Apoptosis In Diabetic Rats Research Articles

Effect of apelin-13 on myocardium apoptosis in diabetic rats

Objective To investigate the effect of exogenous apelin-13 on oxidative stress, myocardial inflammatory cytokines and apoptosis in diabetic model rats. Methods A total of 40 male Wistar rats were randomly divided into 2 groups: normal control group (NC, n=8) and experimental group (EX, n=32). Diabetes was induced by feeding with high-sugary and high-fat diet for 8 weeks and a single intraperitoneal injection of streptozotocin (STZ) (30 mg/kg). The well-established 28 diabetic model rats were then randomly divided into 2 subgroups: model group (DM, n=14) and apelin-13 administration group (AP, n=14). The rats in AP group were given intraperitoneal administration of apelin-13 at a single dose of 0.1 μmol·kg-1·d-1 for 10 weeks, while NC group and DM group were given 0.9% NaCl in the same way. All rats were sacrificed at the end of the week 10. Blood hydrogen peroxide (H2O2), nitric oxide (NO) and malonaldehyde (MDA) were measured by colorimetry, and superoxide dismutase (SOD) was measured by enzyme-linked immunosorbent assay (ELISA). The expressions of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in rat myocardium were detected by immunohistochemistry.Masson staining was used to observe the myocardial fibrosis in rats of different groups. Cardiomyocyte apoptosis was determined by TUNEL. Results (1) Compared with NC groups, DM group showed that MDA, H2O2and NO were significantly increased, while SOD was significantly decreased (F=22.400, 6.230, 4.267 and 8.901, all P<0.0167). There was a statistically significant difference in the levels of MDA, H2O2,SOD between DM group and AP group. (2) The expression of TNF-α and IL-6 was significantly higher in DM group than in NC group (0.0599±0.0208 vs. 0.0076±0.0031, F=35.139; 0.0503±0.0243 vs. 0.0071±0.0024, F=15.946, both P<0.0167). After 10 weeks of apelin-13 administration, the levels of inflammatory cytokines were significantly decreased in AP group than in DM group. (3) The myocardial apoptosis and fibrosis were significantly increased in DM group than in NC group 〔0.0293±0.0061 vs. 0.0030±0.0013 and 0.0708±0.0420 vs. 0.0013±0.0003, F=84.930 and 19.420, both P<0.0167〕. The myocardial apoptosis and fibrosis were significantly decreased in AP group than in DM group (both P<0.0167). Conclusions To some extent, apelin-13 reduces the levels of oxidative stress and myocardial inflammation reaction in type 2 diabetes. Moreover, it may play a vital role in the improvement of myocardial apoptosis and fibrosis. Key words: Diabetes mellitus; Apoptosis; Myocytes, cardiac; Adipokines

Effect of Tongxinluo on Podocyte Apoptosis via Inhibition of Oxidative Stress and P38 Pathway in Diabetic Rats.

Diabetic nephropathy (DN) has been the leading cause of end-stage renal disease (ESRD). Podocyte apoptosis is a main mechanism of progression of DN. It has been demonstrated that activated P38 and caspase-3 induced by oxidative stress mainly account for increased podocyte apoptosis and proteinuria in DN. Meanwhile, Tongxinluo (TXL) can ameliorate renal structure disruption and dysfunction in DN patients in our clinical practice. However, the effect of TXL on podocyte apoptosis and P38 pathway remains unclear. To explore the effect of TXL on podocyte apoptosis and its molecular mechanism in DN, our in vivo and in vitro studies were performed. TXL attenuated oxidative stress in podocyte in DN in our in vivo and in vitro studies. Moreover, TXL inhibited the activation of P38 and caspase-3. Bcl-2 and Bax expression was partially restored by TXL treatment in our in vivo and in vitro studies. More importantly, TXL decreased podocyte apoptosis in diabetic rats and high glucose cultured podocyte. In conclusion, TXL protects podocyte from apoptosis in DN, partially through its antioxidant effect and inhibiting of the activation of P38 and caspase-3.

