ml of saline; Group 2, diabetic control rats given 2 ml of saline; Group 3, diabetic rats given aqueous solution of cogent db (0.45 g/body kg weight); and Group 4, diabetic rats given aqueous solution of glibenclamide (600 micro g/kg body weight). The treatment was given for 40 days. After the treatment, fasting blood glucose, plasma insulin, urine sugar and the activities of hepatic glucose metabolic enzymes were determined in normal and experimental animals. Treatment with cogent db resulted in a significant reduction in blood glucose and the activities of glucose-6-phosphatase and fructose-1,6-bisphosphatase in the liver, whereas the level of plasma insulin and hepatic hexokinase activity were significantly increased in alloxan-diabetic rats. The present investigation suggests that cogent db controls the blood glucose level by increasing glycolysis and decreasing gluconeogenesis with a lower demand of pancreatic insulin than in untreated rats. This is possible because it regulates the activities of hepatic glucose metabolic enzymes.

Intracerebroventricular administration of somatostatin octapeptide counteracts the hormonal and metabolic responses to stress in normal and diabetic dogs

Intracerebroventricular (ICV) injection of carbachol elicits hormonal and metabolic responses similar to moderate stress. In normal dogs, ICV carbachol stimulated marked counterregulatory hormone release, but altered plasma glucose only marginally because the marked increment in glucose production (R a) was almost matched by the increment of utilization (R d), even though plasma insulin was unchanged. In alloxan-diabetic dogs, R d did not match R a and plasma glucose increased substantially. Since somatostatin octapeptide (ODT8-SS) inhibits some sympathetic mechanisms of the stress response, we explored the extent to which ODT8-SS can alleviate the counterregulatory responses to stress induced by carbachol, and particularly whether it can restore glycemic control in diabetes. ODT8-SS (20 nmol) was ICV-injected (1) in normal dogs (n = 5), and (2) prior to ICV carbachol before (n = 7) and after (n = 6) the induction of alloxan-diabetes. ODT8-SS did not affect basal values, but when administered before ICV carbachol there were no significant increments in plasma epinephrine, cortisol, arginine vasopressin (AVP), insulin, glucose, or lactate. There were significant increases in norepinephrine, glucagon, R a, R d, and the glucose metabolic clearance rate (MCR), although they were much smaller than seen previously with ICV carbachol alone. After induction of alloxan-diabetes, R d and MCR did not change with ICV ODT8-SS and carbachol as in normal dogs, but norepinephrine, epinephrine, glucagon, lactate, plasma glucose, and R a increased, although with the exception of glucagon these increases were much smaller than seen previously with ICV carbachol alone. ODT8-SS administered before ICV carbachol in normal or diabetic animals resulted in increased free fatty acid (FFA) levels. The increases in glycerol were less than and those in FFA greater than seen previously with ICV carbachol alone. Since ODT8-SS does not alter basal counterregulatory hormone release but suppresses the release during stress, this is a useful probe to analyze some of the metabolic responses to stress. When the response to carbachol from our previous report is compared with the responses to carbachol + ODT8-SS, it is indicated that the stress-related increase in R a was consistent with stimulation of the sympathetic nervous system, whereas increased R d is related to an unknown stress-related neuroendocrine mechanism that requires a permissive effect of insulin, since it was not seen in the frankly diabetic animals. We hypothesize that the stress-induced increase in R d occurs not only in muscle but also in adipocytes, and that the somatostatin-induced attenuation of R d decreased FFA re-esterification and consequently markedly increased stress-induced FFA release. Although ODT8-SS substantially decreased the R a response in diabetic dogs, the hyperglycemic effect of carbachol is only partially attenuated. Thus, in diabetes moderate stress can disturb glucose homeostasis substantially even when the sympathetic nervous system has been markedly suppressed.

