Injection Of Streptozocin Research Articles

Modeling of age-dependent disorders: relationship between the nervous and endocrine systems

Age-dependent disorders are a challenging problem of modern society. Among the most significant age-dependent disorders are Alzheimer's disease (AD), diabetes, metabolic syndrome, etc.; these conditions may be associated to each other and have, at least in part, an interconnecting character. An experimental model of AD induced by intracerebroventricular administration of streptozocin (STZ) mimics some key characteristics of sporadic AD, altering insulin metabolism. The aim of this work was to study glucose metabolism in rats at different periods after intracerebroventricular injection of STZ. To obtain an AD model, STZ in a 0.9% NaCl solution at a dose of 3 mg/kg in 10 μl was administered bilaterally in the brain lateral ventricles on stereotaxic operations. Two and seven weeks after the administration, the weight of the animals was determined, and the glucose levels in tail vein whole blood after intraperitoneal glucose administration at a dose of 1.5 g/kg was measured. A standard glucose tolerance test was performed, and hyperglycemic and postglycemic ratios were calculated. As a result, an impairment of glucose metabolism in rats 7 weeks after intracerebroventricular application of STZ was detected for the first time. Close connection of Alzheimertype neurodegenerative changes and glucose metabolism revealed on this model allows using it for deeper assessment of relationships between the nervous and endocrine systems, including translational studies of novel therapeutic strategies.

Aerobic Exercise Training Alleviates Renal Injury by Interfering with Mitochondrial Function in Type-1 Diabetic Mice.

BackgroundDiabetic nephropathy was one of the most serious and harmful diabetic complications, characterized by progressive loss of renal function and renal fibrosis. Aerobic exercise training is an important non-pharmacologic method to prevent and treat diabetes mellitus and diabetic complications.Material/MethodsIntraperitoneal (i.p.) injection of streptozocin (STZ) was used to construct a type 1 diabetic mouse model. Renal function and mitochondrial function were measured by urinary protein level, Masson staining and ATP, superoxide production, and membrane potential, respectively. The purpose of the research was to explore the effect of aerobic exercise training on renal and renal mitochondrial function, as well as the expression of Sirt1and PGC1α in type-1 diabetic mice.ResultsSedentary diabetic mice exhibited increased urinary protein level, blood glucose, and collagen deposition in renal tissues compared with sedentary control mice, which were significantly mitigated by aerobic exercise training. Diabetic mice displayed renal tissue mitochondrial dysfunction (decreased mitochondrial ATP production and membrane potential), as well as increased mitochondrial superoxide production, which were reversed by aerobic exercise. By using Western blot analysis, we identified the decreased expression of Sirt1 and PGC1α in the renal tissue of diabetic mice, which were partly reversed by aerobic exercise training. Data showed that silencing of Sirt1 abrogated the beneficial effect of aerobic exercise training against diabetes-induced mitochondrial abnormalities and renal damage in mice.ConclusionsAerobic exercise training alleviates diabetes-induced renal injury by improving mitochondrial function.

Astrocyte elevated gene-1 induces autophagy in diabetic cardiomyopathy through upregulation of KLF4.

Astrocyte elevated gene-1 (AEG-1), also known as metadherin, 3D3, and lysine-rich carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) coisolated, has emerged as an important oncogene that is overexpressed in a variety of cancers. Previous studies revealed that AEG-1 is also involved in multiple physiological and pathological processes, such as development, inflammation, neurodegeneration, migraine, and Huntington's disease. However, the function of AEG-1 in diabetic cardiomyopathy (DCM) has not been reported yet. Therefore, we conducted this study to characterize the potential role and mechanism of AEG-1 in DCM rats. DCM was induced by injections of streptozocin (STZ) in Wistar rats. Rats were randomized to be injected with lentivirus carrying AEG-1 small interfering RNA. Haemodynamic changes of Wistar rats, assessment of cardiac weight index, and the expression of AEG-1 and KLF4 were detected and compared among these three groups. The expressions of AEG-1 and KLF4 in the STZ group were significantly elevated in cardiac tissues compared with the control group. Knockdown of AEG-1 significantly increased the values of left ventricular ejection fraction, ±dp/dt max , repressed autophagy, as well as upregulated the expression of KLF4. Knockdown of AEG-1 suppresses autophagy in DCM by downregulating the expression of KLF4. This study provide first-notion evidence for the potential value of AEG-1 as a therapeutic target for the treatment of the patients with DCM.