Subconjunctivally Implanted Hydrogels for Sustained Insulin Release to Reduce Retinal Cell Apoptosis in Diabetic Rats.

Diabetic retinopathy (DR) is a leading cause of blindness in diabetic patients that involves early-onset retinal cell loss. Here, we report our recent work using subconjunctivally implantable hydrogels for sustained insulin release to the retina to prevent retinal degeneration. The hydrogels are synthesized by UV photopolymerization of N-isopropylacrylamide and a dextran macromer containing oligolactate-(2-hydroxyetheyl methacrylate) units. Insulin was loaded into the hydrogels during the synthesis. The ex vivo bioactivity of insulin released from the hydrogels was tested on fresh rat retinas using immunoprecipitation and immunoblotting to measure insulin receptor tyrosine and Akt phosphorylation. The biosafety and the effect on the blood glucose of the hydrogels were evaluated in rats 2 months after subconjunctival implantation. The release of insulin from the hydrogels was studied both in vitro in PBS (pH 7.4), and in vivo using confocal microscopy and RIA kit. The in vivo bioactivity of the released insulin was investigated in diabetic rats using DNA fragmentation method. The hydrogels could load insulin with approximately 98% encapsulation efficiency and continuously release FITC-insulin in PBS (pH = 7.4) at 37°C for at least 5 months depending on their composition. Insulin lispro released from the hydrogels was biologically active by increasing insulin receptor tyrosine and Akt serine phosphorylation of ex vivo retinas. In vivo studies showed normal retinal histology 2 months post subconjunctival implantation. Insulin released from subconjunctivally implanted hydrogels could be detected in the retina by using confocal microscopy and RIA kit for 1 week. The implanted hydrogels with insulin lispro did not change the blood glucose level of normal and diabetic rats, but significantly reduced the DNA fragmentation of diabetic retinas for 1 week. The developed hydrogels have great potential to sustain release of insulin to the retina via subconjunctival implantation to minimize DR without the risk of hypoglycemia.

Stimulation of autophagy promotes functional recovery in diabetic rats with spinal cord injury.

In this study we examined the relationship between autophagy and apoptosis in diabetic rats after spinal cord injury (SCI), also we determined the role of autophagy in diabetes-aggravated neurological injury in vivo and in vitro. Our results showed that diabetes decreased the survival of neurons, promoted astrocytes proliferation, increased inflammatory cells infiltration and inhibited functional recovery after SCI. Diabetes was shown to confer increased activation of apoptotic pathways, along with an increase in autophagy; similar effects were also observed in vitro in neuronal PC12 cells. Treatment with rapamycin, an autophagy activator, partially abolished the adverse effect of diabetes, suggesting that diabetes may enhance neurological damage and suppress locomotor recovery after SCI, in addition to its effects on apoptosis and autophagy. In contrast, further stimulation of autophagy improved neurological function via inhibition of apoptosis. These results explained how diabetes exacerbates SCI in cellular level and suggested autophagy stimulation to be a new therapeutic strategy for diabetic SCI.

Role of ERK1/2 and JNK phosphorylation in iodine contrast agent-induced apoptosis in diabetic rat kidneys

