Adipocyte dysfunction in rats with streptozotocin-nicotinamide-induced diabetes

Anti-diuretic and anti-glycemic properties of Jatropha gossypiifolia L. leave extract on wistar rats

Background

Jatropha gossypiifolia L. is a widespread plant in tropical and sub-tropical countries used in traditional medicine. This study investigated the anti-diuretic and anti-hyperglycemia activities of J. gossypiifolia leave extract on streptozotocin-induced diabetic rats.

Methods

The leaves was shade dried, pulverized and prepared into extract. 30, 50 and 100 mg/kg of the leaves extracts of J. gossypiifolia was subject to diuretics and hyperglycemic properties using established protocol of diuretic and diabetes test on the rat bladders emptied via mild compression in the pelvic region and gently pulling of their tails. 0.5 ml/kg normal saline, reference drug and the tested were administered with a single dose of the various drugs, and Streptozotocin (STZ) was freshly prepared in 0.1 M citrate buffer with pH 4.5 prior to induction, animals were fasted 24 h and single dose of 45 mg STZ per kg body weight was administered intraperitoneally. Urine and blood samples were isolated from rats and centrifuged for the determination of renal function test. Diuretic and antidiabetic indexes where evaluated using adopted method.

Results

This study showed that, graded doses of the extract significantly increased diuretic effect, specifically at 100 mg/kg increased diuretic index at 4.29 and urine volume 5.06 and 10 mg/kg Hydrochlorothiazide with 6.23 ml when compared untreated group (1.18 ml) (p < 0.0001). Also, it regulated renal function in homeostatic state. Graded doses at (30, 50 and 100 mg/kg) of the extract significantly reduced streptozotocine induced increased blood glucose level at day 14 (84.00, 60.67 and 42.00 IU/mL) when compared with 20 mg/kg glibenclamide and diabetics control (81.67 and 463.00 IU/mL) (p > 0.05). Also, the extract maintained a normal body mass indexes, biochemical and anatomical structure.

Conclusion

The effect associated with J. gossypiifolia potentiated its anti-diuretic and anti-hyperglycemic properties as early stated in the ethnomedicinal reports.

Branched chain amino acids-friend or foe in the control of energy substrate turnover and insulin sensitivity?

Branched chain amino acids (BCAA) and their derivatives are bioactive molecules with pleiotropic functions in the human body. Elevated fasting blood BCAA concentrations are considered as a metabolic hallmark of obesity, insulin resistance, dyslipidaemia, nonalcoholic fatty liver disease, type 2 diabetes and cardiovascular disease. However, since increased BCAA amount is observed both in metabolically healthy and obese subjects, a question whether BCAA are mechanistic drivers of insulin resistance and its morbidities or only markers of metabolic dysregulation, still remains open. The beneficial effects of BCAA on body weight and composition, aerobic capacity, insulin secretion and sensitivity demand high catabolic potential toward amino acids and/or adequate BCAA intake. On the opposite, BCAA-related inhibition of lipogenesis and lipolysis enhancement may preclude impairment in insulin sensitivity. Thereby, the following review addresses various strategies pertaining to the modulation of BCAA catabolism and the possible roles of BCAA in energy homeostasis. We also aim to elucidate mechanisms behind the heterogeneity of ramifications associated with BCAA modulation.

High-Intensity Interval Training Does Not Change Vaspin and Omentin and Does Not Reduce Visceral Adipose Tissue in Obese Rats

This study aimed to determine the expression of omentin and vaspin, inflammatory markers, body composition, and lipid profile in diet-induced obese rats and high-intensity interval training (HIIT). Forty Wistar rats were divided into four groups: untrained normal diet, trained normal diet (T-ND), untrained high-fat diet (Unt-HFD), and trained high-fat diet (T-HFD). For the animals of the Unt-HFD and T-HFD groups, a high-fat diet was offered for 4 weeks. After that, all the animals in the T-ND and T-HFD groups were submitted to HITT, three times per week, for 10 weeks (2 weeks of adaptation and 8 weeks of HIIT). Muscle (gastrocnemius), liver, epididymal adipose tissue, retroperitoneal adipose tissue, visceral adipose tissue (VAT), and serum were collected to analyze TNF-α, IL-6, PCR, IL-8, IL-10, IL-4, vaspin, and omentin. A body composition analysis was performed before adaptation to HIIT protocol and after the last exercise session using dual-energy X-ray absorptiometry. Omentin and vaspin in the VAT were quantified using Western blotting. The results showed that, when fed a high-fat diet, the animals obtained significant gains in body fat and elevated serum concentrations of vaspin and blood triglycerides. The HIIT was able to minimize body fat gain but did not reduce visceral fat despite the increase in maximum exercise capacity. Moreover, there was a reduction in the serum levels of adiponectin, IL-6, and IL-10. Finally, we concluded that, although the training protocol was able to slow down the weight gain of the animals, there was no reduction in visceral fat or an improvement in the inflammatory profile, including no changes in omentin and vaspin.

