Fucoidan--a α-D-glucosidase inhibitor from Sargassum wightii with relevance to type 2 diabetes mellitus therapy

The present study was conducted to screen the α-d-glucosidase inhibitory activity of fucoidan extracted from Sargassum wightii collected at Mandapam coastal area, Tamil Nadu, India. Fucoidan was extracted from the sporophyll of S. wightii using ethanol, acetone and CaCl2 precipitation. The average yield was 1.8 ± 0.16% and the extracted fucoidan was found to contain 53 ± 0.52% of fucose and 36 ± 0.60% of sulphate. FT-IR, NMR and in vitro α-d-glucosidase activity of purified fucoidan were performed. Fucoidan at the concentration of 31.25, 62.5, 125 and 250 μg exhibited 19, 31, 38 and 71% inhibition against α-d-glucosidase respectively in a dose dependent manner. The IC50 value against α-D-glucosidase of fucoidan is found to be 132.9 μg which is more effective than that of acarbose (1mg). The diverse biological activities of Fucoidan include anticancer, anti inflammatory and antimicrobial but the α-d-glucosidase inhibitory activity of native fucoidan from S. wightii for type 2 diabetes therapy is first of its kind.

Nutritional composition of Stevia rebaudiana, a sweet herb, and its hypoglycaemic and hypolipidaemic effect on patients with non-insulin dependent diabetes mellitus

BACKGROUND

The prevalence of diabetes is rapidly rising all over the globe at an alarming rate. India shelters the highest number of diabetics and is thus known as the 'Diabetes Capital of the World'. The chemical management of diabetes has side effects and hence the present study was undertaken to assess the hypoglycaemic and hypolipidaemic effect of Stevia rebaudiana in patients with type 2 diabetes, non-insulin dependent diabetes mellitus (NIDDM). Its nutritional composition and use as a sweetener substitute were also assessed.

RESULTS

Chemical analysis of dried Stevia leaf powder revealed it to be a nutritious herb with a good iron and fibre content. Intervention trials in diabetics revealed that it significantly lowered fasting and post-prandial blood glucose levels. The serum triglycerides and VLDL-C levels were also significantly reduced.

CONCLUSION

Hence it can be said that Stevia can safely be used as an anti-diabetic herb, as a sweetener substitute and may help to prevent cardiovascular diseases in patients with long-standing diabetes. © 2016 Society of Chemical Industry.

Galectin-1 is a new fibrosis protein in type 1 and type 2 diabetes

Chronic exposure of tubular renal cells to high glucose contributes to tubulointerstitial changes in diabetic nephropathy. In the present study, we identified a new fibrosis gene called galectin-1 (Gal-1), which is highly expressed in tubular cells of kidneys of type 1 and type 2 diabetic mouse models. Gal-1 protein and mRNA expression showed significant increase in kidney cortex of heterozygous Akita^+/- and db/db mice compared with wild-type mice. Mouse proximal tubular cells exposed to high glucose showed significant increase in phosphorylation of Akt and Gal-1. We cloned Gal-1 promoter and identified the transcription factor AP4 as binding to the Gal-1 promoter to up-regulate its function. Transfection of cells with plasmid carrying mutations in the binding sites of AP4 to Gal-1 promoter resulted in decreased protein function of Gal-1. In addition, inhibition of Gal-1 by OTX-008 showed significant decrease in p-Akt/AP4 and protein-promoter activity of Gal-1 and fibronectin. Moreover, down-regulation of AP4 by small interfering RNA resulted in a significant decrease in protein expression and promoter activity of Gal-1. We found that kidney of Gal-1^-/- mice express very low levels of fibronectin protein. In summary, Gal-1 is highly expressed in kidneys of type 1 and 2 diabetic mice, and AP4 is a major transcription factor that activates Gal-1 under hyperglycemia. Inhibition of Gal-1 by OTX-008 blocks activation of Akt and prevents accumulation of Gal-1, suggesting a novel role of Gal-1 inhibitor as a possible therapeutic target to treat renal fibrosis in diabetes.-Al-Obaidi, N., Mohan, S., Liang, S., Zhao, Z., Nayak, B. K., Li, B., Sriramarao, P., Habib, S. L. Galectin-1 is a new fibrosis protein in type 1 and type 2 diabetes.

