Non-diabetic Animals Research Articles

Proangiogenic Effect of Metformin in Endothelial Cells Is via Upregulation of VEGFR1/2 and Their Signaling under Hyperglycemia-Hypoxia.

Cardiovascular disease is the leading cause of morbidity/mortality worldwide. Metformin is the first therapy offering cardioprotection in type 2 diabetes and non-diabetic animals with unknown mechanism. We have shown that metformin improves angiogenesis via affecting expression of growth factors/angiogenic inhibitors in CD34+ cells under hyperglycemia-hypoxia. Now we studied the direct effect of physiological dose of metformin on human umbilical vein endothelial cells (HUVEC) under conditions mimicking hypoxia-hyperglycemia. HUVEC migration and apoptosis were studied after induction with euglycemia or hyperglycemia and/or CoCl2 induced hypoxia in the presence or absence of metformin. HUVEC mRNA was assayed by whole transcript microarrays. Genes were confirmed by qRT-PCR, proteins by western blot, ELISA or flow cytometry. Metformin promoted HUVEC migration and inhibited apoptosis via upregulation of vascular endothelial growth factor (VEGF) receptors (VEGFR1/R2), fatty acid binding protein 4 (FABP4), ERK/mitogen-activated protein kinase signaling, chemokine ligand 8, lymphocyte antigen 96, Rho kinase 1 (ROCK1), matrix metalloproteinase 16 (MMP16) and tissue factor inhibitor-2 under hyperglycemia-chemical hypoxia. Therefore, metformin’s dual effect in hyperglycemia-chemical hypoxia is mediated by direct effect on VEGFR1/R2 leading to activation of cell migration through MMP16 and ROCK1 upregulation, and inhibition of apoptosis by increase in phospho-ERK1/2 and FABP4, components of VEGF signaling cascades.

Hyperglycemia aggravates decrease in alpha-synuclein expression in a middle cerebral artery occlusion model

Hyperglycemia is one of the major risk factors for stroke. Hyperglycemia can lead to a more extensive infarct volume, aggravate neuronal damage after cerebral ischemia. α-Synuclein is especially abundant in neuronal tissue, where it underlies the etiopathology of several neurodegenerative diseases. This study investigated whether hyperglycemic conditions regulate the expression of α-synuclein in middle cerebral artery occlusion (MCAO)-induced cerebral ischemic injury. Male Sprague-Dawley rats were treated with streptozotocin (40 mg/kg) via intraperitoneal injection to induce hyperglycemic conditions. MCAO were performed four weeks after streptozotocin injection to induce focal cerebral ischemia, and cerebral cortex tissues were obtained 24 hours after MCAO. We confirmed that MCAO induced neurological functional deficits and cerebral infarction, and these changes were more extensive in diabetic animals compared to non-diabetic animals. Moreover, we identified a decrease in α-synuclein after MCAO injury. Diabetic animals showed a more serious decrease in α-synuclein than non-diabetic animals. Western blot and reverse-transcription PCR analyses confirmed more extensive decreases in α-synuclein expression in MCAO-injured animals with diabetic condition than these of non-diabetic animals. It is accepted that α- synuclein modulates neuronal cell death and exerts a neuroprotective effect. Thus, the results of this study suggest that hyperglycemic conditions cause more serious brain damage in ischemic brain injuries by decreasing α-synuclein expression.

ACE gene dosage determines additional autonomic dysfunction and increases renal angiotensin II levels in diabetic mice

OBJECTIVES:The present study aimed to investigate cardiovascular autonomic modulation and angiotensin II (Ang II) activity in diabetic mice that were genetically engineered to harbor two or three copies of the angiotensin-converting enzyme gene.METHODS:Diabetic and non-diabetic mice harboring 2 or 3 copies of the angiotensin-converting enzyme gene were used in the present study. Animals were divided into 4 groups: diabetic groups with two and three copies of the angiotensin-converting enzyme gene (2CD and 3CD) and the respective age-matched non-diabetic groups (2C and 3C). Hemodynamic, cardiovascular, and autonomic parameters as well as renal Ang II expression were evaluated.RESULTS:Heart rate was lower in diabetic animals than in non-diabetic animals. Autonomic modulation analysis indicated that the 3CD group showed increased sympathetic modulation and decreased vagal modulation of heart rate variability, eliciting increased cardiac sympathovagal balance, compared with all the other groups. Concurrent diabetes and either angiotensin-converting enzyme polymorphism resulted in a significant increase in Ang II expression in the renal cortex.CONCLUSION:Data indicates that a small increase in angiotensin-converting enzyme activity in diabetic animals leads to greater impairment of autonomic function, as demonstrated by increased sympathetic modulation and reduced cardiac vagal modulation along with increased renal expression of Ang II.

