General administration of cyclohexenonic long-chain fatty alcohol ameliorates hyperreactivity of STZ-induced diabetic rat aorta

Diabetic neuropathy, a major complication of diabetes mellitus, is associated with the development of vascular dysfunction and autonomic neuropathy. We studied the effects of cyclohexenonic long-chain fatty alcohol (FA) on streptozotocin-diabetic hyperreactivity in the rat aorta smooth muscle. The rats were divided randomly into four groups and were maintained for 4 weeks: age-matched control rats, diabetic rats without treatment with FA, and diabetic rats treated with FA (2 and 8 mg/kg, i.p. everyday). The serum glucose and insulin levels were determined, and the contractile responses of the aorta induced by a thromboxane A2 agonist, U46619 and KCl were investigated. Treatment with FA did not alter rats' diabetic status, i.e., body weight, thickness of the aorta, serum glucose levels, and serum insulin levels, but significantly improved the diabetic-induced hyperreactivity of the rat aorta in a dose-dependent manner. Removal of endothelium did not change contractile force between groups. In histological examinations, thinning of smooth muscle bundle in the wall of aorta was observed in the diabetic rat, which was not significantly improved by treatment with FA. Our data indicate that FA can prevent hyperreactivity in the diabetic aorta.     

CLOCK/BMAL1 regulates human nocturnin transcription through binding to the E-box of nocturnin promoter

We attempted to clarify the effects of cyclohexenonic long-chain fatty alcohol (N-hexacosanol) on nitric oxide synthase (NOS) in streptozotocin-induced diabetic nephropathy. After induction of experimental diabetes with streptozotocin, rats were maintained for 8 weeks with or without treatment by N-hexacosanol (8 mg/kg i.p. every day). Urinary albumin excretion, blood chemistry, immunoblot analysis, and real-time polymerase chain reactions (real-time PCR) of endothelial nitric oxide synthase (eNOS), inducible NOS (iNOS), and neuronal NOS (nNOS) were investigated. Although N-hexacosanol had no effects on serum glucose or insulin level, it normalized serum creatinine and urinary albumin excretion. N-hexacosanol was found to improve the diabetes-induced alterations in the eNOS, iNOS, and nNOS protein and their mRNA levels. Histologically, N-hexacosanol inhibited the progression to glomerular sclerosis. Our data suggest that N-hexacosanol improves diabetes-induced NOS alterations in the kidney, resulting in the amelioration of diabetic nephropathy.     

Effects of long-chain fatty alcohol on peripheral nerve conduction and bladder function in diabetic rats

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.     

Contractile activity increases glucose uptake by muscle in severely diabetic rats

Muscle contractile activity is associated with an acceleration of glucose transport into muscle. It has been reported that the acceleration of glucose uptake by contractile activity in perfused rat muscles requires the presence of insulin in the perfusate. This claim was investigated using the perfused rat hindlimb preparation in the present study. Rats were made diabetic by injection of 125 mg/kg of streptozotocin and either studied 72 h later or maintained on insulin for 2 wk and then studied 3 days after cessation of insulin therapy. Only rats with plasma insulin levels too low to measure were used. The hindlimbs were washed out with 630 ml of medium over 75 min using a single flow-through washout before muscle stimulation. Despite the absence of insulin in the perfusion medium, stimulation of muscle contraction resulted in large increases in glucose uptake in both the diabetic and control rats. These findings do not support the claim that the stimulatory effect of muscle contraction on glucose uptake by perfused rat muscles requires the presence of insulin.     