Background: The risk of contrast-induced acute kidney injury (CIAKI) is significantly increased in patients with diabetes mellitus. This study aimed to investigate molecular mechanisms of contrast media-induced apoptosis in diabetic rat kidneys, especially the involvement of ERK1/2 and JNK signal pathways. Methods: Diabetic Sprague–Dawley rats were induced by intraperitoneal injection of streptozotocin. Ten weeks later the normal and diabetic rats were administered high-osmolar contrast media (HOCM; meglumine diatrizoate) or normal saline (10 mL/kg) injection for 2 consecutive days. At 24 h after the operation, the rats were sacrificed, the blood samples were collected for examining serum creatinine and the kidneys were collected for determining the expression of caspase-3 by immunohistochemistry and the expression of Bcl-2, Bax, upstream signal molecule p-JNK, and p-ERK1/2 by western blotting. Results: The serum creatinine was significantly increased in diabetes + contrast media group (DC group) after operation compared with in the diabetic group (D group; 103.89 ± 9.01 μmol/L vs. 71.52 ± 7.03 μmol/L, p < 0.05). While creatinine clearance rate (Ccr) was significantly decreased in DC group after operation (1.49 ± 0.33 mL/min vs. 2.60 ± 0.54 mL/min, p < 0.05). Especially, in the diabetic kidney, the expression of caspase-3 was also significantly increased after intravenous injection of HOCM compared with normal saline. The expression level of upstream signal molecule p-JNK protein was apparently increased, but p-ERK1/2 protein was significantly decreased (both p < 0.05). Conclusions: The ionic HOCM-induced renal cells apoptosis in diabetic rats through activating the caspase-3 apoptotic pathway, which might be mediated by upstream MAPK (inhibiting p-ERK1/2 expression and promoting p-JNK expression) signal pathways.

Xuezhikang () reduced renal cell apoptosis in streptozocin-induced diabetic rats through regulation of Bcl-2 family.

To investigate the effect of Xuezhikang (, XZK) on renal cell apoptosis in diabetic rats and the possible mechanism. Sixty-six rats were randomly divided into 3 groups: the normal, model and XZK groups. In each group, the rats were further randomly divided into 3-month and 6-month subgroups, respectively. Diabetes of rats was induced by a single intraperitoneal injection of 1% streptozocin at 60 mg/kg body weight. Rats in the XZK group received gastric perfusion of XZK (1200 mg/kg body weight) everyday for 3 or 6 months, while rats in the normal and model groups received equal volume of saline. Twenty-four hours' urine was collected for urinary albumin excretion (UAE) measurement. Periodic acid-Schiff (PAS) and Masson's trichrome staining were used for saccharides and collagen detection. Cell apoptosis of renal cortex was investigated by TdT-mediated dUTP nick end labeling (TUNEL) staining. Bax and Bcl-2 expressions were detected by immunohistochemistry and Western blot, respectively. Cytochrome C (Cyt C) and caspase-9 concentration were detected by Western blot. Compared with the model group, XZK treatment could significantly decrease the kidney hypertrophy index, 24 h UAE, renal cell apoptosis, cytoplasmic Cyt C level and active caspase-9 level, as well as suppress the increment of Bax and up-regulate the expression of Bcl-2, leading to the suppression of Bax/Bcl-2 ratio at 3 and 6 months (P<0.05 or P<0.01). Moreover, XZK treatment could alleviate the deposition of PAS-stained saccharides and Masson's trichromestained collagen to different extent. Renal cell apoptosis was observed in diabetic kidney, in which mitochondrial apoptotic pathway might be involved. XZK treatment could attenuate pathological changes in diabetic kidney and reduce renal cell apoptosis, probably via the suppression of Bax/Bcl-2 ratio, which lead to inhibition of Cyt C release and following caspase-9 activation.

Curcumin ameliorates streptozotocin-induced liver damage through modulation of endoplasmic reticulum stress-mediated apoptosis in diabetic rats

We investigated the effect of curcumin on liver injury in diabetic rats induced by streptozotocin (STZ) through modulation of endoplasmic reticulum stress (ERS) and unfolded protein response (UPR). Experimental diabetes was induced by a single intraperitoneal injection of STZ (55 mg/kg), and curcumin was given at 100 mg/kg by gavage for 56 days. We observed that curcumin improved the morphological and histopathological changes, significantly decreased hepatic ERS marker protein: glucose-regulated protein 78, and improved liver function in diabetic rats. Moreover, treatment with curcumin markedly decreased the sub-arm of the UPR signaling protein such as phospho–double-stranded RNA-dependent protein kinase-like ER kinase, CCAAT/enhancer-binding protein homologous protein, tumor necrosis factor receptor-associated factor 2, and inositol-requiring enzyme1α; and inhibited tumor necrosis factor α, interleukin 1β, phospho-p38 mitogen-activated protein kinase, and apoptosis signal-regulating kinase 1 in liver tissues of diabetic rats. Apoptotic and anti-apoptotic signaling proteins, such as cleaved caspase-3 and B-cell lymphoma 2, were significantly increased and decreased, respectively in diabetic rats; curcumin treatment prevented all of these alterations. In summary, our results indicate that curcumin has the potential to protect the diabetic liver by modulating hepatic ERS-mediated apoptosis, and provides a novel therapeutic strategy for the diabetic liver damage.