ROS induces epithelial-mesenchymal transition via the TGF-β1/PI3K/Akt/mTOR pathway in diabetic nephropathy.

Oxidative stress has been reported to serve an important role in the development and progression of diabetic nephropathy (DN). Epithelial-mesenchymal transition (EMT) of renal tubular epithelial cells promotes renal fibrosis in DN, while the mechanism of reactive oxygen species (ROS)-mediated EMT is not fully understood. The aim of the present study was to investigate the effect of high glucose-induced ROS on the activation of the transforming growth factor (TGF)-β1/phosphoinositide 3 kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) pathway in a normal rat kidney tubular epithelial cell line (NRK-52E) and rats with type 1 diabetes. In vitro, high glucose-stimulated ROS production resulted in increased TGF-β1 expression as well as an increase in the Akt and mTOR phosphorylation ratio, resulting in EMT. When cells were pre-treated with ROS inhibitors, changes in TGF-β1, Akt and mTOR were significantly ameliorated. In vivo, diabetic rats experienced a significant decline in renal function and severe renal fibrosis compared with control rats at 8 weeks following streptozocin injection. Levels of malondialdehyde and TGF-β1/PI3K/Akt/mTOR pathway activation were increased in the renal cortex of rats with diabetes compared with the control rats. Furthermore, renal fibrosis was further aggravated in DN compared with the control rats. The results of the present study suggest that ROS serves an important role in mediating high glucose-induced EMT and inhibits activation of the TGF-β1/PI3K/Akt/mTOR pathway. ROS may therefore have potential as a treatment approach to prevent renal fibrosis in DN.

Effect of gbpapentin on the expression of Nrf2 in dorsal root ganglion neurons of diabetic neuropathic pain rats

Objective To investigate the effect of systemic administration of gabapentin on the expression of Nrf2 in dorsal root ganglion neurons in a rat model of diabetic neuropathic pain (DNP). Methods 60 male SD rats weighing 200-220 g were randomly divided into 4 groups (n=15 each): control group (group C), DNP group, saline group (SC+ DNP group) and gabapentin group (GBP+ DNP group). Diabetes was induced with streptozocin (70 mg/kg) subcutaneously. Paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermal latency (PWTL) were measured at 1d before and 3, 7, 10, 14, 21, and 28 d after streptozocin injection, and 21 and 28 d after administration of gabapentin (50 mg·kg-1·d-1, once) intraperitoneally. Saline and gabapentin (50 mg·kg-1·d-1) were given intraperitoneally once a day for 7 d starting from 15 d after streptozocin injection in saline and gabapentin groups respectively. The expression of Nrf2 was determined at 21 d after streptozocin injection by immune-histochemistry and Western blot. Results Compared with group C, PWMT(3.95±0.57) was significantly decreased, PWTL(6.3±0.81) was significantly shorten, Nrf2 in expression was significantly decreased in DNP, SC+ DNP and group (P 0.05). Conclusion Systemic administration of gabapentin attenuates diabetic neuropathic pain by enhancing the expression of Nrf2 in DRG neurons. (Chin J Endocrinol Metab, 2018, 34: 951-954) Key words: Gabapentin; Diabetic neuropathic pain; Dorsal root ganglion; Nrf2

The phosphodiesterase type 4 inhibitor roflumilast suppresses inflammation to improve diabetic bladder dysfunction rats.

To demonstrate that phosphodiesterase type 4 (PDE4) inhibitors could potentially treat diabetic bladder dysfunction (DBD) through modulation of the systemic inflammatory response. In this 6-week study, 60 female Sprague-Dawley rats were divided into three groups: (i) vehicle-treated control rats; (ii) vehicle-treated streptozocin (STZ)-injected rats; and (iii) roflumilast-treated STZ-injected rats. Oral roflumilast (5mg/kg/day) was administered during the last 4 weeks of STZ injection to induce diabetes in the test group. At 6 weeks, a urodynamic study was performed in each group. The expression of nuclear factor kappa B (NF-κB), tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, and IL-1β in detrusor smooth muscle (DSM) was analyzed using quantitative reverse transcription-polymerase chain reaction and Western blotting. A significant decrease in bodyweight and significant increases in bladder weight and blood glucose level were observed in the diabetic rats and were not ameliorated by roflumilast treatment. Cystometry showed the increased bladder capacity, voiding volume, residual urine volume, and voiding interval in the diabetic rats and the prevention of these changes by roflumilast. These changes were accompanied by significantly enhanced expression of NF-κB, TNF-α, IL-6, and IL-1β in DSM tissue from diabetic rats. Furthermore, roflumilast attenuated the expression of inflammatory factors in DSM tissue. Oral treatment with roflumilast in diabetic rats improves bladder function and inhibits the expression of inflammatory factors in DSM tissue, indicating that PDE4 is a potential therapeutic target for DBD.