Effect of chronic treatment with Bis(maltolato)oxovanadium (IV) in rat model of non-insulin-dependent-diabetes

Effect of chronic treatment with Bis(maltolato)oxovanadium (IV) (BMOV) was studied in streptozotocin (STZ)-induced neonatal non-insulin-dependent-diabetic (NIDDM) rats. Intraperitoneal injection of STZ (90 mg kg(-1)) in Wistar rat pups (day 2 old) produced mild hyperglycemia, impaired glucose tolerance and insulin resistance at the age of 3 months. Treatment with BMOV (0.23 mM kg(-1)) in drinking water for 6 weeks produced a significant decrease in elevated serum glucose levels without any significant change in serum insulin levels in diabetic rats. BMOV treatment significantly decreased integrated area under the glucose curve without any significant change in integrated area under the insulin curve indicating improved glucose tolerance. Treatment also significantly increased K(ITT) value of diabetic rats indicating increased insulin sensitivity. BMOV treatment significantly reduced hypercholesterolemia in diabetic rats. Treatment also significantly decreased serum triglyceride levels in both diabetic and non-diabetic rats. The data suggest that chronic BMOV treatment improves glucose and lipid homeostasis. These effects appear to be due to the insulin sensitizing action of vanadium.     

Gender differences in myosin heavy chain-beta and phosphorylated phospholamban in diabetic rat hearts

The objective of this study was to determine whether a gender difference exists in myosin heavy chain (MHC) isoform or sarcoplasmic reticulum protein levels in diabetic rat hearts. As is the case with normal rodent hearts, all four chambers of the control rat hearts expressed almost 100% MHC-alpha. In 6-wk diabetic rats, MHC-beta expression in ventricles of males was significantly greater (78 +/- 7%) than in females (50 +/- 5%). The cardiac sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA2a) protein level was decreased and the phospholamban (PLB) protein level was increased in the left ventricle of diabetic rats, but there was no difference between male and female diabetic rats. The phosphorylated PLB level was decreased more in male than in female diabetic rats. Insulin treatment completely normalized blood glucose level, cardiac SERCA2a and PLB protein levels, and the decrease in MHC-beta levels in both male and female diabetic rats. Insulin treatment completely normalized serum insulin and almost completely normalized phosphorylation of PLB at serine 16 in male diabetic rats. Although insulin treatment completely normalized serum insulin levels in male diabetic rats, in females it only partially normalized serum insulin levels. Also, insulin treatment almost completely normalized phosphorylation of PLB at threonine 17 in female diabetic rats; however, the increase was significantly greater than that identified for insulin-treated male diabetic rats. We conclude that higher levels of MHC-beta and dephosphorylated PLB may contribute to more contractile dysfunction in male than in female diabetic rat hearts, and that phosphorylation of PLB at threonine 17 is more responsive to insulin in female diabetic rat hearts.     

Effect of coenzyme Q10 on catalase activity and other antioxidant parameters in streptozotocin-induced diabetic rats

Although coenzyme Q10 (CoQ10) is a component of the oxidative phosphorylation process in mitochondria that converts the energy in carbohydrates and fatty acids into ATP to drive cellular machinery and synthesis, its effect in type I diabetes is not clear. We have studied the effect of 4 wk of treatment with CoQ10 (10 mg/kg, ip, daily) in streptozotocin (STZ)-induced (40 mg/kg, iv in adult rats) type I diabetes rat models. Treatment with CoQ10 produced a significant decrease in elevated levels of glucose, cholesterol, triglycerides, very-low-density lipoprotein, lowdensity lipoprotein, and atherogenic index and increased high-density lipoprotein cholesterol levels in diabetic rats. CoQ10 treatment significantly decreased the area under the curve over 120 min for glucose in diabetic rats, without affecting serum insulin levels and the area under the curve over 120 min for insulin in diabetic rats. CoQ10 treatment also reduced lipid peroxidation and increased antioxidant parameters like superoxide dismutase, catalase, and glutathione in the liver homogenates of diabetic rats. CoQ10 also lowered the elevated blood pressure in diabetic rats. In conclusion, CoQ10 treatment significantly improved deranged carbohydrate and lipid metabolism of experimental chemically induced diabetes in rats. The mechanism of its beneficial effect appears to be its antioxidant property.     

