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Query: UMLS:C0011854 (type 1 diabetes)
 20,749 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Several lines of evidence suggest that hypertension is a contributing factor to diabetic nephropathy, a major cause of mortality in diabetes mellitus patients. The present study tested the hypotheses (1) that insulin dependent diabetes (IDD) causes hypertension, and (2) that simultaneous hypertension and IDD causes greater renal damage than would be expected from the independent contributions of each disease. IDD was induced by injection of streptozotocin (STZ, 65 mg/kg i.p.) into male Wistar rats, causing severe hyperglycaemia within 4 days. Seven days after the STZ treatment, hypertension was initiated by subcutaneous implantation of deoxycorticosterone acetate and administration of 1% saline in the drinking water (DOCA-NaCl). IDD rats not receiving DOCA-NaCl displayed a small elevation of blood pressure one week after STZ treatment, but thereafter displayed significant hypotension. The IDD rats receiving DOCA-NaCl displayed elevated systolic arterial pressure throughout the study, but by the end of the experiment, their mean systolic arterial pressure was significantly lower than that of the rats treated with DOCA-NaCl alone. Only the IDD/DOCA-NaCl rats displayed significant signs of renal dysfunction, i.e. greatly increased proteinuria and morphological renal damage, including marked distension of distal tubules and occasional casts. No other group displayed these abnormalities.
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PMID:Effects of simultaneous diabetes and hypertension in an insulin dependent diabetic model. 176 11

One of the earliest histopathological signs of diabetic retinopathy is a selective loss of intramural pericytes from retinal capillaries. In the present study, the retinal vessels of rats with streptozotocin-induced diabetes (STZ Wistar) and rats with genetically-induced insulin dependent diabetes mellitus (BB Wistar) and non-insulin dependent diabetes mellitus (SHR/N-corpulent) were examined after 6 to 8 months duration for diabetes-related retinal microangiopathies. The SHR/N-corpulent (cp) rats were fed a 54% sucrose diet, whereas the STZ Wistar and BB Wistar rats were fed laboratory chow for 32 to 36 weeks. In all the diabetic rats, the retinal capillaries in enzyme-digested flat mounts exhibited an increase in periodic-acid-Schiff (PAS) staining and loss of pericytes compared to their respective euglycemic controls. Pericyte "ghosts", like those defined in human diabetes as intramural pockets lacking normal cell contents, were documented by high resolution micrographs in all the diabetic rats. Endothelial cell proliferation, capillary dilation, and varicose loop formation were noted in some of the diabetic rats. Hence, similar capillary lesions were found in very different groups of diabetic rats. The findings suggest that a chronic high tissue concentration of glucose is the underlying factor which triggers pathogenesis in the pericyte. Hyperglycemia-induced activation of endogenous aldose reductase of the polyol pathway is probably the initial insult, but other factors such as advanced glycosylation products may affect the final outcome.
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PMID:Degenerated intramural pericytes ('ghost cells') in the retinal capillaries of diabetic rats. 182 96

1. Diabetes mellitus type I was induced in 3-month old male C57 BL/KS-mdb mice (N = 24) by ip injection of streptozotocin (STZ, 45 mg/kg body weight) for 5 days. 2. To determine the possible protective effects of nitric oxide inhibition against hyperglycemia, the STZ-diabetic rats received two doses of NG-nitro-L-arginine- methyl ester (L-NAME) (10 mg/kg body weight and 10 mg/mouse) dissolved in PBS for 45 consecutive days. Another group of STZ-treated rats was similarly treated with L-arginine (5 mg/mouse). 3. Blood glucose levels were 118 +/- 37 mg/dl after 8 days of L-NAME administration (10 mg/kg body weight, N = 12) and 186 +/- 22 mg/dl (N = 12) after 5 days of L-NAME administration at the 5 mg/mouse dose. Treatment with L-arginine (5 mg/mouse, N = 12) caused a significant increase in blood glucose level to 151 +/- 17.5 mg/dl, showing the relevance of nitric oxide formation in this type of diabetes. 4. In STZ-diabetic mice treated with L-NAME (N = 12), diuresis was reduced by approximately 58% compared to STZ animals, whereas in L-arginine-treated animals (N = 12) diuresis returned to STZ levels. Urinary protein excretion, which was significantly affected by STZ (123% compared to control) was significantly reduced by 66% after treatment with L-NAME for 45 days, whereas treatment with L-arginine caused a return to STZ values. 5. Urinary kallikrein excretion, which was reduced by 80% in STZ mice compared to control, returned to control levels after L-NAME treatment. 6. The present results suggest a relationship between nitric oxide levels and the reduction of diabetic state and improved renal function by L-NAME.
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PMID:Streptozotocin-induced hyperglycemia is decreased by nitric oxide inhibition. 774 93

