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.

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.

NADH intraperitoneal injection prevents massive pancreatic beta cell destruction in a streptozotocin-induced diabetes in rats

Diabetes mellitus is a chronic metabolic disease characterized by persistent hyperglycemia, revealing a decrease in insulin efficiency. The sustained glucotoxic pancreatic microenvironment increases reactive oxygen species generation, resulting in chronic oxidative stress responsible for massive DNA damage. This triggers PARP-1 activation with both NAD+ and ATP depletion, affecting drastically pancreatic beta cells' energy storage and leading to their dysfunction and death. The aim of the present study is to highlight the main histological changes observed in pancreatic islets pre-treated with a unique NADH intraperitoneal injection in a streptozotocin-(STZ)-induced diabetes model. In order to adjust NADH doses, a preliminary study with three different doses, 500 mg/kg, 300 mg/kg, and 150 mg/kg, respectively, was conducted. Subsequently, and on the basis of the results of the aforementioned study, Wistar rats were randomly divided into four groups: non-diabetic control group, diabetics (STZ 45 mg/kg), NADH-treated group (150 mg/kg) 15 min before STZ administration, and NADH-treated group (150 mg/kg) 15 min after STZ administration. The effect of NADH was assessed by blood glucose level, TUNEL staining, histo-morphological analysis, and immunohistochemistry. The optimum protective dose of NADH was 150 mg/kg. NADH effectively decreased hyperglycemia and reduced diabetes induced by STZ. Histologically, NADH pre-treatment revealed a decrease in beta cell death favoring apoptosis over necrosis and therefore preventing inflammation with further beta cell destruction. Our data clearly demonstrate that NADH prior or post-treatment could effectively prevent the deleterious loss of beta cell mass in STZ-induced diabetes in rats and preserve the normal pancreatic islet's function.

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.

Nephroprotective effect of cranberry (Vaccinium oxycoccos) in streptozocin-induced diabetic nephropathy in mice

OBJECTIVES

Diabetic nephropathy is a chief reason of mortality particularly in individuals with renal dysfunction. The current research was aimed to assess the nephroprotective portion of Vaccinium oxycoccos toward mice diabetic nephropathy induced by streptozotocin (STZ). V. oxycoccos was purchased and used for hydroalcoholic extraction.

METHODS

Sixty male mice were subjected to STZ-intraperitoneal injection (45 mg/kg). After diabetes induction, mice were divided into five groups of diabetic control (received only STZ), non-diabetic control (received only citrate buffer), two V. oxycoccos treatment (received V. oxycoccos extract (200 and 400 mg/kg) oral daily by gavage), and metformin treatment (received metformin (500 mg/kg) oral daily by gavage). Glucose and weight of mice were checked weekly.

RESULTS

After 28 days, the effect of V. oxycoccos extract on serum and urine parameters were assessed. STZ caused significant decreased in the mice body weight. Mice treated with the V. oxycoccos (400 mg/kg) harbored the lowest weight loss at day 28 (70.2±1.38 g). STZ caused significant increase in the mice FBS. Mice treated with the V. oxycoccos (400 mg/kg) harbored the lowest FBS at day 28 (189.2±1.20 mg/dL). Treatment of mice with V. oxycoccos (400 mg/kg) caused the lowest increase in the levels of cholesterol, HbA1c and triglycerides compared to the diabetic control mice. Compared to the diabetic control group, mice treated with V. oxycoccos (400 mg/kg) had the highest HDL, insulin, SOD, and GSH (p<0.05). The lowest serum BUN, CR, and UR were found in mice treated with V. oxycoccos (400 mg/kg). Anti-inflammatory effects of V. oxycoccos (400 mg/kg) was shown by the lowest TNF-α, IL-6, and TGF-β1 concentration in mice treated with V. oxycoccos (400 mg/kg).

CONCLUSIONS

The current study disclosed that treatment with V. oxycoccos resulted in substantial development in the serum and urine parameters and also antioxidant and anti-inflammatory response of STZ-induced diabetic mice.