Resveratrol loaded glycyrrhizic acid-conjugated human serum albumin nanoparticles for tail vein injection II: pharmacokinetics, tissue distribution and bioavailability

There are many kinds of biological activities of resveratrol itself, but its clinical application is limited by its poor solubility in water and low bioavailability. Therefore, we have prepared glycyrrhizic acid-conjugated human serum albumin nanoparticles wrapping resveratrol nanoparticles (GL-HSA-RESNPs). The purpose of this study was to investigate the bioavailability, pharmacokinetics and tissue distribution of resveratrol in rats after single-dose tail vein injection administration of GL-HSA-RESNPs. A sensitive and reliable high performance liquid chromatography (HPLC) method was established to verify the content of resveratrol in rat plasma and organs. The C_max value after GL-HSA-RESNPs administration was significantly higher than that of resveratrol suspension (933 ± 76.64 ng/mL vs. 618 ± 42.54 ng/mL, p < .01). The T_max value obtained after GL-HSA-RESNPs administration was significantly shorter than that after resveratrol suspension administration (0.17 ± 0.01 h vs. 0.25 ± 0.01 h, p < .001). The bioavailability of GL-HSA-RESNPs was 4.25 times higher than that of the pure resveratrol. The concentration of resveratrol in the main organs of rats treated with the GL-HSA-RESNPs was higher than that in rats treated with the pure resveratrol. Rats treated with GL-HSA-RESNPs had the highest concentration of resveratrol in their liver. It is indicated that GL-HSA-RESNPs is a promising liver-targeted delivery system that improves the in vivo bioavailability of resveratrol.

Cyclohexane extract of walnut leaves improves indices of oxidative stress, total homocysteine and lipids profiles in streptozotocin-induced diabetic rats

This study aimed to evaluate the effect of two doses of cyclohexane extract of walnut leaves on total homocysteine, lipids profiles, and indices of oxidative stress including superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), and malondialdehyde (MDA) in diabetic rats. Diabetes was induced by a single intraperitoneal (IP) injection of streptozotocin (50 mg/kg BW). Twenty-eight male Sprague Dawley rats were randomly divided into four groups, group I: control (received sesame oil as vehicle), group II: diabetic control (received sesame oil), group III and IV: diabetic rats treated by 150 and 250 mg/kg body weight (BW) per day extract of walnut leaves, respectively. All groups were treated for 28 days via oral gavage. Fasting blood glucose (FBG) level and body weight measured before injection, 3 days after injection, and on days 0, 7, 14, 21, and 28 of treatment. At the end the 28th day of the experiment, blood samples collected via heart puncture and the sera were used for estimation of the above-mentioned parameters. The results showed a decrease in FBS, TC, TG, LDL-c, VLDL-c, homocysteine, and MDA level and increase in the level of HDL-c in diabetics treated by walnut leave extracts in a dose-dependent manner after 28 days. The activity of antioxidant enzymes significantly increased in treated groups compared with diabetic control. It can be concluded that cyclohexane extract of walnut leaves has an overall beneficial effect on body weight, fasting blood glucose, lipids profile, antioxidant enzyme activities, and homocysteine.

Adiponectin Mediates Running-Restored Hippocampal Neurogenesis in Streptozotocin-Induced Type 1 Diabetes in Mice

Streptozotocin (STZ)-induced diabetes impairs learning and memory performance and reduces adult hippocampal neurogenesis. Physical exercise brings beneficial effects. We have previously shown that adiponectin, an adipocyte-secreted hormone critically involved in the pathology of diabetes, is a key mediator for exercise-enhanced adult hippocampal neurogenesis. Here, we tested whether adiponectin is required for exercise to restore adult hippocampal neurogenesis in an animal model of diabetes. The findings showed that a single injection of 195 mg/kg STZ-induced diabetes significantly increased serum levels of corticosterone and reduced hippocampal adiponectin levels in adult mice. STZ injection also significantly reduced the number of Ki67 and doublecortin (DCX) positive cells and the ratio of co-labeling of DCX and bromodeoxyuridine (BrdU) in the hippocampal dentate region, indicating a decrease in adult hippocampal neurogenesis. Two-week voluntary wheel running significantly restored hippocampal neurogenesis in the diabetic wild-type mice, but not adiponectin knockout mice, indicating that adiponectin is critical for physical exercise to restore hippocampal adult neurogenesis in mice with diabetes. The results suggest that increasing adiponectin levels could be a therapeutic approach to restore hippocampal neurogenesis impairment in individuals with diabetes.