Neuroprotective action of diazepam at very low and moderate doses in Alzheimer's disease model rats

Early manifestations of Alzheimer's disease (AD) include neuroinflammation, disrupted neurotransmission and cognitive deficits. Impairment of the GABAergic system is essentially involved in the pathogenesis of AD. Traditionally, agonists of GABAA receptors at doses above 1 mg/kg are known to possess memory impairing effects. However, we have previously found that GABAA receptor GABA site ligand muscimol at very low doses acted contrary – enhanced spatial learning/memory, as well as prevented neuroinflammation and augmented neurotransmission in AD model rats. Therefore, in the present study we focused on the assessment of the effects of non-sedative – very low (0.05 mg/kg) and moderate (1 mg/kg) – doses of diazepam, a positive allosteric modulator of benzodiazepine site of GABAA receptors. Its effects on spatial learning/memory and brain proteins related to neuroinflammation (GFAP and Iba-1), synaptic plasticity (SYP1), as well as acetylcholine breakdown and GABA biosynthesis were studied. Non-transgenic AD model rats (intracerebroventricular streptozocin injection) were used with the aim to mimic the pre-dementia stage of AD in humans. The obtained data showed that diazepam at both doses protected against streptozocin induced detrimental effects by enhancing spatial learning/memory, preventing neuroinflammation, preserving synaptic plasticity, as well as normalizing the hippocampal and cortical protein expression related to acetylcholine breakdown and GABA biosynthesis. One may suggest that at low and moderate doses diazepam is targeting non-specific, probably allosteric GABAA receptor sites, thus leading to stimulatory effects that can be beneficial for diazepam use in early pre-dementia stages of AD.

ALDH2 attenuates early-stage STZ-induced aged diabetic rats retinas damage via Sirt1/Nrf2 pathway

AimsAcetaldehyde dehydrogenase 2 (ALDH2) was reported for its protective properties on myocardial damage, stroke and neurodegeneration disease, but the effects and mechanisms of ALDH2 in the modulation of diabetic retinopathy remain unclear. The present study evaluated the protection effects of ALDH2 on streptozocin (STZ)-induced aged diabetic rats retinas damage. Main methods24 aged male diabetic Sprague-Dawley (SD) rats induced by a single intraperitoneal injection of STZ were randomly divided into Alda1-treated group and dimethylsulfoxide (DMSO) group. Rats were intraperitoneally injected with 10 mg/kg ALDH2 activator Alda1 (or DMSO) 3 days before STZ injection and 30 days afterwards. A series of detections on retinal structural, functional and molecular levels were applied at 1 d, 7 d and 30 d after aged diabetic rats model established. Key findingsOptical coherence tomography (OCT) revealed that the thickness of outer nuclear layer (ONL) and whole retinas in Alda1-treated group were thicker than DMSO group. Full field electroretinograms (ffERG) showed a higher amplitude wave (dark-adaptation 3.0 and OPs) in Alda1-treated group. In addition, the levels of retinal tumor necrosis factor (TNF-α) and interleukin-6 (IL-6) from Alda1-treated group were lower whereas superoxide dismutase (SOD) activity was notably higher. Moreover, the expressions of ALDH2, silence information regulation factor 2 related enzyme I (Sirt1) and nuclear factor erythroid 2-related factor 2 (Nrf2) in Alda1-treated group retinas were significantly increased, while the expression of vascular endothelial growth factor (VEGF-α) was dramatically decreased. SignificanceALDH2 could ameliorate early-stage STZ-induced aged diabetic rats retinas damage possibly via increasing Sirt1 and Nrf2 expression.

Nuciferine ameliorates hepatic steatosis in high-fat diet/streptozocin-induced diabetic mice through a PPARα/PPARγ coactivator-1α pathway.