A comparison of the anti-diabetic potential of d-ribose-l-cysteine with insulin, and oral hypoglycaemic agents on pregnant rats.

Over 18% of pregnant women are affected by diabetes mellitus (DM) and Insulin has been the commonest drug used in its treatment. There are reports of noncompliance to insulin due to trypanophobia, with suggestions for the use of oral hypoglycaemic agents (OHAs). However, the opposing views about the benefits and risk of oral hypoglycaemic agents (OHAs) warrant a continuous search for an alternative regimen. Therefore, this study is aimed at comparing the antidiabetic effects of d-ribose-l-cysteine (riboceine) with vildagliptin, glibenclamide, metformin, glipizide and insulin in diabetes in pregnancy. Forty (40) female Sprague-Dawley (SD) rats were mated with twenty (20) male SD rats. Diabetes was induced by streptozotocin and the female SD rats were divided into 8 groups of five (5) rats each. The animals were administered either of the OHAs vildagliptin, glibenclamide, metformin, glipizide and riboceine for a period of 19 gestational days. The results showed that streptozotocin (STZ) significantly (p < 0.05) decreased the weights of the animals, increased malondialdehyde, blood glucose levels and altered reproductive hormones. These effects of STZ were better ameliorated in animals that received insulin and riboceine compared to the other OHAs. While progesterone levels were significantly (p < 0.05) higher in animals that received riboceine compared to insulin. Glibenclamide increased (p < 0.05) foetal weights compared to non-diabetic animals. In conclusion, glibenclamide may be a threat to mother`s life in the management of diabetes in pregnancy however, riboceine as well as vildagliptin, metformin and glipizide are effective oral hypoglycaemic agents which could serve as a potent adjuvant comparable to insulin in the management of diabetes during gestation.

Clinical and Pathological Assessment of Aloe Vera and Propolis for Wound Healing in Normal and Diabetic Albino Rats

The study was conducted to evaluate the role of topical application of either aloe vera gel extract or propolis ointment on wound healing in diabetic and non-diabetic animals. Ninety adult female albino rats weighing (180±200 gm) were divided into 2 groups (A; non-diabetic) and (B; diabetic), each group was further subdivided into 3 subgroups. Group A contains subgroups 1, 2 and 3 but group B contains subgroups 4, 5 and 6. Subgroups (1, 4) were experimentally punched for induction of skin wound and left untreated for 2 weeks. The wound in both subgroups (2, 5) were treated with Aloe vera extract topically daily. Subgroups (3, 6) skin wound was treated with 10% propolis ointment topically twice daily for 2 weeks. The rats were examined daily during the experiment for any abnormality or mortality rates. Blood samples were collected, besides skin wound specimen from all sacrificed rats on 3, 7, and 14 dpi for cellular immune response and histopathological examination, respectively. Both treated rats mainly (subgroup 2, 3 and 6) were responded to treatment with rapid healing which begin from 7 dpi compared to (subgroups 1, 5) which showed delayed healing. However, subgroup (4) was difficult to response to recovery until 14 dpi. It could be concluded that both propolis and Aloe vera accelerated the healing process in both diabetic and non-diabetic wounded animals.

Intrauterine hyperglycemia-induced inflammatory signalling via the receptor for advanced glycation end products in the cardiac muscle of the infants of diabetic mother rats.

