G protein subunit alpha i2's pivotal role in angiogenesis.

Here we explored the potential role of Gαi2 (G protein subunit alpha i2) in endothelial cell function and angiogenesis. Methods: Genetic methodologies such as shRNA, CRISPR/Cas9, dominant negative mutation, and overexpression were utilized to modify Gαi2 expression or regulate its function. Their effects on endothelial cell functions were assessed in vitro. In vivo, the endothelial-specific Gαi2 shRNA adeno-associated virus (AAV) was utilized to silence Gαi2 expression. The impact of this suppression on retinal angiogenesis in control mice and streptozotocin (STZ)-induced diabetic retinopathy (DR) mice was analyzed. Results: Analysis of single-cell RNA sequencing data revealed Gαi2 (GNAI2) was predominantly expressed in retinal endothelial cells and expression was increased in retinal endothelial cells following oxygen-induced retinopathy (OIR) in mice. Moreover, transcriptome analysis linking Gαi2 to angiogenesis-related processes/pathways, supported by increased Gαi2 expression in experimental OIR mouse retinas, highlighted its possible role in angiogenesis. In various endothelial cell types, shRNA-induced silencing and CRISPR/Cas9-mediated knockout (KO) of Gαi2 resulted in substantial reductions in cell proliferation, migration, invasion, and capillary tube formation. Conversely, Gαi2 over-expression in endothelial cells induced pro-angiogenic activities, enhancing cell proliferation, migration, invasion, and capillary tube formation. Furthermore, our investigation revealed a crucial role of Gαi2 in NFAT (nuclear factor of activated T cells) activation, as evidenced by the down-regulation of NFAT-luciferase reporter activity and pro-angiogenesis NFAT-targeted genes (Egr3, CXCR7, and RND1) in Gαi2-silenced or -KO HUVECs, which were up-regulated in Gαi2-overexpressing endothelial cells. Expression of a dominant negative Gαi2 mutation (S48C) also down-regulated NFAT-targeted genes, slowing proliferation, migration, invasion, and capillary tube formation in HUVECs. Importantly, in vivo experiments revealed that endothelial Gαi2 knockdown inhibited retinal angiogenesis in mice, with a concomitant down-regulation of NFAT-targeted genes in mouse retinal tissue. In contrast, Gαi2 over-expression in endothelial cells enhanced retinal angiogenesis in mice. Single-cell RNA sequencing data confirmed increased levels of Gαi2 specifically in retinal endothelial cells of mice with streptozotocin (STZ)-induced diabetic retinopathy (DR). Importantly, endothelial Gαi2 silencing ameliorated retinal pathological angiogenesis in DR mice. Conclusion: Our study highlights a critical role for Gαi2 in NFAT activation, endothelial cell activation and angiogenesis, offering valuable insights into potential therapeutic strategies for modulating these processes.

Pharmacological Action of Baicalin on Gestational Diabetes Mellitus in Pregnant Animals Induced by Streptozotocin via AGE-RAGE Signaling Pathway.

OBJECTIVE: Baicalin (BC) is a flavonoid reported to have various pharmacological activities, including antioxidant, anti-cancer, anti-inflammatory, anti-allergy, immune regulation, and anti-diabetic. This study examines the probable mechanism for gestational diabetes mellitus (GDM) brought on by streptozotocin (STZ) and the impact of BC on fetal development via AGEs (advanced serum glycation end products) and RAGE (the role of advanced glycation end products). MATERIAL AND METHOD: STZ has been used in the current experimental study to induce diabetes mellitus in pregnant animals (gestational diabetes mellitus). GDM pregnant animals were separated into five groups and were treated with BC in a dose-dependent pattern for 19 days. At the end of the experiment, the fetus and blood samples were drawn from all the pregnant rats to assess the biochemical parameter as well as AGE-RAGE. RESULT: Administration of BC at varying doses leads to enhancement in the weight of the fetus body and placenta while gestational diabetic pregnant animals induced by STZ had a lower weight of the fetus body and placenta. The dose-dependent pattern of BC also enhanced fasting insulin (FINS), high-density lipoprotein (HDL), serum insulin, and hepatic glycogen. It also significantly enhanced the content of the antioxidant profile and pro-inflammatory cytokines and modulated the gene expression (VCAM- 1, p65, EGFR, MCP-1, 1NOX2, and RAGE) in various tissues in gestational diabetes mellitus pregnant rats. CONCLUSION: Baicalin demonstrated the potential impact on the embryo's development via the AGE-RAGE signaling pathway in STZ-induced GDM pregnant animals.

Observation of the neuroprotective efficacy of vitamin K in a streptozocin-induced diabetes model in chick embryos.

Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia due to insulin deficiency and/or resistance. Vitamin K (VK) is a group of fat-soluble molecules, including naturally occurring vitamin K1 (phylloquinone). vitamin K2 (menaquinone), and synthetic vitamin K3 (menadione). Beyond coagulation, the health benefits of VK have been described to play different roles in both physiological and pathological processes such as inflammation, energy metabolism, neuroprotection, cellular growth, and survival. It was aimed to observe the antioxidant and/or neuroprotective activity of vitamin K1 in our model of chick embryo diabetic neuropathy (DN) induced by streptozotocin (STZ). Ninety White Leghorn, fertile and 0-day-old SPF (specific pathogen-free) eggs (57 ± 4 gr) were used in the study. Chick embryo blood brain tissues were taken for biochemical evaluation. Plasma insulin and glucose levels were measured. In addition, brain tissue total antioxidant level (TAS), total oxidant level (TOS), malondialdehyde (MDA), and vascular endothelial growth factor (VEGF) levels were measured. Plasma glucose levels were higher in the STZ-treated groups and lower in the treatment groups. Plasma insulin levels were observed to be higher in STZ groups in groups treated with high VK. Low TAS, high MDA, TOS, and VEGF levels were recorded in brain tissue STZ groups. Low VEGF, TOS, and MDA levels were recorded in the group treated with the highest VK, while high TAS levels were observed. In our STZ-induced chick embryo diabetic neuropathy model, we observed that VK1 reduced oxidant damage by showing antioxidant properties or by modulating antioxidant enzymes.

Antidiabetic Effect of Combined Leaf Extracts of Portulaca oleracea L., Beta vulgaris L., and Cichorium intybus L. in Streptozotocin-Induced Diabetic Rats.

Purslane (P), chard (CHA), and chicory (CHI) leaf extracts are individually and traditionally used in the treatment of diabetes mellitus. Polyphenols, flavonoids, the polyphenolic profile of the extracts, and their antioxidant activity were determined. This study evaluated the antidiabetic activity of combinations of these extracts in streptozotocin-induced diabetic rats. Diabetic groups were administered orally and daily for 40 days with the investigated extracts at 250 mg/kg body weight (b.w.) or metformin (100 mg/kg b.w.) as a drug. Fasting blood glucose, oral glucose tolerance, insulin, and fructosamine were assessed. The combined extracts with high levels of P or CHI exerted potent hypoglycemic activity compared with metformin in addition to the restoration of the histopathological changes in the liver and pancreas of diabetic rats to a near-normal state. Therefore, these combined extracts could be developed as natural drugs for diabetes.

Withaferin-A attenuates diabetes mellitus induced male reproductive dysfunction mediated by ERα in brain and testes of Swiss albino mice.

Diabetes mellitus (DM) is a chronic metabolic disease, characterized by persistent hyperglycemia resulting from diminished insulin secretion or insulin resistance. The present study evaluated the ameliorative effects of Withaferin-A (WA) on DM-induced reproductive dysfunction in mice. For the same, mice were intraperitoneally injected with Streptozotocin (STZ), (40 mg/kg/day) for 5 consecutive days to induce DM. Mice were then treated with WA (8 mg/kg/day) in normal and diabetic conditions (STZ + WA). Next, blood glucose levels, oral glucose tolerance, intraperitoneal insulin tolerance, oxidative stress and reproductive parameters were estimated. For reproductive performance, immunofluorescent localization of gonadotropin-releasing hormone (GnRH-I) and estrogen receptor alpha (ERα) in the preoptic area and paraventricular nucleus region of hypothalamus and ERα in testes was performed. STZ-induced diabetes triggered reproductive dysfunctions as mediated by low GnRH-I and ERα in the brain and ERα in the testes along with declined testosterone and estradiol levels. Treatment with WA significantly reduced the blood glucose levels and enhanced glucose clearance accompanied by reduced oxidative stress in the brain, pancreas and testes as indicated by the low levels of H2O2 and MDA in diabetic mice treated with WA (STZ + WA). This study reports, for the first time, that WA can efficiently ameliorate DM-induced reproductive dysfunctions by enhancing endogenous testosterone, estrogen and increased GnRH-I and ERα in the brain and ERα in the testes of DM-induced male mice.

Esculeoside A Decreases Diabetic Cardiomyopathy in Streptozotocin-Treated Rats by Attenuating Oxidative Stress, Inflammation, Fibrosis, and Apoptosis: Impressive Role of Nrf2.

Background and Objectives: This experiment evaluated the preventative influence of the tomato-derived Esculeoside A (ESA) on diabetic cardiomyopathy in type 1 diabetes mellitus (T1DM) in rats induced by streptozotocin (STZ). It also examined whether the activation of Nrf2 signaling affords this protection. Materials and Methods: Adult male Wistar control nondiabetic rats and rats with T1DM (STZ-T1DM) were given either carboxymethylcellulose as a vehicle or ESA (100 mg/kg) (eight rats/group) orally daily for 12 weeks. A group of STZ-T1DM rats was also treated with 100 mg/kg ESA and co-treated i.p. with 2 mg/kg (twice/week), brusatol, and Nrf2 inhibitors for 12 weeks. Results and Conclusions: Treatment with ESA prevented the gain in heart weight and cardiomyocyte hypertrophy and improved the left ventricular (LV) systolic and diastolic function (LV) in the STZ-T1DM rat group. Likewise, it reduced their serum levels of triglycerides, cholesterol, and low-density lipoproteins (LDL-c), as well as their LV mRNA, cytoplasmic total, and nuclear total levels of NF-κB. ESA also reduced the total levels of malondialdehyde, tumor necrosis factor-α, interleukine-6 (IL-6), Bax, cytochrome-c, and caspase-3 in the LV of the STZ-T1DM rats. In parallel, ESA enhanced the nuclear and cytoplasmic levels of Nrf2 and the levels of superoxide dismutase, glutathione, and heme oxygenase-1, but decreased the mRNA and cytoplasmic levels of keap-1 in the LVs of the STZ-T1DM rats. Interestingly, ESA did not affect the fasting insulin and glucose levels of the diabetic rats. All of these beneficially protective effects of ESA were not seen in the ESA-treated rats that received brusatol. In conclusion, ESA represses diabetic cardiomyopathy in STZ-diabetic hearts by activating the Nrf2/antioxidant/NF-κB axis.