The association between endostatin and kidney disease and mortality in patients with type 2 diabetes

AIM

Circulating endostatin, a biologically active derivate of collagen XVIII, is considered to be a marker of kidney disease and a risk factor for its related mortality. However, less is known of the role of endostatin in diabetes and the development of diabetic nephropathy. For this reason, our study investigated the associations between circulating endostatin and the prevalence and progression of kidney disease, and its mortality risk in patients with type 2 diabetes (T2D).

METHODS

This was a cohort study of 607 patients with T2D (mean age: 61 years, 44% women). Estimated glomerular filtration rate (eGFR), calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine equation, was used to assess the patients' kidney function decline and mortality.

RESULTS

Of the total study cohort, 20 patients declined by ≥20% in eGFR over 4 years, and 44 died during the follow-up (mean duration: 6.7 years). At baseline, participants with diabetic nephropathy (defined as eGFR<60mL/min/1.73m²) and/or microalbuminuria [defined as a urinary albumin-to-creatinine ratio (ACR)>3g/mol] had higher median levels of endostatin than those without nephropathy (62.7μg/L vs 57.4μg/L, respectively; P=0.031). In longitudinal analyses adjusted for age, gender, baseline eGFR and ACR, higher endostatin levels were associated with a higher risk of decline (≥20% in eGFR, OR per 1 SD increase: 1.73, 95% CI: 1.13-2.65) and a higher risk of mortality (HR per 1 SD increase: 1.57, 95% CI: 1.19-2.07).

CONCLUSION

In patients with T2D, circulating endostatin levels can predict the progression of kidney disease and mortality independently of established kidney disease markers. The clinical usefulness of endostatin as a risk marker in such patients merits further studies.

Oxidative stress in metabolic syndrome

As antioxidants play a protective role in the pathophysiology of diabetes and cardiovascular diseases, understanding the physiological status of antioxidant concentration among people at high risk for developing these conditions, such as Metabolic Syndrome, is of interest. In present study out of 187 first degree non-diabetic relatives and 192 non-diabetic spouses, 33.1% and 19.7% were found to have metabolic syndrome respectively. Subjects with metabolic syndrome (≥3 risk factors) had poor antioxidants status as reflected by significantly low levels of vitamin A, C & E and significantly increased (p<0.01) oxidative stress as compared to those without metabolic syndrome. At the same time serum insulin levels and insulin resistance were found to be significantly high (p<0.001) in metabolic syndrome. A strong positive correlation (r=0.946; p<0.001) between oxidative stress and insulin resistance was observed in metabolic syndrome. Low levels of antioxidants and increased oxidative stress with insulin resistance in metabolic syndrome suggests that besides therapeutic life style changes (TLC) as suggested in ATP III guidelines inclusion of antioxidant vitamins, fruits and vegetable could be beneficial to ward off the consequences of metabolic syndrome.

Fucoidan - An α-amylase inhibitor from Sargassum wightii with relevance to NIDDM

The present experiment was conducted to screen the α-amylase inhibitory activity of fucoidan extracted from Sargassum wightii collected at the coastal area of Mandapam, Tamil Nadu, India. Fucoidan was extracted from the sporophyll of S. Wightii by ethanol and CaCl2 precipitation method. The average yield was 1.8±0.16% and the extracted fucoidan was found to contain 53±0.52% of fucose and 36±0.60% of sulphate. Structural elucidation (FT-IR and NMR) and in vitro α-amylase activity of purified fucoidon were performed. Fucoidan at the concentration of 62.5, 125 and 250μg exhibited 24.81, 62.50 and 99.24% inhibition against α-amylase, respectively, in a dose dependent manner. Fucoidan from S. wightii also inhibits α-glucosidase which clearly indicates dual inhibitory activity of the compound. The IC50 value against α-amylase of fucoidan is found to be 103.83μg which is more effective than that of acarbose (16mg).