Cytoprotective Effect of Silymarin against Diabetes-Induced Cardiomyocyte Apoptosis in Diabetic Rats

ObjectiveThe beneficial effects of silymarin have been extensively studied in the context of inflammation and cancer treatment, yet much less is known about its therapeutic effect on diabetes. The present study was aimed to investigate the cytoprotective activity of silymarin against diabetes-induced cardiomyocyte apoptosis. MethodsRats were randomly divided into: control group, untreated diabetes group and diabetes group treated with silymarin (120 mg/kg·d) for 10 d. Rats were sacrificed, and the cardiac muscle specimens and blood samples were collected. The immunoreactivity of caspase-3 and Bcl-2 in the cardiomyocytes was measured. Total proteins, glucose, insulin, creatinine, AST, ALT, cholesterol, and triglycerides levels were estimated. ResultsUnlike the treated diabetes group, cardiomyocyte apoptosis increased in the untreated rats, as evidenced by enhanced caspase-3 and declined Bcl-2 activities. The levels of glucose, creatinine, AST, ALT, cholesterol, and triglycerides declined in the treated rats. The declined levels of insulin were enhanced again after treatment of diabetic rats with silymarin, reflecting a restoration of the pancreatic β-cells activity. ConclusionThe findings of this study are of great importance, which confirmed for the first time that treatment of diabetic subjects with silymarin may protect cardiomyocytes against apoptosis and promote survival-restoration of the pancreatic β-cells.

Sitagliptin alleviated myocardial remodeling of the left ventricle and improved cardiac diastolic dysfunction in diabetic rats

ObjectiveSitagliptin, a dipeptidyl peptidase IV (DPP-Ⅳ) inhibitor, has a biological role in improving the serum levels of glucagon-like peptide 1 (GLP-1). Hence, we sought to determine the effect of sitagliptin on myocardial inflammation, collagen metabolism, lipid content and myocardial apoptosis in diabetic rats. Materials and methodsThe type 2 diabetic rat model was induced by low-dose streptozotocin and a high-fat diet. Characteristics of diabetic rats were evaluated by electrocardiography, echocardiography and blood analysis. Cardiac inflammation, fibrosis, cardiomyocyte density, lipid accumulation, and receptor-interacting protein kinase 3 (RIP3) level, related to apoptosis, were detected by histopathologic analysis, RT-PCR and western blot analysis to evaluate the effects of sitagliptin on myocardial remodeling of the left ventricle. ResultsDiabetic rats showed myocardial hypertrophy or apoptosis, inflammation, lipid accumulation, myocardial fibrosis, elevated collagen content, RIP3 overexpression, and left-ventricular dysfunction. Sitagliptin could reverse the overexpression of RIP3 and alleviate cellular apoptosis in myocardial tissues. It could significantly improve left-ventricular systolic pressure and +dp/dt max, reduce the E/E′ ratio, left ventricular end diastolic pressure, −dp/dt max and Tau in diabetic rats. ConclusionsSitagliptin might have a myocardial protective effect by inhibiting apoptosis, inflammation, lipid accumulation and myocardial fibrosis in diabetic rats, for a potential role in improving left-ventricular function in diabetes.