链尿佐菌素加高糖高脂饮食复制大鼠2型糖尿病模型

目的链尿佐菌素加高糖高脂饮食诱导大鼠2型糖尿病模型的建立。方法SD雄性大鼠高糖高脂饲料喂养3周后,采血检测空腹血糖及血清胰岛素,按25mg/g体重剂量一次性腹腔内注射链尿佐菌素,3d后,行糖耐量实验,对糖耐量异常大鼠继续喂以高糖高脂饲料,在第2、第4周再两次采血检测糖尿病鼠空腹血糖及血清胰岛素。结果与对照组比较,高糖高脂喂养大鼠血清胰岛素明显上升（P〈0.01）,但血糖无变化（P〉0.05）,糖尿病鼠血糖及血清胰岛素均显著的高于对照组（P〈0.01）。结论高糖高脂喂养能致大鼠明显的高胰岛素血症,辅以小剂量一次性注射链尿佐菌素而造成的糖耐量异常,可成功复制出2型糖尿病大鼠模型。     

金耳菌丝体多糖对实验性2型糖尿病大鼠的降血糖作用研究

本文研究了金耳菌丝体多糖(TMP)对实验性2型糖尿病大鼠血糖、血脂、胰岛素敏感性和抗氧化能力的影响。采用烟酰胺,链脲佐菌素和高脂饲料诱导2型糖尿病大鼠模型,以50和100mg/(kg.d)剂量的TMP连续灌胃48d,监测血糖,测定血清胰岛素、体重、脂代谢及抗氧化系统部分相关指标,并进行口服糖耐量实验。结果显示,TMP可明显降低2型糖尿病大鼠的血清葡萄糖、总胆固醇、甘油三酯和丙二醛水平,并极显著提高受试模型鼠的胰岛素敏感指数,血清超氧化物歧化酶活性和肝脏过氧化氢酶活性。此外,TMP能显著降低糖耐量实验中糖负荷后120min时糖尿病大鼠的血糖含量。上述结果表明TMP可有效降低实验性2型糖尿病大鼠的血糖水平,纠正脂代谢紊乱,改善胰岛素抵抗,增强抗氧化能力。     

高糖高脂饮食联合注射STZ制备2型糖尿病大鼠缺血性心脏病模型

目的：制备2型糖尿病缺血性心脏病大鼠模型。方法：雄性Wistar大鼠20只,随机分为正常组和糖尿病模型组（n=10）。糖尿病模型组给予高糖高脂饮食饲喂4周后,一次性腹腔注射链脲佐菌素40mg/kg,制备糖尿病大鼠模型。每周常规监测血糖、血清胰岛素、体重的变化。糖尿病模型组与正常组大鼠,使用BL-41O生物机能试验系统,每周测定肢体2导联心电图。最后检测血清中的肌酸激酶和乳酸脱氢酶的含量。结果：高糖高脂饲料饲喂4周后胰岛素升高至4．05ng/ml,糖尿病模型组注射SIZ后空腹血糖迅速升高,达到17．9mmol/L。在第14周,糖尿病模型组出现S-T段抬高,并且与正常组比较,血清肌酸激酶（creatine kinase,CK）和乳酸脱氢酶（lactate dehydrogenase,LDH）均升高。结论：本实验成功建立的2型糖尿病缺血性心脏病大鼠模型,为研究糖尿病缺血性心脏病提供理想的动物模型。     

Preventive effects of cyclohexenonic long-chain fatty alcohol on diabetic cystopathy in the rat