Preliminary clinical assessment and non- toxicity evaluation of an ayurvedic formulation BGR-34 in NIDDM

In view of the overall health impact of NIDDM, inventers understand the necessity of improving glycemic control in adults with type 2 diabetes. BGR-34 provides an effective treatment option for adults with type 2 diabetes who have been inadequately controlled on lifestyle with or without other oral hypoglycemic agents (OHGAs) such as metformin, sulfonylurea, or a glitazones. BGR-34 is an appropriate option to consider for addition to a managed care drug formulary. Treatment with BGR-34 produced clinically relevant and statistically significant reductions in all three key measures of glucose control studied -FPG, PPBG and HbA1c- when compared with placebo. BGR-34, showed the promising result with respect to glycemic parameters in NIDDM patient with a significant reduction in fasting blood sugar by 34.3%, postprandial blood sugar 35.5% & glycosylated haemoglobin by 20.31% as compared to placebo group showing a reduction by 13.2%, 10.9% & 10.87% respectively. The trial has also been registered to CTRI, India. This study has been registered in the clinical trial registry-India.

Serum trace elements in insulin-dependent and non-insulin-dependent diabetes: a comparative study

BACKGROUND

Diabetes mellitus is associated with imbalance in body trace elements. The aim of the current investigation was to compare the levels of trace elements (Zn, Mg, Mn, Cu, Na, K, Fe, Ca, Cr, and Se) in insulin dependent (IDDM) and non-insulin dependent (NIDDM) diabetes.

METHODS

A total of 100 patients with diabetes (40 IDDM and 60 NIDDM) and 50 healthy subjects were recruited in the study from both genders. Biochemical measures include glucose, lipids, and HbA1C.

RESULTS

The results showed that Zn, Mg, Cu and Cr were significant lower in patients with diabetes compared to the control group (P<0.01). In addition, Zn and Cr were significantly lower in IDDM than NIDDM (P<0.05). Moreover, Zn and Mg levels were inversely correlated with HbA1c in IDDM and NIDDM (P<0.05). Zn was inversely correlated with fasting blood glucose in IDDM (P<0.05). Finally, no correlation between trace element levels with BMI was found (P>0.05).

CONCLUSION

Disturbance in trace element profile among IDDM and NIDDM is similar.

Resistin hormone in diabetic kidney disease and its relation to iron status and hepcidin

BACKGROUND

Resistin, a potent adipocyte-secreted hormone, may contribute to and modulate iron status and hepcidin level in patients with non-insulin-dependent diabetes mellitus (NIDDM) and end-stage renal disease (ESRD).

CONTEXT

The cross-sectional study aimed to determine the possible role of resistin in the iron status pathway in patients with NIDDM and ESRD events are sparse with conflicting results.

METHODS

A total of 130 patients and 42 healthy subjects were included in the study and grouped into four none obese groups with normal C-reactive protein (CRP) level: Group 1 (control), Group 2 (NIDDM), Group 3 (ESRD on hemodialysis), and Group 4 (NIDDM + ESRD on hemodialysis). Resistin hormone, ferritin, hepcidin, serum iron, TIBC, and TS% were estimated.

RESULTS

Resistin, hepcidin, and ferritin were significantly increased in all groups when compared to control. TIBC significantly increased in ESRD and NIDDM + ESRD when compared to controls. Serum iron and TS% significantly decreased in all groups when compared to controls. Resistin showed a significant positive correlation with hepcidin and ferritin.

CONCLUSION

It was determined that serum resistin elevated in patients and correlated directly with hepcidin and ferritin levels. The present finding regarding receiver-operating characteristic curve (ROC curve) analysis of resistin hormone proposed that resistin could be represented as a biomarker for iron dysfunction in NIDDM and ESRD.