Effects of Physalis peruviana L. (leaf crude extracts) on blood glucose and functional biomarkers in streptozotocin-nicotinamide-induced diabetic rats

Promoting antidiabetic phytomedicines necessitates evidence-based preclinical investigations, particularly in animal models. The present study investigated the validity of using the streptozotocin-nicotinamide-induced type 2 diabetic (STZ/NA-induced T2DM) model to evaluate the effects of Physalis peruviana leaf crude extracts on controlling blood glucose levels and regulating physiological biomarkers in rats. Aqueous and methanol extracts dissolved in carboxymethylcellulose 1% (100, 200, mg/kg/day) were administered orally to STZ/NA-induced T2DM rats alongside glibenclamide (5 mg/kg) as the standard drug for four weeks. Blood samples were collected in fasting rats on days 1, 7, 14, 21, and 28 to measure glucose concentration, lipoprotein-cholesterol, and common serum biomarkers. Nutrition characteristics were also monitored, as well as the pancreas histology. Administration of STZ/NA in Wistar rats induced the T2DM significantly lower than did STZ alone (glycaemia 200 vs 400 mg/dL). The significant effects observed with plant extracts compared to untreated diabetic rats were blood glucose reduction (28-52 %), HDL-C increase, LDL-C decrease, ALAT increase, WBC increase, body weight gain (24%), and pancreas protection. The findings confirm the antidiabetic effect of P. peruviana in T2DM animal model.

Protective Effect of Betulin on Streptozotocin-Nicotinamide-Induced Diabetes in Female Rats

Type 2 diabetes is characterized by hyperglycemia and a relative loss of β-cell function. Our research investigated the antidiabetic potential of betulin, a pentacyclic triterpenoid found primarily in birch bark and, intriguingly, in a few marine organisms. Betulin has been shown to possess diverse biological activities, including antioxidant and antidiabetic activities; however, no studies have fully explored the effects of betulin on the pancreas and pancreatic islets. In this study, we investigated the effect of betulin on streptozotocin-nicotinamide (STZ)-induced diabetes in female Wistar rats. Betulin was prepared as an emulsion, and intragastric treatments were administered at doses of 20 and 50 mg/kg for 28 days. The effect of treatment was assessed by analyzing glucose parameters such as fasting blood glucose, hemoglobin A1C, and glucose tolerance; hepatic and renal biomarkers; lipid peroxidation; antioxidant enzymes; immunohistochemical analysis; and hematological indices. Administration of betulin improved the glycemic response and decreased α-amylase activity in diabetic rats, although insulin levels and homeostatic model assessment for insulin resistance (HOMA-IR) scores remained unchanged. Furthermore, betulin lowered the levels of hepatic biomarkers (aspartate aminotransferase, alanine aminotransferase, and alpha-amylase activities) and renal biomarkers (urea and creatine), in addition to improving glutathione levels and preventing the elevation of lipid peroxidation in diabetic animals. We also found that betulin promoted the regeneration of β-cells in a dose-dependent manner but did not have toxic effects on the pancreas. In conclusion, betulin at a dose of 50 mg/kg exerts a pronounced protective effect against cytolysis, diabetic nephropathy, and damage to the acinar pancreas and may be a potential treatment option for diabetes.

Combined administration of gallic acid and glibenclamide mitigate systemic complication and histological changes in the cornea of diabetic rats induced with streptozotocin

PURPOSE

To determine the effect of gallic acid or its combination with glibenclamide on some biochemical markers and histology of the cornea of streptozotocin (STZ) induced diabetic rats.

METHODS

Following induction of diabetes, 24 male albino rats were divided into four groups of six rats each. Groups 1 and 2 (control and diabetic) received rat pellets and distilled water; group 3 (gallic acid) received rat pellets and gallic acid (10 mg/kg, orally) dissolved in the distilled water; and group 4 (gallic acid + glibenclamide) received rat pellets, gallic acid (10 mg/kg, orally), and glibenclamide (5 mg/kg, orally) dissolved in the distilled water. The treatments were administered for three months after which the rats were sacrificed after an overnight fast. Blood and sera were collected for the determination of biochemical parameters, while their eyes were excised for histology.

RESULTS

STZ administration to the rats induced insulin resistance, hyperglycemia, microprotenuria, loss of weight, oxidative stress, inflammation, and alteration of their cornea histology, which was abolished following supplementation with gallic acid or its combination with glibenclamide.

CONCLUSIONS

The study showed the potentials of gallic acid and glibenclamide in mitigating systemic complication and histological changes in the cornea of diabetic rats induced with STZ.

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.

Investigation on Anti-diabetic Efficacy of a Cucurbitaceae Food Plant from the North-East Region of India: Exploring the Molecular Mechanism through Modulation of Oxidative Stress and Glycosylated Hemoglobin (HbA1c)

BACKGROUND

The medicinal plants of the Cucurbitaceae family, such as Solena heterophylla Lour. fruits, have significant ethnobotanical value and are readily accessible in North East India.