Modulation of PPAR-γ, SREBP-1c and inflammatory mediators by luteolin ameliorates ß-cell dysfunction and renal damage in a rat model of type-2 diabetes mellitus.

BACKGROUND: Natural products have been recommended as a complementary therapy for type 2 diabetes mellitus (T2DM) due to constraints of safety and tolerability of existing anti-diabetic agents. Luteolin exhibits anti-diabetic and anti-inflammatory effects. Hence, the impact of luteolin on glucose homoeostasis and organ damage was investigated in high-fat diet (HFD) and streptozotocin (STZ) induced T2DM in rats. METHODS AND RESULTS: Male Wistar rats were maintained on HFD (provided 55% energy as fat) for 10 days. Subsequently, a single dose of 40 mg/kg STZ was injected intraperitoneally on the 11th day. Seventy-two hours after STZ administration, diabetic rats with established hyperglycemia (fasting serum glucose > 200 mg/dL) were randomized into different groups having six rats each and orally administered either 0.5% hydroxy propyl cellulose or pioglitazone (10 mg/kg) or luteolin (50 mg/kg or 100 mg/kg) once daily for 28 days, while continuing HFD for respective groups. Luteolin significantly reduced hyperglycaemia, homoeostasis model assessment (HOMA) of insulin resistance (HOMA-IR) levels, and improved hypoinsulinemia and HOMA of b-cell function (HOMA-B) in a dose-dependent manner. Increased TNF-α, IL-6 and NFκB levels in diabetic rats were significantly regulated. Additionally, luteolin significantly augmented PPAR-γ expression while attenuating sterol regulatory element binding protein-1c (SREBP-1c) expression. Histopathological scrutiny validated that luteolin effectively attenuated HFD-STZ-induced injury in pancreatic ß-cells and kidneys to near normalcy. CONCLUSION: Our study showed that luteolin ameliorated hyperglycemia and improved hypoinsulinemia, ß-cell dysfunction, and renal impairment in HFD-STZ-induced diabetic rats by attenuating inflammation and dysregulated cytokine secretion through modulation of PPAR-γ, TNF-α, IL-6 and NF-kB expression and down-regulation of SREBP-1c.

Silibinin ameliorates STING-mediated neuroinflammation via downregulation of ferroptotic damage in a sporadic Alzheimer's disease model.

Ferroptosis, an iron-dependent cell death, is caused by lipid peroxidation. Noteworthily, accumulation of iron and lipid peroxidation are found in the proximity of the neuritic plaque, a hallmark of Alzheimer's disease (AD), but the relationship between ferroptosis and neuroinflammation in AD is unclear. Silibinin, extracted from the Silybum marianum, is possibly developed as an agent for AD treatment from its neuroprotective effect, but the effect of silibinin on sporadic AD that accounts for more than 95% of AD remains unclear. To determine whether silibinin alleviates the pathogenesis of sporadic AD and investigate the underlying mechanisms, STZ-treated HT22 murine hippocampal neurons and intracerebroventricular injection of streptozotocin (ICV-STZ) rats, a sporadic AD model, were used in this study. Results show that silibinin not only promotes survival of STZ-treated HT22 cells, but also ameliorates the cognitive impairment and anxiety/depression-like behavior of ICV-STZ rats. We here demonstrate that silibinin evidently inhibits the protein level of p53 as well as upregulates the protein level of cystine/glutamate antiporter SLC7A11 and ferroptosis inhibitor GPX4, but not p21, leading to the protection against STZ-induced ferroptotic damage. Immunofluorescent staining also shows that accumulation of lipid peroxidation induced by ferroptotic damage leads to increased fluorescence of 8-oxo-deoxyguanosine (8-OHDG), a maker of oxidized DNA. The oxidized DNA then leaks to the cytoplasm and upregulates the expression of the stimulator of interferon gene (STING), which triggers the production of IFN-ß and other inflammatory cascades including NF-κB/TNFα and NLRP3/caspase 1/IL-1ß. However, the treatment with silibinin blocks the above pathological changes. Moreover, in HT22 cells with/without STZ treatment, GPX4-knockdown increases the protein level of STING, indicating that the ferroptotic damage leads to the activation of STING signaling pathway. These results imply that silibinin exerts neuroprotective effect on an STZ-induced sporadic AD model by downregulating ferroptotic damage and thus the downstream STING-mediated neuroinflammation.

