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Query: UMLS:C0020505 (hyperphagia)
 6,116 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The present study was undertaken to clarify the mechanism of the diabetogenic activity of streptozotocin. Experiments were conducted to determine the resistance of animals to the diabetogenic action of streptozotocin; to follow the time course of irreversible beta-cell damage, and to determine the influence on streptozotocin action of certain compounds. Streptozotocin, a broad spectrum antibiotic, with antitumoral properties, was shown to be diabetogenic in rats and mice, but not in cats, rabbits, or guinea pigs. Intravenous or intraperitoneal administration of 65 mg/kg body weight of streptozotocin to male Wistar rats evoked a tri-phasic blood sugar response. It induced an initial hyperglycemic peak with no apparent change in plasma insulin concentrations, followed by profound hypoglycemia caused by liberation of large amounts of insulin from the pancreas. Forty-eight hours after injection, the animals were completely diabetic. Light- and electron-microscopic exadminations during the first forty-eight hours after the injection of streptozotocin showed pyknosis, degranulation and marked degeneration of the beta-cells. 1egenerative and necrotic changes were also seen in a few alpha-cells. These streptozotocin-induced diabetic rats revealed polydipsia, polyuria, polyphagia and glucosuria, and decreased body weight. Blood sugar, plasma FFA and insulin concentrations were examined after oral administration of glucose (OGTT: 3g/kg). Blood sugar and plasma FFA were significantly elevated but plasma insulin concentrations were markedly decreased, so insulin treatments were most effective in these animals. It has been reported that nicotinamide prevents the diabetogenic activity of streptozotocin and the deformity action of 6-aminonicotinamide and 3-acetylpridine. Pre-treatment with picolinamide, methyl-nicotinamide, and nicotinohydroxamic acid also blocked its diabetogenic action, but nicotinic acid, mannoheptulose and glucose were ineffective. N-nitrosodimethylamin and ethyl-N-nitrosomethylcarbamate were devoid of diabetogenicity. It seems that streptozotocin interfers with NAD formation in the beta-cell. Functioning pancreatic islets cell tumors were observed on the rats both at 407 days after streptozotocin administration and at 473 days after streptozotocin administration with nicotinamide (500 mg/kg, i.p.).
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PMID:[Studies on the mechanism of the diabetogenic activity of streptozotocin and on the ability of compounds to block the diabetogenic activity of streptozotocin (author's transl)]. 16 68

Streptozotocin-induced diabetes in the rat alters intestinal function, causes hyperphagia and arrests body growth, but stimulates intestinal growth, particularly in the mucosa. Therefore we measured several indices of epithelial cell proliferation to gain insight on possible factors responsible for the increased mucosal cell mass in the small intestine. We examined epithelial cell proliferation in upper jejunum and terminal ileum of weight-matched control and diabetic rats pair fed or eating ad libitum. Cell proliferation was measured two ways: (1) isolating whole crypts 1 hr after injection of [3H]thymidine ([3H]TdR) and calculating disintegrations per minute per crypt (dpm per crypt), and (2) autoradiography of mucosal sections to obtain labeled cells per crypt, total cells per crypt-villus column, and cell migration rates. Autoradiography showed diabetes: (1) increased cell number of crypt-villus columns and increased labeled cells per crypt section, primarily jejunum, and (2) did not alter cell migration except for an increase in the ileum of diabetics eating ad libitum. Cell proliferation measured as dpm per crypt virtually doubled in diabetics in both segments regarless of dietary regimen. Dpm per crypt is a three-dimensional measurement based on the whole crypt. The increase in cell number and labeled cells per crypt in jejunal sections is also consistent with increased cell division, but shows a much smaller effect. The nature of the histological technique (two-dimensional) limits its usefulness for measuring morphological changes, and this may explain the discrepancy. Hence, the primary effect of diabetes is increased DNA synthesis (dpm per crypt) and this appears to be the main explanation for stimulated mucosal growth.
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PMID:Proliferation rate and transit time of mucosal cells in small intestine of the diabetic rat. 91 75