Curcumin enhances recovery of pancreatic islets from cellular stress induced inflammation and apoptosis in diabetic rats

The phytochemical, curcumin, has been reported to play many beneficial roles. However, under diabetic conditions, the detail mechanism of its beneficial action in the glucose homeostasis regulatory organ, pancreas, is poorly understood. The present study has been designed and carried out to explore the role of curcumin in the pancreatic tissue of STZ induced and cellular stress mediated diabetes in eight weeks old male Wistar rats. Diabetes was induced with a single intraperitoneal dose of STZ (65mg/kg body weight). Post to diabetes induction, animals were treated with curcumin at a dose of 100mg/kg body weight for eight weeks. Underlying molecular and cellular mechanism was determined using various biochemical assays, DNA fragmentation, FACS, histology, immunoblotting and ELISA. Treatment with curcumin reduced blood glucose level, increased plasma insulin and mitigated oxidative stress related markers. In vivo and in vitro experimental results revealed increased levels of proinflammatory cytokines (TNF-α, IL1-β and IFN-γ), reduced level of cellular defense proteins (Nrf-2 and HO-1) and glucose transporter (GLUT-2) along with enhanced levels of signaling molecules of ER stress dependent and independent apoptosis (cleaved Caspase-12/9/8/3) in STZ administered group. Treatment with curcumin ameliorated all the adverse changes and helps the organ back to its normal physiology. Results suggest that curcumin protects pancreatic beta-cells by attenuating inflammatory responses, and inhibiting ER/mitochondrial dependent and independent pathways of apoptosis and crosstalk between them. This uniqueness and absence of any detectable adverse effect proposes the possibility of using this molecule as an effective protector in the cellular stress mediated diabetes mellitus.

Insulin-like growth factor-1 inhibits colonic smooth muscle cell apoptosis in diabetic rats with colonic dysmotility

Cellular apoptosis and colonic dysmotility are involved in diabetes mellitus (DM) complications. Insulin-like growth factor-1 (IGF-1) is known to affect apoptosis and proliferation. Here, we demonstrated that the treatment of 1500ng/kg IGF-1 partly recovers the decrease of the muscle thickness, body weight and gastrointestinal transit rate in DM rats. The gastrointestinal transit rate is positively correlated with the IGF-I level, but negatively correlated with the level of colonic cellular apoptosis. The DM-induced colonic apoptosis is also attenuated by the IGF-1 stimulation. Moreover, IGF-1 inhibits the apoptosis of the isolated colonic SMCs in vitro via the activation of PI3K/Akt and ERK1/2 signaling pathways. Taken together, our data indicated that IGF-1 inhibits the DM-induced colonic SMC apoptosis and might be involved in the alleviation of colonic dysmotility in diabetic rats.

Fish oil modulates glycogen synthase kinase-3 signaling pathway in diabetes-induced hippocampal neurons apoptosis

Previous research has demonstrated that diabetes induces learning and memory deficits. However, the mechanism of memory impairment induced by diabetes is poorly understood. Dietary fatty acids, especially polyunsaturated fatty acids, have been shown to enhance learning and memory and prevent memory deficits in various experimental conditions. The present study investigated the effects of fish oil supplementation on the neuron apoptosis in the hippocampus of streptozotocin (STZ)-induced diabetes rats, further explored the effect of fish oil on the phosphorylation of protein kinase B and glycogen synthase kinase-3 beta. The effects of diabetes and fish oil treatment on the spatial learning and memory were also evaluated using the Morris Water Maze. STZ-induced diabetes impaired spatial learning and memory of rats, which was associated with the apoptosis of hippocampal neurons and oxidative stress. Fish oil administration ameliorated cognitive deficit, reduced oxidative stress, increased AKT phosphorylation, decreased GSK-3β phosphorylation, and decreased pro-apoptotic molecules expression, which protected the hippocampal neurons from apoptosis in diabetic rats. These results suggested a potential role for fish oil as an adjuvant therapy for the prevention and treatment of diabetic complications.

