STZ-induced Hyperglycemia Research Articles

CX3CR1–Fractalkine Dysregulation Affects Retinal GFAP Expression, Inflammatory Gene Induction, and LPS Response in a Mouse Model of Hypoxic Retinopathy

Diabetic retinopathy (DR) causes vision loss due to sustained inflammation and vascular damage. The vascular damage is evident by fibrinogen leakage, angiogenesis, and hypoxia. Neuronal regulation of microglia via the CX3CL1 (Fractalkine or FKN)-CX3CR1 pathway plays a significant role in retinal pathology. Defects in FKN or CX3CR1 exacerbate inflammation, vascular damage, and vision impairment. However, the contribution of hypoxic astrocytes to the pathological process of DR is unclear. A hypoxic model (7 days of systemic 7.5% O2) was utilized to induce retinal damage in adult mice in the absence of systemic inflammatory signals. This model induced vascular and microglial responses similar to 10 weeks of STZ-induced hyperglycemia. The goal of this study is to characterize retinal damage in WT and mice with defects in the FKN-CX3CR1 signaling axis and hence assess the impact of the microglial inflammatory responses to hypoxic retinopathy. Tissues were analyzed by immunostaining, RNA sequencing, and cytokine quantification. We found that CX3CR1 deficiency in hypoxic animals induced reactive astrogliosis and that Müller glial responses to hypoxia and systemic inflammation were dependent on FKN signaling. Exacerbated microglial reactivity to hypoxic conditions significantly altered the expression of HIF transcripts. Microglial dysregulation was found to reduce the anti-inflammatory response to hypoxic conditions, downregulate hypoxia-responsive gene expression, and restrained LPS-induced inflammatory responses. We found that microglia dysregulation alters the hypoxic response by inhibiting the upregulation of HIF2α/3α, increasing CD31 immunoreactivity, and altering the expression of ECM-associated transcripts such as type I, III, and XVIII collagens to hypoxic conditions.

GLUT1 exacerbates trophoblast ferroptosis by modulating AMPK/ACC mediated lipid metabolism and promotes gestational diabetes mellitus associated fetal growth restriction

BackgroundGestational diabetes mellitus (GDM) has been associated with several fetal complications, such as macrosomia and fetal growth restriction (FGR). Infants from GDM associated FGR are at increased risk for adult-onset obesity and associated metabolic disorders. However, the underlying mechanisms of GDM associated FGR remain to be explored.MethodsWe analyzed placentas from GDM patients with FGR for ferroptosis markers and GLUT1 expression. High glucose conditions were established by adding different concentrations of D-Glucose to the 1640 cell culture medium. RSL3 were used to test ferroptosis sensitivity in trophoblast cells. GLUT1 was inhibited using siRNA or its inhibitor WZB117 to assess its impact on ferroptosis inhibition in HTR8/SVneo cell line. Mechanistic studies explored the effects of GLUT1 on AMPK and ACC phosphorylation, which in turn impacted lipid metabolism and ferroptosis. In mouse models, streptozotocin (STZ)-induced GDM was treated with WZB117 and the ferroptosis inhibitor liproxstatin-1 (Lip-1). Finally, AMPK and ACC phosphorylation levels were evaluated in GDM patient samples.ResultsIn this study, placentas from GDM patients with FGR showed signs of ferroptosis and upregulation of GLUT1. In cell models, high glucose conditions sensitized trophoblast cells to ferroptosis and induced GLUT1 expression. Interestingly, GLUT1 inhibition significantly suppressed ferroptosis in trophoblast cells under high glucose conditions. Mechanistically, elevated GLUT1 inhibited AMPK phosphorylation and reduced ACC phosphorylation, thereby promoting lipid synthesis and facilitating ferroptosis. In pregnant mice, STZ-induced hyperglycemia led to FGR, and treatment with either the GLUT1 inhibitor WZB117 or the ferroptosis inhibitor Lip-1 alleviated the FGR phenotype. Moreover, in vivo elevation of GLUT1 increased ferroptosis markers, decreased AMPK/ACC phosphorylation, and resulted in altered lipid metabolism, which likely contributed to the observed phenotype. Finally, placental samples from GDM patients showed reduced AMPK and ACC phosphorylation.ConclusionsOur findings suggest a potential role of ferroptosis in GDM associated FGR and indicate that the dysregulated GLUT1-AMPK-ACC axis may be involved in the pathogenesis of GDM associated FGR in clinicals.