Low glycemic index potato biscuits alleviate physio-histological damage and gut dysbiosis in rats with type-2 diabetes mellitus induced by high-sugar and high-fat diet and streptozotocin.

Type 2 diabetes mellitus (T2DM) is the most common type of diabetes globally and poses a major concern for human health. This study aimed to investigate the effects on T2DM of low-glycemic index (GI) potato biscuits with oat bran and inulin as functional additives. T2DM was induced in rats by streptozotocin (STZ) and a high-sugar and high-fat diet. The alleviation of T2DM by low-GI potato biscuits at different doses was evaluated based on the analysis of glycolipid levels, histological observations, inflammatory markers, and gut microbiota structure. Compared to wheat biscuits, low-GI potato biscuits resulted in lower postprandial blood glucose levels. After 8 weeks of intervention, fasting blood sugar levels were 16.9% lower in T2DM rats fed high-dose low-GI potato biscuits than in untreated T2DM rats. Moreover, the intervention with low-GI potato biscuits significantly alleviated T2DM-induced pathological damage, glucose and lipid metabolic disorders, and inflammation by reversing the levels of total cholesterol, triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, transforming growth factor-ß, interleukin-1ß, interleukin-6 and tumor necrosis factor-α. Moreover, the levels of short-chain fatty acids and gut microbiota structure in T2DM rats were significantly reversed. The abundance of beneficial bacteria (e.g., Bifidobacterium, Lachnoclostridium, Roseburia) in the gut of T2DM rats was significantly increased whereas the abundance of Escherichia-Shigella and Desulfovibrio decreased. The present study revealed that low-GI potato biscuits alleviated damages caused by high-sugar and high-fat diet- and STZ-induced T2DM in rats, as well as reversed disturbances in the gut microbiota. Thus, low-GI potato biscuits are potentially beneficial to T2DM patients.

HM-Chromanone Alleviates Hyperglycemia by Protecting Pancreatic Islet Cells in Streptozotocin-Induced Diabetic Mice.

We examined the effects of HM-chromanone (HMC) on alleviating hyperglycemia and protecting pancreatic ß-cells from streptozotocin (STZ)-induced damage in C57BL/6J mice. HMC was administered to STZ-induced diabetic mice at 10 or 30 mg/kg, for 14 days. Thereafter, changes in fasting blood glucose levels, insulin-secretion, histopathological examination of pancreas islet cell and apoptotic protein levels, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay were determined. The results revealed that HMC dose-dependently improved blood glucose concentrations and alleviated pancreatic islet cells damage. In diabetic mice, degeneration of the islet cells was observed wherein they appeared shrunken, with hyaline deterioration, nuclear dissolution, and condensation. However, morphology of the islet cell was restored, and nuclei were visibly rounded in the HMC (30 mg/kg)-administered diabetic mice. In addition, ß-cell numbers were markedly increased in HMC mice compared to STZ-induced diabetic mice, and the number of cells stained with glucagon was decreased. HMC markedly decreased the expression of proapoptotic proteins and increased antiapoptotic proteins, and the number of apoptotic cells detected by TUNEL was elevated. HMC decreased expression of interleukin (IL)-1ß, IL-6, and tumor necrosis factor-α in diabetic mice. Moreover, HMC increased antioxidant-enzymes activity, and decreased reactive oxygen species generation. In conclusion, the results demonstrate the potential of HMC to alleviate hyperglycemia by protecting the pancreatic ß-cells in diabetic mice.

Preventing muscle wasting: pro-insulin C-peptide prevents loss in muscle mass in streptozotocin-diabetic rats.

BACKGROUND: C-peptide therapy exerts several positive actions on nerves, vasculature, smooth muscle relaxation, kidney function and bone. To date, the role of C-peptide in preventing type 1 diabetes-related muscle atrophy has not been investigated. Our aim was to evaluate if C-peptide infusion prevents muscle wasting in diabetic rats. METHODS: Twenty-three male Wistar rats were randomly divided into three groups: normal control group, diabetic group and diabetic group plus C-peptide. Diabetes was induced by streptozotocin injection, and C-peptide was administered subcutaneously for 6 weeks. The blood samples were obtained at baseline, before streptozotocin injection and at the end of the study to assess C-peptide, ubiquitin and other laboratory parameters. We also tested the ability of C-peptide to regulate the skeletal muscle mass, the ubiquitin-proteasome system, the autophagy pathway as well as to improve muscle quality. RESULTS: C-peptide administration reversed hyperglycaemia (P = 0.02) and hypertriglyceridaemia (P = 0.01) in diabetic plus C-peptide rats compared with diabetic control rats. The diabetic-control animals displayed a lower weight of the muscles in the lower limb considered individually than the control rats and the diabetic plus C-peptide rats (P = 0.03; P = 0.03; P = 0.04; P = 0.004, respectively). The diabetic-control rats presented a significantly higher serum concentration of ubiquitin compared with the diabetic plus C-peptide and the control animals (P = 0.02 and P = 0.01). In muscles of the lower limb, the pAmpk expression was higher in the diabetic plus C-peptide than the diabetic-control rats (in the gastrocnemius, P = 0.002; in the tibialis anterior P = 0.005). The protein expression of Atrogin-1 in gastrocnemius and tibialis was lower in the diabetic plus C-peptide than in diabetic-control rats (P = 0.02, P = 0.03). After 42 days, the cross-sectional area in the gastrocnemius of the diabetic plus C-peptide group had been reduced by 6.6% while the diabetic-control rats had a 39.5% reduction compared with the control animals (P = 0.02). The cross-sectional area of the tibialis and the extensor digitorum longus muscles was reduced, in the diabetic plus C-peptide rats, by 10% and 11%, respectively, while the diabetic-control group had a reduction of 65% and 45% compared with the control animals (both P < 0.0001). Similar results were obtained for the minimum Feret's diameter and perimeter. CONCLUSIONS: C-peptide administration in rats could protect skeletal muscle mass from atrophy induced by type 1 diabetes mellitus. Our findings could suggest that targeting the ubiquitin-proteasome system, Ampk and muscle-specific E3 ubiquitin ligases such as Atrogin-1 and Traf6 may be an effective strategy for molecular and clinical intervention in the muscle wasting pathological process in T1DM.