AIMS

We conducted a study on Solena heterophylla Lour. fruits to evaluate their anti-diabetic activity in vivo, standardize their HPTLC, and profile their metabolites using LC-QTOF-MS. We aimed to explore the molecular mechanism behind their effects on oxidative stress and glycosylated hemoglobin (HbA1c).

METHODS

Firstly, the ethyl acetate fraction of Solena heterophylla Lour. fruits was standardized using Cucurbitacin B as a standard marker by conducting HPTLC evaluation. Next, we delved into analyzing metabolite profiling. In addition, the standardized fraction was utilized in an experimental study to investigate the molecular mechanism of action in an in vivo high-fat diet and a low dose of streptozotocin-induced diabetic model.

RESULTS

We have reportedly identified 52 metabolites in the ethyl acetate fraction of Solena heterophylla (EASH). In the in vitro tests, it has been observed that this extract from plants possesses notable inhibitory properties against α-amylase and α-glucosidase. Solena heterophylla fruits with high levels of Cucurbitacin B (2.29% w/w) helped lower FBG levels in animals with EASH treatment. EASH treatment reduced HbA1c levels and normalized liver lipid peroxidation and antioxidant enzyme levels. SGOT, SGPT, and SALP serum enzyme levels also returned to normal.

CONCLUSION

Based on the current evaluation, it was found that EASH exhibited encouraging hypoglycemic effects in diabetic rats induced by a low dose of STZ and high-fat diet, which warrants further investigation.

Dehulled Adlay (Coix lachryma-jobi L.) ameliorates hepatic gluconeogenesis and steatosis in streptozotocin/high-fat diet-induced diabetic rats

Adlay (Coix lachryma-jobi L.) is a traditional Chinese herbal medicine with various biological activities. We investigated the anti-diabetic effects of different parts of adlay seeds, including polished adlay (PA), adlay bran (AB) and dehulled adlay (DA) in a streptozotocin (STZ)/high fat diet (HFD) diabetic rat model (DM). DM rats supplemented with or without PA (43%), AB (3%), or DA (46%) diet for 8 weeks. The plasma glucose and insulin levels and the insulin resistance index (HOMA-IR) were increased in DM group; among the three adlay diets, DA has the best effects attenuating all of these alterations in DM rats. Both AB and DA alleviated diabetes-impaired glucose tolerance. The increased hepatic phosphoenolpyruvate carboxykinase protein expression in DM group was improved by all of the three adlay diets. The increased ratio of glucose-6-phosphatase to glucokinase in DM group was suppressed by DA supplementation, further suggesting DA diet is most effective among the three diets. Both AB and DA diets had beneficial effects against hepatic steatosis, with better effects observed in DA group. These results suggest that the DA diet, composed of both polished adlay and adlay bran, possesses the best potential to improve glucose homeostasis, at least in part, by alleviating hepatic glucose metabolism and steatosis.

Protective effect of tretinoin derivative and TXNRD1 protein on streptozotocin induced gestational diabetes via an age-rage signaling-pathway

BACKGROUND

In the present study effect of tretinoin derivative was investigated on the pathogenesis of gestational diabetes mellitus (GDM) in mice model in vivo.

MATERIALS AND METHODS

Diabetes was induced in mice by injecting Streptozotocin (STZ) for 5consecutive days at a dose of 65 mg/kg body weight through the intraperitoneal route. Tretinoin derivative was given to the mice at 0.12 and 0.25 mg/kg doses through gavage in normal saline alternately for one week after STZ injection.

RESULTS

The results demonstrated that tretinoin derivative administration to the diabetic mice significantly (P<0.05) alleviated the blood FBG and FINS levels. Administration of tretinoin derivative to the diabetic mice significantly (P<0.05) promoted the blood HDL level and alleviated TC and TG levels. The administration of tretinoin derivative to the diabetic mice significantly (P<0.05) alleviated the CRP, IL-6and TNF-α production in pancreatic tissues. Tretinoin derivative administration to the diabetic mice significantly (P<0.05) elevated the SOD activity, and CAT level and lowered the MDA level in pancreatic tissues. The TXNRD1 expression in diabetic mice was comparable to that in the normal group after administration of tretinoin derivativeat the dose of 0.25 mg/kg dose. In silico data demonstrated that tretinoin derivativeinteracts with TXNRD1 protein with the binding affinity ranging from -10 to 9.4 kcal/ mol.