Hyperglycemia Exacerbates Periodontal Destruction via Systemic Suppression of Regulatory T Cell Number and Function.

Diabetes is a significant risk factor that exacerbates the pathological progression of periodontal disease. In recent years, attention has focused on the effect of regulatory T cells (Tregs), which play a central role in immune tolerance, on inflammatory processes in periodontal tissue, suggesting a link with diabetes-associated periodontitis. In this study, we examined the dynamics of Tregs in periodontal tissue of mice with streptozotocin (STZ)-induced hyperglycemia. Eleven-week-old male C57BL/6J mice were divided into four treatment groups: Untreated (C group), ligature placed around the maxillary second molars with silk sutures (PD group), intraperitoneal administration of STZ (HG group), and ligature placed after STZ administration (PHG group). Establishment of hyperglycemia was assessed 14 days after STZ administration, and ligation was performed 7 days later. After another 7 days of ligation, the mice were euthanized. The right side of the maxilla was observed histopathologically, whereas the palatal gingiva on the left side of the maxilla was analyzed genetically, and the microstructure of the alveolar bone was also assessed. In addition, lymphocytes from peripheral blood, spleen, and periodontal tissue were analyzed using flow cytometry. In bone structure analyses, alveolar bone height, bone volume/tissue volume (BV/TV), and bone mineral density (BMD) were lower in the PHG group than the PD group. In the gingival tissue, expression of the Foxp3 gene was up-regulated in the PHG group compared with the C group, and IL-17a was up-regulated in the PHG group compared with the PD group. Flow cytometry analyses showed that the number of Tregs (CD4+CD25+Foxp3+ cells) in the blood and gingival tissue was significantly higher in the PD and PHG groups than the C group. The number of CD4+CD25-Foxp3+ cells, which are reportedly functionally attenuated as Tregs, was increased in blood of the PHG group. Immunofluorescence staining of periodontal tissue showed that the number of CD25+Foxp3+ cells was significantly increased only in the PD group, whereas a trend toward an increased number of CD25-Foxp3+ cells was observed in the PHG group. The present study showed that STZ-induced hyperglycemia numerically and functionally attenuates Tregs in a mouse model of experimental periodontitis. Furthermore, impaired immune tolerance capacity appears to be involved in exacerbating inflammation and bone destruction in periodontal tissue.

Hyperglycemia sensitizes female mice to stress-induced depressive-like behavior in an inflammation-independent manner

BackgroundDepression is a multifaceted disorder that represents one of the most common causes of disability. The risk for developing depression is increased in women and among individuals with chronic diseases. For example, individuals in the United States with diabetes mellitus (DM) are at a twofold increased risk of developing depression compared to the general population and approximately one-quarter of women with diabetes have comorbid depression. The neurobiological mechanisms underlying this association between diabetes and depression is not fully understood and is particularly under-investigated in female models. We sought to explore the role of neuroinflammation in diabetes-induced depression in a female mouse model of hyperglycemia. MethodsTo this end, we utilized female C57BL/6 J mice to (1) characterize the depressive-like symptoms in response to 75 mg/kg/day dose of streptozotocin (STZ) over 5 days, a dose reported to induce hyperglycemia in female mice (n=20), (2) determine if female hyperglycemic mice are sensitized to unpredictable chronic mild stress (UCMS)-induced depressive-like behavior and neuroinflammation (n=28), and (3) investigate if female hyperglycemic mice are primed to respond to a subthreshold dose of lipopolysaccharide (LPS), an acute inflammatory challenge (n=21). ResultsOur results demonstrate that female mice exhibit robust hyperglycemia but limited evidence of depressive-like behavior in response to 75 mg/kg STZ. Additionally, we observe that healthy female mice have limited response to our stress protocol; however, hyperglycemic mice display increased stress-sensitivity as indicated by increased immobility in the forced swim test. While STZ mice show evidence of mild neuroinflammation, this effect was blunted by stress. Further, STZ mice failed to display a sensitization to inflammation-induced depressive-like behavior. ConclusionWe interpret this data to indicate that while STZ-induced hyperglycemia does increase vulnerability to stress-induced depressive-like behavior, this effect is not a consequence of neuroinflammatory priming. Future studies will seek to better understand the mechanisms underlying this sensitization.