Berberine reduces ischemia/reperfusion-induced myocardial apoptosis via activating AMPK and PI3K–Akt signaling in diabetic rats

Diabetes increases the risk of cardiovascular diseases. Berberine (BBR), an isoquinoline alkaloid used in Chinese medicine, exerts anti-diabetic effect by lowering blood glucose and regulating lipid metabolism. It has been reported that BBR decreases mortality in patients with chronic congestive heart failure. However, the molecular mechanisms of these beneficial effects are incompletely understood. In the present study, we sought to determine whether BBR exerts cardioprotective effect against ischemia/reperfusion (I/R) injury in diabetic rats and the underlying mechanisms. Male Sprague-Dawley rats were injected with low dose streptozotocin and fed with a high-fat diet for 12 weeks to induce diabetes. The diabetic rats were intragastrically administered with saline or BBR (100, 200 and 400 mg/kg/d) starting from week 9 to 12. At the end of week 12, all rats were subjected to 30 min of myocardial ischemia and 3 h of reperfusion. BBR significantly improved the recovery of cardiac systolic/diastolic function and reduced myocardial apoptosis in diabetic rats subjected to myocardial I/R. Furthermore, in cultured neonatal rat cardiomyocytes, BBR (50 μmol/L) reduced hypoxia/reoxygenation-induced myocardial apoptosis, increased Bcl-2/Bax ratio and decreased caspase-3 expression, together with enhanced activation of PI3K-Akt and increased adenosine monophosphate-activated protein kinase (AMPK) and eNOS phosphorylation. Pretreatment with either PI3K/Akt inhibitor wortmannin or AMPK inhibitor Compound C blunted the anti-apoptotic effect of BBR. Our findings demonstrate that BBR exerts anti-apoptotic effect and improves cardiac functional recovery following myocardial I/R via activating AMPK and PI3K-Akt-eNOS signaling in diabetic rats.

Down-Regulation of PERK-ATF4-CHOP Pathway by Astragaloside IV is Associated with the Inhibition of Endoplasmic Reticulum Stress-Induced Podocyte Apoptosis in Diabetic Rats

Background: Endoplasmic reticulum (ER) stress-induced podocyte apoptosis plays a critical role in the development of diabetic nephropathy (DN). Here, we tested the hypothesis that suppression of PERK-ATF4-CHOP pathway by Astragaloside IV (AS-IV) is associated with inhibition of ER stress-induced podocyte apoptosis in streptozotocin (STZ)-induced diabetic rats. Methods: Diabetic rats were treated with AS-IV at 5 and 10 mg· kg^-1· d^-1, p.o., for 12 weeks. Albuminuria examination, hematoxylin & eosin staining and TUNEL analysis were performed. Immunohistochemistry, western blot, and real-time PCR were used to detect renal expression of ER chaperone GRP78 and ER-associated apoptosis proteins. Results: Treatment with AS-IV ameliorated albuminuria and renal histopathology in diabetic rats. Diabetic rats had significant increment in podocyte apoptosis as well as phosphorylated PERK and eIF2α in the kidneys, which were attenuated by AS-IV treatment. Furthermore, diabetic rats were found to have increased protein and mRNA expressions of GRP78 and ER-associated apoptosis proteins, such as ATF4, CHOP and TRB3, which were also attenuated by AS-IV treatment. Increased Bax expression and decreased Bcl-2 expression were detected in diabetic rats, and these changes were partially restored by AS-IV treatment. Conclusion: The protective effect of AS-IV on ER stress-induced podocyte apoptosis is associated with inhibition of PERK-ATF4-CHOP pathway. Down-regulation of PERK- ATF4-CHOP pathway by AS-IV may be a novel strategy for the treatment of DN.

Atorvastatin ameliorates contrast medium-induced renal tubular cell apoptosis in diabetic rats via suppression of Rho-kinase pathway