Gestational diabetes is associated with increased risk to the health of the mother and her offspring. In particular, the infants of diabetic mothers (IDMs) exhibit elevated levels of preterm birth, macrosomia, hypoglycemia, hypocalcemia, and cardiomyopathy. We have previously reported that IDMs showed abnormalities in cardiac Akt-related insulin signalling, and that these deficiencies in Akt-related signalling were attenuated by supplementing the maternal diet with fish-oil. Herein, we investigated whether the eicosapentaenoic acid (EPA) found in fish oil can be used to attenuate diabetes associated impairments in cardiomyocyte signalling. Pregnant diabetic rats were administered streptozotocin before receiving EPA or water, and their infants were designated IDM/EPA, IDM/W. We assessed the potential molecular pathway for this effect in the primary cardiac cell from newborn rat hearts. Insulin resistance as determined by diminished GLUT4 translocation following insulin stimulation, the levels of advanced glycation end products (AGEs) and reactive oxygen species were elevated in the neonatal hearts of IDM/W compared with that seen in the offspring born from non-diabetic control animals. Similarly, the receptor of AGEs (RAGE) mRNA levels, reactive oxygen species and the amount of nuclear factor-κB (NF-κB), tumor necrosis factor-α (TNF-α), and interleukin 6 (IL-6) mRNA were higher in the hearts from the IDM/W when compared to that observed in the hearts of offspring born to non-diabetic animals. These deleterious effects of gestational diabetes were significantly decreased in the offspring of diabetic mothers receiving EPA supplementation. Taken together, our data suggest that the EPA in fish oil may improve the impaired signalling and the excessive protein glycation in the cardiac muscles of infants exposed to intrauterine hyperglycemia.

Enhanced adhesion of blood platelets to intact endothelium of mesenteric vascular bed in mice with streptozotocin-induced diabetes is mediated by an up-regulated endothelial surface deposition of VWF – In vivo study

Numerous in vitro experiments have confirmed that a dysfunctional endothelium is characterized by, inter alia, a higher affinity for binding of platelets and leukocytes. However, there is still no direct evidence for greater interaction between platelets and intact endothelium in in vivo animal models of diabetes. Therefore, the present study examines the pro-adhesive properties of endothelium change in vivo as an effect of streptozotocin (STZ)-induced diabetes and the role of two key platelet receptors: GPIb-IX-V and GPIIb/IIIa.Mice of C57BL strain with streptozotocin-induced diabetes were used in the study. Flow cytometry was used to assess basal activation and reactivity of platelets. Adhesion of platelets to the vascular wall was visualized with the use of intravital microscopy in mesentery. The contribution of GPIIb/IIIa and GPIb-IX-V was evaluated by the injection of Fab fragments of respective antibodies. The integrity of the endothelium and vWf expression were evaluated histochemically.Basal activation and reactivity of platelets in streptozotocin-diabetic mice were elevated. Blood platelets adhered more often to the vascular wall of diabetic mice than nondiabetic animals: 11.9 (6.4; 32.8) plt/min/mm2 (median [IQR]) vs 2.7 (1.3; 6.4) plt/min/mm2. The injection of anti-GPIbα antibodies decreased the number of adhering platelets from 89.5 (34.0; 113.1) plt/min/mm2 (median [IQR]) in mice treated with isotype antibodies to 3.1 (1.7; 5.6) plt/min/mm2 in mice treated with blocking antibodies. The effect of GPIIb/IIIa blockage was not significant. Immunohistochemistry revealed a higher expression of vWF in the endothelium of STZ mice, but no substantial changes in endothelial morphology were detected.To conclude, the study shows that the platelets interact more frequently with the mesenteric vascular bed in mice with 1-month STZ-induced diabetes than in healthy mice. These interactions are mediated via platelet GPIb-IX-V and are driven by increased expression of vWF in endothelial cells.

Impaired Rhodopsin Generation in the Rat Model of Diabetic Retinopathy

Diabetic retinopathy is a common complication of diabetes mellitus. Diabetic patients experience functional deficits in dark adaptation, contrast sensitivity, and color perception before microvascular pathologies become apparent. Herein, we evaluated early changes in neural retinal function and in retinoid metabolism in the eye in diabetes. Streptozotocin-induced diabetic rats showed decreased a- and b-wave amplitudes of scotopic and photopic electroretinography responses 4 months after diabetes induction compared to nondiabetic controls. Although Western blot analysis revealed no difference in opsin expression, rhodopsin content was decreased in diabetic retinas, as shown by a difference in absorbance. Consistently, levels of 11-cis-retinal, the chromophore for visual pigments, were significantly lower in diabetic retinas compared to those in controls, suggesting a retinoid deficiency. Among visual cycle proteins, interphotoreceptor retinoid-binding protein and stimulated by retinoic acid 6 protein showed significantly lower levels in diabetic rats than those in nondiabetic controls. Similarly, serum levels of retinol-binding protein 4 and retinoids were significantly lower in diabetic rats. Overall, these results suggest that retinoid metabolism in the eye is impaired in type 1 diabetes, which leads to deficient generation of visual pigments and neural retinal dysfunction in early diabetes.