Nicotinamide Riboside Improves Enteric Neuropathy in Streptozocin-Induced Diabetic Rats Through Myenteric Plexus Neuroprotection.

BACKGROUND: Diabetes Mellitus causes a systemic oxidative stress due in part to the hyperglycemia and the reactive oxygen species generated. Up to 75% of diabetic patients present with an autonomic neuropathy affecting the Enteric Nervous System. Deficits in the human population are chronic dysmotilities with either increased (i.e., constipation) or decreased (i.e., diarrhea) total gastrointestinal transit times. These are recapitulated in the streptozocin-induced diabetic rat, which is a model of Type I Diabetes Mellitus. AIMS: Examine the effects that a precursor of nicotinamide adenosine dinucleotide (NAD), nicotinamide riboside (NR), had on the development of dysmotility in induced diabetic rats and if fecal microbiota transplant (FMT) could produce the same results. MATERIALS AND METHODS: Utilizing a 6-week treatment paradigm, NR was administered intraperitoneally every 48 h. Total gastrointestinal transit time was assessed weekly utilizing the carmine red method. Three weeks following hyperglycemic induction, FMT was performed between NR-treated animals and untreated animals. SIGNIFICANT RESULTS: There is improvement in overall gastrointestinal transit time with the use of NR. 16S microbiome sequencing demonstrated decreased alpha and beta diversity in induced diabetic rats without change in animals receiving FMT. Improvements in myenteric plexus ganglia density in small and large intestines in diabetic animals treated with NR were seen. CONCLUSIONS: NR treatment led to functional improvement in total gastrointestinal transit time in induced diabetic animals. This was associated with neuroprotection in the myenteric plexuses of both small and large intestines of induced diabetic rats. This represents an important first step in showing NR's benefit as a treatment for diabetic enteric neuropathy. Streptozocin-induced diabetic rats have improved transit times and increased myenteric plexus ganglia density when treated with intraperitoneal nicotinamide riboside.

Co-administration of metformin and/or glibenclamide with losartan reverse NG-nitro-l-arginine-methyl ester-streptozotocin-induced hypertensive diabetes and haemodynamic sequelae in rats.

Over the years, there have been opinions on whether to reduced blood pressure (BP) to a different levels in patients with diabetes mellitus. Hence, this study investigated the efficacy of the co-administration of losartan (angiotensin receptor blocking antihypertensive agent) with metformin and/or glibenclamide (antidiabetic agents) on hypertensive-diabetic experimental rats induced by NG-nitro-l-arginine-methyl-ester hydrochloride (l-NAME), and streptozotocin (STZ). STZ (45 mg/kg, i.p.)-induced diabetic rats combined with l-NAME (40 mg/kg, p.o.)-induced hypertension were allotted into different groups. Group 1 received distilled water (10 mL/kg) and served as normal control, group 2 comprised hypertensive diabetic rats with distilled water, groups 3-5 were hypertensive-diabetic rats but received combination treatments of losartan + metformin, losartan + glibenclamide, and losartan + metformin + glibenclamide daily for 8 weeks, respectively. Our finding revealed no changes in the body weights, but there was a significant increase in fasting blood sugar levels in l-NAME - STZ-induced hypertensive-diabetes, which were lowered by losartan + metformin, losartan + glibenclamide, and losartan + metformin + glibenclamide treatments. Moreover, the increased systolic-BP, mean arterial pressure but not diastolic-BP and heart rate by l-NAME + STZ were attenuated more significantly by losartan + metformin + glibenclamide between weeks 2-8 relative to hypertensive-diabetic control. l-NAME + STZ-induced elevated levels of lactate dehydrogenase and creatinine kinase, were differentially reversed by losartan + metformin, losartan + glibenclamide, and losartan + metformin + glibenclamide. However, l-NAME + STZ-induced decreased nitrite level was significantly restored by all treatments, suggesting increased nitrergic transmission. Additionally, l-NAME + STZ-induced degeneration of pancreatic islet and myocardial cells were dramatically alleviated by losartan + metformin + glibenclamide treatments. Our findings suggest hyperglycemia with raised systolic-BP should be managed with losartan combined with both metformin and glibenclamide than single combination of losartan with antidiabetics.

