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1.
Watanabe T  Miyagawa I 《Life sciences》2002,70(19):2215-2224
Diabetic cystopathy as manifested by an enlarged bladder is mainly caused by peripheral neuropathy. Long-chain fatty alcohol, which has been isolated from the Far-Eastern traditional medicinal plant, Hygrophilia erecta, Hochr., has been found to possess some neurotrophic activities on the central neuron. Cyclohexenonic long-chain fatty alcohol (FA) used in this study were synthesized in order to improve the efficiency of the molecules. The effects of this compound on peripheral nerves, however, have not yet been studied. To get more information, we evaluated the effects of this compound on peripheral nerves in streptozotocin-induced diabetic rats in terms of nerve conduction velocity and bladder function. Three experiments were performed 8 weeks after the administration of streptozotocin to 8-week-old rats: (i) motor sciatic nerve conduction (MNCV), (ii) monitoring micturition behavior in the metabolic cage, and (iii) cystometrogram under urethane anesthesia (CMG). Half of the diabetic rats were treated with FA (8 mg/kg/day, i.p.). The difference in MNCV between control rats (49.0 +/- 2.2 m/s) and untreated diabetic rats (42.4 +/- 0.5 m/s) after 8 weeks reached significance (p = 0.0183). FA-administrated diabetic rats showed an improved MNCV (45.8 +/- 1.2 m/s). We also identified a significant improvement of bladder function in these animals. The diabetic rats had a much higher maximal micturition volume per 24 hours (4.9 +/- 0.4 ml) than control animals (1.5 +/- 0.1 ml). However, the diabetic rats treated with FA had a maximal micturition volume of only 3.7 +/- 0.3 ml. Likewise, the diabetic rats had a CMG bladder capacity of 0.90 +/- 0.14 ml while the diabetic rats treated with FA had a capacity of 0.54 +/- 0.07 ml. These results indicate that cyclohexenonic long-chain fatty alcohol has a beneficial effect on peripheral neuropathy and cystopathy in streptozotocin-induced diabetic rats.  相似文献   

2.
Protein phosphatase-1 and 2A, accounting for all the hepatic activity regulating phosphorylase, were assayed in streptozotocin-induced (8 weeks) diabetic Wistar rats. Cytosolic protein phosphatase-1 and 2A were distinguished by chromatography on heparin-Sepharose and by inhibition with inhibitor-2. Approx. 25-35% increases in type-1 phosphorylase phosphatase activity measured in cytosols were registered in diabetic rats when compared with control and 24 h fasting animals. The enrichment of protein phosphatase-1 in the cytosol of streptozotocin-treated rat livers could not be attributed to the reduced glycogen content with the onset of diabetes, since this elevated level of type-1 phosphatase was not observed in fasting rats with low glycogen content. The translocation of type-1 phosphatase from the particulate fraction into the cytosol was also recorded in trypsin-treated samples of diabetic rat livers. The apparent molecular weight of type-1 phosphatase in the cytosol of control and fasted rats was 160,000 as judged by gel filtration. The type-1 phosphatase activity that was released from the particulate fraction by streptozotocin-induced diabetes identified a further enzyme species (Mr 110,000) in the cytosol. Our data imply that the higher levels of cytosolic protein phosphatase-1 in diabetic rat liver could be a consequence of the dissociation of the catalytic subunit of protein phosphatase-1 and the glycogen-binding subunit in rat livers.  相似文献   