Synthesis and oral hypoglycemic effect of novel thiazine containing trisubstituted benzenesulfonylurea derivatives

A new series of 3-(4-substituted phenyl)-1-(4-(4,6-dimethyl-6H-1,3-thiazin-2-yl)phenylsulfonyl)-1-substituted urea (5a-o) was synthesized by an effectual route via sulfonylcarbamates and explores the novel site for substitution in sulfonylurea as well as the way of thiazine can be prepared. The molecules were established by elemental analysis and spectroscopic viz. IR, (1)H NMR, (13)C NMR and MS techniques. All the fifteen derivatives were shown very prominent oral hypoglycemic effect at the dose of 40 mg/kg body weight (p.o.) in respect of standard drug glibenclamide and control. The hypoglycemic effect was studied using oral glucose tolerance test in normal and NIDDM in STZ-rat model. The compounds 5a, 5d, 5f, 5i, 5k and 5n were dominant out of fifteen derivatives for blood glucose lowering activity (more than 80%) when comparing with NIDDM control. These derivatives were either containing simply phenyl ring (5a, 5f and 5k) on to the second amine of sulfonylurea (R' = H) or nitro group at the para position in compound 5d, 5i and 5n (R' = NO2 ) to produce significant oral hypoglycemic effect. Other structural activity relationship is also observed regarding the heteroaromatic and substituted aromatic group at R and R' position respectively.

Safety and efficacy of Momordica charantia Linnaeus in pre-diabetes and type 2 diabetes mellitus patients: a systematic review and meta-analysis protocol

BACKGROUND

Momordica charantia Linnaeus (Cucurbitaceae) has been used traditionally as a nutritious food and as a herbal medicine for type 2 diabetes mellitus. However, human studies that investigated its glycemic control have generated inconsistent findings. Therefore, this systematic review and meta-analysis is aimed at evaluating the safety and efficacy of M. charantia L. preparations in human studies that have investigated its role in glycemic control.

METHODS

This protocol has been prepared according to Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P). The review will include randomized clinical trials and non-randomized clinical trials. The included studies will have assessed glycemic control of M. charantia preparations with placebo or standard oral anti-hyperglycemic agents in adult pre-diabetes and/or type 2 diabetes mellitus patients and have at least 4 weeks of follow-up. The primary outcomes of review are fasting blood glucose levels, glycosylated hemoglobin A1c, and post-prandial blood glucose level. Electronic database search for published literatures will be conducted without language restriction in EMBASE, MEDLINE/PubMed, the Cochrane Library, SCOPUS, Web of Sciences, and CINAHL databases. Search for gray literatures and references of the retrieved full-text articles will be conducted in Google, Google Scholar, OpenGrey, ProQuest dissertations & Theses, British Library EThos, and university digital library systems. Two independent reviewers will later evaluate full texts, extract data, and assess risk of bias of eligible articles. Publication biases will be assessed by testing asymmetry of funnel plot using Egger's or Begg's tests while heterogeneity will be assessed using Cochran Q test, P value, and I2. Revman software version 5.3 will be used for meta-analysis including subgroup and sensitivity analysis.

DISCUSSION

This systematic review and meta-analysis will investigate both safety and efficacy of M. charantia preparations in type 2 diabetes mellitus. The review results will be published in a peer-reviewed journal. The results will bring better understanding of clinical outcomes in treatment of type 2 diabetes mellitus patients and highlight gaps for future research.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42018083653 .

Complications of Diabetes: An Insight into Genetic Polymorphism and Role of Insulin

BACKGROUND

Diabetes Mellitus (DM) is an advanced and chronic endocrine disorder characterized by an insufficiency of insulin secretion from pancreatic β-cells and liver, adipose tissues, and skeletal muscles.

OBJECTIVE

The main objective of this study is to understand the mechanism and genes which are responsible for the prevalence of diabetes. The study also covers various types of diabetic complications with special reference to insulin role and defects.