Antihyperglycemic Effect of Rhamnus alaternus L. Aqueous Extract in Streptozotocin-induced Diabetic Rats.

BACKGROUND: Traditionally, the aerial parts of Rhamnus alaternus L. have been widely used in Mediterranean countries, including Morocco, to cure diabetes. AIM: This study aimed to evaluate the antidiabetic effect of Rhamnus alaternus aqueous extract in streptozotocin(STZ)-induced diabetic rats. OBJECTIVE: This work aimed to evaluate the antihyperglycemic effect of Rhamnus alaternus aqueous extract (RAAE) in normal and diabetic rats. Then the phytochemical composition, antioxidant capacity, and potential toxicity of RAAE were also assessed. METHODS: The effects of acute (6 h) and subchronic (7 days) oral administration of RAAE (20 mg/kg) on blood glucose levels and lipid profiles were evaluated in normal and diabetic rats. Besides, a preliminary phytochemical screening, quantification of phenolic, flavonoid, and tannin contents as well as the antioxidant activity, using the DPPH method, were evaluated. Additionally, the toxicity of the aqueous extract (5 mg/kg) was also studied and the LD50 value was determined. RESULTS: RAAE (20 mg/kg) over 7 days of oral administration significantly decreased the blood glucose levels both in normal and diabetic rats. In diabetic rats, this extract also improved oral glucose tolerance. In addition, RAAE possessed significant antioxidant activity. According to preliminary phytochemical research, RAAE contains several chemical compounds, including alkaloids, polyphenols, flavonoids, cyanidins, anthraquinones, and sterols. On the other hand, the quantitative phytochemical study of the aqueous extract revealed a considerable amount of total phenolic compounds (497.93 ± 3.38 mg GAE/1g of RAAE), flavonoids (100.42 ± 0.32 mg RE/ g of RAAE), and tannins (14.32 ± 0.37 mg CE/1g of RAAE). CONCLUSION: We conclude that RAAE exerts a significant antihyperglycemic effect in STZ-induced diabetic rats at a low dose. Indeed, more research is still required to support the use of this plant in the Moroccan population's diabetes care.

Renoprotective Effect of Thymoquinone against Streptozotocin-Induced Diabetic Nephropathy: Role of NOX2 and Nrf2 Signals.

OBJECTIVE: Diabetic nephropathy is an unavoidable complication of chronic uncontrolled diabetes mellitus. The pathogenesis of diabetic nephropathy is multifactorial, and the development of an effective therapy remains to be elucidated. The aim of the present study was to assess the role of NOX2 and Nrf2 in the protective mechanism of thymoquinone (THQ) against streptozotocin (STZ)-induced diabetic nephropathy. METHODS: Rats were injected with STZ (55 mg/kg) to induce diabetes. The diabetic rats were orally treated with THQ (10 mg/kg/day) for eight weeks. RESULTS: STZ-treated rats exhibit an elevation of serum creatinine, serum urea, and creatinine clearance. The renal abnormalities were associated with increased NADPH oxidase isoform, NOX2 protein expression, and activity, along with elevated malondialdehyde (MDA). In addition, the tumor necrotic factor-alpha (TNF-α) level and nitric oxide (NO) bioavailability, as well as the transforming growth factor-beta (TGF)-ß, were markedly increased. On the other hand, the nuclear factor-E2-related factor (Nrf2) protein expression was significantly reduced in diabetic rats compared to the control. However, treatment with THQ significantly reversed these alterations with subsequent ameliorating renal dysfunction and pathological abnormalities. CONCLUSION: The present study demonstrates that THQ could protect against STZ-induced diabetic nephropathy by modulating the Nrf2/NOX2 signaling pathway.

Protective effect of the tunneling nanotube-TNFAIP2/M-sec system on podocyte autophagy in diabetic nephropathy.