A bioluminescent Pseudomonas aeruginosa wound model reveals increased mortality of type 1 diabetic mice to biofilm infection.

To examine how bacterial biofilms, as contributing factors in the delayed closure of chronic wounds in patients with diabetes, affect the healing process. We used daily microscopic imaging and the IVIS Spectrum in vivo imaging system to monitor biofilm infections of bioluminescent Pseudomonas aeruginosa and evaluate healing in non-diabetic and streptozotocin-induced diabetic mice. Our studies determined that diabetes alone did not affect the rate of healing of full-depth murine back wounds compared with non-diabetic mice. The application of mature biofilms to the wounds significantly decreased the rate of healing compared with non-infected wounds for both non-diabetic as well as diabetic mice. Diabetic mice were also more severely affected by biofilms displaying elevated pus production, higher mortality rates and statistically significant increase in wound depth, granulation/fibrosis and biofilm presence. Introduction of a mutant Pseudomonas aeruginosa capable of producing high concentrations of cyclic di-GMP did not result in increased persistence in either diabetic or non-diabetic animals compared with the wild type strain. Understanding the interplay between diabetes and biofilms may lead to novel treatments and better clinical management of chronic wounds.

Podocyte-specific knockout of cyclooxygenase 2 exacerbates diabetic kidney disease.

Enhanced expression of cyclooxygenase 2 (COX2) in podocytes contributes to glomerular injury in diabetic kidney disease, but some basal level of podocyte COX2 expression might be required to promote podocyte attachment and/or survival. To investigate the role of podocyte COX2 expression in diabetic kidney disease, we deleted COX2 specifically in podocytes in a mouse model of Type 1 diabetes mellitus (Akita mice). Podocyte-specific knockout (KO) of COX2 did not affect renal morphology or albuminuria in nondiabetic mice. Albuminuria was significantly increased in wild-type (WT) and KO Akita mice compared with nondiabetic controls, and the increase in albuminuria was significantly greater in KO Akita mice compared with WT Akita mice at both 16 and 20 wk of age. At the 20-wk time point, mesangial expansion was also increased in WT and KO Akita mice compared with nondiabetic animals, and these histologic abnormalities were not improved by KO of COX2. Tubular injury was seen only in diabetic mice, but there were no significant differences between groups. Thus, KO of COX2 enhanced albuminuria and did not improve the histopathologic features of diabetic kidney disease. These data suggest that 1) KO of COX2 in podocytes does not ameliorate diabetic kidney disease in Akita mice, and 2) some basal level of podocyte COX2 expression in podocytes is necessary to attenuate the adverse effects of diabetes on glomerular filtration barrier function.

Effect of non-coherent infrared light (LED, λ945±20nm) on bone repair in diabetic rats-morphometric and spectral analyses.

Phototherapy using coherent light (lasers) and non-coherent light (light-emitting diodes (LEDs)) has been investigated for the purpose of biomodulation in biological tissues. Several effects can be expected, including pain moderation, biostimulation of cellular tropism, anti-inflammatory effects, regular circulatory stimulation, and tissue repair. The aim of this study was to evaluate the effect of LED (λ945±20nm, 48mW) therapy on the regeneration process in femoral lesions of rats (Wistar). Seven irradiation sessions were held, with a 48-h interval between sessions. The animals were euthanised 14, 21, and 28days after surgery. Bone samples were analysed by histomorphometry, micro X-ray fluorescence spectroscopy, scanning electron microscopy, and optical densitometry. The results demonstrated the effective positive influence of low-intensity LED therapy using the near-infrared region on the tissue repair process in diabetic animals, especially in the early stages of repair (14 and 21days after surgery). It can be concluded that LED therapy positively influences bone formation in the early stages of the bone repair process in non-diabetic and diabetic animals, without causing changes in the optical density and volume of tissue in the final stages. No influence of LED therapy was observed on the percentage of calcium, percentage of phosphorus, Ca/P ratio, or optical mineral density in non-diabetic animals. However, increased mineral concentration was evident in the diabetic animals treated with the LED during the repair process.

