Olive leaf down-regulates the oxidative stress and immune dysregulation in streptozotocin-induced diabetic mice

Type 1 diabetes is an endocrinologic disorder characterized by uncontrolled glucose regulation and oxidative stress. Olive leaves have been studied extensively for their antioxidant activity and capacity to improve immune function. We hypothesized that olive leaf powder supplementation will be effective in inhibiting the oxidative stress and immune dysregulation in streptozotocin (STZ)-induced diabetic mice. Mice were assigned to 1 of 5 groups: control (C), STZ-induced diabetes (D), and STZ-induced diabetes supplemented with very low dose (VLOL), low dose (LOL), or high dose of olive leaf powder (HOL). Blood glucose in the VLOL and LOL groups was lower than that in the D group (P < .05). Insulin levels were increased in all experimental groups in comparison with that in the D group, (P < .05). Superoxide dismutase, glutathione peroxidase, and catalase activities were shown to decrease in the D group, whereas these were increased in the VLOL and LOL groups. Nitric oxide levels decreased in the VLOL and LOL groups, as compared with the D group. The messenger RNA expression levels of inducible nitric oxide synthase were significantly decreased in the VLOL and HOL groups, and interferon-γ levels were significantly decreased in the liver of the VLOL, LOL, and HOL groups compared with the levels in the D group. Interleukin-17 levels were significantly decreased in the VLOL and HOL groups. Th1 and Th17 cytokine levels were increased in the D group but decreased in all the experimental groups. Th2 cytokine levels were increased in all olive leaf–supplemented groups compared with those in the D group. These results indicate a reduction in the levels of proinflammatory cytokines, suggesting that olive leaves have the potential to provide therapeutic inhibition of diabetic complications.     

Antidiabetic effect of total flavonoids from Sanguis draxonis in type 2 diabetic rats

Ethnopharmacological relevance

Sanguis draxonis (SD) is a kind of red resin obtained from the wood of Dracaena cochinchinensis (Lour.) S. C. Chen (Dracaena cochinchinensis). It is a Chinese traditional herb that is prescribed for the handling of diabetic disorders, which is also supported by an array of scientific studies published in recent years. Although chemical constituents of this plant material have also been previously evaluated ( 33 and 37), it still remains poorly understood which constituent is the major contributor to its antidiabetic activities. Moreover, very little is known about the molecular mechanisms underlying antidiabetic activities of SD. Flavonoids exist at a high level in SD. The aim of this study is to evaluate the antidiabetic effects of total flavonoids from SD (SDF) in type 2 Diabetes mellitus (T2DM) rats.

Materials and methods

T2DM rats were induced by 4 weeks high-fat diet and a singular injection of streptozotocin (STZ) (35 mg/kg). Then T2DM rats were treated with SDF for 21 days, using normal saline as the negative control. For comparison, a standard antidiabetic drug, metformin (200 mg/kg), was used as a positive control. Three weeks later, relative biochemical indexes were determined and histopathological examinations were performed to assess the antidiabetic activities of SDF.

Results

SDF not only exhibited a significant hypoglycemic activity, but also alleviated dyslipidemia, tissue steatosis, and oxidative stress associated with T2DM. Moreover, considerable pancreatic islet protecting effects could be observed after SDF treatment. Further investigations revealed a potential anti-inflammation activity of SDF by determining serum levels of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and C-reactive protein (CRP).

Conclusions

This study demonstrates both hypoglycemic and hypolipidemic effects of SDF in T2DM rats, suggesting that flavonoids are the major active ingredients accounting for the antidiabetic activity of SD. Alleviating chronic inflammation responses and protecting pancreatic islets are possible mechanisms involved in the antidiabetic activity of SDF.     

Consumption of green tea alters glial fibriliary acidic protein immunoreactivity in the spinal cord astrocytes of STZ-diabetic rats

Abstract

We examined the effect of green tea consumption on glial fibriliary acidic protein (GFAP) expression in spinal cord of streptozotocin (STZ) treated rats. Three groups (n = 10) were used in this study: (i) controls; (ii) STZ-induced diabetic rats given tap water; and (iii) an STZ-induced diabetic group given green tea. Immunohistochemistry showed a significant (P < 0.001) decrease in the number of GFAP immunoreactive astrocytes in spinal cord sections of diabetic rats compared to non-diabetic controls. Diabetic rats treated with green tea showed a significant (P < 0.01) increase in the number GFAP-immunoreactive astrocytes in all the spinal cord gray areas as compared to water-drinking diabetic rats. Immunoblotting confirmed that the diabetic spinal cord tissue expressed 71.0 ± 7.0% less GFAP compared to non-diabetic controls and that the GFAP content in diabetic rats increased up to 86.34 ± 18.74% compared to non-diabetic controls after 12 weeks of green tea consumption. In conclusion, consumption of green tea may represent an achievable adjunct therapy for improving changes seen in diabetic spinal cord.     