Nuciferine, an alkaloid found in Nelumbo nucifera leaves, alleviates dyslipidemia in vivo. However, whether it improves liver injury in diabetic conditions and the underlying mechanism is unclear. The present study aimed to investigate the effects of nuciferine on lipid and glucose metabolism in a murine model of Type 2 diabetes mellitus (T2DM) and to determine the underlying mechanisms of these effects. A murine model of T2DM was induced by high-fat diet (HFD) feeding combined with streptozocin (STZ) injections, and the diabetic mice were treated with nuciferine in their food. The underlying mechanism of the anti-steatotic effect of nuciferine was further explored in HepG2 hepatocytes cultured with palmitic acid. Major signalling profiles involved in fatty acid oxidation were then evaluated, using Western blot, RT-qPCR and si-RNA techniques, along with immunohistochemistry. Nuciferine restored impaired glucose tolerance and insulin resistance in diabetic mice. Hepatic levels of total cholesterol, triglycerides and LDL were decreased, as were the number of lipid droplets, by nuciferine treatment. Furthermore, nuciferine up-regulated β-oxidation related genes in livers of diabetic mice. Luciferase reporter cell assay showed that nuciferine directly reversed palmitic acid-induced inhibition of PPARα transcriptional activity. Silencing PPARγ coactivator-1α (PGC1α) expression in HepG2 cells abolished the effects of nuciferine in accelerating β-oxidation. Nuciferine improved lipid profile and attenuated hepatic steatosis in HFD/STZ-induced diabetic mice by activating the PPARα/PGC1α pathway. Nuciferine may be a potentially important candidate in improving hepatic steatosis and the management of T2DM.

PO-078 Effects of aerobic and resistance training on cardiac diastolic dysfunction in type 2 diabetic rats

Objective To compare the effects of two types of physical training on cardiac diastolic dysfunction in type 2 diabetes mellitus and investigate the role of passive tension regulators—titin and collagen.
 Methods Sprague-Dawley (SD) male rats were divided into two groups: control and diabetes. Each group was subdivided into three subgroups: sedentary rats, rats submitted to aerobic trained and rats submitted to resistance training. Diabetic rats were induced by high-fat diet combined with low-dose injections of streptozocin (STZ). Aerobic trained rats ran on a treadmill at 21m/min for 60 min per day, while resistance trained rats climbed a ladder with incremental loads. The train period lasted for 8 weeks.
 Results All diabetic rats had increased fasting blood glucose (FBG) and left ventricular end diastolic pressure (LVEDP), a lower down stroke of the pressure curve (dp/dt min), longer exponential time constants of relaxation (Tau) in relation to control rats, while the protein expression of titin was decreased significantly, and the expression of collagen I, TGFβ1 were increased slightly, the ratio of type I and III collagen was raised in diabetic rats. Both types of training promoted a decrease in FBG and HOMA-IR in diabetic rats. Aerobic exercise trained diabetic rats had significant higher –dp/dtmin, and shorter Tau, but -dp/dtmin and Tau in resistance exercise trained diabetic rats had no significant been improved, even more aggravation. Moreover, aerobic training increased the protein expression of titin and HSP27, and the amount of co-localization of titin and HSP27 elevated, the protein expression of collagen I, TGFβ1 were decreased, and the ratio of type I and type III got close to normal. Resistance training further decreased the expression of titin, collagen I, and TGFβ1, collagen volume fraction (CVF) was increased significantly, and the ratio of type I and III collagen was disturbed, but the co-localization of titin and HSP27 elevated slightly.
 Conclusions Aerobic training ameliorates cardiac diastolic dysfunction in diabetes and this improvement may be related to increase titin repaired by HSP27, while resistance training aggravates the cardiac diastolic dysfunction in early diabetes mellitus and it could be caused by worsening myocardial interstitial fibrosis.

A1904 Metabolic surgery remits diabetic cardiomyopathy through shifting cardiac metabolic pattern in rats

