GABA agonists differentially modify blood glucose levels of diabetic rats.

This study described the effects of GABA agonists on glucose plasma concentrations of streptozotocin-induced diabetic rats. Low doses of an indirect GABA agonist, AOAA (aminooxyacetic acid); a GABA(A) and a GABA(B) agent, THIP (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridone) and baclofen, respectively; and a benzodiazepine were administered to non-diabetic and to diabetic rats. Plasma glucose concentrations were estimated during fasting and after an oral glucose load. Diazepam (1 mg/kg), baclofen (1 mg/kg) and AOAA (30 mg/kg), significantly decreased glycemia after oral glucose overload of streptozotocin-induced diabetes. None of the GABA-acting agents tested changed fasting or glucose overload glycemia of normal rats. Diazepam was the only drug to increase the fasting blood glucose concentration of diabetic rats. Treatment with AOAA or diazepam was accompanied by increased insulin plasma concentrations in diabetic rats to levels similar to the ones of non-diabetic animals. These results demonstrate that benzodiazepines and other GABA drugs act the endocrine pancreas in vivo, ultimately increasing plasma insulin and decreasing high blood glucose levels of diabetic rats. The acute and prolonged effects of the multitude of drugs acting on the GABA(A)-benzodiazepine-chloride ionophore complex remain to be broadly investigated as a therapeutic tool in diabetes.     

Pharmacologic profile and insulin secretagogue effect of linogliride (McN-3935), a new,orally effective hypoglycemic agent

Linogliride (McN-3935) [N-(1-methyl-2-pyrrolidinylidene)-N'-phenyl-4-morpholinecarboximidamide] was selected for clinical evaluation as a potential orally effective hypoglycemic agent for treatment of noninsulin-dependent diabetes mellitus. Linogliride is structurally unrelated to sulfonylureas and biguanides. It produced a dose-dependent hypoglycemic effect in nondiabetic rats, mice, and dogs. The minimum effective oral doses that lowered fasting blood glucose levels and improved glucose tolerance were 1–5 mg/kg. Comparison of the dose-response curves from fasting rat studies showed linogliride to be approximately two times more potent than the related compound pirogliride and approximately eight times more potent than tolbutamide. Tolerance to its hypoglycemic effect did not develop in rat and dog 3-day repeat dose studies. Linogliride did not alter plasma lactic acid levels in normal and streptozotocin-induced diabetic rats, and it improved glucose tolerance whether the glucose was administered orally or parenterally. In nondiabetic rats and dogs, decreases in fasting blood glucose levels following linogliride administration were associated with elevated (two- to fourfold) plasma insulin concentrations. Linogliride was inactive in depancreatized diabetic dogs. In genetically diabetic (db/db) mice and streptozotocin-induced diabetic rats, linogliride (25–100 mg/kg p.o.) produced variable, nondose-dependent reductions of blood glucose levels, unlike the sulfonylureas, which were consistently ineffective in these diabetic rodent models. In conclusion, although the observed activity in diabetic rodent models is suggestive of a potential nonpancreatic mechanism, the experimental evidence to date indicates that the acute effectiveness of linogliride as a hypoglycemic agent is due primarily to stimulation of insulin release.     