A decreased insulin response, preferentially to glucose, has been considered a hallmark of non-insulin dependent diabetes mellitus (Type 2) in humans. Syndromes resembling human diabetes occur spontaneously in many animal species and can also be induced by treating animals with drugs or viruses, excising their pancreases or manipulating their diet. Among these models, rat diabetes induced by neonatal streptozotocin administration (n-STZ models) has been first recognized as an adequate tool to study the long-term consequences of a gradually reduced beta-cell mass. More recently, the GK (Goto Kakisaki) Wistar rat has become available and is now considered as a promising spontaneous rat model of non-insulin dependent diabetes. We and others have found that defects in insulin secretion and action develop in the n-STZ and the GK models, which in many ways resemble those described in human non-insulin dependent diabetes. This review is aimed to sum up with a comparative approach, the informations so far collected in the n-STZ and GK models concerning the cellular mechanisms leading to the desensitization of their beta-cells to glucose. Taken together, the data reinforce the view that the impairment of glucose-induced insulin release in n-STZ and GK rats is clearly related to a defect in oxidative glycolysis. This leads to a severe decrease in the mitochondrial oxidative catabolism of glucose-derived pyruvate. Its coincides with a lower ATP/ADP ratio in glucose-stimulated islets and a subsequent alteration of ionic events tightly coupled to the fuel function of the hexose in islet cells, i.e. the decrease in K+ conductance.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Glucose refractoriness of pancreatic beta-cells in rat models of non-insulin dependent diabetes. 780 48

We have previously reported that chronic hypertension develops consistently in Wistar rats with a 25% reduction in renal mass (RRM) following the induction of insulin dependent diabetes mellitus (IDDM) with streptozotocin (STZ, 65 mg/kg body weight, intravenously). In this study, we examined the role of the endogenous digitalis-like substance in the development of hypertension. Four groups of rats were studied: 1) 25% RRM rats with STZ-induced IDDM (25-DM), 2) normal rats with STZ-induced IDDM (2K-DM), 3) 25% RRM rats with vehicle treatment (25-V), and 4) normal rats with vehicle treatment (2K-V). In 25-DM rats, blood pressure progressively increased during the 3 weeks after STZ treatment and was associated with microalbuminuria, low plasma renin activity, and extracellular volume expansion. In contrast, the 2K-DM, 25-V, and 2K-V rats remained normotensive. Furthermore, the plasma and urine levels of digoxin-like immunoreactive factor (DIF), determined by digoxin radioimmunoassay (Baxter), were significantly higher in hypertensive 25-DM rats than in their controls. The same was the case for plasma digitalis-like substance (DLS), determined by exposing canine Na+,K(+)-ATPase to plasma fractions and observing the percent inhibition. Increased DIF and DLS in hypertensive 25-DM rats was associated with a significant decrease in Na+,K(+)-ATPase activity of microsomes prepared from the left and right ventricles, when compared with microsomes from normotensive 2K-DM animals. Microsomal 5'-nucleotidase, a plasma membrane marker, was unchanged. The DIF and DLS correlated significantly with each other and with myocardial Na+,K(+)-ATPase activity and mean blood pressure. These results suggest that increased endogenous digitalis-like substance, which inhibits cardiovascular muscle cell Na(+)-K(+)-pump activity, may be involved in the mechanism of hypertension associated with IDDM in 25% RRM rats.
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PMID:Role of digitalis-like substance in the hypertension of streptozotocin-induced diabetes in reduced renal mass rats. 839 Feb 68