Microvascular vasodilator properties of the angiotensin II type 2 receptor in a mouse model of type 1 diabetes

Diabetes Mellitus is associated with severe cardiovascular disorders involving the renin-angiotensin system, mainly through activation of the angiotensin II type 1 receptor (AT1R). Although the type 2 receptor (AT2R) opposes the effects of AT1R, with vasodilator and anti-trophic properties, its role in diabetes is debatable. Thus we investigated AT2R-mediated dilatation in a model of type 1 diabetes induced by streptozotocin in 5-month-old male mice lacking AT2R (AT2R−/y). Glucose tolerance was reduced and markers of inflammation and oxidative stress (cyclooxygenase-2, gp91phox p22phox and p67phox) were increased in AT2R−/y mice compared to wild-type (WT) animals. Streptozotocin-induced hyperglycaemia was higher in AT2R−/y than in WT mice. Arterial gp91phox and MnSOD expression levels in addition to blood 8-isoprostane and creatinine were further increased in diabetic AT2R−/y mice compared to diabetic WT mice. AT2R-dependent dilatation in both isolated mesenteric resistance arteries and perfused kidneys was greater in diabetic mice than in non-diabetic animals. Thus, in type 1 diabetes, AT2R may reduce glycaemia and display anti-oxidant and/or anti-inflammatory properties in association with greater vasodilatation in mesenteric arteries and in the renal vasculature, a major target of diabetes. Therefore AT2R might represent a new therapeutic target in diabetes.

Effects of local vanadium delivery on diabetic fracture healing.

This study evaluated the effect of local vanadyl acetylacetonate (VAC), an insulin mimetic agent, upon the early and late parameters of fracture healing in rats using a standard femur fracture model. Mechanical testing, and radiographic scoring were performed, as well as histomorphometry, including percent bone, percent cartilage, and osteoclast numbers. Fractures treated with local 1.5 mg/kg VAC possessed significantly increased mechanical properties compared to controls at 6 weeks post-fracture, including increased torque to failure (15%; p = 0.046), shear modulus (89%; p = 0.043), and shear stress (81%; p = 0.009). The radiographic scoring analysis showed increased cortical bridging at 4 weeks and 6 weeks (119%; p = 0.036 and 209%; p = 0.002) in 1.5 mg/kg VAC treated groups. Histomorphometry of the fracture callus at days 10 and 14 showed increased percent cartilage (121%; p = 0.009 and 45%; p = 0.035) and percent mineralized tissue (66%; p = 0.035 and 58%; p = 0.006) with local VAC treated groups compared to control. Additionally, fewer osteoclasts were observed in the local VAC treated animals as compared to controls at day 14 (0.45% ± 0.29% vs. 0.83% ± 0.36% of callus area; p = 0.032). The results suggest local administration of VAC acts to modulate osteoclast activity and increase percentage of early callus cartilage, ultimately enhancing mechanical properties comparably to non-diabetic animals treated with local VAC. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2174-2180, 2017.

Diabetes alters myelin lipid profile in rat cerebral cortex: Protective effects of dihydroprogesterone

Due to the emerging association of diabetes with several psychiatric and neurodegenerative events, the evaluation of the effects of this pathology on the brain function has now a high priority in biomedical research. In particular, the effects of diabetes on myelin compartment have been poorly taken into consideration. To this purpose, we performed a deep lipidomic analysis of cortical myelin in the streptozotocin-induced diabetic rat model. In male rats three months of diabetes induced an extensive alterations in levels of phosphatidylcholines and phosphatidylethanolamines (the main species present in myelin membranes), plasmalogens as well as phosphatidylinositols and phosphatidylserines. In addition, the levels of cholesterol and myelin basic protein were also decreased. Because these lipids exert important functional and structural roles in the myelin compartment, our data indicate that cerebral cortex myelin is severely compromised in diabetic status. Treatment for one-month with a metabolite of progesterone, dihydroprogesterone, restored the lipid and protein myelin profiles to the levels observed in non-diabetic animals. These data suggest the potential of therapeutic efficacy of DHP to restore myelin in the diabetic brain.