Contrast medium-induced acute kidney injury (CI-AKI) remains a leading cause of iatrogenic, drug-induced acute renal failure. This study aimed to investigate the protective effects of atorvastatin against renal tubular cell apoptosis in diabetic rats and the related mechanisms. CI-AKI was induced by intravenous administration of iopromide (12ml/kg) in streptozotocin-induced diabetic rats. Atorvastatin (ATO) was administered intragastrically at the dose of 5, 10 and 30mg/kg/d in different groups, respectively, for 5 days before iopromide injection. Renal function parameters, kidney histology, renal tubular cell apoptosis, the expression of apoptosis regulatory proteins, caspase-3 and Rho-associated protein kinase 1 (ROCK-1), and the phosphorylation of myosin phosphatase target subunit -1 (MYPT-1), were determined. Atorvastatin was shown to notably ameliorate contrast medium induced medullary damage, restore renal function, and suppress renal tubular apoptosis. Meanwhile, atorvastatin up-regulated the expression of Bcl-2, down-regulated the expression of Bax, caspase-3 and ROCK-1, restored the ratio of Bcl-2/Bax, and suppressed the phosphorylation of MYPT-1 in a dose-dependent manner. Thus, atorvastatin pretreatment could dose-dependently ameliorate the development of CI-AKI, which was partly attributed to its suppression of renal tubular cell apoptosis by inhibiting the Rho/ROCK pathway.

Altered expression of mitofusin 2 in penile tissues of diabetic rats

Diabetic erectile dysfunction (ED) is a common complication in diabetes mellitus, and the efficacy of first-line therapies is not satisfactory. Recent studies revealed that corporal apoptosis was responsible for the nonresponsiveness of severe ED to phosphodiesterase type 5 inhibitors. Mitofusin 2 (Mfn2) is a versatile protein, regulating mitochondrial morphology and playing an important role in apoptosis. Several studies showed that expression of Mfn2 was decreased in STZ-induced diabetic rats' kidney, myocardium and retina, which was associated with diabetic nephropathy, cardiomyopathy and retinopathy respectively. In this study, our aim was to explore the expression of Mfn2 and apoptosis in diabetic rats' penes. We found that erectile function (ICP/MAP) elicited by electrical stimulation of cavernous nerve was markedly impaired in diabetic rats compared with the normal rats. The mRNA and protein levels of Mfn2 were found to be significantly reduced in diabetic rats' penile tissues. Compared with normal rats, the content of smooth muscle and B-cell lymphoma 2 (Bcl-2)/Bcl-2-associated X protein (Bax) ratio were dramatically decreased, and penile apoptotic index and expression of activated-caspase-3 were dramatically increased in diabetic rats. This data indicated that repression of Mfn2 in diabetic rats' penes might be associated with excessive apoptosis in diabetes-induced severe ED.

Hesperetin rescues retinal oxidative stress, neuroinflammation and apoptosis in diabetic rats

The purpose of the study was to evaluate the effects of hesperetin (Hsp) on diabetes-induced retinal oxidative stress, neuroinflammation and apoptosis in rats. The Hsp treatment (100mg/kg body weight) was carried for twenty four weeks in STZ-induced diabetic rats and evaluated for antioxidant (Superoxide dismutase; SOD, Catalase; CAT and glutathione; GSH) enzymes, inflammatory cytokines (TNF-α, IL-1β), caspase-3, glial fibrillary acidic protein (GFAP) and aquaporin-4(AQP4) expression. Histological changes were evaluated by light and transmission electron microscopic (LM and TEM) studies. Retinal GSH levels and anti-oxidant enzymes (SOD and CAT) activity were significantly decreased in diabetic group as compared to normal group. However, in Hsp-treated rats, retinal GSH levels were restored close to normal levels and positive modulation of anti-oxidant enzyme activity was observed. Diabetic retinae showed significantly increased expression of Pro-inflammatory cytokines (TNF-α and IL-1β) as compared to normal retinae. While Hsp-treated retinae showed significantly lower levels of cytokines as compared to diabetic retinae. Diabetic retinae showed increased caspase-3, GFAP and AQP4 expression. However, Hsp-treated retinae showed inhibitory effect on caspase-3, GFAP and AQP4 expression. LM images showed edematous Müller cell endfeet, and also degenerated photoreceptor layer; however, protective effect of Hsp was seen on Müller cell processes and photoreceptors. TEM study showed increased basement membrane (BM) thickness in diabetic retina, while relatively thin BM was recorded in Hsp-treated retina. It can be postulated that dietary flavanoids, like Hsp, can be effective for the prevention of diabetes induced neurovascular complications such as diabetic retinopathy.