Untreated insulin-deficient diabetes causes hyperphagia and neuroendocrine disturbances that may be partly mediated by increased hypothalamic activity of neuropeptide Y (NPY), a potent central appetite stimulant. The metabolic signal that stimulates hypothalamic NPY is unknown. This study aimed to determine whether insulin deficiency or hyperglycemia was responsible. Regional hypothalamic NPY concentrations were compared in streptozocin-diabetic (STZ-D) rats rendered nearly normoglycemic by either insulin replacement or food restriction. Untreated STZ-D rats were hyperphagic and showed significantly increased (p less than 0.01) hypothalamic NPY concentrations in the arcuate nucleus and lateral hypothalamic area. Once-daily ultralente insulin injections corrected hypoinsulinemia and hyperglycemia, abolished hyperphagia, and normalized NPY concentrations in all hypothalamic regions. By contrast, food restriction effectively lowered glycemia without raising insulin levels. In these underfed diabetic rats, NPY concentrations rose further and were significantly higher than nondiabetic and untreated diabetic levels in most hypothalamic regions. We conclude that insulin deficiency is a major stimulus to hypothalamic NPY in STZ-D, whereas hyperglycemia may exert an inhibitory influence. These findings support the hypothesis that hypothalamic NPY responds to specific metabolic cues and is involved in regulating energy balance and conserving body weight.
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PMID:Insulin deficiency is a specific stimulus to hypothalamic neuropeptide Y: a comparison of the effects of insulin replacement and food restriction in streptozocin-diabetic rats. 143 14

We previously reported that dog diabetes results in hypercholesterolemia and the accumulation of a high-density lipoprotein (HDL) subclass, HDL1. Hypercholesterolemic diabetic rodents exhibit hyperphagia, intestinal hypertrophy, and increased intestinal cholesterol synthesis and absorption; intestinal 3-hydroxy-3-methylglutaryl (HMG) CoA reductase activity is increased, whereas hepatic activity is unchanged or reduced. To determine whether similar mechanisms operate in the hypercholesterolemic diabetic dog, we measured hepatic and intestinal cholesterologenesis. Streptozocin-alloxan-induced diabetic dogs allowed access to food ad libitum were hyperphagic and hypercholesterolemic (10.1 vs. 4.47 mM) but normotriglyceridemic. Plasma HDL1 concentrations were markedly increased. Differences in renal and hepatic function were not statistically significant, except serum alkaline phosphatase, which was elevated 4-fold (P = 0.0003). Urinary mevalonate, an index of whole-body cholesterol synthesis, was increased 6-fold. Intestinal and hepatic weights were both increased, and direct measurements showed crypt and villus thickening. The activity of HMG CoA reductase per gram organ weight was increased 1.7-fold in liver and 2.1-fold in intestine. Calculated whole-organ activity in intestine was nearly twice that in liver. These observations provide strong evidence that intestinal cholesterogenesis is involved in the pathogenesis of hypercholesterolemia in dog diabetes and support the conclusion that increased cholesterol synthesis plays a role in the hypercholesterolemia of diabetes.
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PMID:Intestinal and hepatic cholesterogenesis in hypercholesterolemic dyslipidemia of experimental diabetes in dogs. 175 3

Experimental diabetes adversely affects hypothalamic control of gonadotropin secretion and sex behavior and induces hyperphagia accompanied by severe body weight loss. Neuropeptide-Y (NPY) stimulates pituitary gonadotropin release, inhibits sexual behavior, and stimulates robust feeding in rats by acting at different sites in the hypothalamus. Therefore, we tested the hypothesis that altered hypothalamic NPY neurosecretion may mediate the constellation of effects observed in streptozotocin-induced diabetic (STZ-D) rats. Adult male rats were made diabetic by a single injection of STZ (50 mg/kg). Five months later, in vitro NPY release from the hypothalamic fragment encompassing the medial basal hypothalamus and preoptic area and NPY concentrations in seven hypothalamic sites were assessed. Basal NPY release was not significantly changed after STZ treatment. However, in response to a 30-min pulse of KCl (45 mM), NPY release from the medial basal hypothalamus-preoptic area of STZ-D rats was significantly increased compared to that in age-matched controls. In the STZ-D rats, NPY concentrations in six of the seven microdissected nuclei, including those mediating control of pituitary gonadotropin, sexual, and feeding behaviors, were increased compared to control values. In an additional study similar increments in NPY concentrations in the hypothalamic sites were observed 6 months after STZ treatment. The effects of insulin on NPY levels in microdissected hypothalamic sites in STZ-treated and BB diabetic rats was next assessed. One group of rats was treated with STZ, and the other group of rats was additionally treated with insulin (6 U/kg.day) for 3 months after development of diabetes with STZ. Again, STZ treatment alone, even for 3 months, increased NPY levels in all seven nuclei, including the suprachiasmatic nuclei. Insulin therapy completely prevented the STZ-induced increments in NPY levels in all hypothalamic sites, and the blood glucose level was 233 +/- 22 mg/dl in insulin-treated STZ-D rats and 496 +/- 6 mg/dl in untreated STZ-D rats. Similarly, NPY concentrations in five of the seven nuclei were unchanged in spontaneously diabetic BB rats (blood glucose, 435 +/- 67 mg/dl) maintained on insulin (5-8 U/kg.day). These results demonstrate that STZ-D rats have a widespread increase in NPY levels in hypothalamic sites, and there is an increase in the evoked release of NPY from the hypothalamus.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Neuropeptide-Y concentration in microdissected hypothalamic regions and in vitro release from the medial basal hypothalamus-preoptic area of streptozotocin-diabetic rats with and without insulin substitution therapy. 213 23