Hair corticosterone measurement in mouse models of type 1 and type 2 diabetes mellitus

In diabetes, glucocorticoid secretion increases secondary to hyperglycemia and is associated with an extensive list of disease complications. Levels of cortisol in humans, or corticosterone in rodents, are usually measured as transitory biomarkers of stress in blood or saliva. Glucocorticoid concentrations accumulate in human or animal hair over weeks and could more accurately measure the cumulative stress burden of diseases like chronic diabetes. In this study, corticosterone levels were measured in hair in verified rodent models of diabetes mellitus. To induce type 1 diabetes, C57BL/6J mice were injected with streptozotocin and blood and hair samples were collected 28days following induction. Leptin receptor deficient (db/db) mice were used as a spontaneous model of type 2 diabetes and blood and hair samples were collected at 8weeks of age, after the development of hyperglycemia and obesity. Corticosterone levels from serum, new growth hair and total growth hair were analyzed using an enzyme immunoassay. Corticosterone levels in new growth hair and serum were significantly elevated in both models of diabetes compared to controls. In contrast, corticosterone levels in old hair growth did not differ significantly between diabetic and non-diabetic animals. Thus, hair removal and sampling of new hair growth was a more sensitive procedure for detecting changes in hair corticosterone levels induced by periods of hyperglycemia lasting for 4weeks in mice. These results validate the use of hair to measure long-term changes in corticosterone induced by diabetes in rodent models. Further studies are now needed to validate the utility of hair cortisol as a tool for measuring the stress burden of individuals with diabetes and for following the effects of long-term medical treatments.

Murine strain differences in inflammatory angiogenesis of internal wound in diabetes.

Genetic susceptibility is associated with inflammation, neovascularization, and diabetes phenotypes. However, to what extent this susceptibility influences inflammatory angiogenesis in internal injuries in diabetes has not been fully investigated. Using the subcutaneous implantation of a synthetic matrix as an internal wound model in Swiss, C57BL/6 and Balb/c mice, we have studied inflammation, angiogenesis, and cytokine production in the fibrovascular tissue induced by implants in diabetic animals. The hyperglycemic levels (mg/dl) after the diabetogenic treatment were 455.0±15 in Swiss, 393.0±22 in C57BL/6, and 190.0±10 in Balb/c mice. Angiogenesis in Swiss implants from non-diabetic animals were higher than those in the implants from the other strains. However, the angiogenic inducers VEGF and nitric oxide (NO) were higher in implants from non-diabetic Swiss and Balb/c mice. Strain-related differences were also observed in the angiogenic parameters in implants from diabetic mice. Hb content and number of vessels decreased more than 40% in Swiss implants. In contrast, Hb content did not alter in implants from Balb/c diabetic mice and the number of vessels decreased. VEGF levels increased in implants from Swiss and C57BL/6 diabetic mice, but decreased in Balb/c implants. The levels of pro-inflammatory markers intra-implant also varied among the strains in both conditions. In the hyperglycemic environment, almost all inflammatory markers increased in implants from diabetic Swiss mice. These findings demonstrate the major contribution of genetic background in the pattern of inflammatory angiogenesis components of internal injury, in both normoglycemic and hyperglycemic animals.

Hyperglycemia reduces PP2A subunit B expression in a middle cerebral artery occlusion animal model.

Diabetes is a metabolic disorder that worsens clinical outcome following cerebral ischemia. Protein phosphatase 2A (PP2A) is a conserved, heterotrimeric, serine/threonine phosphatase with various cellular functions. PP2A subunit B is abundant in brain tissue and modulates PP2A function. The aim of this study was to investigate PP2A subunit B protein expression in the cerebral cortex of non-diabetic and diabetic animals with middle cerebral artery occlusion (MCAO) injury. Sprague-Dawley rats were injected with streptozotocin (40 mg/kg, i.p.) to induce diabetic conditions. After 4 weeks of streptozotocin treatment, the rats underwent MCAO to induce focal cerebral ischemia. The cerebral cortex tissue was collected 24 hr after MCAO. Body weight and blood glucose were measured, and Western blot analysis was performed to elucidate the expression of PP2A subunit B. We confirmed decreased body weight and increased blood glucose in diabetic animals. Reverse transcription-PCR and Western blot analyses showed decreased PP2A subunit B expression in the cerebral cortices of MCAO-injured animals. Moreover, diabetic animals with MCAO showed more severe decreases in PP2A subunit B protein levels than non-diabetic animals following MCAO. The decline of PP2A subunit B indicates degradation of neuronal function. These findings suggest that conspicuous decreases in PP2A subunit B may exacerbate cerebral ischemia under diabetic conditions following MCAO.