Antihyperglycemic,hypolipidemic and antioxidant activities of total saponins extracted from Aralia taibaiensis in experimental type 2 diabetic rats

Ethnopharmacological relevance

As a well-known traditional Chinese medicine the root bark of Aralia taibaiensis has multiple pharmacological activities, including relieving rheumatism, promoting blood circulation to arrest pain, inducing diuresis to reduce edema, and antidiabetic action. It has long been used as a folk medicine for the treatment of traumatic injury, rheumatic arthralgia, nephritis, edema, hepatitis and diabetes mellitus in China.

Aim of study

To evaluate the antihyperglycemic, hypolipidemic and antioxidant activities of total saponins extracted from Aralia taibaiensis (SAT) in experimental type 2 diabetic mellitus (T2DM) rats.

Materials and methods

Acute toxicity was studied in rats to determine the safe oral dose of SAT. Then, SAT was given orally to normal and streptozotocin–nicotinamide induced T2DM rats at 80, 160 and 320 mg/kg doses for a series of 28 days to determine the antihyperglycemic activity. Glibenclamide (600 μg/kg), a standard antidiabetic drug, was used as a positive control drug. At the end of treatment, biochemical parameters and antioxidant levels were measured to evaluate the hypolipidemic and antioxidant activities of SAT.

Results

Oral administration of SAT did not exhibit toxicity and death at a dose not more than 2000 mg/kg. SAT dose-dependently improved the symptoms of polydipsia, polyuria, polyphagia and weight loss in diabetic rats. Compared with diabetic control group, administration of 320 mg/kg SAT resulted in significant (P<0.05) fall in the levels of fasting blood glucose, glycosylated hemoglobin, creatinine, urea, alanine transarninase, aspartate aminotransferase, total cholesterol, triglycerides, low density lipoprotein cholesterol and malondialdehyde, but significant (P<0.05) increase in the levels of serum insulin, superoxide dismutase and reduced glutathione. However, SAT did not have any effect on the normal rats.

Conclusions

SAT had excellent antihyperglycemic, hypolipidemic and antioxidant activities in T2DM rats and might be a promising drug in the therapy of diabetes mellitus and its complications.     

黄芪注射液对糖尿病动物不同器官病理进程的影响

目的探讨黄芪注射液对糖尿病大鼠心、肾、肝、胰腺器官病理改变进程的影响,寻找出黄芪治疗的敏感器官,有针对性地使用该中药制剂进行糖尿病治疗。方法注射使Wistar大鼠建立糖尿病模型,将糖尿病大鼠分为糖尿病组(DM)和黄芪治疗组(RA),另设一正常组动物。黄芪治疗组动物每天给予黄芪注射液腹腔注射3.3 ml/kg,糖尿病组动物每天给予生理盐水腹腔注射3.3 ml/kg,连续注射30天,观察各组大鼠肝脏、肾脏、心脏和胰腺形态的变化。结果 RA治疗7 d、14 d、30 d和60 d时,RA组和DM组大鼠的肝脏、肾脏和心脏的病理改变没有显著的差异,与正常大鼠的组织结构相似。30 d时,DM组大鼠的胰腺的病理改变明显,胰腺内有较多的炎细胞浸润,并且细胞数目减少。RA治疗60天时,RA组和DM组大鼠肝脏、心脏的病理组织改变不明显,与正常大鼠的组织结构相似。与RA组相比较,60 d时,DM组大鼠肾脏和胰腺的病理改变明显,胰岛内细胞松散明显,细胞数明显减少,细胞核大小不一,半数细胞内可见明显的空泡,可见明显的炎细胞浸润。RA治疗组大鼠的肾脏和胰腺的病理组织改变不明显,与正常大鼠的组织结构相似。结论 RA能够延缓或阻止STZ诱导的糖尿病大鼠组织器官的病理进程。     