Alloxan diabetes alters the rabbit transarterial wall oxygen gradient

Purpose: Atherosclerotic vascular occlusive disease is the most common complication of diabetes mellitus and accounts for 75% of deaths in diabetic patients. Determining the initiator and continuing stimulus for the cellular events in the formation of atherosclerotic lesions in diabetic patients could lead to the prevention of this common and deadly complication. Diabetes-induced arterial wall hypoxia is proposed as an initiator and continuing stimulus for atherosclerotic vascular occlusive disease.Methods: Transarterial wall oxygen gradient measurements were performed on the infrarenal aorta with an oxygen microelectrode 14 to 16 weeks after the induction of alloxan diabetes in rabbits.Results: Both insulin-treated and untreated alloxan diabetic rabbits revealed significantly decreased oxygen tensions throughout the arterial wall compared with control rabbits. There was no significant difference in the transarterial wall oxygen gradient between the two groups of diabetic rabbits. This effect was noted despite no difference in the partial pressure of oxygen in arterial blood or visual evidence of atherosclerotic lesion formation in the three groups.Conclusions: These findings suggest that diabetes induces arterial wall hypoxia independent of insulin therapy and before the formation of atherosclerotic lesions. Diabetes-induced arterial wall hypoxia may contribute to the formation of atherosclerotic lesions.

Purification and the immunological characterization of rat protein phosphatase 2A: enzyme levels in diabetic liver and heart.

Protein phosphatase 2A1 was purified from rat skeletal muscle and used to produce antisera to the three subunits of the holoenzyme. Affinity purified antibodies specific for the subunits of the phosphatase enzyme were found to recognize the type 2A1 and 2A2 phosphatase from rat skeletal muscle, heart, liver, brain and erythrocytes and were used to investigate the effects of diabetes on the levels of this enzyme in liver and heart. Phosphorylase phosphatase assays coupled with immunoblot analysis of fractionated rat liver and heart cytosol from normal and diabetic animals show no apparent differences in the quantity or activity of these enzymes following the induction of alloxan diabetes. When considering these results and the normal physiological concentrations of known effectors of these enzymes, it is likely that protein phosphatase 2A1 and 2A2 are not responsible for the dephosphorylation of phosphorylase a under physiological conditions.

Mechanism of glucoregulatory responses to stress and their deficiency in diabetes.

During exercise, increased energy demands are met by increased glucose production that occurs simultaneously with the increased glucose uptake. We had previously observed that, during exercise, metabolic clearance rate of glucose (MCR) increases markedly in normal, but only marginally in poorly controlled diabetic dogs. We wished to determine (i) whether in a more general model of stress matched increases in rate of appearance of glucose and MCR also occur, or if MCR is suppressed, as during catecholamine infusion; and (ii) whether diabetes affects stress-induced changes in rate of glucose appearance and MCR. Therefore, we injected carbachol (27 nmol/50 microliters), an analog of acetylcholine, intracerebroventricularly in seven conscious dogs before and after induction of alloxan diabetes. In normal dogs, plasma epinephrine and cortisol increased 4- to 5-fold, whereas norepinephrine and glucagon doubled. Plasma insulin, however, remained unchanged. Tracer-determined hepatic glucose production increased rapidly, but transiently, by 2.5-fold. This increment can be fully explained by the observed increments in the counterregulatory hormones. Surprisingly, however, MCR also promptly increased, and therefore, plasma glucose changed only marginally. After induction of diabetes, the animals were given intracerebroventricular carbachol while plasma glucose was maintained at moderate hyperglycemia (9.0 +/- 0.4 mM). Increments in counterregulatory hormones were similar to those seen in normal dogs, except for exaggerated norepinephrine release. Peripheral insulin levels were higher in diabetic than in normal dogs; however, MCR was markedly reduced and the lipolytic response to stress increased, indicating insulin resistance. Interestingly, the hyperglycemic response to stress was 6-fold greater in diabetic than normal animals, relating mainly to the failure of MCR to rise. Plasma lactate increased equivalently in diabetic and normal animals despite suppression of MCR in the diabetics, indicating either greater muscle glycogenolysis and/or impairment in glucose oxidation. We conclude that in this stress model MCR increases as in exercise in normal but not in diabetic dogs. We speculate that glucose uptake in stress could be mediated through an insulin-dependent neural mechanism.

Insulin and the parasympathetic dependence of pancreatic juice secretion in healthy and alloxan diabetic sheep.

Pancreatic function was measured in four ewes following vagal stimulation under control conditions and after the induction of alloxan diabetes. The volume and protein content of the pancreatic juice was measured along with simultaneous measurement of blood glucose and plasma insulin. The volume of pancreatic juice and its protein content decreased markedly in the diabetic state and returned to the initial value after insulin treatment. In normal animals, vagal stimulation markedly increased; the volume of pancreatic secretion and its protein content as well as the plasma insulin concentration. In the diabetic animals vagal stimulation caused only a slight increase in the protein content of pancreatic juice and plasma insulin concentration. It is suggested that insulin is probably one of the more important factors directly regulating the secretion of pancreatic juice.