Food restriction promotes damage reduction in rat models of type 2 diabetes mellitus

There are several animal models of type 2 diabetes mellitus induction but the comparison between models is scarce. Food restriction generates benefits, such as reducing oxidative stress, but there are few studies on its effects on diabetes. The objective of this study is to evaluate the differences in physiological and biochemical parameters between diabetes models and their responses to food restriction. For this, 30 male Wistar rats were distributed in 3 groups (n = 10/group): control (C); diabetes with streptozotocin and cafeteria-style diet (DE); and diabetes with streptozotocin and nicotinamide (DN), all treated for two months (pre-food restriction period). Then, the 3 groups were subdivided into 6, generating the groups CC (control), CCR (control+food restriction), DEC (diabetic+standard diet), DER (diabetic+food restriction), DNC (diabetic+standard diet) and DNR (diabetic+food restriction), treated for an additional two months (food restriction period). The food restriction (FR) used was 50% of the average daily dietary intake of group C. Throughout the treatment, physiological and biochemical parameters were evaluated. At the end of the treatment, serum biochemical parameters, oxidative stress and insulin were evaluated. Both diabetic models produced hyperglycemia, polyphagia, polydipsia, insulin resistance, high fructosamine, hepatic damage and reduced insulin, although only DE presented human diabetes-like alterations, such as dyslipidemia and neuropathy symptoms. Both DEC and DNC diabetic groups presented higher levels of protein carbonyl groups associated to lower antioxidant capacity in the plasma. FR promoted improvement of glycemia in DNR, lipid profile in DER, and insulin resistance and hepatic damage in both diabetes models. FR also reduced the protein carbonyl groups of both DER and DNR diabetic groups, but the antioxidant capacity was improved only in the plasma of DER group. It is concluded that FR is beneficial for diabetes but should be used in conjunction with other therapies.

Effects of Melatonin on Glucose Homeostasis, Antioxidant Ability, and Adipokine Secretion in ICR Mice with NA/STZ-Induced Hyperglycemia

Diabetes is often associated with decreased melatonin level. The aim was to investigate the effects of different dosage of melatonin on glucose hemostasis, antioxidant ability and adipokines secretion in diabetic institute for cancer research (ICR) mice. Forty animals were randomly divided into five groups including control (C), diabetic (D), low-dosage (L), medium-dosage (M), and high-dosage (H) groups. Groups L, M, and H, respectively, received oral melatonin at 10, 20, and 50 mg/kg of BW (body weight) daily after inducing hyperglycemia by nicotinamide (NA)/ streptozotocin (STZ). After the six-week intervention, results showed that melatonin administration increased insulin level and performed lower area under the curve (AUC) in H group (p < 0.05). Melatonin could lower hepatic Malondialdehyde (MDA) level in all melatonin-treated groups and increase superoxide dismutase activity in H group (p < 0.05). Melatonin-treated groups revealed significant higher adiponectin in L group, and lower leptin/adiponectin ratio and leptin in M and H groups (p < 0.05). Melatonin could lower cholesterol and triglyceride in liver and decrease plasma cholesterol and low-density lipoprotein-cholesterol (LDL-C) in L group, and increase plasma high-density lipoprotein-cholesterol (HDL-C) in H group (p < 0.05). Above all, melatonin could decrease oxidative stress, increase the adiponectin level and improve dyslipidemia, especially in H group. These data support melatonin possibly being a helpful aid for treating hyperglycemia-related symptoms.