3.
Diabetes mellitus is associated with various structural and functional liver abnormalities that affect the glycogen and lipid metabolisms. The effects of streptozotocin-induced diabetes and of insulin supplementation to Sprague-Dawley diabetic rats on ganglioside patterns in liver were determined. Diabetic livers showed a tendency to hepatomegaly 3 weeks after STZ-induction of diabetes. The concentration of total gangliosides in diabetic and non-diabetic livers was similar, but the concentration of total gangliosides in the liver of insulin-stabilized rats was slightly increased. Bidimensional TLC chromatographic analysis of gangliosides isolated from normal diabetic and insulin-stabilized diabetic livers showed quantitative and qualitative changes. In comparison with normal controls, the densitometric analyses of diabetic liver ganglioside patterns had increased amounts of GM3, GM1, GD1b, and GT1b gangliosides, while GM2 could not be detected. The hepatic ganglioside pattern of insulin-stabilized diabetic rats was partially restored, resembling the profile of normal rats. The activity of GalNAcT, GalT-2 and SialT-4 transferases was measured in liver microsomal fractions of the different groups of animals. Diabetic rats showed an increased activity of GalNAcT and a decrease in the activity of GalT-2 and SialT-4 compared with the controls. The enzymatic activities found in insulin-treated rats showed a tendency to return to the values observed in normal control animals. The results evidenced that streptozotocin-induced diabetes affects the liver ganglioside pattern and the ganglioside synthesis enzyme activity. The alterations found in ganglioside metabolism could represent one of the earliest changes associated with the diabetic pathology.  相似文献   

4.
Urinary epidermal growth factor (EGF) excretion was calculated as ng EGF per mg creatinine and ng EGF per 24 hr. It was increased 4-9 fold in rats with genetic (BB) or streptozotocin-induced diabetes. It decreased to 2-3 fold control values in insulin-treated animals. In contrast, EGF concentration in serum was lower in diabetic than in control rats (360 +/- 72 vs 524 +/- 150 pg/ml, P .086); EGF level in plasma was unchanged (319 +/- 67 vs 313 +/- 96 pg/ml). In diabetic rats EGF content was increased in submaxillary glands (1018 +/- 259 vs 738 +/- 122 pg/mg protein, P .060) but unchanged in the kidneys (70 +/- 18 vs 65 +/- 6 pg/mg protein in controls). EGF binding to the liver microsomes in diabetic rats was decreased by 30-40% and was not restored by insulin therapy. Binding to the kidneys also showed a tendency to decrease in diabetic animals. The EGF excretion and receptor binding were normal in obese normoglycemic Zucker fa/fa rats. We suggest that hyperglycemia and/or glucosuria may affect EGF synthesis and/or excretion in the kidneys and EGF synthesis or accumulation in the megakaryocytes. The mechanism of decreased EGF receptor binding remains to be clarified.  相似文献   

5.
This study was undertaken to elucidate the effect of glibenclamide, one of sulfonylurea drugs, on thyroid hormone metabolism in vivo and on the conversion of thyroxine (T4) to 3,5,3'-triiodothyronine (T3) in the isolated perfused rat liver and kidney. Glibenclamide (0.2 mg/kg body weight) was intraperitoneally administered to normal and streptozotocin-induced (50 mg/kg) diabetic rats for 14 days. The liver and kidney of normal rats were perfused for 30 minutes with a synthetic medium containing 20 micrograms/dl T4 and glibenclamide (200 or 400 ng/ml), and production of T3 in the tissues was measured by radioimmunoassay. Serum T4 and T3 levels in control and streptozotocin-induced diabetic rats were not changed by daily intraperitoneal glibenclamide administration. The production of T3 (111 +/- 40 and 95 +/- 16 ng/g/30 min, mean +/- SD) and the conversion rate of T4 to T3 (11.1 +/- 2.9 and 10.2 +/- 2.3%) in the liver perfused with glibenclamide (200 and 400 ng/ml) were not significantly different from those in controls (109 +/- 41 ng/g/30 min and 12.8 +/- 5.4%). And those (120 +/- 33 and 99 +/- 19 ng/g/30 min, and 3.5 +/- 0.6 and 2.5 +/- 0.4%) in the kidney perfused with glibenclamide (200 and 400 ng/ml) were similar to those in controls (98 +/- 33 ng/g/30 min and 3.0 +/- 1.5%).  相似文献   