Reversible phosphorylation of pyruvate dehydrogenase in rat skeletal-muscle mitochondria. Effects of starvation and diabetes.

The total activity of pyruvate dehydrogenase (PDH) complex in rat hind-limb muscle mitochondria was 76.4 units/g of mitochondrial protein. The proportion of complex in the active form was 34% (as isolated), 8-14% (incubation with respiratory substrates) and greater than 98% (incubation without respiratory substrates). Complex was also inactivated by ATP in the presence of oligomycin B and carbonyl cyanide m-chlorophenylhydrazone. Ca2+ (which activates PDH phosphatase) and pyruvate or dichloroacetate (which inhibit PDH kinase) each increased the concentration of active PDH complex in a concentration-dependent manner in mitochondria oxidizing 2-oxoglutarate/L-malate. Values giving half-maximal activation were 10 nM-Ca2+, 3 mM-pyruvate and 16 microM-dichloroacetate. Activation by Ca2+ was inhibited by Na+ and Mg2+. Mitochondria incubated with [32P]Pi/2-oxoglutarate/L-malate incorporated 32P into three phosphorylation sites in the alpha-chain of PDH; relative rates of phosphorylation were sites 1 greater than 2 greater than 3, and of dephosphorylation, sites 2 greater than 1 greater than 3. Starvation ( 48h ) or induction of alloxan-diabetes had no effect on the total activity of PDH complex in skeletal-muscle mitochondria, but each decreased the concentration of active complex in mitochondria oxidizing 2-oxoglutarate/L-malate and increased the concentrations of Ca2+, pyruvate or dichloracetate required for half-maximal reactivation. In extracts of mitochondria the activity of PDH kinase was increased 2-3-fold by 48 h starvation or alloxan-diabetes, but the activity of PDH phosphatase was unchanged.

Effects of alloxan diabetes and insulin in vivo on rat parotid gland.

Parotid gland growth and secretory enzyme levels were studied in male Sprague-Dawley rats following the induction of alloxan diabetes. Diabetes resulted in a retardation of parotid gland, as well as body growth, and in a reduction of parotid gland DNA, RNA, and total protein compared with control rats. Morphologically, parotid glands of diabetic animals were characterized by an intracellular accumulation of lipid within acinar and intercalated ductal cells. Parotid amylase was reduced 40% in diabetic rats compared with control rats. In contrast, peroxidase levels increased by 54%, and DNase was unaffected. Insulin treatment of diabetic rats led to a restoration of gland and body growth. Parotid gland DNA, RNA, total protein, and secretory enzyme levels returned to control values within 7 days. Thus, insulin in vivo may play a major role in the regulation of parotid gland growth and function.

Effect of food intake on intestinal absorption and mucosal hydrolases in alloxan diabetic rats

The relation between food intake and enzyme activity of the small intestine and rate of intestinal absorption were studied in rats 15 days after induction of alloxan diabetes. Diabetic rats were given an ad lib. semisynthetic diet or a restricted diet on the basis of either daily intake or body weight. The rates of absorption of 5m M D-galactose and L-valine were determined in vitro by the everted sac method. The rates of absorption of the substances, expressed per unit weight or per length of intestine, were higher in diabetic rats than in controls, regardless of the amount of food consumed. Maltase and sucrase activities were significantly increased in diabetic rats, regardless of the amount of food consumed. The activity of intestinal alkaline phosphatase was increased in diabetic rats fed ad lib., but not in those on a restricted diet. These findings suggest that in alloxan diabetic rats the increased disaccharidase activity in the small intestine is due to insulin deficiency, and that the increased activity of alkaline phosphatase is only a secondary effect of insulin deficiency, caused by increased food intake resulting from insulin deficiency.

Maintenance of lactose secretion during acute insulin deficiency in lactating goats.