IDDM in humans and STZ-induced diabetes in rats are both characterized in the early phase of the disease by glomerular hypertrophy; and, in the chronic phase of the disease, by mesangial expansion and glomerular basement membrane thickening. Decreases in glomerular intracellular protein degradation rates in diabetic individuals could contribute to the glomerular hypertrophy by allowing a build-up of cellular protein. Decreases in extracellular protease activity could contribute to the build-up of matrix protein in the mesangium and glomerular basement membrane. In this study, the levels of lysosomal cathepsin activities and glomerular metalloprotease activities were measured in isolated glomerular homogenates from STZ-induced diabetic rats at 4 days and 5 wk after administration of the drug. Some of the rats in the 5-wk study were treated with daily insulin; others were untreated. After 4 days of diabetes, cathepsin B and L activities were decreased by 15-45% when correlated with the levels of glomerular protein or DNA. Glomerular metalloprotease activity was decreased by 75% in the diabetic rats when compared with controls. After 5 wk of diabetes, cathepsin activities either were unchanged (for cathepsin B and L together or cathepsin S) or increased (cathepsin B alone) in insulin-treated diabetic rats, and continued to be decreased in untreated diabetic rats. A 40-50% decrease in glomerular metalloprotease activity continued in both diabetic groups. These data strongly suggest that decreases in the lysosomal cathepsin activities may contribute to IDDM-induced glomerular cellular hypertrophy. The data further indicate that a decrease in glomerular metalloprotease activity may contribute to diabetes-induced mesangial expansion and glomerular basement membrane thickening.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:STZ-induced diabetes results in decreased activity of glomerular cathepsin and metalloprotease in rats. 839 28

Diabetes during pregnancy carries short- and long-term consequences for the offspring. Improved obstetrical and diabetic care has resulted in decreased morbidity and mortality in the neonate of the diabetic mother. Mild hyperglycemia is still found in both IDDM pregnant women and women with GDM. The long-term consequences of exposure to mild hyperglycemia in utero remain to be determined. In an effort to develop an appropriate animal model of mild diabetes during pregnancy, we mated female STZ-induced diabetic rats previously transplanted with specific numbers of islets of Langerhans (2500, 1000, 700, or 500 islets). Diabetic and nondiabetic sham-transplanted control groups also were studied. During pregnancy, the plasma glucose levels in the diabetic rats and the group receiving 500 islets (26.5 +/- 1.1 and 10.0 +/- 0.8 mM, respectively) were significantly greater than in control animals (5.4 +/- 0.5 mM, P < 0.0001). The mean glucose levels in rats receiving 700 or 1000 transplanted islets (6.8 +/- 0.2 and 6.5 +/- 0.2 mM) also were significantly greater than in control animals (P < 0.001). No difference was evident between control rats and the group receiving 2500 islets (5.8 +/- 0.2 mM). No gross congenital abnormalities were apparent in the offspring. The pup plasma glucose was significantly greater in the offspring of dams receiving either none (diabetic) or 500 islets (10.6 +/- 0.7 and 11.1 +/- 1.1 mM, respectively) compared with the offspring of nondiabetic control dams (4.4 +/- 0.3 mM, P < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:A new model for the study of mild diabetes during pregnancy. Syngeneic islet-transplanted STZ-induced diabetic rats. 842 67