LUTEOLIN LIMITS INFARCT SIZE AND IMPROVES CARDIAC FUNCTION AFTER MYOCARDIUM ISCHAEMIA/

ObjectivesThe present study was to investigate the effects and mechanism of Luteolin on myocardial infarct size, cardiac function and cardiomyocyte apoptosis in diabetic rats with myocardial ischaemia/reperfusion (I/R) injury.MethodsDiabetic rats...

Luteolin Limits Infarct Size and Improves Cardiac Function after Myocardium Ischemia/Reperfusion Injury in Diabetic Rats

Background The present study was to investigate the effects and mechanism of Luteolin on myocardial infarct size, cardiac function and cardiomyocyte apoptosis in diabetic rats with myocardial ischemia/reperfusion (I/R) injury.Methodology/Principal FindingsDiabetic rats underwent 30 minutes of ischemia followed by 3 h of reperfusion. Animals were pretreated with or without Luteolin before coronary artery ligation. The severity of myocardial I/R induced LDH release, arrhythmia, infarct size, cardiac function impairment, cardiomyocyte apoptosis were compared. Western blot analysis was performed to elucidate the target proteins of Luteolin. The inflammatory cytokine production were also examined in ischemic myocardium underwent I/R injury. Our results revealed that Luteolin administration significantly reduced LDH release, decreased the incidence of arrhythmia, attenuated myocardial infarct size, enhanced left ventricular ejection fraction and decreased myocardial apoptotic death compared with I/R group. Western blot analysis showed that Luteolin treatment up-regulated anti-apoptotic proteins FGFR2 and LIF expression, increased BAD phosphorylation while decreased the ratio of Bax to Bcl-2. Luteolin treatment also inhibited MPO expression and inflammatory cytokine production including IL-6, IL-1a and TNF-a. Moreover, co-administration of wortmannin and Luteolin abolished the beneficial effects of Luteolin.Conclusions/SignificanceThis study indicates that Luteolin preserves cardiac function, reduces infarct size and cardiomyocyte apoptotic rate after I/R injury in diabetic rats. Luteolin exerts its action by up-regulating of anti-apoptotic proteins FGFR2 and LIF expression, activating PI3K/Akt pathway while increasing BAD phosphorylation and decreasing ratio of Bax to Bcl-2.

Diazoxide inhibits aortic endothelial cell apoptosis in diabetic rats via activation of ERK

Endothelial cell (EC) survival is critical in the maintenance of endothelial function as well as in the regulation of angiogenesis and vessel integrity since endothelial dysfunction is the initial lesion of atherosclerosis. The goal of this study was to examine the effect of diazoxide, a mitochondrial ATP-sensitive K(+)(mito K(ATP)) channel opener, on aorta ECs apoptosis and its potential mechanism in Otsuka Long-Evans Tokushima Fatty (OLETF) rats at prediabetic stage. Diazoxide (25 mg kg(-1) day(-1)) was administered intraperitoneally from age 8 weeks to age 30 weeks. Thoracic aorta and cultured thoracic aortic ECs were used. The thickening of thoracic aortic wall and apoptosis of ECs were markedly increased in OLETF rats early from the age of 16 weeks, at the impaired glucose tolerance stage, compared with Long-Evans Tokushima Otsuka rats, in conjunction with intimal hyperplasia and perivascular fibrosis. In contrast, diazoxide treatment inhibited these changes. Further study strongly demonstrated that extracellular signal-regulated kinases (ERKs) are key regulatory proteins in protecting ECs from apoptosis. Diazoxide could significantly enhance phosphorylation of ERK via opening mito K(ATP) channels. This role was reversed by both 5-hydroxydecanoate, selectively closing mito K(ATP) channels, and PD-98509, MEK inhibitors. The present studies demonstrate that diazoxide prevents the onset and development of macrovascular disease in OLETF rats by inhibiting apoptosis directly via phosphorylated ERK increase in aorta ECs. Our findings establish the basis for the therapeutic potential of diazoxide in atherosclerotic disease.