In this study, we investigated the preventive effect of n-hexacosanol on diabetes-induced bladder dysfunction in the rat. Diabetes was induced in 8-week-old male Sprague-Dawley rats by administering an injection of streptozotocin (50 mg/kg, i.p.). The rats were randomly divided into 4 groups (age-matched control rats, diabetic rats without treatment with n-hexacosanol, and diabetic rats treated with n-hexacosanol (2 and 8 mg/kg, i.p. every day)) and maintained for 4 weeks. The serum glucose and serum insulin levels were determined, and the functions of bladder were estimated by voiding behavior, cystometric, and functional studies to carbachol and KCl. Furthermore, we examined possible diabetic induced histological changes in these rats. Treatment with n-hexacosanol did not alter diabetic status including body mass, bladder mass, and serum glucose and serum insulin levels, but significantly improved the maximum contraction pressure of the detrusor and residual urine volume in cystometric studies and Emax values to carbachol in functional studies in a dose-dependent manner. Diabetes induced bladder smooth muscle hypertrophy, which tended to be ameliorated by treatment with n-hexacosanol in a dose-dependent manner. Treatment with n-hexacosanol did not alter the diabetic status, but significantly improved diabetic cystopathy in a dose-dependent manner.     

Insulin-sparing effect of hydroxychloroquine in diabetic rats is concentration dependent.

To study the effect of hydroxychloroquine (HCQ) on glucose and insulin homeostasis, healthy rats were dosed with 160 mg x kg (-1) x day(-1) of HCQ orally, and streptozocin-induced diabetic rats received 80, 120, and 160 mg x kg(-1) x day(-1) of HCQ, while controls received normal saline. Ten days after treatment with HCQ, healthy animals were challenged intravenously with insulin or glucose, while diabetic rats were given only an i.v. injection of insulin. In healthy rats, the areas within and under the glucose concentration - time curve following insulin and glucose challenge were estimated. In diabetic animals, the areas under the curve for both the percent change in serum glucose from baseline (AUG) and the percent change in serum insulin from baseline (AUI) were used as pharmacodynamic end points. In healthy rats, HCQ did not influence fasting serum glucose concentrations or glycemic profiles following i.v. administration of glucose or insulin. In diabetic rats, AUG and AUI were increased dependent on blood HCQ concentrations. The normal homeostatic mechanisms responsible for insulin-glucose regulation may compensate for possible HCQ-induced reduction of insulin metabolism in healthy rats. The HCQ dose- or concentration-effect relationships for glucose and insulin were linear over the range of HCQ concentrations tested. It is concluded that HCQ significantly elevated insulin blood concentration resulting in reduced glucose levels in a concentration-dependent fashion in diabetic rats. HCQ may have therapeutic potential in the treatment of type I and type II diabetes.     

The relationship between nitric oxide and leptin in the lung of rat with streptozotocin-induced diabetes

Lung structural changes and immunoreactivity of endothelial (eNOS)- and inducible nitric oxide synthase (iNOS) were investigated by light microscopy in lungs of treated and untreated diabetic rats. Diabetes was induced by a single intraperitoneal (i.p.) injection of 65 mg kg(-1) streptozotocin (STZ) in Wistar albino male rats. Diabetic rats received daily i.p. doses of dexamethasone (2 mg kg(-1)), leptin (0.5 microg kg(-1)) and intramuscular insulin (20 U kg(-1)) or a combination of these drugs for 1 week starting 4 weeks after the STZ injections. After treatment, the blood levels of glucose, leptin, insulin and nitrate/nitrite (NO(3) (-)/NO(2) (-)) were measured. Dilatation of alveoli and alveolar ducts, partial alveolar wall thickening and increased eNOS- and iNOS characterized the diabetic rat lungs. High blood glucose and nitrate/nitrite levels as well as low insulin and leptin levels were also present. Treatment with insulin, dexamethasone and a combination of these drugs resulted in improvement of the structural and immunohistochemical abnormalities. The most effective treatment was insulin therapy. Leptin administration resulted in increased relative amounts of extracellular material, which led to noticeable respiratory efficiency in the diabetic rat lungs. All treatments except leptin lowered blood glucose levels. The combination of insulin and dexamethasone increased blood leptin and insulin, while the remaining diabetic rats had blood with low leptin and insulin concentrations. These results suggest that therapy with insulin plus dexamethasone but not therapy with leptin is beneficial for diabetics.     