Objectives: Diabetic cardiomyopathy (DC) is a severe complication of diabetes mellitus (DM), but effective treatments for DC are lacking. Roux-en-Y bypass surgery (RYGB) has been shown to be the most durable and effective treatment for DM and its complications. We examined if RYGB can improve DC and explore its potential mechanism in DM rats. Methods: DC was induced by streptozocin injection in Sprague–Dawley rats. RYGB was undertaken 4 weeks after streptozocin injection. Cardiac structure and function were determined by echocardiography. Cardiac ultrastructure was assessed by transmission electron microscopy. Mitochondrial function and mitochondrial supercomplexes in cardiac tissues were examined. Results: RYGB remitted hyperglycemia in STZ-induced DM rats rapidly. Compared with DM rats without RYGB, cardiac dysfunction was improved significantly 4 weeks after RYGB. Cardiac hypertrophy and myocardial fibrosis were ameliorated considerably in DM rats after RYGB. Mitochondria of DM rats were swollen and cristae absent, and myocardial fibers exhibited breaks and structural change. Cardiac mitochondrial function was improved significantly and the number of mitochondrial supercomplexes increased. Compared with DM rats without surgery, RYGB inhibited fatty-acid metabolism and related pathways according to mRNA microarray chip analysis, and these data were verified by measurement of expression of mRNA and protein. Conclusion: RYGB improved DM-related cardiac damage significantly through improvement of mitochondrial function and metabolism in the hearts of DM rats.

A14319 The glomerular endothelial cells regulates inflammasome activation on podocyte in DK

Objectives: Diabetic kidney disease (DKD) is one of the most common vascular complication of Diabetes mellitus (DM). Previous studies indicated that 30–40% of patients with DM develop overt nephropathy, but the detailed mechanism is not clear. We reported that endothelial dysfunction, such as an impaired endothelial nitric oxide (NO) synthase (eNOS)-NO pathway, promotes podocyte damage in diabetic glomerulopathy. However it is not clear molecular mechanism of relationship between endothelial dysfunction and podocyte damage. Then we focus on the NLRP3 inflammasome in podocyte for the progression of DKD. Now, we investigated if NO suppresses inflammasome activation in diabetic kidney disease. Methods: We used wild-type (WT) and eNOS deficient mice (eNOSKO) to determine the role ofeNOS-NO pathway. Diabetes was induced by a single intraperitoneal injection of streptozocin. Then we divided four groups; WT, WT/STZ, eNOSKO, and eNOS/STZ. At 4 weeks after induction of DM, the mice were sacrificed and kidney tissue were harvested. Results: Urinary albumin excretion was increased in WT/STZ compared with WT. Theses urinary albumin excretion were increased in eNOS/STZ than much more than WT/STZ. The glomeruli were more damaged in eNOSKO/STZ compared with WT/STZ. In immunehistochemical analyses, the expression of ASC was coexistence at podocyte which detected by podocalyxin staining in eNOSKO/STZ. This data suggested that NLRP3 Inflammasome activation was located in podocyte. In isolated glomeruli, mRNA of inflammasome component, NLRP3, IL-1β and IL-18 were higher in eNOSKO/STZ than in WT/STZ. Conclusion: In eNOS deficient, inflammasome was activated in podocyte and glomerular injury were exacerbated. Our data suggested that eNOS/NO signaling suppressed inflammasome activation in podocyte.

The impact of low alcohol consumption on the liver and inflammatory cytokines in diabetic rats.

Diabetes mellitus (DM) and alcohol consumption is still one of the important research models that simulate variable clinical conditions and metabolic diseases, such as alcoholic liver diseases. The aim of this study was to evaluate the long-term cumulative effects of low alcohol consumption on the liver tissue, biochemical assays and some inflammatory cytokines in experimentally-induced DM rats. Ethanol was administered in the drinking water (3% v/v) for 30 days to adult male Sprague-Dawley rats, with or without DM induced by streptozocin injection. Histological and biochemical parameters as well as some inflammatory cytokines - interleukin (IL)-4, IL-6, IL-10, and tumor necrosis factor alpha (TNF-α) - were measured. A significant increase in blood glucose level in the combination group was accompanied by a significant decrease in plasma insulin (p < 0.001 vs controls). Hepatic histopathology of the combination group revealed steatosis and fibrosis in addition to a significant increase in the gamma-glutamyltransferase (γ-GT) and alkaline phosphatase (ALP) levels (p < 0.05 and p < 0.001, respectively). A non-high-density lipoprotein (HDL) lipid profile (total cholesterol (TC), triglycerides (TG) and low-density lipoprotein (LDL)) revealed a significant increase in comparison to controls (p < 0.05), while HDL showed no significant change. The IL-4 and IL-6 levels were significantly higher (p < 0.05), while IL-10 and TNF-α revealed non-significant changes. Depletion of the hyperglycemic response in the case of low alcohol consumption in DM rats was associated with elevated plasma cytokines, especially IL-6 and IL-4, which could be a part of a host defense mechanism to repair the hepatic and pancreatic damage through this inflammatory process. The severe liver damage under insult of low alcohol consumption and DM could serve as inhibitory factors in gluconeogenesis and glycogenolysis, with little or no impact on insulin levels.