松果菊苷对脑缺血大鼠纹状体细胞外液中氨基酸水平的影响

目的研究松果菊苷(ECH)对急性脑缺血大鼠纹状体细胞外液中4种氨基酸水平和脑梗死率的影响,以探讨ECH对脑神经保护作用的可能机制。方法 SD大鼠随机分为假手术对照组、模型组、阳性药川芎嗪组(CXQ,40 mg.kg-1)、ECH高剂量(ECH 40 mg.kg-1)组、ECH低剂量(ECH 20mg.kg-1)组和ECH配伍冰片(ECH 40 mg.kg-1,冰片400mg.kg-1)组。各组大鼠给予相应的药物或者生理盐水腹腔注射,每天1次,连续7 d。在给药d 3,脑纹状体埋置探针套管,末次给药1 h后,制作大鼠局灶性脑缺血模型(MCAO),模型成功后立刻进行微透析。将透析液注入高效液相-荧光检测器(HPLC-RF),此方法较氨基酸分析仪相比较,具有最低检测限低等特点,检测各组纹状体细胞外液中天门冬氨酸(Asp)、谷氨酸(Glu)、甘氨酸(Gly)、γ-氨基丁酸(GABA)的含量。结果与假手术对照组相比,模型组的Asp、Glu、Gly、GABA水平均明显升高;ECH给药组与模型组相比,ECH高剂量组能明显降低Asp、Glu的水平,而ECH低剂量组与ECH配伍冰片组Asp、Glu降低均不明显;ECH高、低组与配伍冰片组对Gly、GABA的影响均不明显;与模型组相比,ECH高、低剂量组能明显地缩小脑梗死面积。结论 ECH对脑神经的保护作用可能与对抗脑缺血后兴奋性氨基酸升高有关。     

Ethopharmacology of the antidepressant effect of clonazepam in diabetic rats

Diabetes-associated depression may occur due to changes in the quality of life imposed by treatment, or may be a consequence of the biochemical changes accompanying the disease. It was our objective to evaluate the behaviors of diabetic rats through an animal model of depression, and determine if a positive GABA modulator agent, clonazepam, is an effective antidepressant. Wistar male rats were submitted to the forced-swimming test after 26 days of the induction of diabetes with streptozotocin (60 mg/kg). Test and retest days analyzed with an ethological approach. Clonazepam (control, 0.25, 0. 5, and 1.0 mg/kg) was administered IP 24, 5, and 1 h before the retest. Diabetic rats presented longer immobility duration during test and retest of forced swimming. Diabetic rats dived significantly less during the test. Clonazepam 0.25 and 0.5 mg/kg decreased immobility of diabetic rats with no consequences on the behaviors of nondiabetic rats. These results demonstrate that diabetic rats present more intense depressive-like behavior, such as immobility and lack of interest in exploring the environment, when exposed to the forced-swimming test. It is possible that decreased GABA function is involved in depression associated with diabetes, because a benzodiazepine partially counteracts these changes without modifying blood glucose and glycogen parameters.     

Effects of atorvastatin and pravastatin on glucose tolerance in diabetic rats mildly induced by streptozotocin

Effects of atorvastatin and pravastatin on glucose tolerance in mildly induced diabetic rats by streptozotocin at 24 mg/kg, i.v. were studied. Non-diabetic and diabetic rats were given orally 0.5% carboxymethylcellulose (control), 8 mg/kg atorvastatin or 8 mg/kg pravastatin once a day for 6 weeks. An oral glucose tolerance test (OGTT) was carried out 1, 2, 3, and 6 weeks after the administration. The blood glucose and plasma insulin levels measured before OGTT in the diabetic rats were not different from those in the non-diabetic rats. However, the hyperglycemic response to OGTT in the diabetic rats significantly exceeded that in the non-diabetic rats. The plasma insulin increased by OGTT in the diabetic rats appeared to be lower than that in the non-diabetic rats. Statin treatments for 1 week did not modify the OGTT-induced hyperglycemia appreciably, although there were some significant differences. More than 2 weeks after administration, the blood glucose levels at several time points after a glucose intake in the atorvastatin-treated diabetic rats were significantly higher than the respective levels in the control diabetic rats. Neither atorvastatin nor pravastatin modified the OGTT-induced insulin secretion. Statins, especially atorvastatin, may influence the glucose tolerance in mildly induced diabetic rats without alterations of insulin secretion.     

Antidiabetic activity of aqueous root extract of Ichnocarpus frutescens in streptozotocin-nicotinamide induced type-II diabetes in rats

Objective:

To evaluate the antidiabetic activity of aqueous extract of roots of Ichnocarpus frutescens in streptozotocin-nicotinamide induced type-II diabetes in rats.