The diabetic Zucker fatty rat

A noninsulin-dependent diabetes appeared in fatty rats in our Zucker rat colony. A breeding program yielded a genetic pattern of diabetes consistent with a dominant gene not closely linked to the fatty gene. Fatty males were more frequently affected than fatty females. Since no markers could be identified for heterozygous carriers and since affected fatty rats were 6 months old when diabetes appeared, the diabetic trait could not be sustained in our small colony. Glucose tolerance tests showed that the diabetic fatty rats had little increase in plasma insulin concentration after a glucose load was administered. Plasma insulin concentrations were unchanged relative to control fatty rats. Percentage body fat and plasma triglyceride values were decreased in fatty diabetic rats relative to control fatty rats, however, consistent with insulin resistance in fat and liver. The content of pancreatic insulin was markedly decreased in the diabetic fatty rat relative to either the ad libitum or diet-restricted fatty rats. The occurrence of a genetically based diabetes in a normally outbred colony underscores the importance of genetic traits that interact with obesity in determining diabetes in rodent models.     

Effects of streptozotocin-induced diabetes and insulin on calcium responsiveness of the rat vas deferens

In the present study, effects of streptozotocin-induced diabetes and insulin treatment on the reactivity of rat vas deferens to KCl and calmidazolium, a calmodulin antagonist, were evaluated and calmodulin levels in vas deferens tissue from diabetic and insulin-treated rats were determined. Diabetes was induced in rats by a single injection of streptozotocin. Five weeks after the induction of diabetes, one group of diabetic rats was injected with insulin for 3 weeks. After 8 weeks, vas deferens tissues on one side of diabetic and insulin-treated diabetic rats and their controls were mounted in organ bath to measure isometric tension, while the tissues on the other side of rats were homogenized to determine calmodulin levels by radioimmunoassay. Concentration-response curves to KCl were obtained in vas deferens tissues in the absence and presence of calmidazolium. The effects of KCl and calmidazolium on vas deferens isolated from 8-weeks diabetic rats were decreased. Calmodulin levels were also found to be decreased in vas deferens from diabetic rats. Decreased calmodulin levels in diabetic rat vas deferens were not corrected by insulin treatment. Only a partial correction following insulin treatment was observed in contractile effect of KCl on diabetic rat vas deferens, whereas insulin treatment increases the affinity of calmodulin in this muscle. Experimental diabetes causes an impairment in calcium/calmodulin-dependent contractile process of vas deferens, which is correctable partially following insulin therapy. The changes in the function of rat vas deferens due to streptozotocin diabetes seem to be related to impaired sexual functions in human diabetes.     

Adenosine 3',5'cyclic monophosphate in adipose tissue of diabetic rats.

Normal male rats were made chronically diabetic by injection of alloxan or acutely diabetic by injection of anti-insulin serum. The concentration of cyclic AMP in epididymal adipose tissue was increased approximately 2 1/2-fold 24 h after alloxan administration and up to 7-fold 72 h post-alloxan. Treatment of alloxan-diabetic rats with insulin for 4 h completely suppressed lipolysis but only partially suppressed cyclic AMP levels; 6 h following insulin treatment cyclic AMP levels were normal. When segments of the epididymal fat bodies were incubated in vitro the high cyclic AMP levels were not maintained but instead decreased spontaneously. Addition of insulin to the incubation media decreased lipolysis in tissues of diabetic rats to levels measured in tissues of normal rats and accelerated the decline in cyclic AMP levels but did not return cyclic AMP levels to normal. Rats rendered acutely insulin deficient by injection of anti-insulin serum showed increased plasma glucose and free fatty acid levels and increased adipose tissue free fatty acid, and cyclic AMP levels 30 min following injection of the antiserum. Plasma glucagon levels increased but not until 2 h following anti-insulin serum, thereby excluding the possibility that an increment in plasma glucagon is the primary stimulus for the acceleration of lipolysis in diabetes. These data are consistent with the view that control of adipose tissue cyclic AMP levels in situ is an important physiologic action of insulin.     