6.
Earlier work describing increased biliary excretion of the acetaminophen-cysteine conjugate advanced the hypothesis that streptozotocin-induceddiabetes increases <γ > -glutamyltranspeptidase (GGT) expression in Sprague–Dawley rats. To test this hypothesis, rats were divided into control, diabetic, and insulin-treated diabetic groups. Diabetes was induced by intravenous injection of 45 mg streptozotocin/kg body weight and was effectively controlled by insulin treatment in the appropriate group. Densitometric quantification demonstrated that hepatic GGT activity in diabetic rats was significantly increased when compared to normal and insulin-treated diabetic controls. Histochemical staining of liver was greater in female than in male rats, and staining increased in female rat liver as the duration of diabetes lengthened from 30 to 90 days. GGT activity was increased by diabetes in liver canalicular-enriched and basolateral-enriched membrane preparations, and it was unchanged in renal brush border-enriched membranes. Total mRNA isolated from diabetic and insulin-treated diabetic rat livers did not conclusively demonstrate an elevation of GGT mRNA relative to normal. Western blot analysis showed no differences in the amount of GGT in diabetic versus normal rat livers. These data indicate that streptozotocin-induced diabetes does not alter the expression of, but does increase the activity of, GGT in liver. © 1998 John Wiley & Sons, Inc. J Biochem Toxicol 12: 219–225, 1998  相似文献   

7.
Ouabain-sensitive ATPase activity (expressed as nmol ADP produced/h/mg (wet) nerve +/- SEM) was measured in homogenates of sciatic nerve from control rats and rats with streptozotocin-induced diabetes of 8 wk duration. Nerves from diabetic rats showed activity (21.7 +/- 2.0) which was significantly (p less than 0.05) less than that of controls (34.6 +/- 4.8). These animals also showed a deficit in conduction velocity (m/sec +/- SEM) of sciatic nerve motoneurones (50.7 +/- 0.4 vs. 57.7 +/- 0.7 in controls; p less than 0.001). In parallel, matched control and diabetic groups were treated daily with mixed gangliosides extracted from bovine brain (10 mg/kg i.p.). After such treatment for 8 wk the deficit in ouabain-sensitive ATPase activity did not develop in the diabetic group (treated diabetics, 31.9 +/- 3.7; treated controls, 34.5 +/- 3.8). However, the treatment did not affect the deficit in motor nerve conduction velocity (treated diabetics, 50.9 +/- 1.1 vs. treated controls, 57.9 +/- 0.5; p less than 0.001). Accumulations of the polyol pathway metabolites--sorbitol and fructose--together with depletion of nerve myo-inositol were similar in both diabetic groups. These data indicate an etiology for the conduction velocity deficit which differs from that of the deficit in ouabain-sensitive ATPase.  相似文献   

8.
Characteristics of lipoprotein receptors of the isolated liver parenchymal cells prepared from the streptozotocin-induced diabetic rats were investigated. Streptozotocin-induced diabetic rats fed 1.0% cholesterol showed the exaggerated hypercholesterolemia as compared to control rats fed 1.0% cholesterol. The present study was designed to elucidate the role of lipoprotein receptor mechanisms of liver parenchymal cells in the diabetic dyslipoproteinemia. 125I-labeled lipoproteins (rat beta-VLDL, human LDL2 or rat HDL3) were incubated with liver parenchymal cells isolated by liver perfusion using collagenase. According to the Scatchard analysis, the apparent dissociation constant (kd) and maximum beta-VLDL binding (Bmax) for the higher affinity binding site in the diabetic rats (n = 6) were (11.9 +/- 5.1) X 10(2) ng/ml and 307.5 +/- 145.2 ng/10(6) cells, respectively. These binding characteristics of the diabetic rats were not significantly different from the control rats. Furthermore, there were no significant differences in the binding characteristics of human LDL2 and rat HDL3 between the diabetic rats and the control rats. The data presented suggest that significant role of alteration of lipoprotein receptor characteristics in liver parenchymal cells is not played in the diabetic dyslipoproteinemia.  相似文献   