Guava polysaccharides attenuate high fat and STZ-induced hyperglycemia by regulating gut microbiota and arachidonic acid metabolism

This study investigated the hypoglycemic mechanism of guava polysaccharides (GP) through the gut microbiota (GM) and related metabolites. Our findings demonstrated that GP significantly mitigated high-fat diet- and streptozotocin-induced hyperglycemia, insulin resistance, hyperlipidemia, elevated alanine aminotransferase, high hepatic inflammation levels, and prevented pancreatic atrophy and hepatomegaly. Interestingly, the benefits of GP were attributed to alterations in the GM. GP decreased the ratio of Firmicutes to Bacteroidetes, significantly inhibiting deleterious bacteria, including Uncultured_f_Desulfovibrionaceae, Bilophila, and Desulfovibrio, while promoting the proliferation of probiotic Bifidobacterium and Bacteroides. In addition, GP promoted the generation of short-chain fatty acids. Notably, the arachidonic acid (AA) metabolism pathway was enriched in liver metabolites. GP significantly elevated hepatic AA and 15-hydroxyeicosatetraenoic acid, while reducing prostaglandin E2 and 5- and 12-hydroxyeicosatetraenoic acid. This modulation is accompanied by the downregulation of hepatic cyclooxygenase-1, 12-lipoxygenase, P38, and c-Jun N-terminal kinase mRNA expression, and the upregulation of cytochrome P4502J5 and insulin receptor substrate 1/2 mRNA expression. However, GP antibiotic treatment did not induce significant alterations in FBG and AA levels or gene expression. Overall, our findings suggest that the hypoglycemic effect of GP may be intricately linked to alterations in AA metabolism, which depends on the GM.

Effects of empagliflozin on gonadal functions of hyperglycemic male wistar rats.

Empagliflozin (EMPA) showed antiapoptotic, oxidative and anti-inflammatory potential effect. EMPA attenuates the inflammation and oxidative stress biomarkers in patients with heart failure while significantly decreases the malondialdehyde (a lipid peroxidation marker) levels in the plasma of diabetic patients. The present study examined the effects of moderate hyperglycemia on reproductive function. Sixty male Wister rats ‎ were divided and randomly allocated into four groups of 15 animals each‎‎. Diabetes was induced by a single intraperitoneal injection of a prepared solution containing STZ diluted in 0.1 M sodium citrate buffer (pH 4.5) at a dosage of 40 mg/kg body weight in selected in groups II and III for seven days before starting the treatment with EMPA. The current study revealed that EMPA for eight weeks prevented testicular high glucose-induced oxidative stress markers such as penile nitric oxide (NO), glutathione peroxidase (GPX) and total anti-oxidant capacity (TAC) in STZ-induced hyperglycemia in a rat model. In addition, EMPA ameliorated the high levels of endogenous Interleukin-6 (IL-6) present in gonads in response to an acute inflammatory found in the hyperglycemic STZ-induced rats. The present study further suggested the protective effects of EMPA and how it has a beneficial role and can effectively attenuate hyperglycemia-induced testicular oxidative damage and inflammatory markers as well as androgen dependent testicular enzymes activity as a protective role against the consequences of hyperglycemia and male sub-infertility.

The administration of Cerebrolysin elicits neuroprotective and neurorepair effects in an animal model of type 1 diabetes mellitus

Diabetes mellitus (DM) is a metabolic disorder impacting cerebral function. The administration of Streptozotocin (STZ) is a well-known animal model of insulinopenic type 1 DM in rats. STZ-induced DM results in a myriad of alteration in the periphery and central nervous system (CNS). Cerebrolysin (CBL) is a neuropeptide preparation that promotes synaptic and neuronal plasticity in various animal models. In all cases, CBL was administered when the model was established. This research aims to investigate the neuroprotective and neurorepair effect of CBL on the cytoarchitecture of neurons and spine density in pyramidal neurons of the prefrontal (PFC) and the CA1 region of the dorsal hippocampus, as well as spheroidal neurons of the dentate gyrus (DG), in STZ-induced DM. In the first experimental condition, STZ and CBL are administered at the same time to evaluate the potential preventive effect of CBL. In the second experimental condition, CBL was administered two months after establishing the DM model to measure the potential neurorepair effect of CBL. STZ-induced hyperglycemia remained unaltered by the administration of CBL in both experimental conditions. In the first experimental condition, CBL treatment preserved the neuronal morphology in PFC layer 3, PFC layer 5 and the DG of the hippocampus, while also maintaining spine density in the PFC-3, DG and CA1 hippocampus. Furthermore, CBL induced neurorepair in neurons within the PFC-3, PFC-5 and CA1 regions of the hippocampus, along with an increase in spine density in the PFC-3, DG and CA1 hippocampus. These findings suggest that CBL´s effects on neuroplasticity could be observed before or after the damage was evident.