Improvement of vascular dysfunction by argirein through inhibiting endothelial cell apoptosis associated with ET-1/Nox4 signal pathway in diabetic rats

Endothelial cell apoptosis plays an important role in the pathophysiological mechanism of vascular complications in type 2 diabetes mellitus (T2DM). Argirein, a new synthetic compound was demonstrated to inactivate NADPH oxidase to alleviate cardiac dysfunction in T2DM. Here, we investigated whether argirein medication attenuated the vascular dysfunction in T2DM by inhibiting endothelial cell apoptosis which was associated with NADPH oxidase. The rat aortic endothelial cells (RAECs) were incubated with glucose (30 mM) for 48 hour in vitro. It was shown that high glucose significantly increased the protein expression of BAX (Bcl-2 Associated X protein) and Caspase-3 and decreased Bcl2 (B-Cell Leukemia/Lymphoma 2) protein level in RAECs, which was normalized by argirein medication. The annexin V-FITC bound cell percentage and DNA fragments in agarose electrophoresis were markedly suppressed by argirein to confirm the anti-apoptotic property of argirein in RAECs. Furthermore, we found that argirein blocked the endothelin (ET)-1/Nox4 signal-dependent superoxide (O2−.) generation, which regulated endothelial cell apoptosis in RAECs. In vivo, argirein intervention relieved the vasodilatory response to acetylcholine and restored the expressions of Nox4 and BAX in the aorta endothelium of high-fat diet (HFD)-fed rats following streptozocin (STZ) injection. For the first time, we demonstrated that argirein could inhibit vascular endothelial cell apoptosis, which was attributed to blocking ET-1/Nox4 signal-dependent O2− generation in RAECs. This current study revealed the therapeutic effects of argirein to prevent the vascular complication in T2DM through inhibiting endothelial cell apoptosis which was associated with the anti-oxidative property of argirein.

Anti-Inflammatory Effect of Adlay Seed Protein in Diabetic Mice

In this study, the effect of adlay seed protein on inflammation in diabetic mice and the regulation mechanism of IKK/NF-κB inflammatory pathway were investigated. A model of type 2 diabetes mellitus was established using a high-fat diet combined with intraperitoneal injection of streptozocin in mice. Doses of adlay seed protein, polysaccharides and a mixture were administered to diabetic mice. After gavage for four weeks, organ indices were measured. Enzyme linked immunosorbent assay was used to detect serum levels of tumor necrosis factor-α, interleukin-1α, interleukin-1β, interleukin-6 and cyclooxygenase-2 content. Semi-quantitative PCR was used to detect nuclear factor-kappa B inhibitor protein kinase complex (IKKβ), nuclear factor kappa-β (NF-κB) p65 and toll-like receptor 4 (TLR4). The results suggested that adlay seed protein and polysaccharide gavage can effectively reduce organ index, reduce the levels of many inflammatory cytokines, and significantly decrease the expression of IKKβ, NF-κB p65 and TLR4 genes. This indicates that adlay seed protein can effectively improve insulin resistance and inflammation in diabetic mice. The mechanism of this finding could be the inhibition of the IKK/NF-κB inflammatory pathway, which reduces the secretion of pro-inflammatory cytokines, thereby decreasing inflammatory responses in diabetic mice.

Protective effect of myocardial calcitonin gene-related peptide gene transduction on myocardial ischemia/reperfusion injury in diabetic rats