9.
Increased microalbuminuria is seen early in rats with both streptozotocin-induced and genetic (Bio-Breeding) diabetes. This study examines the roles of angiotensin II-dependent mechanism(s) and sulfation of glomerular proteoglycans in this phenomenon, as both processes have been implicated by several lines of circumstantial evidence. Anionic sites in the glomerular basement membrane, attributed to the presence of heparan sulfate, were quantitated by polyethyleneimine staining at 15, 21, and 70 days of diabetes in rats treated with streptozotocin, with or without insulin, and at 70 days in the Bio-Breeding rats. All diabetic rats developed increased microalbuminuria: control, 0.08 +/- 0.03 microgram/mL glomerular filtration rate, mean +/- SD; streptozotocin without insulin at 15 days, 0.92 +/- 0.06 microgram/mL (p < 0.05); streptozotocin with insulin at 21 days, 0.61 +/- 0.37 microgram/mL (p < 0.05 vs. control). At 70 days, both the Bio-Breeding and the streptozotocin rats sustained their microalbuminuria to the same degree (p < 0.05 vs. control). Enalapril (250 mg/L) in the drinking water of diabetic animals did not reduce the microalbuminuria. Although the polyethyleneimine-stained heparan sulfate sites decreased significantly in the streptozotocin rats, they remained unchanged in the Bio-Breeding rats. To determine the cause of reduced heparan sulfate staining, the in vitro synthesis and degree of sulfation of proteoglycans by glomeruli isolated from control and streptozotocin diabetic rat kidneys were compared. The amount of heparan sulfate synthesis and degree of sulfation were unchanged in diabetic glomeruli, although lower incorporation into the extracellular matrix and greater secretion into the medium were noted.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

10.
11.
Acute effects of triiodothyronine (T3) on postischemic myocardial stunning and intracellular Ca2+ contents were studied in the isolated working hearts of streptozotocin-induced diabetic rats and age-matched controls. After two weeks of diabetes, serum T3 and T4 levels were decreased to 62.5% and 33.9% of control values. Basal preischemic cardiac performance did not differ between diabetic and control rats. In contrast, during reperfusion after 20-min ischemia, diabetic rats exhibited an impaired recovery of heart rate (at 30-min reperfusion 57.5% of baseline vs. control 88.5%), left ventricular (LV) systolic pressure (44.1% vs. 89.5%), and cardiac work (23.1% vs. 66.0%). When 1 and 100 nM T3 was added before ischemia, heart rate was recovered to 77.2% and 81.8% of baseline, LV systolic pressure to 68.3% and 81.9%, and cardiac work to 50.8% and 59.0%, respectively. Diabetic rat hearts showed a higher Ca2+ content in the basal state and a further increase after reperfusion (4.96+/-1.17 vs. control 3.78+/-0.48 micromol/g, p<0.01). In diabetic hearts, H+ release was decreased after reperfusion (5.24+/-2.21 vs. 8.70+/-1.41 mmol/min/g, p<0.05). T3 administration caused a decrease in the postischemic Ca2+ accumulation (lnM T3 4.66+/-0.41 and 100 nM T3 3.58+/-0.36) and recovered the H+ release (lnM T3 16.2+/-3.9 and 100 nM T3 11.6+/-0.9). T3 did not alter myocardial O2 consumption. Results suggest that diabetic rat hearts are vulnerable to postischemic stunning, and T3 protects the myocardial stunning possibly via inhibiting Ca2+ overload.  相似文献   

12.
The mechanism underlying the increased insulin binding found in hepatic plasma membranes from streptozotocin-diabetic rats was evaluated by measuring insulin binding to intact and Triton X-100-soluble extracts of plasma membranes prepared from the livers of control rats and rats administered streptozotocin (85 mg/kg). In addition, to assess whether the cellular content of hepatic insulin receptors is also increased in diabetic animals, we measured insulin-binding activity in intact and soluble extracts of total hepatic cellular membrane preparations (100,000 X g cellular pellets). The data indicate that while insulin binding is increased (52 +/- 3%) in intact hepatic plasma membranes from diabetic rats compared to control rats, there is no comparable increase in insulin binding in intact total cellular membranes or in Triton X-100-soluble extracts of plasma membranes or total cellular membranes. We therefore conclude that the enhanced insulin binding found in the livers of diabetic rats is the result of a local redistribution of plasma membrane insulin receptors from cryptic to exposed sites. Finally, the data suggest the presence of a negative modulator of insulin-binding affinity in intact plasma and total cellular membranes.  相似文献   

