• Biomolecules & Therapeutics
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• 제4권4호
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• pp.437-442
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• 1996

Hypoglycemic effect of Tabebuia avellandae was investigated in the streptozotocin(STZ)-induced diabetic rats. Diabetes was induced in male Sprague-Dawley rats by injections of STZ (45 mg/kg, i.v.). Rats weighing 200-250 g were divided into 6 groups: normal, STZ-control, hexane fr., CHCl$_3$fr., BuOH fr. and $H_2O$ fr. group. Normal and STZ-control rats received 3% Tween 80 only. Four groups of diabetic rats were administered orally at doses of 100, 400, 300 and 400 mg/kg/day of hexane, CHC1$_3$, BuOH and $H_2O$ fr. respectively. Fractions were administered orally to the rats for 7 days after STZ injection. All rats were anesthetized with ether, blood samples were taken by cardiac puncture for clinical chemistry and the rats were killed by exsanguination. Liver, kidney, heart and spleen were removed, weighed and analyzed. We measured glucose, protein, cholesterol and triglyceride levels in the plasma and glycogen, cholesterol and triglyceride levels in liver. The extent of blood glucose decrement in rats administered $H_2O$ fraction was greater than that in the STZ-control rats. The serum cholesterol and triglyceride levels were significantly lowered by administration of $H_2O$ fraction compared with those of STZ-control group. Treatment of rats with Tabebuia avellandae fractions caused decreases in STZ-induced elevation of cholesterol and triglyceride. Liver triglyceride level was significantly lowered hexane and BuOH fraction group compared with STZ-control group. These results suggest that $H_2O$ fraction of Tabebuia avellandae has the hypoglycemic action against STZ-induced diabetic rats.

• The Korean Journal of Physiology and Pharmacology
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• 제3권4호
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• pp.375-382
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• 1999

Growing evidence indicates that enhanced generation or actions of nitric oxide (NO) are implicated in the pathogenesis of hypertension in spontaneously hypertensive rats and diabetic nephropathy in streptozotocin (STZ)-induced diabetic rats. We investigated whether inducible nitric oxide synthase (iNOS) expression in STZ-induced diabetic rats is responsible for the alterations of vascular reactivity. Diabetic state was confirmed 28 days after injection of STZ (i.p) in rats by measuring blood glucose. In order to evaluate whether short term (4 weeks) diabetic state is related with altered vascular reactivity caused by iNOS expression, isometric tension experiments were performed. In addition, plasma nitrite/nitrate (NOx) levels and expression of iNOS in the lung and aorta of control and STZ-treated rats were compared by using Griess reagent and Western analysis, respectively. Results indicated that STZ-treated rats increased the maximal contractile response of the aorta to phenylephrine (PE), and high $K^+,$ while the sensitivity remained unaltered. Endothelium-dependent relaxation, but not SNP-mediated relaxation, was reduced in STZ-treated rats. Plasma nitrite/nitrates are significantly increased in STZ-treated rats compared to controls. The malondialdehyde (MDA) contents of liver, serum, and aorta of diabetic rats were also significantly increased. Furthermore, nitrotyrosine, a specific foot print of peroxynitrite, was significantly increased in endothelial cells and smooth muscle layers in STZ-induced diabetic aorta. Taken together, the present findings indicate that enhanced release of NO by iNOS along with increased lipid peroxidation in diabetic conditions may be responsible, at least in part, for the augmented contractility, possibly through the modification of endothelial integrity or ecNOS activity of endothelium in STZ-diabetic rat aorta.

• Food Science and Biotechnology
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• 제18권3호
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• pp.712-716
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• 2009

The purpose of this study was to investigate the effect of dietary supplementation of sea tangle (Laminaria japonica) on the blood glucose and lipid metabolism in streptozotocin (STZ)-induced diabetic rats. Male Sprague-Dawley rats were divided into 3 groups fed control, sea tangle powder (15%, w/w), or sea tangle water extract (4%, w/w) diet. Diabetes was induced by a single injection of STZ (60 mg/kg, i.p.) in citrate buffer. The animals were fed each of the experimental diet for 13 weeks. Serum insulin was increased by dietary supplementation of sea tangle in diabetic rats. Dietary sea tangle reduced blood glucose level of diabetic rats compared to the diabetic rats fed control diet. Dietary sea tangle also reduced the serum total cholesterol, low density lipoprotein (LDL)-cholesterol, and triglyceride in the diabetic rats. While hepatic lipids were reduced, fecal excretion of lipids was increased by supplementation with dietary sea tangle in the diabetic rats. These results indicate that dietary sea tangle decreased blood glucose and improved lipid metabolism in STZ-induced diabetic rats and this effect might be exerted by increases in serum insulin and fecal excretion of lipids.