The significance of portal venous drainage after whole-pancreas transplantation both for metabolic control and development of diabetic nephropathy was investigated. Streptozotocin-diabetic inbred LEW rats received a duct-ligated pancreas graft with either systemic or portal venous drainage and were followed for up to one year. Normal and untreated diabetic rats (n=18 in each group) served as controls. Irrespective of the route of venous drainage pancreas transplants normalized the diabetic polyuria, polyphagia, and polydipsia. Growth rates and general health did not differ from normal rats. Pancreas transplantation with portal venous drainage furthermore normalized nonfasting blood glucose and peripheral insulin levels, and intravenous glucose tolerance. Pancreas transplantation with systemic venous drainage, however, was associated with peripheral hyperinsulinemia, slightly elevated nonfasting blood glucose levels, and supranormal K-values in intravenous glucose tolerance tests. Though portal venous drainage was associated with better metabolic control than systemic venous drainage, both techniques of pancreas transplantation proved equally effective to prevent the development of diabetic glomerular membrane thickening determined 6 and 12 months posttransplant.
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PMID:Significance of portal venous drainage after whole-organ pancreas transplantation for endocrine graft function and prevention of diabetic nephropathy. 240 87

Myogenic satellite cells were isolated from nondiabetic and streptozotocin-diabetic rats and studied in vitro. Streptozotocin (STZ) administration produced both hyperglycemia and glucosuria in adult rats when compared to controls. (P less than 0.01), with 12.5% mortality in untreated animals. Insulin therapy diminished blood glucose levels to those found in nondiabetic animals. Only STZ-diabetic rats displayed symptoms of Type I diabetes, including polydipsia, polyuria, and hyperphagia. STZ-treated rats possessed less leg muscle mass and less subcutaneous, intermuscular, and intramuscular fat. Conversely, nondiabetic rats had a greater mean body weight (P less than 0.01) at the end of the experiment than did diabetic rats. Primary cultures of diabetic-derived satellite cells displayed decreased overall ability (P less than 0.01) to fuse to form multinucleated myotubes in vitro than controls. In addition, secondary cultures of diabetic-derived satellite cells achieved maximal fusion one day later than secondary cultures of control-derived cells. Collectively, these data provide preliminary evidence to suggest that untreated insulin-dependent diabetes results in altered fusion characteristics of myogenic satellite cells. Additional studies utilizing satellite cells from diabetic animals will provide valuable definition of the satellite cell involvement in skeletal muscle autophagy which is a symptom of type I diabetes.
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PMID:Satellite cells derived from streptozotocin-diabetic rats display altered fusion parameters in vitro. 252 36