Objective To evaluate the feasibility of lentivirus (Lv) mediated calcitonin gene-related peptide(CGRP) gene transduction in diabetic rats by myocardial injection and whether this method has a protective effect on diabetic myocardium during ischemia/reperfusion(I/R) injury. Methods Sixty healthy male SD rats, weighing 200-220 g, were randomly divided into control group (group C), diabetes mellitus group (group DM), Sham transduction group (group Sham), myocardial injection control group (group MC) and myocardial injection experiment group(group ME), in accordance with a random number table. Rats in group Sham, group MC and group ME were given with normal saline, at a titer of 2×107 virus genomes(vg)/ml Lv-enhanced green fluorescent protein (eGFP) and Lv-CGRP-eGFP 50 μl respectively by myocardial injection. One week later, rats in group DM, group Sham, group MC and group ME received streptozocin(STZ) 50 mg/kg intraperitoneal injection to induce diabetes. Eight weeks after the injection of STZ, myocardial I/R was induced by occlusion and release of left anterior descending branch of coronary artery. The latency of tail flick reflection, the expression of eGFP, the transcription level of CGRP, the expression of CGRP in myocardium, spinal cord and dorsal root ganglion(DRG) and myocardial ischemia area, infarct size(IS) area were measured. Results Compared with group C, the latency of tail flick reflection in group DM, group Sham, group MC and group ME were significantly prolonged in the 4th week after diabetic model successfully manufactured(P<0.05). The transcription levels of CGRP in the ischemic myocardium, spinal cord T1-T5 and DRG T1-T5 in group DM, group Sham and group MC were lower than those in group C and group ME (P<0.05). The level of CGRP in ischemic myocardium and DRG T1-T5 of group ME was higher than that in group C(P<0.05). The content of CGRP in cord T1-T5, DRG T1-T5, ischemic myocardium and serum in group C and group ME were higher than those in group DM, group Sham and group MC (P<0.05). The content of CGRP in cord T1-T5, ischemic myocardium in group ME was higher than that in group C (P<0.05). The infarct size in group DM, group Sham, group MC were higher than that in group C and group ME(P<0.05), the infarct size of group ME was higher than that in group C(P<0.05). Conclusions Intramyocardial injection of CGRP gene can effectively enhance the expression of CGRP at I/R of diabetic rat′ heart. Increased CGRP may reduce cardiac I/R injury in diabetic rats. Key words: Calcitonin gene-related peptide; Diabetes mellitus; Myocardium; Ischemia-reperfusion

Ammoxetine attenuates diabetic neuropathic pain through inhibiting microglial activation and neuroinflammation in the spinal cord

BackgroundDiabetic neuropathic pain (DNP) is a common and distressing complication in patients with diabetes, and the underlying mechanism remains unclear. Tricyclic antidepressants (TCAs) and serotonin and norepinephrine reuptake inhibitors (SNRIs) are recommended as first-line drugs for DNP. Ammoxetine is a novel and potent SNRI that exhibited a strong analgesic effect on models of neuropathic pain, fibromyalgia-related pain, and inflammatory pain in our primary study. The present study was undertaken to investigate the chronic treatment properties of ammoxetine on DNP and the underlying mechanisms for its effects.MethodsThe rat model of DNP was established by a single streptozocin (STZ) injection (60 mg/kg). Two weeks after STZ injection, the DNP rats were treated with ammoxetine (2.5, 5, and 10 mg/kg/day) for 4 weeks. The mechanical allodynia and locomotor activity were assayed to evaluate the therapeutic effect of ammoxetine. In mechanism study, the activation of microglia, astrocytes, the protein levels of pro-inflammatory cytokines, the mitogen-activated protein kinases (MAPK), and NF-κB were evaluated. Also, microglia culture was used to assess the direct effects of ammoxetine on microglial activation and the signal transduction mechanism.ResultsTreatment with ammoxetine for 4 weeks significantly relieved the mechanical allodynia and ameliorated depressive-like behavior in DNP rats. In addition, DNP rats displayed increased activation of microglia in the spinal cord, but not astrocytes. Ammoxetine reduced the microglial activation, accumulation of pro-inflammatory cytokines, and activation of p38 and c-Jun N-terminal kinase (JNK) in the spinal cord of DNP rats. Furthermore, ammoxetine displayed anti-inflammatory effects upon challenge with LPS in BV-2 microglia cells.ConclusionOur results suggest that ammoxetine may be an effective treatment for relieving DNP symptoms. Moreover, a reduction in microglial activation and pro-inflammatory release by inhibiting the p-p38 and p-JNK pathways is involved in the mechanism.

Evaluation of hematoprotective and hepatoprotective properties of aqueous extract of Ceterach officinarum DC against streptozotocin-induced hepatic injury in male mice