13.
The effect of streptozotocin-induced diabetes mellitus on two different models of acute tubular necrosis (ATN), was studied: (i) the nephrotoxic model of HgCl2-induced ATN and (ii) the ischemic model of renal artery clamping for 60 min. Induction of ATN with HgCl2 in normal rats decreased CrCl from 0.67 +/- 0.05 to 0.1 +/- 0.019 ml/min (P less than 0.001) after 24 hr, and it deteriorated further to 0.03 +/- 0.013 ml/min after 48 hr; whereas, in the diabetic rats, HgCl2 decreased CrCl from 0.98 +/- 0.11 only to 0.31 +/- 0.037 ml/min (P less than 0.0001), but CrCl recovered to 0.50 +/- 0.08 ml/min after 48 hr. Bilateral clamping of renal arteries for 60 min in control and diabetic rats extremely decreased CrCl in both groups. Twenty-four hours after clamping, two of nine rats from the diabetic group died, whereas none from the control group died. Forty-eight hours after clamping, all nine rats from the diabetic group died, whereas only two rats from the control group died, and in the four surviving rats CrCl recovered slightly. Our study shows that streptozotocin-induced diabetes could not confer a general protection against ATN. It was protective against a nephrotoxic insult but aggravated the ischemic insult. An attempt to reconcile these discrepant effects is made in the Discussion.  相似文献   

14.
Liver blood flow and hepatic uptake of some indicator substances have been reported to fall with age in both rats and humans. We used an isolated liver system, which was perfused in one pass with hemoglobin free buffer, to investigate the effect of albumin concentration, buffer flow rate, and age upon hepatic clearance of the dye, indocyanine green. We measured the half-life of a bolus of indocyanine green given intravenously to male Sprague-Dawley rats aged 10 and 24 months and then examined its clearance in vitro using their isolated perfused livers. After perfusion, the livers were homogenized and separated into subcellular fractions. The mean liver weight declined significantly (young, 19.7 +/- 2.9 g vs. old, 13.9 +/- 2.6 g; p less than 0.02). In vivo the indocyanine green clearance was reduced in the aged rats (3.2 +/- 1.0 vs. 5.1 +/- 1.7 mL/min; p less than 0.05). In the isolated perfused liver system, extraction ratio showed an inverse curvilinear correlation with albumin concentration and buffer flow rate, but did not differ with age. Hepatic protein content and dye subcellular localization did not differ between the two groups. In conclusion, the fall in indocyanine green clearance in vivo is not paralleled by the ability of the organs to extract the dye in vitro, and likely reflects a decline in hepatic mass and blood flow.  相似文献   

15.
16.
I P Maly  D Sasse 《Histochemistry》1985,83(5):431-436
Microquantitative measurements of ADH-activity were carried out on the livers of male and female rats, guinea-pigs and horses (two geldings and a mare). Lyophilized cryostat sections of liver parenchyma were microdissected the whole way along the sinusoidal length from the terminal afferent vessels to the terminal efferent venule. ADH activity in samples of about 50-150 ng was measured in a microbiochemical assay using the oil-well technique without enzymatic cycling, by direct luminometric determination of NADH. On the basis of the single measurements, mean values of total hepatic ADH activity could be calculated and the specific distribution patterns graphically demonstrated. Total activity of ADH in the liver of the female rat is 1.6 times higher than in the male; the male distribution pattern exhibits a relative maximum in the intermediary zone of the acinus while the activity in the liver of female rats increases towards a perivenous maximum. Mean values for total ADH activity in the livers of male and female guinea-pigs are almost equal and there is, moreover, no clear intra-acinar gradient. Mare and castrated male horses show high hepatic ADH activity which is evenly distributed in the liver acinus.  相似文献   