Podocyte injury leading to albuminuria is a characteristic feature of diabetic nephropathy (DN). Hyperglycemia and advanced glycation end products (AGEs) are major determinants of DN. However, the underlying mechanisms of podocyte injury remain poorly understood. The cytosolic protein TNFAIP2/M-Sec is required for tunneling nanotubes (TNTs) formation, which are membrane channels that transiently connect cells, allowing organelle transfer. Podocytes express TNFAIP2 and form TNTs, but the potential relevance of the TNFAIP2-TNT system in DN is unknown. We studied TNFAIP2 expression in both human and experimental DN and the renal effect of tnfaip2 deletion in streptozotocin-induced DN. Moreover, we explored the role of the TNFAIP2-TNT system in podocytes exposed to diabetes-related insults. TNFAIP2 was overexpressed by podocytes in both human and experimental DN and exposre of podocytes to high glucose and AGEs induced the TNFAIP2-TNT system. In diabetic mice, tnfaip2 deletion exacerbated albuminuria, renal function loss, podocyte injury, and mesangial expansion. Moreover, blockade of the autophagic flux due to lysosomal dysfunction was observed in diabetes-injured podocytes both in vitro and in vivo and exacerbated by tnfaip2 deletion. TNTs allowed autophagosome and lysosome exchange between podocytes, thereby ameliorating AGE-induced lysosomal dysfunction and apoptosis. This protective effect was abolished by tnfaip2 deletion, TNT inhibition, and donor cell lysosome damage. By contrast, Tnfaip2 overexpression enhanced TNT-mediated transfer and prevented AGE-induced autophagy and lysosome dysfunction and apoptosis. In conclusion, TNFAIP2 plays an important protective role in podocytes in the context of DN by allowing TNT-mediated autophagosome and lysosome exchange and may represent a novel druggable target.Abbreviations: AGEs: advanced glycation end products; AKT1: AKT serine/threonine kinase 1; AO: acridine orange; ALs: autolysosomes; APs: autophagosomes; BM: bone marrow; BSA: bovine serum albumin; CTSD: cathepsin D; DIC: differential interference contrast; DN: diabetic nephropathy; FSGS: focal segmental glomerulosclerosis; HG: high glucose; KO: knockout; LAMP1: lysosomal-associated membrane protein 1; LMP: lysosomal membrane permeabilization; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; PI3K: phosphoinositide 3-kinase; STZ: streptozotocin; TNF: tumor necrosis factor; TNFAIP2: tumor necrosis factor, alpha-induced protein 2; TNTs: tunneling nanotubes; WT: wild type.

Propofol protects rats against intra-cerebroventricular streptozotocin-induced cognitive dysfunction and neuronal damage.

BACKGROUND: Cognitive dysfunction is a severe issue of Alzheimer's disease. Thus, the present study was conducted to enumerate the protective effect of propofol (PPL) in rats against intra-cerebroventricular streptozotocin (STZ)-induced cognitive dysfunction and neuronal damage. MATERIALS AND METHODS: The effect of PPL was investigated to evaluate behavioural changes in STZ-induced cognitive dysfunction in Wistar rats using Object Recognition Task (ORT) for nonspatial, Morris Water Maze (MWM) for spatial and locomotor activity. The effect of PPL was also investigated on acetylcholine (ACh) esterase (AChE) activity and oxidative stress markers, e.g., nitrite, malonaldehyde (MDA), superoxide dismutase (SOD), and glutathione (GSH). The level of pro-inflammatory cytokines, e.g., tumour necrosis factor (TNF)-α, interleukin (IL)-1ß, and IL-6, was also studied in the PPL-treated group. The effect of PPL on the level of neurotransmitters, e.g., dopamine (DA), serotonin (5-HT), and norepinephrine (NE) and their metabolites 3,4-dihydroxyphenylacetic acid (DOPAC), 5-hydroxyindoleacetic acid (5-HIAA), and homovanillic acid (HVA) levels were also estimated in frozen hippocampal tissues by high-performance liquid chromatography. Histopathology analysis of neurons in the hippocampus of rats was performed using haematoxylin and eosin (H&E) staining. RESULTS: Propofol showed significant improvement in the spatial and nonspatial memory deficit of rats in the MWM test and ORT in rats. It also causes improvement in locomotor activity of rats by preserving ACh via inhibition of AChE. It also potentiates the expression of DA, 5-HT, and NE with a simultaneous reduction in the level of metabolites (DOPAC, HVA, and 5-HIAA). PPL showed a reduction of oxidative stress in rats by restoring the level of nitrite, SOD, MDA, and GSH near to normal. In the PPL-treated group, the level of TNF-α, IL-1ß, and IL-6 was found reduced in a dose-dependent manner. In histopathology analysis of neurons in the hippocampus of the STZ rats, PPL causes dose-dependent reduction of pyknosis in the nucleus, which confirmed the protective effect of PPL. CONCLUSIONS: The present study demonstrated that PPL could significantly attenuate cognitive dysfunction and neuronal damage in STZ-induced rats.

Tert-butylhydroquinone Mitigates Renal Dysfunction in Pregnant Diabetic Rats via Attenuation of Oxidative Stress and Modulation of the iNOs/ NFkB/TNF Alpha Signalling Pathway.