Hyperglycemia aggravates decreases of PEA-15 and its two phosphorylated forms in cerebral ischemia.

Diabetes is a metabolic health disorder and an important risk factor for stroke. Phosphoprotein enriched in astrocytes 15 (PEA-15) is a multifunctional protein modulating cell proliferation, survival, apoptosis and glucose metabolism. This study investigated whether diabetes modulates the expression of PEA-15 and two phosphorylated forms (Ser 104 and Ser 116) in middle cerebral artery occlusion (MCAO)-induced brain injury. Male Sprague-Dawley rats were administrated with streptozotocin (40 mg/kg) and were underwent right middle cerebral artery occlusion (MCAO) 4 weeks after streptozotocin injection. Brain tissues were collected 24 hr after MCAO and stained using triphenyltetrazolium chloride. Western blot analysis was performed to elucidate the expression of PEA-15 and two phosphorylated forms (Ser 104 and Ser 116) in right cerebral cortex. Infarct volume during MCAO injury was severely increased in diabetic animals compared to non-diabetic animals. We identified the decrease in PEA-15 in animals that underwent MCAO using proteomic approach. PEA-15 expression during MCAO was strongly decreased in diabetic animals compared to non-diabetic animals. Western blots analysis confirmed that diabetes exacerbated the decrease in PEA-15 expression after MCAO. Moreover, decrease in expression of phospho-PEA-15 (Ser 104 and Ser 116) was greater in diabetic than in non-diabetic animals. These results suggested that a diabetic condition may aggravate brain damage through decreasing expression of PEA-15 and phospho-PEA-15 (Ser 104 and Ser 116) in ischemic brain injury.

The Cardioprotective Effects of Metformin in Myocardial Infarction Patients Without Diabetes: Current Status and Future Prospects

Metformin is a first-line drug in type 2 diabetes mellitus (T2DM) treatment. Evidence is mounting that metformin can improve the long-term prognosis of myocardial infarction (MI) patients with diabetes. However, the therapeutic effect of metformin in MI patients without diabetes is a controversial subject. Some studies have revealed that metformin plays a nonsignificant role in determining the prognosis of these patients. In contrast, other clinical trials have noted that metformin plays a protective role and may have direct beneficial effects on the heart. In this review, we focus on therapeutic targets of metformin in non-diabetic MI patients. Different key mechanisms and signalling pathways that may be responsible for the cardioprotective effects of metformin are summarized. We conclude that metformin use is associated with limited MI size, preserved left ventricular (LV) function, and improved prognosis in experimental studies, including in non-diabetic MI animal models; furthermore, metformin treatment can reduce mortality and lead to improvements in some cardiovascular risk factors in non-diabetic MI patients. However, more clinical trials will be needed to clarify its effects on MI size, progression of atherosclerosis and cardiac function in these patients.

Antihyperglycemic, Antidiabetic, and Antioxidant Effects of Garcinia pedunculata in Rats.

The antihyperglycemic, antidiabetic, and antioxidant potentials of the methanolic extract of Garcinia pedunculata (GP) fruit in rats were investigated. The acute antihyperglycemic effect of different doses of GP was studied in normal male Wistar rats. Diabetes was induced by streptozotocin (STZ) injection in another cohort of male Wistar rats and they showed significantly higher blood glucose and glycated hemoglobin (HbA1c) levels, altered lipid profiles, and lower insulin levels compared to nondiabetic control animals. There were increased lipid peroxidation and reduced levels of cellular antioxidant enzymes in different tissues of diabetic rats. However, oral administration of GP extracts, especially the highest dose (1000 mg/kg), significantly ameliorated hyperglycemia (42%); elevated insulin levels (165%); decreased HbA1c (29.4%); restored lipid levels (reduction in TG by 25%, TC by 15%, and LDL-C by 75% and increase in HDL-C by 4%), liver and renal function markers, and lipid peroxidation (reduction by 52% in the liver, 39% in the kidney, 44% in the heart, and 46% in the pancreas); and stimulated tissue antioxidant enzymes to near normalcy. Overall, the findings suggest that GP fruit is effective against hyperglycemia and could be used in the treatment of diabetes and its complications and other oxidative stress-mediated pathological conditions.