Materials and Methods:

Streptozotocin-nicotinamide induced type-II diabetic rats (n = 6) were administered aqueous root extract (250 and 500 mg/kg, p.o.) of Ichnocarpus frutescens or vehicle (gum acacia solution) or standard drug glibenclamide (0.25 mg/kg) for 15 days. Blood samples were collected by retro-orbital puncture and were analyzed for serum glucose on days 0, 5, 10, and 15 by using glucose oxidase-peroxidase reactive strips and a glucometer. For oral glucose tolerance test, glucose (2 g/kg, p.o.) was administered to nondiabetic control rats and the rats treated with glibenclamide (10 mg/kg, p.o.) and aqueous root extract of Ichnocarpus frutescens. The serum glucose levels were analyzed at 0, 30, 60, and 120 min after drug administration. The effect of the extract on the body weight of the diabetic rats was also observed.

Results:

The aqueous root extract of Ichnocarpus frutescens (250 and 500 mg/kg, p.o.) induced significant reduction (P < 0.05) of fasting blood glucose levels in streptozotocin-nicotinamide induced type-II diabetic rats on the 10^th and 15^th days. In the oral glucose tolerance test, the extract increased the glucose tolerance. It also brought about an increase in the body weight of diabetic rats.

Conclusion:

It is concluded that Ichnocarpus frutescens has significant antidiabetic activity as it lowers the fasting blood sugar level in diabetic rats and increases the glucose tolerance.     

GABA tea prevents cardiac fibrosis by attenuating TNF-alpha and Fas/FasL-mediated apoptosis in streptozotocin-induced diabetic rats

GABA tea is a tea product that contains a high level of gamma-aminobutyric acid (GABA). This study investigated the effects of GABA tea on the heart in a diabetic rat model. Male Wistar rats were injected with 55 mg/kg streptozotocin (STZ) to induce diabetes for 2 weeks and then orally given dosages of 4.55 and 45.5 mg/kg/day GABA tea extract for 6 weeks. The results revealed that fasting blood glucose levels returned to normal levels in GABA tea-treated diabetic rats, but not in the untreated diabetic rats. Additionally, GABA tea effectively inhibited cardiac fibrosis induced by STZ. Further experiments showed that the STZ-induced protein levels of tumor necrosis factor-alpha (TNF-alpha), Fas, activated caspase-8 and caspase-3 were significantly inhibited by the GABA tea treatment. Therefore, our data suggest that the inhibiting effect of GABA tea on STZ-induced cardiac fibrosis in diabetic rats may be mediated by reducing blood glucose and further attenuating TNF-alpha expression and/or Fas/Fas ligand (FasL)-mediated apoptosis. These findings will provide implications for the potential anti-diabetic properties of GABA tea.     

HMG-CoA reductase inhibitors do not improve glucose intolerance in spontaneously diabetic Goto-Kakizaki rats

We examined whether 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) improve glucose intolerance in spontaneously diabetic Goto-Kakizaki (GK) rats or not. The fasting blood glucose, plasma insulin, and serum cholesterol levels were significantly higher in GK rats than those in age-matched Wistar rats. All rats were given orally once a day 0.5% carboxymethylcellulose, pravastatin 8 mg/kg, simvastatin 8 mg/kg, or atorvastatin 8 mg/kg. An oral glucose tolerance test (OGTT) was performed before and 3, 6 and 12 weeks after statin treatments. The hyperglycemic response to OGTT in GK rats significantly exceeded that in Wistar rats. The plasma insulin level in GK rats increased with age until 14-week-old (treated for 6 weeks), and then decreased. Glucose intake significantly increased the plasma insulin in almost all rats. The increment of plasma insulin due to OGTT in GK rats appeared to be less than that in Wistar rats, because the basal level was already high in GK rats. Pravastatin, simvastatin, and atorvastatin did not modify changes in blood glucose and plasma insulin induced by glucose intake. In conclusion, long-term treatments of GK rats with statins did not improve glucose intolerance observed during OGTT.     

Qi盐对正常及糖尿病模型大鼠血糖的影响

目的观察Qi盐对正常小鼠和糖尿病模型大鼠的降血糖作用.方法尾静脉注射四氧嘧啶制作大鼠糖尿病模型,连续灌胃给Qi盐14 d,葡萄糖氧化酶法测血糖.结果Qi盐1.6,0.8,0.4 g·kg-1对正常小鼠血糖及糖耐量均无明显影响,但0.8,0.4 g·kg-1可降低四氧嘧啶模型大鼠血糖,改善糖耐量.结论Qi盐对糖尿病模型大鼠有降血糖作用.     