The growth and metabolic effects of a radiation-induced rat insulinoma were examined after subcutaneous subscapular transplantation into normal and streptozotocin diabetic NEDH rats. Streptozotocin diabetic rats exhibited hyperglycaemia, hypoinsulinaemia, impaired glucose tolerance without an insulin response, polyuria, polydipsia, hyperphagia and weight loss. Transplantation of tumour fragments gradually improved the physical and metabolic state over the following 3 weeks. Coincident with a progressive rise in plasma insulin between 10 and 17 days, the diabetic rats gained weight and reduced their food intake. The rats remained hyperglycaemic during this time, but developed hypoglycaemia with marked hyperinsulinaemia by 24 days. Furthermore, plasma glucose and insulin concentrations were not increased by an intraperitoneal glucose challenge, indicating greatly accelerated glucose clearance. Both the streptozotocin-treated and normal insulinoma-bearing rats incurred a fatal hypoglycaemic coma by 28-33 days after transplantation. Final body weights, tumour weights and concentrations of glucose and insulin were similar in the two groups. This study demonstrates reversal of streptozotocin diabetes by insulinoma transplantation. The hyperglycaemia and the accompanying diabetic environment did not modify tumour growth and development.
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PMID:Reversal of diabetes by syngeneic transplantation of a radiation-induced rat insulinoma. 303 49

Previous reports have suggested that insulin may not regulate the breakdown of myofibrillar proteins in skeletal muscle. To further test the role of insulin, insulinopenia was produced by treating rats with streptozocin. After treatment, protein breakdown in skeletal muscle was evaluated with the isolated perfused rat hindquarter preparation. After the inhibition of protein synthesis with cycloheximide, total and myofibrillar protein breakdown were assessed by measuring the release of tyrosine and 3-methylhistidine, respectively, in the perfused hindquarters of diabetic and age-matched control rats. Streptozocin-induced (65 mg/kg) diabetes (3- to 28-day duration) resulted in hyperglycemia, hypoinsulinemia, hyperphagia, increased plasma lipid levels, arrested body and muscle growth, and increased urea and 3-methylhistidine excretion. Despite this, protein breakdown in skeletal muscle diminished. The release of 3-methylhistidine by the perfused hindquarters of diabetic rats decreased, whereas the release of tyrosine remained unchanged, suggesting that the breakdown of myofibrillar proteins was affected specifically. 3-Methylhistidine (unbound) levels in skeletal muscle of unperfused diabetic rats as well as in skin decreased, whereas they increased twofold in the gastrointestinal tract. More severe diabetes (125 mg/kg streptozocin), which resulted in ketoacidosis, augmented protein breakdown in muscle; however, this response was due to a marked fall in food consumption (it was also evident when control rats were pair fed). These data reinforce previous conclusions that insulin does not play a major role in the regulation of myofibrillar protein breakdown in skeletal muscle.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Myofibrillar protein breakdown in skeletal muscle is diminished in rats with chronic streptozocin-induced diabetes. 309 8

Central and lateral hypothalamic concentrations of 10 regulatory peptides were measured by radioimmunoassay in streptozocin-induced diabetic (STZ-D) and matched control rats between 1 day and 14 wk after diabetes induction. After 2 wk, both central and lateral hypothalamic neuropeptide Y (NPY) concentrations in STZ-D rats were consistently higher than those found in control rats, with significant 30-50% increases at 4 wk in the central hypothalamus, and at 6 and 14 wk in both central and lateral hypothalamus. Immunocytochemical studies in 4- and 6-wk STZ-D animals showed the appearance of intensely NPY-positive swollen cell bodies in the supraoptic nucleus and a subjective increase in NPY staining of medial hypothalamic nerve fibers. Central hypothalamic concentrations of three other peptides were significantly greater in STZ-D animals than those in control animals at single points (neurotensin, 1 day; calcitonin gene-related peptide, 2 wk; neurokinin, 4 wk). Hypothalamic concentrations of the other six peptides examined (bombesin, galanin, neuromedin B, substance P, somatostatin, and vasoactive intestinal peptide) did not differ significantly between STZ-D and control groups at any time. However, galanin immunostaining in the supraoptic and magnocellular paraventricular nuclei was strikingly concentrated in a reduced number of distended cell bodies. Hypothalamic peptide changes in STZ-D could be related to metabolic disturbance, changes in energy and water balance, altered pituitary function, or other factors. Persistently elevated concentrations of NPY, a very potent central stimulant of eating and drinking, may mediate the hyperphagia and polydipsia characteristic of STZ-D.
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PMID:Increased hypothalamic neuropeptide Y concentrations in diabetic rat. 328 97


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