METHODS

The scientific literature and patents were reviewed and analyzed based on their suitability and relevance to the theme of the study. The scientific literature was covered from the authentic databases such as Elsevier, Springer, and Bentham Science. The patents were reviewed from http://www.freepatentsonline.com.

RESULTS

Glucokinase (ATP: D-glucose-6-phosphotransferase; GCK), initiates glycolysis and acts as a glucose sensor and metabolic signal producer in liver and pancreas. PCR-sequencing showed qualitative differences in diabetic patients in comparison to healthy subjects. Glucokinase is the most important component in glucose detection of pancreatic islet beta cells in diabetes because glucokinase mutations can be one of the most common single gene disorders described. It is known that a genetic variation of a human glucokinase gene, including a point mutation, causes MODY, the concentration of plasma glucose increased and it is supposed to be the cause of diabetes of the present study subjects. Owing to hyperglycemia and individual components of the insulin resistance (metabolic) syndrome, people with Type II DM are prone to the high threat for microvascular complications (including nephropathy, retinopathy, and neuropathy) and macrovascular complications (such as Ischemic Heart Disease). There were also significant differences (P < 0.0001) in glycation levels (0.90, 0.4838mole/mole), random blood sugar (348.8, 105.8mg/dL), cholesterol levels (235.3, 161.8mg/dL), low density lipoprotein in diabetic subjects (155.3, 28.46mg/dL) and in healthy donors. GCK gene mutations were found in 70% of the patients while 30% are non-mutated.

CONCLUSION

In conclusion, lipids, glucose, and protein play an essential role in the initiation of AGE's or diabetic complications (Micro and Macrovascular Complications). The importance of the clinical results should also be recognized in the genetic analysis of heterogeneous disorders as NIDDM/ Type II DM.

Effects of insulin, glimepiride and combination therapy of insulin and metformin on blood sugar and lipid profile of NIDDM patients

In the present study the efficacies of therapy with insulin, sulphonylurea or insulin + metformin on NIDDM patients are compared. One group which was on a definite dose of insulin therapy, but with uncontrolled diabetes was treated by doubling the insulin dose, a second group whose diabetes was not controlled by glibenclamide was switched over to another sulphonylurea viz; glimepiride and a third group whose diabetes was not controlled by insulin therapy was switched over to a combination therapy with insulin +metformin. After recording their initial blood parameters all the groups were treated as above for 3 months, and the parameters were again determined. The fasting blood sugar and serum lipids of the first group were controlled significantly, but the values were far above normal range. However HDL Cholesterol and atherogenic index were near normal range. In glimepiride treated group, none of the parameters showed any amelioration. In the combined therapy group, control of blood sugar and atherogenic index was more or less the same as for group 1, but hyperlipidemia remained slightly above that of the same. From the findings we can infer that in long term diabetes treatment higher doses of insulin and combined therapy with insulin and metformin may be more beneficial than with low doses of insulin or sulfonyl urea alone.

Hyperlipidemia, increased lipid peroxidation and changes in antioxidant enzymes, Na(+)-K(+)-ATPase in erythrocytes of type 2 diabetic patients in andhra pradesh

Plasma levels of lipids, lipoproteins and lipid peroxides and erythrocyte Na(+)-K(+) ATPase, Mg(2+)ATPase and antioxidant enzymes were measured in type-2 diabetic patients. A significant decrease in Na(+)-K(+)-ATPase activity was observed in diabetic patients which was negatively correlated with blood glucose and lipid peroxides, while the Mg(2+)-ATPase activity was increased. In the diabetic subjects the plasma concentrations of Na(+) and K(+) were increased where as erythrocyte levels of Na(+) were increased and K(+) were decreased. Hyperlipidaemia and increased levels of lipid peroxides were observed in the diabetic subjects. There was a significant increase in erythrocyte catalase activity in diabetics which positively correlated with their lipid peroxides. There was no change in GPx activities between controls and diabetics.