Hypoglycemic effect of aqueous extract of Ammi visnaga in normal and streptozotocin-induced diabetic rats

The effect of the aqueous extract of Ammi visnaga (Apiaceae) on blood glucose levels was investigated in fasting normal and streptozotocin-induced diabetic rats after single and repeated oral administration. The aqueous extract of Ammi visnaga (AV) at a dose of 20 mg/kg significantly reduced blood glucose in normal rats six hours after a single oral administration (P < 0.005) and nine days after repeated oral administration (P < 0.05). This hypoglycemic effect is more pronounced in streptozotocin (STZ) diabetic rats (P < 0.001). Acute toxicity (LD50) and general behavioural effects of an aqueous extract of AV fruits was studied in mice. The LD50 of intraperitoneal (i.p.) and oral administration was 3.6 and 10.1 g/kg, respectively. These findings suggest that the aqueous extract of AV possess significant hypoglycemic effect in both normal and STZ diabetic rats and support, therefore, its claimed clinical use by the Moroccan population.     

Nicardipine does not cause deterioration of glucose homoeostasis in man: A placebo controlled study in elderly hypertensives with and without diabetes mellitus

Summary The effect of the calcium antagonist nicardipine on insulin secretion and glucose homoeostasis was investigated in elderly hypertensives with and without diabetes mellitus; 15 patients with essential hypertension for at least 10 years and normal glucose tolerance according to standard criteria (Group I) and 15 elderly hypertensive patients affected by Type 2 diabetes mellitus and on treatment with diet or oral drugs (Group 2).In the basal state, all patients were submitted to an oral glucose tolerance test (OGTT, 75 g) and an iv arginine test (30 g), on two different days and in random order. The same tests were repeated after one month of treatment with nicardipine 60 mg/day, in three spaced doses, the last being given 1 h before the post-treatment test. Nicardipine did not change overall glucose homoestasis, as assessed by haemoglobin Alc and fructosamine, nor did it significantly affect the plasma insulin response either to glucose or arginine in Groups 1 and 2. Only the glucagon response to arginine was significantly reduced in diabetic hypertensives. Small, non-significant variations in the metabolic and hormonal parameters were seen in additional two groups of patients (Groups 3 and 4), matched with Groups 1 and 2 for age, sex and diseases, who took capsules containing placebo.Thus, nicardipine did not produce any significant over-all alteration in glucose homoestasis when given to elderly diabetic or nondiabetic hypertensive subjects.     

白藜芦醇衍生物改善2型糖尿病大鼠血糖及胰岛素抵抗作用的研究

目的探讨白藜芦醇衍生物BTM-0512对2型糖尿病大鼠血糖及胰岛素抵抗作用的影响。方法单次腹腔注射链脲佐菌素（STZ,35mg·kg^-1）结合高脂饮食建立2型糖尿病大鼠模型。糖尿病大鼠分为3组（模型组、BTM-0512低剂量组、BTM-0512高剂量组）,药物灌胃3周。检测空腹血糖（FBG）、糖基化血红蛋白（HblAC）、空腹血清胰岛素（Fins）和口服糖耐量（OGTT）;计算HOME．IR、胰岛素敏感指数（1AD、胰岛素分泌指数（IS）,以此评价胰岛素抵抗（IR）。结果BTM-0512能剂量依赖性降低2型糖尿病大鼠FBG和HblAC,改善HOME．IR和IAI,但对OGTT与IS没有影响。结论BTM0512可以降低2型糖尿病大鼠血糖并改善IR。     

Antidiabetic effect of Phlomis anisodonta: effects on hepatic cells lipid peroxidation and antioxidant enzymes in experimental diabetes.