This study investigated the effect of IDDM on cartilage anabolic activity in rats. Rats were injected with STZ to induce IDDM, were hypophysectomized, or were injected with STZ and hypophysectomized. After 14 days, control (intact and sham-Hx) and Hx rats were normoglycemic, whereas the rats with IDDM exhibited hyperglycemia and glycosuria. The HxDb rats, however, had normal blood glucose levels and no glycosuria. Both growth, serum levels of IGF-I, and basal cartilage 35SO4 incorporation measured in vitro were decreased in the Hx, IDDM, and HxDb groups. IGF-I added in vitro significantly stimulated 35SO4 incorporation by cartilage explants from control and Hx animals, whereas explants from the animals with IDDM were unresponsive. Explants from the HxDb rats, however, were stimulated by IGF-I in a dose-related manner. Because Hx corrected the glycemic status of the IDDM rats and restored cartilage responsiveness to IGF-I, a second set of experiments was undertaken to further investigate the relationship between cellular metabolism and anabolic activity in cartilage. Cartilage explants from rats fasted for 48 h showed significantly decreased basal 35SO4 incorporation, which was as low as that in explants from rats with severe IDDM. Whereas explants from the IDDM rats were completely unresponsive, those from the fasted rats (and fed rats) were significantly stimulated by the added IGF-I. However, incubation in the presence of 2-D-G, which causes intracellular glucopenia, or in the absence of glucose, completely blocked the anabolic response to IGF-I in otherwise responsive tissues. In conclusion, an important component of diabetic growth inhibition appears to be tissue resistance to the anabolic action of IGF-I, a condition that is correctable by Hx and that may be a result of metabolic impairment at the tissue level.
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PMID:An insulin-like growth factor I-resistant state in cartilage of diabetic rats is ameliorated by hypophysectomy. Possible role of metabolism. 843 17

N-Myristoyltransferase (NMT) catalyses the transfer of myristate from myristoyl-CoA to the NH2-terminal glycine residue of several proteins and are important in signal transduction. STZ-induced diabetes (an animal model for insulin-dependent diabetes mellitus, IDDM) resulted in a 2-fold increase in rat liver NMT activity as compared with control animals. In obese Zucker (fa/fa) rats (an animal model for non-insulin dependent diabetes mellitus, NIDDM) there was a approximately 4.7-fold lower liver particulate NMT activity as compared with the control lean rat livers. Administration of sodium orthovanadate to the diabetic rats normalised liver NMT activity. These results would indicate that the rat liver particulate N-myristoyltransferase activity appears to be inversely proportional to the level of plasma insulin, implicating insulin in the control of N-myristoylation.
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PMID:In vivo modulation of N-myristoyltransferase activity by orthovanadate. 892 31

We have evaluated the suitability of different rat models for the study of effects of antihypertensives on cardiovascular and metabolic complications of diabetes mellitus and hypertension. IDDM was induced in Wistar and spontaneously hypertensive (SH) rats by single tail vein injection of STZ (45 mg/kg, i.v.). Neonatal STZ-diabetes (nSTZ) was induced by administering STZ, 70 mg/kg (i.p.) to 5 day old Wistar rat pups. DOCA-hypertension was induced in Wistar and STZ-diabetic rats using deoxycorticosterone acetate (DOCA, 5 mg/kg, s.c.) and NaCl (2%) in drinking water. Intravenous injection of STZ produced cardinal signs of diabetes mellitus including hyperglycemia, loss of body weight, polyphagia and polydipsia. STZ-diabetic rats also showed hyperlipidemia and hypoinsulinemia. STZ-treated rats developed hypertension and bradycardia. nSTZ rats were found to have mild hyperglycemia and were hypertensive and hyperinsulinemic. The OGTT and ITT revealed that nSTZ rats are insulin resistant. SH rats were also found to be hyperinsulinemic and hypertensive. Although, these rats were found to be insulin resistant, they did not demonstrate hyperglycemia. DOCA-treated STZ-diabetic rats were found to have milder hyperglycemia when compared to STZ-diabetic rats not treated with DOCA. Although, DOCA treatment was not found to alter serum levels of glucose and insulin, results of OGTT revealed enhanced glucose disposal in DOCA-treated Wistar rats, suggesting that DOCA probably produces some effect on glucose homeostasis in rats. The present data also suggest that STZ-diabetic rat may be considered a suitable model for IDDM. On the other hand, nSTZ and SH rats were hyperinsulinemic and insulin resistant and may be used as models to study insulin sensitivity. DOCA-hypertensive rat may not be a suitable model for studying the effects of various drug interventions on glucose homeostasis and insulin sensitivity as DOCA itself appears to influence these factors.
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PMID:Comparative evaluation of different rat models with co-existing diabetes-mellitus and hypertension. 1084 25


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