20两种实验性糖尿病模型小鼠的比较

目的：通过对链脲佐菌素（STZ）模型鼠和db／db模型鼠的糖尿病模型鼠的特点以及对三类降糖药反应性的比较,客观评价两种糖尿病模型鼠在药物研究中的应用价值。方法：离乳、雄性BALB／c小鼠高脂饲料喂养4周后,空腹12hSTZ（45mg／kg）腹腔注射,连续3次,一周后检测糖耐量受损、空腹血糖大于8．0mmol／L的为STZ模型鼠。将STZ模型鼠和8周龄空腹血糖大于8．0mmol／L的db／db模型鼠各随机分组,每组8只分别给予罗格列酮（12mg／kg）、格列苯脲（45mg／kg）、胰岛素（1U／kg）和生理盐水（0．1mL／10g）,每天1次,连续给药4周后检测两模型鼠及其对照组糖脂代谢相关的生化指标及激素水平。结果：STZ模型鼠和db／db模型鼠分别与正常BALB／c鼠、C57BL鼠对比,STZ模型鼠和db／db模型鼠均口服葡萄糖耐量试验（OG—TT）异常,空腹血糖、血TG和TC显著升高。但STZ模型鼠的胰岛素与C肽水平低于正常;而db／db鼠血C肽、胰岛素浓度显著升高;3种降糖药给药4周后STZ模型鼠的空腹血糖均明显降低,OGTT显著改善;罗格列酮对db／db模型鼠也可显著降低空腹血糖并改善糖耐量,但相同剂量的格列苯脲和胰岛素对db／db模型鼠的空腹血糖和糖耐量无影响。给予3倍剂量的胰岛素,db／db模型鼠才表现出空腹血糖的显著降低。结论：STZ模型鼠胰岛功能受损并有一定程度的胰岛素抵抗,对3种降糖药均敏感。db／db模型鼠表现出高度的胰岛素耐受,对内源性和外源性的胰岛素都不敏感,对罗格列酮的敏感性与STZ模型鼠相当。     

实验性糖尿病大鼠肝,肾,心,脑脂肪酸代谢的动态变化

报道对链脲佐菌素（STZ）诱导的实验性糖尿病大鼠几种重要脏器（肝、肾、心、脑）卵磷脂、脑磷脂中脂肪酸构成的变化。不饱和脂肪酸变化的模式（C18：2n-6，C20：3n-6，C22：5n-3，C22：6n-3增加，C20：4n-6降低）基本相同，改变的先后顺序是肝→心、肾→脑。     

Characterization of pancreatic islet cell tumors and renal tumors induced by a combined treatment of streptozotocin and nicotinamide in male SD rats

We herein investigated the histopathological features, including proliferative activity and immunoexpression, of pancreatic islet cell tumors (ICTs) in male SD rats induced by streptozotocin (STZ) and nicotinamide (NA), and discussed their relevance to biological behaviors and prognoses. A total of 70 and 43% of rats developed ICTs 37–45 weeks after the treatment with STZ (50 or 75 mg/kg, i.v.) and NA (350 mg/kg, twice, p.o.), respectively. Among the islet tumors observed in the STZ/NA-treated groups, 75% were adenomas, while 25% were carcinomas. Most STZ/NA-induced carcinomas were characterized by well-differentiated tumor cells with/without local invasion into the surrounding tissues, and weak proliferative activity. No outcome such as distance metastasis and death was noted. All of the ICTs strongly expressed insulin, part of which had hormone productivity; however there were no hypoglycemia-related clinical signs such as convulsion in these rats 36 weeks after the treatment. These results suggested that rat ICTs induced STZ/NA have small impact on biological activity or prognosis. STZ/NA treatment significantly increased of focal proliferative lesions in the kidney, liver and adrenal glands other than pancreatic islets. Of the STZ/NA-induced kidney tumors, more than 60% were renal cell adenomas, and many of them were basophilic type. The incidence of eosinophilic or clear cell type of tumors was less than 10%, respectively. Immunohistochemical analyses revealed that many of the STZ/NA-induced basophilic type of renal tumors were derived from proximal tubules, whereas the clear cell and eosinophilic types were derived from collecting tubules.