17.
Male Wistar rats fed with ferrocene had high hepatic iron loading (7.24 +/- 1.97 mg Fe/g tissue) after 6 weeks, principally located in lysosomes, which was comparable to the levels and distribution determined in human haemochromatosis. The two iron-storage proteins, ferritin and haemosiderin were isolated from the livers of the ferrocene-loaded rats and their iron cores were investigated by M?ssbauer spectroscopy and inductively coupled plasma-emission spectrometry. Ferrihydrite was the predominant form of iron present in both ferritin and haemosiderin, while haemosiderin contained higher amounts of phosphorus, magnesium, calcium and barium, then either normal or ferrocene-loaded ferritin. Free-radical-mediated damage in the iron-loaded livers was inferred by the significant depletion of alpha-tocopherol in both the livers and subcellular hepatic lysosomal fraction, which inversely correlated with the increasing iron content (r = -0.61; P less than 0.05) and was associated with increased fragility of the lysosomal membranes.  相似文献   

18.
To evaluate the possible role of somatomedin-C, insulin-like growth factor I, in renal hypertrophy in early diabetes, kidney tissue SmC concentrations were measured in streptozotocin-induced (80 mg/kg ip) diabetic rats. Body weight, liver weight, plasma SmC concentration, and SmC concentration in the liver of diabetic rats were significantly lower than those of controls. Seven days after induction of diabetes, the kidney weight (898 +/- 95 mg) in diabetic rats was significantly greater than that in controls (755 +/- 69 mg), while SmC concentration in the kidney of diabetic rats (1.7 +/- 0.3 U/g kidney) was significantly lower than that of control rats (5.4 +/- 0.6 U/g kidney). These results suggest that renal SmC may not have an important role in renal hypertrophy in early stages of diabetes and that renal production of SmC may be impaired by insulin deficiency in rats.  相似文献   

19.
Livers from normal, adrenalectomized, and diabetic rats were perfused invitro in order to investigate the mode of action of insulin in the control of glycogenesis by glucose. Control of glycogen synthase and phosphorylase by glucose is completely lost in livers from 2 and 6 day alloxan diabetic rats. Three hour treatment of normal rats with anti-insulin serum results in a decrease in the effect of glucose on hepatic glycogenesis. Glucose infusion into isolated perfused livers from fed normal and adrenalectomized rats promotes an increase in glycogen synthase activation and phosphorylase inactivation. These data clearly demonstrate that the presence of insulin rather than glucocorticoids is an absolute requirement in the control of hepatic glycogen synthesis by glucose.  相似文献   

20.
Eucalyptus leaves contain a high proportion of essential oils comprising of a complex mixture of monoterpenes such as 1,8-cineole, alpha-pinene, d-limonene and p-cymene. In this study, hepatic levels of microsomal lauric acid hydroxylase and peroxisomal cyanide-intensive palmitoyl coenzyme A oxidative activities were examined in livers of possums given an artificial diet consisting of the above monoterpenes for 10 days. These values were compared with those of possums fed a control diet containing only fruits and cereals. Peroxisomal cyanide-intensive palmitoyl coenzyme A oxidative activity was significantly higher in livers of treated possums relative to that of control possums (2.96+/-0.93 vs. 0.98+/-0.88 nmol/mg protein per min, P<0.01) (mean+/-S.D., n=4). A small increase in microsomal lauric acid hydroxylase activity was observed in the treated possum in comparison with the control group (4.40+/-0.85 vs. 3.60+/-0.48 nmol/mg protein per min) (mean+/-S.D., n=4). A higher NAD/ NADP ratio was observed in treated possums as compared with control possums (4.73+/-0.65 vs. 3.51+/-0.64 nmol/mg protein per min, P<0.05) (mean+/-S.D., n=4). No other statistically significant differences in pyridine nucleotide contents were found between control and treated possums. Northern blot analysis of mRNA from rat, human, terpene treated and control possum livers, using the corresponding koala cDNA probes, detected a more intense acyl CoA oxidase (AOX) mRNA band in livers of terpene fed possums. Negligible differences in the intensity of CYP4A and PPARalpha mRNA bands were observed between the two groups. These data suggest that Eucalyptus terpenes elevate hepatic AOX expression in possums.  相似文献   

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