• 한국식품과학회지
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• 제34권1호
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• pp.103-108
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• 2002

본 연구는 streptozotocin으로 유발된 당뇨 흰쥐에게 흑진미 과피에서 추출한 각 용매 분획물을 14일간 경구투여한 후 혈당과 지질함량을 분석하였으며 다음과 같은 결론을 얻었다. 당뇨 대조군과 비교시 모든 용매 분획물 투여군에서 실험동물의 체중이 증가되었으나 유의적인 차이를 보이지는 않았다. 또한 acetone과 anthocyanin 분획물 투여시 실험 14일째에 혈당, 중성지방 및 유리지방산이 당뇨 대조군과 비교시 유의적으로 감소되었으며, 혈장 HDL-cholesterol 함량은 유의적으로 증가하였다. 이같은 결과는 흑진미 과피에 존재하는 특정 생리활성 물질이 실험 당뇨쥐의 혈당 및 혈중 지질함량 감소에 효과가 있음을 보여주고 있다.

• Nutritional Sciences
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• 제7권1호
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• pp.3-7
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• 2004

This study was performed to investigate the effect of a raw diet (RD) on blood glucose and immune function in non-diabetic (normal) and streptozotocin (STZ)-induced diabetic rats. Male Sprague-Dawley rats were assigned to four groups (normal control, normal RD, diabetic control and diabetic RD). The control groups and the RD groups were fed an AIN-diet and RD for four weeks, respectively. Weight gain was statistically lower in the RD groups than in the controls. Fasting plasma glucose was significantly lower in the diabetic RD group than in the diabetic control group. The $CD4^+$ T-cell population was higher along with the $CD4^+/CD8^+$ ratio of the mesenteric lymph nodes in the normal RD group compared to the other groups. It can be concluded that RD may reduce the plasma fasting glucose concentration in diabetic rats and improve mesenteric lymph node immune function in normal rats.

• 동아시아식생활학회지
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• 제23권6호
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• pp.704-712
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• 2013

This study was designed to examine the effects of bitter melon (BM) on the plasma blood glucose and cholesterol levels in diabetic rats. Diabetes mellitus was induced in male Sprague-Dawley rats through an injection of streptozotocin (STZ) dissolved in a citrate buffer into the tail vein at a dose of 45 mg/kg of body weight. Sprague-Dawley rats were then fed for four weeks, with the experimental groups receiving a modified diet containing 5% or 10% powder derived from BM. The experimental groups were divided into 4 groups, consisting of the normal control group, STZ-control group and diabetic fed with BM 5% & 10% treated groups. The rats' body weight, blood glucose and cholesterol values were measured along with the hematocrit (Hct) values and aminotransferase activities. Body weight losses were observed in the diabetic groups, whereas the control rats gained weight. There were significant differences in kidney weight between the control group and the diabetic groups. The Hct levels of the diabetic BM-treated group were significantly higher than the STZ-control group. Aspartate aminotransferase activity was lower in the non-diabetic group compared to the diabetic experimental groups. Further, the blood glucose was significantly decreased in the 5% & 10% BM of the diabetic group. There were no significant difference in cholesterol levels among the diabetic groups. These results indicate that the supplementation of bitter melon may have a favorable influence on reducing the blood glucose level in STZ-induced diabetic rats.

• Journal of Community Nutrition
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• 제2권2호
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• pp.164-169
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• 2000

The purpose of this study was to examine the effect of taurine supplementation time on the activity of the enzymes metabolizing lipid peroxide in the liver of streptozotocin(STZ)-induced diabetic rats, Sprague-Dawley male rats were fed the purified diet for 7 weeks. They were supplemented with or without 1% taurine in drinking water before or after STZ injection or during all experimental procedure. In comparison to diabetic group without taurine, glucose-6-phosphatase(G6Pase) activity was decreased in diabetic group supplemented with taurine before STZ injection, and it was increased in diabetic group supplemented with taurine after STZ injection, but the difference was not significant. Glutathione S-transferase(GST) activity was significantly increased by the injection of STZ. However, the GST activities of diabetic groups exposed to taurine after STZ injection or during all experimental procedure were significantly decreased. Glutathione peroxidase(GPx) activities was significantly decreased by STZ injection. However, only in diabetic group supplemented with taurine before STZ injection, GPx activities was not decreased by the STZ injection. These results suggest that taurine supplementation may change the activities of GSH-related enzymes metabolizing lipid peroxide in the liver of streptozotocin(STZ)-induced diabetic rats and that may be helpful for the prevention of diabetic complication.