Evaluation of 4-methyl-2-[(2-methylbenzyl) amino]-1,3-thiazole-5-carboxylic acid against hyperglycemia, insulin sensitivity, and oxidative stress-induced inflammatory responses and β-cell damage in the pancreas of streptozotocin-induced diabetic rats

4-Methyl-2-[(2-methylbenzyl) amino]-1,3-thiazole-5-carboxylic acid (bioactive compound (BAC)), a novel thiazole derivative, is a xanthine oxidase inhibitor and free radical scavenging agent. Effects of BAC on hyperglycemia, insulin sensitivity, oxidative stress, and inflammatory mediators were evaluated in streptozotocin (STZ)-induced neonatal models of non-insulin-dependent diabetes mellitus (NIDDM) rats where NIDDM was induced in neonatal pups with single intraperitoneal injection of STZ (100 mg/kg). The effect of BAC (10 and 20 mg/kg, p.o.) for 3 weeks was evaluated by the determination of blood glucose, oral glucose tolerance test (OGTT), HbA1c level, insulin level, insulin sensitivity, and insulin resistance (IR). Furthermore, inflammatory mediators (tumor necrosis factor-alpha and interleukin-6) and oxidative stress were estimated in serum and pancreatic tissue, respectively. Significant alteration in the level of blood glucose, OGTT, HbA1c, insulin level, insulin sensitivity, in addition variation in the antioxidant status and inflammatory mediators, and alteration in histoarchitecture of pancreatic tissue confirmed the potential of BAC in STZ-induced neonatal models of NIDDM rats. Pretreatment with BAC restored the level of glucose by decreasing the IR and increasing the insulin sensitivity. Furthermore, BAC balanced the antioxidant status and preserved the inflammatory mediators. Histological studies of pancreatic tissues showed normal architecture after BAC administration to diabetic rats. Altogether, our results suggest that BAC successfully reduces the blood glucose level and possesses antioxidant as well as anti-inflammatory activities. This leads to decreased histological damage in diabetic pancreatic tissues, suggesting the possibility of future diabetes treatments.

Metabolite Profiling and Integrated Network Pharmacology Based Mechanism of Benincasa hispida (Thunb.) Cogn. Fruit Against Non-insulin-Dependent Diabetes Mellitus

INTRODUCTION

Benincasa hispida (Thunb.) Cogn. (Cucurbitaceae) is an essential food plant in India possessing antihyperglycemic and antihyperlipidemic activities.

OBJECTIVE

The objective included comparative estimation of α-glucosidase and α-amylase enzyme inhibition potential of B. hispida fractions prepared by microwave-assisted extraction and prediction of metabolite interaction against non-insulin-dependent diabetes mellitus by metabolite profiling based network pharmacology analysis.

METHODS

A validated microwave-assisted extraction method was employed to obtain different fractions of B. hispida fruits. The in vitro enzyme assay was done with p-nitrophenyl-α-D-glucopyranoside and acarbose as standard to evaluate antidiabetic potential. The phytomolecules present in the active fraction were identified by UHPLC-QToF-MS/MS analysis. Network pharmacology analysis gave possible gene and disease association, combination synergy network, and predicted probable mechanism of action.

RESULTS

The highest enzyme inhibition potential (IC50) was shown by the ethyl acetate fraction (0.546 ± 0.17 mg/mL and 1.134 ± 0.42 mg/mL) compared to acarbose (0.298 ± 0.08 mg/mL and 0.532 ± 0.38 mg/mL), respectively, for α-glucosidase and α-amylase addressing the potential role in ameliorating non-insulin-dependent diabetes mellitus. Metabolite profiling resulted in the identification of 17 metabolites, and a synergy between the identified molecules suggested multimolecule action in the amelioration of non-insulin-dependent diabetes mellitus through insulin resistance pathway, AMPK signaling pathway, PPAR signaling pathway, and PI3K-Akt signaling pathway. Combination synergy of identified molecules was observed through a multitarget approach to manage non-insulin-dependent diabetes mellitus.