GHSR Deletion in β-Cells of Male Mice: Ineffective in Obesity, but Effective in Protecting against Streptozotocin-Induced β-Cell Injury in Aging.

Insulin secretion from pancreatic β cells is a key pillar of glucose homeostasis, which is impaired under obesity and aging. Growth hormone secretagogue receptor (GHSR) is the receptor of nutrient-sensing hormone ghrelin. Previously, we showed that β-cell GHSR regulated glucose-stimulated insulin secretion (GSIS) in young mice. In the current study, we further investigated the effects of GHSR on insulin secretion in male mice under diet-induced obesity (DIO) and streptozotocin (STZ)-induced β-cell injury in aging. β-cell-specific-Ghsr-deficient (Ghsr-βKO) mice exhibited no glycemic phenotype under DIO but showed significantly improved ex vivo GSIS in aging. We also detected reduced insulin sensitivity and impaired insulin secretion during aging both in vivo and ex vivo. Accordingly, there were age-related alterations in expression of glucose transporter, insulin signaling pathway, and inflammatory genes. To further determine whether GHSR deficiency affected β-cell susceptibility to acute injury, young, middle-aged, and old Ghsr-βKO mice were subjected to STZ. We found that middle-aged and old Ghsr-βKO mice were protected from STZ-induced hyperglycemia and impaired insulin secretion, correlated with increased expression of insulin signaling regulators but decreased pro-inflammatory cytokines in pancreatic islets. Collectively, our findings indicate that β-cell GHSR has a major impact on insulin secretion in aging but not obesity, and GHSR deficiency protects against STZ-induced β-cell injury in aging.

Antidiabetic Evaluation of Kigelia pinnata Root Bark Extract in Streptozotocin-Induced Type-2 Diabetes Model of Rats.

Diabetes mellitus (DM) is the most common endocrine disorder characterized by increased blood glucose levels resulting from defective insulin secretion, resistance to insulin action, or both. DM is often associated with severe complications, and there is an increasing appreciation that cognitive function declines in DM. The aim of this research work was to evaluate Kigelia pinnata root bark extract in Streptozotocin (STZ)-induced type-2 diabetes. Experimental diabetes was induced by a single administration of STZ (60 mg/kg, intraperitoneal [i.p.]), immediately after the STZ administration, and all animals were fed with normal food and water. Nicotinamide was administered (120 mg/kg, i.p.) 15 min before STZ. The development of hyperglycemia was confirmed by the elevated blood glucose levels determined at fixed intervals, which was confirmed by measuring fasting blood glucose levels in rats' blood taken from the tail vein. Supplementation with ethanolic extract of K. pinnata root bark (EEKP) significantly reduced the elevated blood glucose in STZ-induced hyperglycemia in rats. EEKP significantly restored the biochemical and antioxidant defense system. On the final day of the protocol, the extract also reduced inflammatory cytokines in the blood serum.

Unveiling the chemical profiling and remarkable modulation of carbohydrate metabolism by costus root, Dolomiaea costus (Falc.) in streptozotocin (STZ)-induced diabetic rats

Ethnopharmacological relevanceDolomiaea costus (Falc.), formerly Saussurea costus (Falc.) Lipsch., an ayurvedic medicinal plant, has long been recognized and utilized in diverse indigenous systems of medicine for its multifaceted therapeutic properties, including anti-inflammatory, carminative, expectorant, antiarthritic, antiseptic, aphrodisiac, anodyne, and antidiabetic effects. Aim of the studyThe potential and underlying mechanisms of D. costus root as an antidiabetic agent were investigated in this study. Additionally, the quantification of phenolic and flavonoid compounds, which dominate the extracts, was of particular interest in order to elucidate their contribution to the observed effects. Materials and methodsHigh-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) was employed to analyze the chemical constituents in D. costus root aqueous extract (DCA) and D. costus root ethanolic extract (DCE). Furthermore, the inhibitory potentials of DCE and its respective fractions as well as DCA against α-amylase, α-glucosidase, and lipase enzymes were assessed. Subsequently, the efficacy of DCA and DCE extracts was evaluated using an established streptozotocin (STZ)-induced diabetic animal model; this involved administering the extracts at doses of 200 and 400 mg/kg bwt. and comparing them with a positive control (glibenclamide (Glib.) at 0.6 mg/kg bwt.). After induction of diabetes (except for negative control), all animals received the treatments orally for 21 days consecutively, followed by the collection of rat serum to assess various parameters including, glycemic and lipid profiles, liver and kidney functions, antioxidant activity, glycolysis, and gluconeogenesis pathways. ResultsThe results of HPLC-ESI-MS/MS revealed that isochlorogenic acid A (8393.64 μg/g) and chlorogenic acid (6532.65 μg/g) were the predominant compounds in DCE and DCA, respectively. Both extracts exhibited notable antidiabetic properties, as evidenced by their ability to regulate blood glycemic and lipid profiles (glucose, insulin, HBA1C; HDL, TC, TGs), liver enzymes (ALT, ALP, AST), kidney function (urea, creatinine, uric acid), oxidative stress biomarkers (MDA), antioxidant enzymes (CAT, GSH, SOD), as well as glycolysis (glucokinase) and gluconeogenesis (G-6-P, FBP1) pathways. ConclusionsFurthermore, the administration of D. costus extracts significantly mitigated STZ-induced diabetic hyperglycemia. These results can be attributed, at least partially, to the presence of several polyphenolic compounds with potent antioxidant and anti-inflammatory activities.