COMP-angiopoietin-1 mitigates changes in lipid droplet size, macrophage infiltration of adipose tissue and renal inflammation in streptozotocin-induced diabetic mice

Adipose tissue is considered to be an endocrine organ, and adipocyte size correlates with insulin resistance and metabolic parameters in obesity. There is little data on the effects of angiopoietin-1 in adipose tissue and kidney in streptozotocin (STZ)-induced diabetes. In this study, we investigated the protective effect of COMP-angiopoietin-1 (COMP-Ang1), a potent variant of angiopoietin-1, on vascular endothelial cells in epididymal adipose tissue and its regulatory effect on other metabolic parameters, such as lipid droplet diameter, macrophage infiltration, and renal inflammation in STZ-treated mice. Our data showed that COMP-Ang1 increased the density of platelet endothelial cell adhesion molecule-1 (PECAM-1)-1-positive vascular endothelial cells in adipose tissue, which were significantly decreased by treatment with STZ. COMP-Ang1 ameliorated the STZ–induced decrease in lipid droplet diameter and increase in macrophage infiltration in adipose tissue. Serum free fatty acid and triglyceride levels were decreased after administration of COMP-Ang1. There was a beneficial effect on serum insulin levels after treatment with COMP-Ang1 in STZ-induced diabetic mice. Fasting blood glucose levels in COMP-Ang1-treated mice were significantly lower than those of LacZ-treated mice. Cotreatment with COMP-Ang1 and STZ also had similar effects on the above parameters. Administration of soluble Tie2, an inhibitor of angiopoietin-1, reversed the effects of COMP-Ang1. COMP-Ang1 was found to ameliorate the up-regulation of proinflammatory molecules and F4/80-positive macrophage infiltration in the kidneys of STZ-treated mice. COMP-Ang1 increased the phosphorylation of Akt in epididymal adipose tissue and kidneys of STZ-induced diabetic mice. These data indicate that COMP-Ang1 regulates lipogenic effects in adipose tissue and renal inflammation in STZ-induced diabetic mice.

Dietary nitrate improves glucose tolerance and lipid profile in an animal model of hyperglycemia

Reduction in nitric oxide (NO) production and bioavailability contribute to the pathogenesis of type 2 diabetes. Administration of nitrate has strong NO-like outcomes in both animals and humans. In this study, we examined the effects of dietary nitrate on glucose tolerance and lipid profile in type 2 diabetic rats. Type 2 diabetes was induced by injection of streptozotocin and nicotinamide. Thirty-two male Wistar rats were divided into 4 groups: controls (C), control+nitrate (CN), diabetes (D), and diabetes+nitrate (DN). For 8 weeks, the CN and DN groups consumed sodium nitrate (100 mg/L in drinking water) while the C and D groups consumed tap water. Serum nitrate+nitrite (NOx), glucose, lipid profile, total antioxidant capacity (TAC), and catalase (CAT) activity were measured before and at the end of the study. Systolic blood pressure (SBP) was measured every 10 days. Intravenous glucose tolerance test (IVGTT) was performed at the end of the study. Serum NOx decreased in diabetic rats and dietary nitrate restored it to normal values. Increases in serum glucose levels was significantly lower in the DN group compared to the D group (24.1% vs. 90.2%; p < 0.05). Nitrate therapy in diabetic rats significantly improved lipid profile, glucose tolerance (AUC: 20264 ± 659 vs. 17923 ± 523; p < 0.05 for D and DN groups respectively) and restored elevated SBP to normal values. Diabetic rats had lower TAC and CAT activity and dietary nitrate restored these to normal status. In conclusion, dietary nitrate prevented increase in SBP and serum glucose, improved glucose tolerance and restored dyslipidemia in an animal model of hyperglycemia.

MSC attenuate diabetes-induced functional impairment in adipocytes via secretion of insulin-like growth factor-1

The function of subcutaneous adipocytes in promoting wound healing is significantly suppressed in diabetic wounds. Recent studies have demonstrated the ability of mesenchymal stem cell (MSC) to ameliorate impaired diabetic wound healing. We hypothesized that MSC function may involve subcutaneous adipocytes. The abnormal function of subcutaneous adipocytes from STZ induced diabetic mice including glucose uptake and free fatty acid (FFA) secretion level were assessed. Then these cells were co-cultured with MSC via a transwell system to observe the changes of metabolic index and glucose transporter four (GLUT4) as well as phosphoinositide 3-kinase/protein kinase (PI3K/AKT) signaling pathway expression. The results of metabolic index suggest that MSC obviously attenuated the diabetes-induced functional impairment. Both mRNA and protein expression analyses showed that PI3K/AKT insulin signaling pathway and GLUT4 expression were up-regulated. These changes were substantially associated with a increased level of insulin-like growth factor-1 (IGF-1) secretion from MSC. These findings suggest that MSC could attenuate abnormal function of diabetic adipocytes by IGF-1secretion, which was more or less associated with the beneficial effects of MSC on improving diabetic wound healing.