CONCLUSION

Polyphenol-enriched fraction of B. hispida fruits and identified phytocompounds ameliorate non-insulin-dependent diabetes mellitus. Thus, enriched extract of B. hispida can be further investigated in order to develop high-quality, safe, and effective products for the management of non-insulin-dependent diabetes mellitus.

The role of life events in short term metabolic control of non-insulin dependent diabetes mellitus

For present study 2 groups were first chosen, each consisting of 50 NIDDM patients with matched age, sex and social class. One group (i.e. Group A) had patients with poor metabolic control while other group i.e. Group B had patients with adequate metabolic control. Investigators found that female Group A patients had experienced higher mean number of life events in the one month period proceeding the date of study when compared with Group B females. Similar comparison in males showed increased experience of life events during the six month period. Regardless of sex, Group B patients were not found to differ from matched chronic disease patients (i.e. Group C) regarding the mean number of life events experienced during six month period. Male Group B patients, unlike females, experienced higher number of life events during past six months when compared with male matched disease free subjects (i.e. Group D). Adverse events seemed to have predominant role in diabetes control.

Comparison of Lactate Threshold, Glucose, and Insulin Levels Between OLETF and LETO Rats After All-Out Exercise

Otsuka Long-Evans Tokushima Fatty (OLETF) rats are an animal model for obesity and Non Insulin Dependent Diabetes Mellitus by hyperphagia. The lactate threshold (LT) is used to determinate aerobic capacity and exercise intensity in individuals. The purpose of this study was to determine whether velocity at the LT (VLT), glucose, and insulin levels of OLETF differs from Long-Evans Tokushima (LETO) rats after all-out exercise on treadmill running. In the results, we found that VLT level of OLETF rats (17.8 ± 1.39 m·min(-1)) was significantly lower than that of the LETO rats (20.5 ± 1.33 m·min(-1)). The blood glucose levels immediately after all-out exercise increased in OLETF (from 7.23 ± 0.36 to 9.38 ± 1.77 mmol·L(-1)) and decreased in LETO rats (from 6.36 ± 0.27 to 4.42 ± 0.71 mmol·L(-1)), and the insulin level was decreased in both the OLETF (from 34.4 ± 7.7 to 20.13 ± 8.63 µU·mL(-1)) and LETO (from 15.29 ± 2.6 to 5.72 ± 1.49 µU·mL(-1)) rats immediately after the all-out exercise, but the difference was not significant. Our results suggest that the different VLT, blood glucose and insulin levels should be considered to compensate for the differences between the OLETF and LETO rats. Moreover, the VLT will be a useful reference for the future studies on exercise training of OLETF rats. Key pointsThe VLT of OLETF was significantly lower than that of LETO rats.The changes of the blood lactate levels from rest to all-out exercise showed significant difference between OLETF and LETO rats.The result of low VLT in the OLETF compared to LETO rats implies that the application of relatively low exercise intensity is suitable for OLETF rats.The different VLT should be recognized to compensate for the differences between the OLETF and LETO rats.

Low dietary zinc intake attenuates the efficacy of 2,4-thiazolidinedione on reducing hyperglycemia in db/db mice (Short communication)

Zinc (Zn) has the potential of regulating the action of thiazolidinedione (TZD), an anti-diabetic drug. Since some diabetic patients cannot achieve optimal glycemic control when receiving TZD, we investigated if Zn deficiency affects TZD's efficacy in glucose metabolism. Diabetic mice were fed diets containing 3 or 30 mg/kg Zn for 6 weeks. Thereafter, all mice were oral gavaged with 2,4-thiazolidinedione. Our results showed that blood glucose values at fasting and during the glucose tolerance test were significantly higher in low-Zn mice than those of adequate-Zn mice. Thus, low Zn intake may attenuate TZD's efficacy on reducing diabetic hyperglycemia.