Induction of alloxan diabetes in 5 lactating goats resulted in reduced milk yields in 3 of the animals, while the yield was unchanged in two. After treatment of the diabetic goats with insulin for 4--5 days--the last 24 h intravenously--lactose secretion returned to the control values before alloxan administration provided that normoglycemia developed. In 2 experiments infusion of a large dose of insulin caused hypoglycemia and a 20--30 per cent reduction in lactose secretion rates. In the course of 1 h after withdrawal of the insulin infusion, patent signs of insulin deficiency developed as evidenced by steadily increasing plasma glucose concentrations. Nevertheless, lactose secretion continued at the same rate as during insulin infusion for the 4 h studied after discontinuation of the insulin infusion. In the goats where lactose secretion was reduced due to insulin-induced hypoglycemia, lactose secretion returned to control values when following discontinuation of insulin infusion the plasma glucose concentrations increased into normal and diabetic ranges. It is concluded that during insulin deficiency of short term duration, mammary lactose secretion was maintained at a normal rate. Since lactose is the major product of mammary glucose utilization, it is suggested that glucose uptake in the mammary gland was not reduced by short term insulin deficiency.

Blood glucose, glutathione, and total keto-acids levels in alloxan-diabetic rats.

This study deals with investigations in diabetic disorders. Experiments were carried out on alloxan-induced diabetes in albino rats. Blood glucose, keto acids, and glutathione were determined before and after induction of alloxan diabetes. Blood glucose and keto acids showed an increase after administration of alloxan. Glutathione showed a drop after 1/2 hour, then began to increase till it reached its normal level after 48 hours from the beginning of the diabetic state. The results are discussed.

Role of carnitine in hepatic ketogenesis.

The enhancement of long-chain fatty acid oxidation and ketogenesis in the perfused rat liver, whether induced acutely by treatment of fed animals with anti-insulin serum or glucagon, or over the longer term by starvation or the induction of alloxan diabetes, was found to ba accompanied by a proportional elevation in the tissue carnitine content. Moreover, when added to the medium perfusing livers from fed rats, carnitine stimulated ketogenesis from oleic acid. The findings suggest that the increased fatty acid flux through the carnitine acyltransferase (carnitine palmitoyl-transferase; palmitoyl-CoA:L-carnitine O-palmitoyltransferase; EC 2.3.1.21) reaction brought about by glucagon excess, with or without insulin deficiency, is mediated, at least in part, by elevation in the liver carnitine concentration.

Properties of adaptive hexokinase isozymes of the rat.

Rat liver hexokinase IV splits into 2 bands, designated IVf (fast) and IVa (slow) when EDTA is omitted from the starch gel electrophoresis system. The IVf disappears in diabetes whereas IVa is still present. The fast form also decreases in fasting and reappears after refeeding. Rat epididymal adipose tissue contains 2 hexokinases corresponding to I and II of rat liver. Both hexokinases of adipose tissue drop after 48 hr of fasting and return to normal after 24 hr of refeeding; this recovery does not occur in rats given puromycin or cycloheximide, 2 inhibitors of protein synthesis. The restoration of hexokinase activity produced by addition of insulin in vitro to adipose tissue from fasting rats is likewise blocked by cycloheximide, and by actinomycin D, an inhibitor of some types of RNA synthesis. Total adipose hexokinase activity fell more than 50% 3 days after induction of alloxan diabetes, recovered to normal 24 hr after insulin administration, and was 50% greater than normal after 48 hr. The changes i...

Action of neutral red on the secretion of glucagon and glucose metabolism in the rat.

Neutral red induces marked hyperglycemia in the rat. In order to determine the mechanism of this action, the effects of pretreatment with cortisone, fasting, adrenodemedullation, pancreatectomy, and the induction of alloxan diabetes on the response of the blood sugar and the glycogen content of the liver and muscle to the injection of neutral red and the microscopic appearance of the pancreas were studied. The results indicate that this acute action of the dye is a response to stimulation of the alpha cells of the pancreas and the release of glucagon. Prolonged administration of neutral red, on the other hand, induced chronic hypoglycemia, comparable to the clinical condition attributed to glucagon deficiency. The results of the present study afford further evidence for the role of glucagon in the animal economy. Neutral red by its specific action on the alpha cells of the pancreatic islets is a useful tool for the study of glucagon metabolism and for the induction of glucagon deficiency. (Endocrinology 7...

DECREASE IN THE CONCENTRATIONS OF KETONE BODIES AND FREE FATTY ACIDS IN RAT BLOOD IN RESPONSE TO A GLUCOSE LOAD: ITS POSSIBLE RELATION TO ENDOGENOUS INSULIN ACTIVITY.