The Impact of Obesity on Diabetes Onset and Neovascularization in Mouse Models of Metabolic Stress.

Animal models of metabolic disorders are essential to studying pathogenic mechanisms and developing therapies for diabetes, but the induction protocols vary, and sexual dimorphism often exists. In a chronic diabetic model of diet-induced obesity (DIO) and low-dose streptozotocin (STZ)-induced hyperglycemia, blood glucose and lipid profiles were measured. The high-fat (HF) diet damaged insulin sensitivity and increased triglycerides, total cholesterol, LDL-cholesterol, HDL-cholesterol, and liver lipid deposition. STZ increased blood glucose and liver fibrosis with less effects on blood lipids or liver lipid deposition. The combination of DIO and STZ treatments led to significant liver lipid deposition and fibrosis. Female mice showed delayed body weight gain on HF diet and resisted STZ-induced hyperglycemia. However, once they developed DIO, which occurs around 26 weeks of HF diet, the female mice were prone to STZ-induced hyperglycemia. In hindlimb ischemia, male mice in the DIO-STZ group showed significantly worse neovascularization compared with DIO or STZ groups. The DIO-STZ females showed significantly worse recovery than the DIO-STZ males. Our observations suggest that DIO-STZ is a plausible model for studying metabolic and cardiovascular disorders in obesity and diabetes. Moreover, the findings in female animals stress the need to assess sexual dimorphism and investigate the underlying mechanisms that contribute to the worse vasculopathy manifestations in females in metabolic models.

Attenuation of Streptozotocin-Induced Diabetic Neuropathic Allodynia by Flavone Derivative Through Modulation of GABA-ergic Mechanisms and Endogenous Biomarkers.

Diabetic neuropathic pain is one of the most devasting disorders of peripheral nervous system. The loss of GABAergic inhibition is associated with the development of painful diabetic neuropathy. The current study evaluated the potential of 3-Hydroxy-2-methoxy-6-methyl flavone (3-OH-2'MeO6MF), to ameliorate peripheral neuropathic pain using an STZ-induced hyperglycemia rat model. The pain threshold was assessed by tail flick, cold, mechanical allodynia, and formalin test on days 0, 14, 21, and 28 after STZ administration accompanied by evaluation of several biochemical parameters. Administration of 3-OH-2'-MeO6MF (1,10, 30, and 100mg/kg, i.p) significantly enhanced the tail withdrawal threshold in tail-flick and tail cold allodynia tests. 3-OH-2'-MeO6MF also increased the paw withdrawal threshold in mechanical allodynia and decreased paw licking time in the formalin test. Additionally, 3-OH-2'-MeO6MF also attenuated the increase in concentrations of myeloperoxidase (MPO), thiobarbituric acid reactive substances (TBARS), nitrite, TNF-α, and IL 6 along with increases in glutathione (GSH). Pretreatment of pentylenetetrazole (PTZ) (40mg/kg, i.p.) abolished the antinociceptive effect of 3-OH-2'-MeO6MF in mechanical allodynia. Besides, the STZ-induced alterations in the GABA concentration and GABA transaminase activity attenuated by 3-OH-2'-MeO6MF treatment suggest GABAergic mechanisms. Molecular docking also authenticates the involvement of α2β2γ2L GABA-A receptors and GABA-T enzyme in the antinociceptive activities of 3-OH-2'-MeO6MF.