The present study investigated the effects of aerial parts of Phlomis anisodonta methanolic extract (PAE) on streptozotocin (STZ)-induced diabetic rats by measuring fasting blood glucose, serum insulin, change in body weight, ferric reducing antioxidant power (FRAP), lipid peroxidation (LPO), and liver antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx). Male Wistar rats were randomly divided into six groups of six animals. Treatment of diabetic rats with oral administration of PAE at doses of 100, 200 and 400 mg kg(-1) for 10 days resulted in a significant reduction in fasting blood glucose, and an increase in serum insulin levels in comparison with diabetic control group. PAE also protected rats from STZ-induced loss in body weight. Hepatic FRAP increased and LPO in diabetic rats decreased after treatment by PAE at doses of 200 and 400 mg kg(-1). PAE-treated diabetic rats at three doses indicated a significant increase in hepatic SOD, CAT, and GPx activities. These results suggest that PAE is beneficial in the control of diabetes by reduction of blood glucose and increasing insulin levels and combating oxidative stress by activation of hepatic antioxidant enzymes.     

Effects of the flavonoid fraction from Ginkgo biloba extract on the postprandial blood glucose elevation in rats

The present study investigated the effects of Ginkgo biloba extract and its flavonoid fractions on alpha-amylase and alpha-glucosidase activity in vitro. Ginkgo biloba extracts and their flavonoid fraction significantly inhibited alpha-amylase and alpha-glucosidase activity in vitro. Furthermore, Ginkgo biloba extracts and their flavonoid fraction reduced the elevation of rat plasma glucose level after oral administration of various saccharinity agents. In addition, we examined the effects of the flavonoid fraction isolated from Ginkgo biloba extracts on the plasma glucose level in streptozotocin-induced diabetic rats. When flavonoid fractions were orally administered to the rats three times daily for 9 days, plasma glucose concentrations were decreased compared with those in the water treatment group. Furthermore, flavonoid fractions reduced the elevation of rat plasma glucose levels after oral administration of sucrose and glucose in streptozotocin-induced diabetic rats.     

Effect of dietary protein on striatal dopamine formation following L-dopa administration: an in vivo study.

We varied the diet of rats and monitored extracellular levels of dopamine in the striatum. Following L-dopa administration, the increase in striatal dopamine levels was attenuated by 78% in rats that had consumed a high protein diet as opposed to a low protein diet. Similarly, the increase in striatal dopamine levels was attenuated by 61% in rats that had just eaten a protein-containing meal as compared to fasting animals. These findings demonstrate that dietary protein strongly affects brain dopamine formation from exogenous L-dopa.     

恒顺降糖胶囊对2型糖尿病大鼠胰岛素抵抗的影响

目的观察恒顺降糖胶囊(Hengshun Jiangtang capsules,HS)对2型糖尿病大鼠胰岛素抵抗的影响。方法对连续10d灌胃给予脂肪乳的大鼠腹腔注射四氧嘧啶,72h后血糖值≥16.7mmol·L-1者为2型糖尿病大鼠模型;给药28d,观察HS对空腹血糖(FBG)、糖耐量(OGTT)、空腹血清胰岛素(FINS)、胰岛素耐量(ITT)和胰岛素抵抗指数(Homa-IR)的影响。结果HS能改善2型糖尿病大鼠的OGTT和ITT,降低FGB,FINS和Homa-IR。结论HS明显降低2型糖尿病大鼠的胰岛素血症,改善其对胰岛素的抵抗。     

十二指肠空肠旁路术对非肥胖2型糖尿病大鼠糖代谢的影响

目的探讨十二指肠空肠旁路术(DJB)对非肥胖2型糖尿病GK大鼠糖代谢的影响。方法雄性GK和Wistar大鼠各18只,随机分为GK大鼠手术组(A组)和假手术组(B组)、Wistar大鼠手术组(C组)和假手术组(D组),每组9只。检测术前及术后第1、2、3、4、8周各组体重、平均摄食量、空腹血糖;术前及术后第8周行口服葡萄糖耐量试验(OGTT),并计算葡萄糖曲线下面积(AUC)。结果术后第8周,A组空腹血糖由术前的(8.7±1.3)mmol/L下降到(5.9±0.6)mmol/L(P<0.05)。B组手术前后空腹血糖无明显变化。A组AUC较术前下降约20.6%(P<0.05)。结论 DJB能显著改善非肥胖2型糖尿病大鼠的糖代谢,不依赖于体重和摄食减少,并对正常大鼠血糖值无影响。     