A fall of blood concentration of ketone bodies and free fatty acids as observed in rats and the involvement of endogenous insulin therein were examined. Hypoketonemia caused by glucose load was concluded to be solely dependent on the endogenous insulin activity, in view of the fact that extirpation of the pancreas as well as induction of alloxandiabetes or neutralization of endogenous insulin by anti-insulin serum completely abolished the hypoketonemia. In contrast, the decrease of blood concentration of free fatty acids in rats was at least partly due to a factor other than endogenous insulin activity, since a significant decline of blood level of free fatty acids was observed even in the totally pancreatectomized rats. The difference of ketonemic action between endogenous and exogenous insulin, as well as its dependence on other endocrine factors, is discussed. (Endocrinology 76: 910, 1965)

Effect of testosterone and insulin on rat skeletal muscle RNA.

Castrated, intact alloxan diabetic and castrated alloxan diabetic rats were utilized to study the effects of testosterone, insulin and a combination of these 2 hormones on the RNA and the RNA :DNA ratio of the rectus femoris and levator ani muscles. Castration decreased the RNA:DNA ratio in the levator ani but not in the rectus femoris. Testosterone in the castrated rat increased the RNArDNA ratio in both muscles. However, the increase in the rectus femoris is of doubtful biologic significance. The μg RNA /mg N in the rectus femoris and levator ani was not influenced by castration, but testosterone increased this parameter in the levator ani. Thus the RNA of the levator ani appears to be more sensitive to the effects of castration and testosterone replacement than the RNA of the rectus femoris. Alloxan diabetes resulted in a reduction of the RNA:DNA ratio in the rectus femoris and levator ani, and insulin replacement elevated the ratio in both muscles. Alloxan diabetes did not influence the μg RNA/mg N in the rectus femoris, but it resulted in an elevation in this parameter in the levator ani. Insulin replacement increased the ;μg RNA/mg N in the rectus femoris and further elevated it in the levator ani. In contrast with the effects of castration, the RNA of the rectus femoris and levator ani responded in a somewhat similar manner in alloxan diabetes and insulin replacement. The induction of alloxan diabetes in the castrated rat reduced the RNA: DNA ratio in the levator ani and rectus femoris. Testosterone was capable of elevating the ratio in the levator ani but not in the rectus femoris. Insulin alone was capable of raising the ratio in both muscles, and the combined administration of insulin and testosterone further elevated the ratio in the levator ani but not in the rectus femoris. Apparently an adequate insulin supply is not necessary for testosterone to exert its effects on the RNA of the levator ani. Conversely, an adequate testosterone supply is not necessary for insulin to exert its effect on the RNA of either muscle. However, a greater response was obtained in the levator ani when insulin was administered with testosterone. Although histologically similar, it is evident that the rectus femoris and levator ani are biochemically different.

The role of serotonin in carbohydrate metabolism. VII. In vitro observation suggesting enhanced release of insulin in response to serotonin treatment.

When rat diaphragm was incubated in serum, the glycogen level of diaphragm incubated in serum of the serotonin-treated rat was higher than that in control serum. Either cysteine-treatment of the serum or induction of alloxandiabetes in serum donor rats completely abolished this effect. Thus it was concluded that subcutaneous administration of serotonin resulted in an enhanced secretion of endogenous insulin. With the diaphragm obtained from serotonintreated rat, in vitro effect of insulin or epinephrine disappeared in phosphatebuffered saline but not in Krebs-Ringer bicarbonate solution. Diaphragms excised from alloxan-diabetic rats treated with serotonin was found to exhibit the ordinary response to insulin and epinephrine in either incubation medium. Since preincubation of diaphragm with insulin abolished the effect of added insulin in further incubation in phophate-buffered saline, but not in Krebs-Ringer bicarbonate solution, serotonin-treated tissue was assumed to be bound with endogenous insulin as a result of accelerated pancreatic secretion. A possibility was suggested that serotonin is a physiological accelerator of insulin secretion in organism.

Prevention of hypoglycemia during the induction of alloxan diabetes; the use of glucose and anti-hyaluronidase subcutaneously in the rabbit.

Prevention of hypoglycemia during the induction of alloxan diabetes; the use of glucose and anti-hyaluronidase subcutaneously in the rabbit.