STZ-induced hyperglycemia differentially influences mitochondrial distribution and morphology in the habenulointerpeduncular circuit.

Diabetes is a metabolic disorder of glucose homeostasis that is a significant risk factor for neurodegenerative diseases, such as Alzheimer's disease, as well as mood disorders, which often precede neurodegenerative conditions. We examined the medial habenulainterpeduncular nucleus (MHb-IPN), as this circuit plays crucial roles in mood regulation, has been linked to the development of diabetes after smoking, and is rich in cholinergic neurons, which are affected in other brain areas in Alzheimer's disease. This study aimed to investigate the impact of streptozotocin (STZ)-induced hyperglycemia, a type 1 diabetes model, on mitochondrial and lipid homeostasis in 4% paraformaldehyde-fixed sections from the MHb and IPN of C57BL/6 J male mice, using a recently developed automated pipeline for mitochondrial analysis in confocal images. We examined different time points after STZ-induced diabetes onset to determine how the brain responded to chronic hyperglycemia, with the limitation that mitochondria and lipids were not examined with respect to cell type or intracellular location. Mitochondrial distribution and morphology differentially responded to hyperglycemia depending on time and brain area. Six weeks after STZ treatment, mitochondria in the ventral MHb and dorsal IPN increased in number and exhibited altered morphology, but no changes were observed in the lateral habenula (LHb) or ventral IPN. Strikingly, mitochondrial numbers returned to normal dynamics at 12 weeks. Both blood glucose level and glycated hemoglobin (HbA1C) correlated with mitochondrial dynamics in ventral MHb, whereas only HbA1C correlated in the IPN. We also examined lipid homeostasis using BODIPY staining for neutral lipids in this model given that diabetes is associated with disrupted lipid homeostasis. BODIPY staining intensity was unchanged in the vMHb of STZ-treated mice but increased in the IPN and VTA and decreased in the LHb at 12 weeks. Interestingly, areas that demonstrated changes in mitochondria had little change in lipid staining and vice versa. This study is the first to describe the specific impacts of diabetes on mitochondria in the MHb-IPN circuit and suggests that the cholinergic MHb is uniquely sensitive to diabetesinduced hyperglycemia. Further studies are needed to understand the functional and behavioral implications of these findings.

STZ-induced gestational diabetes exposure alters PTEN/AKT/mTOR-mediated autophagy signaling pathway leading to increase the risk of neonatal hypoxic-ischemic encephalopathy

Exposure to gestational diabetes mellitus (GDM) during pregnancy has significant consequences for the unborn baby and newborn infant. However, whether and how GDM exposure induces the development of neonatal brain hypoxia/ischemia-sensitive phenotype and the underlying molecular mechanisms remain unclear. In this study, we used a late GDM rat model induced by administration of streptozotocin (STZ) on gestational day 12 and investigated its effects of GDM on neonatal brain development. The pregnant rats exhibited increased blood glucose levels in a dose-dependent manner after STZ administration. STZ-induced maternal hyperglycemia led to reduced blood glucose levels in neonatal offspring, resulting in growth restriction and an increased brain to body weight ratio. Importantly, GDM exposure increased susceptibility to hypoxia/ischemia (HI)-induced brain infarct sizes compared to the controls in both male and female neonatal offspring. Further molecular analysis revealed alterations in the PTEN/AKT/mTOR/autophagy signaling pathway in neonatal male offspring brains, along with increased ROS production and autophagy-related proteins (Atg5 and LC3-II). Treatment with the PTEN inhibitor bisperoxovanadate (BPV) eliminated the differences in HI-induced brain infarct sizes between the GDM-exposed and the control groups. These findings provide novel evidence of the development of a brain hypoxia/ischemia-sensitive phenotype in response to GDM exposure and highlight the role of the PTEN/AKT/mTOR/autophagy signaling pathway in this process.

Chiranthodendron pentadactylon Larreat (Sterculiaceae), a Potential Nephroprotector against Oxidative Damage Provoked by STZ-Induced Hyperglycemia in Rats.