Adenosine 3′,5′cyclic monophosphate in adipose tissue of diabetic rats

Normal male rats were made chronically diabetic by injection of alloxan or acutely diabetic by injection of anti-insulin serum. The concentration of cyclic AMP in epididymal adipose tissue was increased approximately 24 h after alloxan administration and up to 7-fold 72 h post-alloxan. Treatment of alloxan-diabetic rats with insulin for 4 h completely suppressed lipolysis but only partially suppressed cyclic AMP levels; 6 h following insulin treatment cyclic AMP levels were normal. When segments of the epididymal fat bodies were incubated in vitro the high cyclic AMP levels were not maintained but instead decreased spontaneously. Addition of insulin to the incubation media decreased lipolysis in tissues of diabetic rats to levels measured in tissues of normal rats and accelerated the decline in cyclic AMP levels but did not return cyclic AMP levels to normal. Rats rendered acutely insulin deficient by injection of anti-insulin serum showed increased plasma glucose and free fatty acid levels and increased adipose tissue free fatty acid, and cyclic AMP levels 30 min following injection of the antiserum. Plasma glucagon levels increased but not until 2 h following anti-insulin serum, thereby excluding the possibility that an increment in plasma glucagon is the primary stimulus for the acceleration of lipolysis in diabetes. These data are consistent with the view that control of adipose tissue cyclic AMP levels in situ is an important physiologic action of insulin.     

Effects of a single oral load of medium-chain triglyceride on serum lipid and insulin levels in man

Analysis of serum free fatty acids by gas-liquid chromatography showed high proportions (27-57%) of octanoic acid for up to 4 hr after the ingestion of a single oral load of medium-chain triglyceride (approximately 1 g/kg body weight) in four volunteers. The effects of a medium-chain triglyceride load on the concentrations of plasma free long-chain fatty acids, plasma glucose, serum insulin, and serum triglyceride were observed and compared with the effects of a glucose load. A rapid fall in the free long-chain fatty acids followed both loads but only a small rise in serum insulin was observed after medium-chain triglyceride. The fall in free long-chain fatty acids following ingestion of medium-chain triglyceride cannot therefore be caused mainly by the release of insulin and may be due to a direct action on adipose tissue. No medium-chain fatty acids were detected in the serum triglyceride after ingestion of medium-chain triglyceride, but there was a small but significant increase in the percentage of hexadecenoic acid in this fraction.     

Superactive somatostatin analog decreases plasma glucose and glucagon levels in diabetic rats

The action of the new analog of somatostatin, D-Phe-Cys-Tyr-D-Trp-Lys-Val-Cys-Trp-NH2 (RC-160), on plasma glucagon and glucose levels was evaluated in streptozotocin-diabetic rats. The effect of this analog on the insulin-induced hypoglycemia in diabetic rats was also investigated in order to evaluate the risk of exacerbating hypoglycemia. Administration of analog RC-160, in a dose of 25 micrograms/kg b. wt. SC, inhibited plasma glucagon secretion and decreased plasma glucose levels. This effect also occurred when plasma glucagon and glucose levels were first elevated by arginine infusion, 1000 mg/kg/hr for 30 min. Subcutaneous injection of regular insulin, 15 U/kg b. wt., produced hypoglycemia with a progressive increase in glucagon levels. Analog RC-160 completely suppressed the hypoglycemia-induced glucagon release for up to 150 min after injection of the analog or insulin. A greater decrease in the plasma glucose level was observed in the group treated with insulin and the analog than in the group injected only with insulin. These results indicate that somatostatin analog RC-160 can produce a marked and prolonged inhibition of glucagon release and a decrease in the plasma glucose level in diabetic rats. This analog may be useful as an adjunct to insulin in the treatment of diabetic patients, although caution should be exercised, to prevent hypoglycemia when using somatostatin analogs together with insulin.