Ceterach officinarum DC has been used in medicine as an antioxidant, anti-inflammatory, antifungal, and antibacterial agent. The aim of the present study was to investigate the hepatoprotective and hematoprotective effects of C. officinarum DC aqueous extract (CO) against streptozocin (STZ)-induced diabetes in mice. In this study, 60 mice were used. Diabetes was experimentally induced by intraperitoneal injection of STZ in 50 mice. Fasting blood glucose levels were assessed everyday by glucometer strips. Mice with plasma glucose level > 250 mg/dL were considered diabetic. After 3 days, they were divided randomly into six groups. Groups 1 and 2 served as non-diabetic and untreated diabetic controls, respectively. Group 3 received 50-mg/kg glibenclamide orally. Groups 4, 5, and 6 were given 50, 100, and 200 mg/kg, respectively, of CO for 20 days orally. At 20th day, the mice were dissected and blood and liver samples collected for hematological, biochemical, and histological parameter analysis. Different doses of CO (especially CO200) could significantly (p ≤ 0.05) decreased the raised levels of ALP, AST, ALT, cholesterol, LDL, WBC, and platelet and increased HDL, SOD, CAT, and RBC parameters as compared to the untreated group. The weight and volume of the hepatic structures were decreased significantly (p ≤ 0.05) in different doses of CO as compared to the untreated group. In conclusion, CO has hepatoprotective and hematoprotective properties, thereby reducing the causation of diabetes in experimental mice.

Involvement of ciliary neurotrophic factor in early diabetic retinal neuropathy in streptozotocin-induced diabetic rats

ObjectiveCiliary neurotrophic factor (CNTF) has been evaluated as a candidate therapeutic agent for diabetes and its neural complications. However, its role in diabetic retinopathy has not been fully elucidated.MethodsThis is a randomized unblinded animal experiment. Wistar rats with streptozocin (STZ)-induced diabetes were regularly injected with CNTF or vehicle control in their vitreous bodies beginning at 2 weeks after STZ injection. A total of five injections were used. In diabetic rats, the levels of CNTF and neurotrophin-3 (NT-3) were evaluated by enzyme-linked immunosorbent assays (ELISA) and real-time PCR. The abundance of tyrosine hydroxylase (TH) and β-III tubulin was detected by western blot. Transferase-mediated dUTP nick-end labeling staining (TUNEL) was used to detect cell apoptosis in the retinal tissue. The activation of caspase-3 was also measured.ResultsThe protein and mRNA levels of CNTF in diabetic rat retinas were reduced compared to control rats. In addition, retinal ganglion cells (RGCs) and dopaminergic amacrine cells appeared to undergo degeneration in diabetic rat retinas, as revealed by transferase-mediated dUTP nick-end labeling staining (TUNEL). Tyrosine hydroxylase (TH) and β-III tubulin protein levels also decreased significantly. Intraocular administration of CNTF rescued RGCs and dopaminergic amacrine cells from neurodegeneration and counteracted the downregulation of β-III tubulin and TH expression, thus demonstrating its therapeutic potential.ConclusionOur study suggests that early diabetic retinal neuropathy involves the reduced expression of CNTF and can be ameliorated by an exogenous supply of this neurotrophin.

Effect of saffron aqueous extract on the level of blood glucose in experimental diabetes mice

To investigate the effects of saffron aqueous extract (SE) on blood glucose, lipid and pancreatic tissue in streptozocin-induced diabetes mice. Diabetes mellitus mice were established by intraperitoneal injection of streptozocin (60 mg/kg) for two consecutive days. The 30 well-established diabetes mice were randomly divided into three groups(n=10):diabetic mellitus (DM) group, SE treated (SE) group and positive control (metformin hydrochloride, MH) group. Another ten normal mice were selected as normal control (NC) group. The mice in SE and MH groups were intragastrically administered with SE 100 mg/kg or MH 100 mg/kg once a day for 6 weeks, mice in DM and NC were given normal saline. The amount of food-intake, water consumption and body weight were measured weekly, the changes of the indicators including fasting blood glucose (FBG), oral glucose-tolerance test (OGTT), glycated serum protein (GSP), insulin (INS) and blood lipid were determined after 6 weeks of continuous administration. The pathologic changes in the pancreas tissues were detected by HE staining. Compared with the normal control group, the amount of food-intake, water consumption, area under the curve, FBG, GSP, and total cholesterol (TC) were significantly increased, while fasting weight, INS and high density lipoprotein cholesterol (HDL-c) were dramatically decreased in DM group. Compared with DM group, the water consumption, FBG, area under the curve and TC in SE group were starkly declined with a notable elevation of HDL-c and INS. In addition, the biopsy from DM mice showed the structure of pancreas islet was destroyed and reduced, and vascular proliferation with irregular shape. The damaged pancreas was obviously repaired by giving SE. The saffron aqueous extract had efficacy on blood glucose and blood lipids reduction, improvement on damaged pancreas in streptozocininduced diabetic mice, which suggested that saffron could be used for the treatment in diabetes.