• Journal of Nutrition and Health
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• 제32권7호
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• pp.767-774
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• 1999

This study was carrid out to examine a part of the mechanism for the etiology of diabetic complications. Thirty normal and forty streptozotocin(STZ)-induced diabetic rats were used as the animal models. Animals were sacrificed at the time points of 3 days, 1, 2, 4 and 6 weeks after STZ-injection and time course in body weight and organ weight, the levels of blood glucose, plasma lipid patterns, and atherogenic index were measured during 6 weeks. The STZ-diabetic animals showed 63% survival rate and fsting blood glucose levels of the diabetic animals measured in the range of 230-410mg/dL during the experimental period. The body weigh of diabetic animals decreased significantly throughout the experimental period and the relative weights of organs to body weight were significantly higher than the normal control ones. The enlargement of the kidney in the diabetic animals was especially remarkable. Plasma triglyceride concentration in diabetic rats substancially increased from the first week of onset of diabetes mellitus and maintained higher levels than the control ones throughout the whole experimental period. The plasma total cholesterol level and atherogenic index in the diabetic rats were significantly higher than the normal ones from the third day after STZ injection and showed a gradual increase with the duration of the disease. Throughout the experiment, the diabetic rats consistently showed a slightly lower HDL-cholesterol level compared to the normal animals. From the results of this study, it appears that the significant changes in blood lipid pattern in STZ-diabetic animals start from the first week after STZ injection.

• 한국식품영양학회지
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• 제36권1호
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• pp.50-57
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• 2023

This study was designed to evaluate antihyperglycemic and antihyperlipidemic effects of ethanol extracts of Taraxacum mongolicum(T.m.) on streptozotocin (STZ)-induced diabetic rats. Sprague-Dawley rats were randomly assigned to five groups: normal (NC), STZ-control (DC), and three experimental groups. Diabetes was induced in Sprague-Dawley rats with a single intravenous injection [45 mg/kg body weight (b.w.)] of STZ. An ethanol extract of T.m. was orally given to diabetic rats for 14 days. Three experimental groups were additionally treated with T.m. extract at doses of 1 g/kg b.w./day for T.m.-1, 2 g/kg b.w./day for T.m.-2, and 3 g/kg b.w./day for T.m.-3. Oral administration of T.m.-2 significantly increased their body weights. T.m.-1 and T.m.-2 significantly decreased aspartate aminotransferase (AST) levels than DC. T.m.-1 and T.m.-2 group significantly decreased blood glucose levels. Total cholesterol, triglycerides, and free fatty acids were significantly decreased whereas high-density lipoprotein cholesterol was significantly increased in groups treated with T.m. extract than those in the DC group. These results support the fact that administration of T.m. extract can reduce hyperglycemia and hyperlipidemia risk in diabetic rats.

• The Korean Journal of Physiology and Pharmacology
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• 제9권5호
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• pp.305-314
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• 2005

Diabetes mellitus is associated with vascular complications, including an impairment of vascular function and alterations in the reactivity of blood vessels to vasoactive substances in various vasculature. In the present study, the authors have observed endothelin-B ($ET_B$) receptor agonist-induced relaxation in precontracted mesenteric arterial segments from streptozotocin (STZ)-induced diabetic rats, which was not shown from control rats or in other arterial segments from diabetic rats. Accordingly, the goal of this study was to investigate in what way STZ-induced diabetes altered reactivity of the mesenteric arterial bed and to examine the causal relaxation, if any, between this $ET_B$ receptor-mediated relaxation and endothelial paracrine function, especially nitric oxide (NO) production. The relaxation induced by $ET_B$ agonists was not observed in mesenteric arteries without endothelium. The relaxation to $ET_B$ agonists was completely abolished by pretreatment with BQ788, but not by BQ610. $N_{\omega}-nitro-L-arginine$ methyl ester and soluble guanylate cyclase inhibitors, methylene blue or LY83583 significantly attenuated the relaxant responses to $ET_B$ agonists, respectively. When the expression of eNOS and iNOS was evaluated on agarose gel stained with ethidium bromide, the expression of eNOS mRNA in diabetic rats was significantly decreased, but the expression of iNOS was increased compared with control rats. Furthermore, the iNOS-like immunostaining was densely detected in the endothelium and slightly in the arterial smooth muscle of diabetic rats, but not in control rats. These observations suggest that $ET_B$ receptor may not play a role in maintaining mesenteric vascular tone in normal situation. However, the alterations in $ET_B$ receptor sensitivity were found in diabetic rats and lead to the $ET_B$ agonist-induced vasorelaxation, which is closely related to NO production. In the state of increased vascular resistance of diabetic mesenteric vascular bed, enhanced NO production by activation of iNOS could lead to compensatory vasorelaxation to modulate adequate perfusion pressure to splanchnic area.