Chiranthodendron pentadactylon, known in Mexico as the "tree of the little hands", flower's infusion is used to treat kidney failure associated with diseases such as diabetes. The aim of this work is to evaluate the antioxidant effect of the methanolic extract of its flowers on oxidative damage in kidneys caused by streptozotocin in rats. The extract phytochemical profile was performed with HPLC. Antioxidant potential in vitro was determined with DPPH and total phenolic tests; antioxidant evaluation in vivo was performed in diabetic rats administered daily via the intragastric route (100 and 200 mg/kg) for 6 weeks; serum glucose/creatinine, food/water consumption, and urinary volume were measured. Relative weight, protein/DNA ratios and oxidative stress were measured in renal tissue. The extract showed 20.53% of total phenolic content and IC50 of 18.05 µg/mL in DPPH, and this was associated with ferulic acid, phloretin and α-amyrin. Both doses showed a moderate decrease in the protein/DNA ratio in renal tissue, and the same behavior was observed for total urinary protein loss and serum creatinine, while the best antioxidant effect was exerted by a lower dose, which increased catalase activity and decreased lipid peroxidation in the kidneys. Results demonstrated that C. pentadactylon methanolic flower's extract improves renal function through antioxidant mechanisms during experimental diabetes.

Anti-Daibetic effect of lime juice extract of Ficus exasperata in streptozotocin-induced diabetic mellitus in rats

Abstract Background: Diabetes is a chronic incapacitating illness that imposes a huge burden on global healthcare. The leaves of Ficus exasperata soaked in lime juice are adopted in folkloric unconventional medicine to treat diabetes. This study was aimed at determining the protective effect of lime juice extract of Ficus exasperata (LFE) in streptozotocin (STZ)-induced diabetes mellitus in rats. Methods: LFE (50, 250, or 500mg/kg) or vehicle was administered before the oral glucose tolerance test (OGTT), insulin tolerance test (ITT), or after establishing diabetes mellitus in the STZ model, in rats. One-hour post-treatment on days 7 and 14, fasting blood glucose and weight were recorded, which was followed by assessment of biochemical, antioxidant and histological parameters. Results: LFE produced dose-dependent and significant control of glycemic index with peak effect at 500mg/kg in OGTT and ITT when compared with vehicle treated control. In addition, LFE also reversed STZ-induced hyperglycemia and oxidative stress in selected organs when compared with vehicle-treated control group. Similarly, STZ-induced hepatic damage, anemia, and immunosuppression were also reversed by LFE administration. Conclusion: Findings from this study showed the beneficial effect of lime juice extract of Ficus exasperata in the management of diabetic mellitus through increase in antioxidant defense signaling

Sex-based impact of pancreatic islet stressors in GluCreERT2/Rosa26-eYFP mice.

The present study examines differences in metabolic and pancreatic islet adaptative responses following streptozotocin (STZ) and hydrocortisone (HC) administration in male and female transgenic GluCreERT2/Rosa26-eYFP mice. Mice received five daily doses of STZ (50 mg/kg, i.p.) or 10 daily doses of HC (70 mg/kg, i.p.), with parameters assessed on day 11. STZ-induced hyperglycaemia was evident in both sexes, alongside impaired glucose tolerance and reduced insulin concentrations. HC also had similar metabolic effects in male and female mice resulting in classical increases of circulating insulin indicative of insulin resistance. Control male mice had larger pancreatic islets than females and displayed a greater reduction of islet and beta-cell area in response to STZ insult. In addition, female STZ mice had lower levels of beta-cell apoptosis than male counterparts. Following HC administration, female mouse islets contained a greater proportion of alpha cells when compared to males. All HC mice presented with relatively comparable increases in beta- and alpha-cell turnover rates, with female mice being slightly more susceptible to HC-induced beta-cell apoptosis. Interestingly, healthy control female mice had inherently increased alpha-to-beta-cell transdifferentiation rates, which was decreased by HC treatment. The number of glucagon-positive alpha cells altering their lineage to insulin-positive beta cells was increased in male, but not female, STZ mice. Taken together, although there was no obvious sex-specific alteration of metabolic profile in STZ or HC mice, subtle differences in pancreatic islet morphology emphasises the impact of sex hormones on islets and importance of taking care when interpreting observations between males and females.

Effect of Hesperidin on Sciatic Nerve Damage in STZ-Induced Diabetic Neuropathy: Modulation of TRPM2 Channel.