Comparison of the effects of various vanadium salts on glucose homeostasis in streptozotocin-diabetic rats

Oral administration of vanadium salts to severely diabetic rats leads to a spectacular decrease of plasma glucose levels in spite of the insulin deficiency of the animals. The insulin-like properties of vanadium have been attributed to the cationic form, vanadyl, into which the anionic form, vanadate, is reduced within cells. This has led to the suggestion that vanadyl is the form of choice for the treatment. In this study, rats made insulin-deficient and diabetic with streptozotocin were treated with three salts of vanadium: sodium orthovanadate, sodium metavanadate and vanadylsulfate. The salts were added to the drinking water, in concentrations that led to ingestion of the same amount of vanadium element by the three groups of rats ( 8 mg/kg per day). The initial, transient, loss of weight that affected the treated rats was slightly smaller in the vanadyl-treated group than in the vanadate-treated groups. However, during steady-state treatment, the three groups exhibited a similar food intake (lower than in controls) and growth rate (higher than in controls). The decreases in plasma glucose levels, in urinary volume and in glucosuria, and the improvement of the tolerance to an oral glucose load were similar regardless of the type of vanadium salt. Withdrawal of the treatment after 14 weeks was followed by a rapid increase in plasma glucose levels which, however, remained clearly lower than in controls for at least 4 weeks, whereas plasma insulin levels increased only transiently. A smaller glucosuria and a slightly better tolerance to oral glucose than in controls were still observed in the previously treated rats. In conclusion, when similar amounts of vanadium are ingested in the form of vanadyl, orthovanadate or metavanadate by insulin-deficient diabetic rats, similar beneficial and adverse effects are observed. Interestingly, a partial improvement of glucose homeostasis persists after withdrawal of the treatment.     

Sensory nerve desensitization by resiniferatoxin improves glucose tolerance and increases insulin secretion in Zucker Diabetic Fatty rats and is associated with reduced plasma activity of dipeptidyl peptidase IV

Sensory nerve desensitization by capsaicin has been shown to improve the diabetic condition in Zucker Diabetic Fatty rats. However, administration of capsaicin to adult rats is associated with an increased mortality. Therefore, in this experiment, we examined the influence of resiniferatoxin, a tolerable analogue of capsaicin suitable for in vivo use, on the diabetic condition of Zucker Diabetic Fatty rats. A single subcutaneous injection of resiniferatoxin (0.01 mg/kg) to these rats was tolerable, with no mortality. When administered to early diabetic rats at 15 weeks of age, the further deterioration of glucose homeostasis was prevented by resiniferatoxin. Further, when administered to overtly diabetic rats at 19 weeks of age, resiniferatoxin markedly improved glucose tolerance at two weeks after administration and this was accompanied by an increased insulin response to oral glucose as well as a reduction in the plasma levels of dipeptidyl peptidase IV. Therefore, resiniferatoxin is a safe alternative to capsaicin for further investigations of the role of the sensory nerves in experimental diabetes.     

缬沙坦对糖尿病大鼠糖代谢及胰腺病理结构的影响

目的探讨血管紧张素受体拮抗剂缬沙坦对链脲佐菌素诱导的糖尿病大鼠糖代谢、氧化应激及胰腺病理结构的影响。方法大鼠随机分为:正常对照组、糖尿病组、缬沙坦组。10周后观察胰腺组织病理形态学变化,检测胰腺组织的丙二醛(MDA)含量、超氧化物歧化酶(SOD)的活力,检测空腹血糖、胰岛素及糖化血红蛋白含量。结果与糖尿病组比较,缬沙坦组糖尿病大鼠胰腺组织病理结构损害减轻,MDA含量下降,SOD活力升高,血糖水平下降,胰岛素水平升高,差异有统计学意义。结论缬沙坦改善糖尿病大鼠糖代谢,减轻胰腺组织的病理结构损害,其机制部分与其对胰腺组织氧化应激增加有抑制作用有关。