AIM: The aim of the study was to determine the effect of tert-butylhydroquinone (tBHQ) supplementation on some biochemical parameters in pregnant diabetic rats and the foetus. BACKGROUND: The global incidence of gestational diabetes mellitus (GDM) has been on the increase despite current interventional therapies, underscoring the need for alternative or complementary therapeutic approaches. OBJECTIVE: The objective is to determine the effect of tBHQ on blood glucose, insulin resistance, body weight, relative liver and kidney weights, serum lipid profile (total cholesterol, triacylglycerol, high-density lipoprotein cholesterol and very low-density lipoprotein cholesterol), liver function (albumin, aspartate and alanine amino transaminases) and kidney function markers (urea, creatinine and uric acid) in the sera, and study maternal and foetal renal levels of oxidative stress and inflammatory markers, foetal weights and histology of the kidney of streptozotocin (STZ)-induced GDM in rats. METHODS: Twenty female pregnant rats were used, and they were divided into four groups of control (normal pregnancy), disease (diabetic untreated), metformin (received 200 mg/kg metformin dissolved in distilled water) and tBHQ groups (received 25 mg/kg tBHQ in 1% corn oil), respectively, with five rats in each group. GDM was induced in the disease and treated groups by intraperitoneal injection of STZ (45 mg/kg in sodium citrate buffer, pH 4.5). RESULTS: STZ induction in the disease group significantly increased their blood glucose levels (P<0.05), altered their body and foetal weights, relative liver and kidney weights, serum lipid profile, liver and kidney function markers in the sera (relative to the control), inducing oxidative stress and inflammation to the maternal and foetal kidneys and altering the maternal kidney histology, which was found to be improved following supplementation with tBHQ in a manner akin to or even better than metformin. CONCLUSION: tBHQ was found beneficial in protecting the foetal kidneys against oxidative stress and the foetus against mortality arising from maternal hyperglycaemia. Finally, the study showed the potential of tBHQ in mitigating histological changes in the maternal kidney arising from STZinduced hyperglycemia in rats.

Ketogenic diet modulates cardiac metabolic dysregulation in streptozocin-induced diabetic rats.

The ketogenic diet (KD) might improve cardiac function in diabetic cardiomyopathy, but the mechanisms remain unclear. This study investigated the effects of KD on myocardial fatty acid (FA), glucose, and ketone metabolism in diabetic cardiomyopathy. Echocardiograms, biochemistry, and micro-positron emission tomography were performed to evaluate cardiac function and glucose uptake in control rats and streptozotocin-induced diabetes mellitus (DM) rats with normal diet (ND) or KD for 6 weeks. Histopathology, adenosine triphosphate measurement, and Western blot were performed in the ventricular myocytes to analyze fibrosis, FA, ketone body, and glucose utilization. The ND-fed DM rats exhibited impaired left ventricular systolic function and increased chamber dilatation, whereas control and KD-fed DM rats did not. The KD reduced myocardial fibrosis and apoptosis in the DM rats. Myocardial glucose uptake in the micro-positron emission tomography was similar between ND-fed DM rats and KD-fed DM rats and was substantially lower than the control rats. Compared with the control rats,  ND-fed DM rats had increased phosphorylation of acetyl CoA carboxylase and higher expressions of CD-36, carnitine palmitoyltransferase-1ß, tumor necrosis factor-α, interleukin-1ß, interleukin6, PERK, and e-IF2α as well as more myocardial fibrosis and apoptosis (assessed by Bcl-2, BAX, and caspase-3 expression); these increases were attenuated in the KD-fed DM rats. Moreover, ND-fed DM rats had significantly lower myocardial adenosine triphosphate, BHB, and OXCT1 levels than the control and KD-fed DM rats. The KD may improve the condition of diabetic cardiomyopathy by suppressing FA metabolism, increasing ketone utilization, and decreasing endoplasmic reticulum stress and inflammation.

Nigericin Abrogates Maternal and Embryonic Oxidative Stress in the Streptozotocin-Induced Diabetic Pregnant Rats.

Hyperglycemic exposure in diabetic pregnancy can lead to many developmental changes, such as delayed development, fetal malformations, and fetal/embryo death. These detrimental complications are collectively known as diabetic embryopathy or teratogenesis. The current study focuses to discover the therapeutic properties of the nigericin against the STZ-stimulated diabetic embryopathy via alleviation of maternal and embryonic oxidative stress. The male and female rats at a 1:1 ratio were permitted to mate overnight to establish the course of pregnancy. The pregnant rats were distributed into four groups control, diabetic pregnant (via administering 40 mg/kg of STZ), and diabetic + 10 and 20 mg/kg of nigericin-administered (via oral gavage from days 5 to 12) groups, respectively. The glucose level, urine output, diet intake, and body weight were determined carefully. The embryo and placenta weight and implantation rates were examined, and data were tabulated. The total protein and lipid profiles were assessed using respective kits. The oxidative stress markers and antioxidant enzymes were examined using respective assay kits. The 10 and 20 mg/kg of nigericin treatment decreased the glucose level and urine output and improved the diet intake and body weight gain in diabetic pregnant rats. The nigericin also decreased the total protein, cholesterol, triglycerides, and very-low-density lipoprotein (VLDL) and improved the high-density lipoprotein (HDL) in the serum of pregnant rats. The levels of malondialdehyde (MDA), reactive oxygen species (ROS), and protein carbonyls were decreased by the nigericin in both liver and embryos of the pregnant rats. The levels of glutathione (GSH), total thiols, and activities of catalase (CAT), glutathione reductase (GR), superoxide dismutase (SOD), glutathione peroxidase (GPX), and glutathione S-transferase (GST) were improved by the nigericin in the diabetic pregnant rats. Altogether, these results provide evidence that nigericin treatment remarkably attenuates the diabetes-stimulated embryopathy in rats. The nigericin effectively decreased embryo lethality, reduced glucose and dyslipidemia, and relieves oxidative stress via upregulating the antioxidant enzyme activities. Hence, it can be a talented therapeutic agent to treat diabetic pregnancy-associated complications.