Diabetic neuropathy (DNP) is a severe complication of diabetes mellitus. In this study, we examined the potential of hesperidin (HES) to attenuate DNP and the involvement of the TRPM2 channel in this process. The rats were given a singledose of 45mg/kg of streptozotocin (STZ) intraperitoneally to induce diabetic neuropathic pain. On the third day, we confirmed the development of diabetes in the DNP and DNP + HES groups. The HES groups were treated with 100mg/kg and intragastric gavage daily for 14days. The results showed that treatment with HES in diabetic rats decreased STZ-induced hyperglycemia and thermal hyperalgesia. Furthermore, in the histopathological examination of the sciatic nerve, HES treatment reduced STZ-induced damage. The immunohistochemical analysis also determined that STZ-induced increased TRPM2 channel, type-4 collagen, and fibrinogen immunoactivity decreased with HES treatment. In addition, we investigated the TRPM2 channel activation in the sciatic nerve damage mechanism of DNP model rats created by STZ application using the ELISA method. We determined the regulatory effect of HES on increased ROS, and PARP1 and TRPM2 channel activation in the sciatic nerves of DNP model rats. These findings indicated that hesperidin treatment could attenuate diabetes-induced DNP by reducing TRPM2 channel activation.

288-LB: CHIP Haplodeficiency Exacerbates Experimental Type 1 Diabetes via the Regulation of DNA Damage Response and Apoptosis

Type 1 diabetes is a disease characterized by hyperglycemia resulting from defects in insulin secretion. Streptozotocin (STZ)-induced pancreatic β-cell damage is commonly used as causing hyperglycemia of type 1 diabetes model. It has been established that the carboxyl terminus of heat shock protein 70-interacting protein (CHIP) contributes to the pathogeneses of diabetic complications. However, the mechanisms linking type 1 diabetes and CHIP-dependent antidiabetic signaling pathway remain to be addressed. Here we utilized STZ-induced murine model of type 1 diabetes to examine DNA damage responses (DDR) during pancreatic β-cell apoptosis. This study was undertaken to explore the mechanism whereby CHIP instigates pancreatic β-cell apoptosis via DDR-dependent signaling pathway. Wild type and CHIP haplodeficient mice were i.p. injected with 50 or 100 mg/kg STZ in order to induce experimental mouse model of type I diabetes. STZ-induced hyperglycemia, glucose intolerance, and inflammatory responses were exacerbated in CHIP haplodeficient mice compared to Wild type. In addition, immunoblotting data revealed that depletion of CHIP with siRNA against rat stub1 enhanced STZ-induced apoptosis and DDR pathway in INS-1 cells, a rat insulinoma cell line. Notably, CHIP inhibition deteriorates STZ-induced cell cycle arrest and oxidative stress in INS-1 cells. In addition to in vitro study, immunohistochemical and immunoblotting study showed that CHIP haplodeficiency exacerbates DDR in pancreas from an experimental mouse model of type I diabetes. These results suggest that CHIP protects against STZ-induced pancreatic β-cell apoptosis and hyperglycemia by interrupting the DDR-mediated apoptotic pathway. Key words: diabetes, CHIP, DNA damage response, apoptosis, β-cell Disclosure A. Hwang: None.

Impact on the Kidney of Pancreas Damage due to Streptozotocin-Induced Hyperglycemia

Highlights: This study observed the histology of pancreatic β-cell damage without any intervention to the kidneys of the animal models. The histological analysis of the kidneys shows that STZ-induced animal models can be used for assessing kidney abnormalities due to hyperglycemia. A scoring system for the histological analysis was developed to evaluate the changes in the kidney cells. Abstract The kidneys are one of the organs affected by microvascular complications due to diabetes mellitus. Hyperglycemia plays an important role in glomerular, mesangial cell, and tubular damage in the kidneys. Metabolic dysregulation, including hyperglycemia, initiates cellular damage in the kidneys. Streptozotocin (STZ) is a chemical compound that is known to damage pancreatic cells and cause hyperglycemia. This study aimed to examine the effects of hyperglycemia on the morphology of the kidneys. Kidney tissues were observed histologically using a light microscope. Samples were taken from the kidneys of experimental animals administered with STZ to induce hyperglycemia. Observation was performed afterwards to investigate any damage to pancreatic cells. A total of 12 kidney samples were divided into two groups: the control group and the STZ-induced group. The samples were prepared before staining with hematoxylin-eosin and Masson's trichrome. The endothelium, podocytes, mesangial cells, and basement membrane of the glomerulus were examined. The tubules of the kidneys were also examined, and the presence or absence of connective tissue formation in both groups was statistically tested. The results suggested a significant difference in tubular damage (p<0.05) and an insignificant difference in an increase in the damage of other components of the kidneys (p>0.05) in the STZ-induced group. Significant morphological changes were observed in the hyperglycemic renal tubules due to the administration of STZ. In conclusion, STZ-induced hyperglycemia caused damage to the kidney components but overall had no significant impact on the kidney.