CONCLUSION

In conclusion, tretinoin derivative administration effectively regulated streptozotocin-induced changes in fasting blood glucose, insulin level, high-density lipid level and triglyceride level in diabetic mice in vivo. The streptozotocin-induced excessive production of C-reactive protein and inflammatory cytokines was also down-regulated in diabetic mice on administration of tretinoin derivative. Therefore, tretinoin derivative can be investigated further as a therapeutic agent for the treatment of gestational diabetes mellitus.

Dalbergiella welwitschia (Baker) Baker f. alkaloid-rich extracts attenuate liver damage in streptozotocin-induced diabetic rats

This experiment was conducted to evaluate the Dalbergiella welwitschia alkaloid-rich extracts on liver damage in streptozotocin-induced diabetic rats. Hence, to induce diabetes, 45 mg/kg body weight of streptozotocin was intraperitoneally injected into the Wistar rats. Subsequently, 5 % (w/v) of glucose water was given to the induced animals for 24 h. Thus, the animals (48) were grouped into five groups (n = 8), containing normal control (NC), diabetic control (DC), diabetic rats placed on low (50 mg/kg body weight) and high (100 mg/kg body weight) doses of D. welwitschi alkaloid-rich leaf extracts (i.e. DWL and DWH respectively), and diabetic rats administered 200 mg/kg body weight of metformin (MET). The animals were sacrificed on the 21st day of the experiment, blood and liver were harvested, and different liver damage biomarkers were evaluated. The results obtained demonstrated that diabetic rats administered DWL, DWH and MET significantly (p < 0.05) increased hepatic AST, ALT, albumin, SOD, CAT, GSH, and GPX levels when compared to DC with no significant (p > 0.05) different when compared with NC. Also, diabetic rats administered DWL, DWH and MET revealed a significant (p < 0.05) decrease in GGT and MDA levels, as well as, fragmented DNA and protein carbonyl levels when compared to DC with no significant (p > 0.05) different when compared with NC. In addition, histological examination revealed that diabetic rats placed on DWL, DWH and MET normalized the hepatocytes. Consequently, it can be inferred that alkaloid-rich extracts from D. welwitschi leaf could be helpful in improving liver damage associated with diabetes mellitus rats.

Morphological and molecular changes in the Harderian gland of streptozotocin-induced diabetic rats

Using a rat model of type 1 diabetes (T1D) obtained by treatment with streptozotocin, an antibiotic that destroys pancreatic β-cells, we evaluated the influence of subsequent hyperglycemia on the morphology and physiology of the Harderian gland (HG). HG is located in the medial corner of the orbit of many terrestrial vertebrates and, in rodents, is characterized by the presence of porphyrins, which being involved in the phototransduction, through photo-oxidation, produce reactive oxygen species activating the autophagy pathway. The study focused on the expression of some morphological markers involved in cell junction formation (occludin, connexin-43, and α-tubulin) and mast cell number (MCN), as well as autophagic and apoptotic pathways. The expression of enzymes involved in steroidogenesis [steroidogenic acute regulatory protein (StAR), and 3β-hydroxysteroid dehydrogenase (3β-HSD)] and the level of lipid peroxidation by thiobarbituric acid reactive species assay were also evaluated. The results strongly indicate, for the first time, that T1D has a negative impact on the pathophysiology of rat HG, as evidenced by increased oxidative stress, morphological and biochemical alterations, hyperproduction and secretion of porphyrins, increased MCN, reduced protein levels of StAR and 3β-HSD, and, finally, induced autophagy and apoptosis. All the combined data support the use of the rat HG as a suitable experimental model to elucidate the molecular damage/survival pathways elicited by stress conditions.

Antihyperglycemic activity of 14-deoxy, 11, 12-didehydro andrographolide on streptozotocin-nicotinamide induced type 2 diabetic rats

BACKGROUND

Diabetic Mellitus is characterized by a lack or failure of insulin to bind to its target receptor or failure of the pancreas to yield insulin. This study evaluated the antihyperglycemic activity of 14-deoxy, 11, 12-didehydro andrographolide on streptozotocin-nicotinamide-induced type 2 diabetic rats. Diabetic conditions were induced by administering streptozotocin at a dosage of 45 mg/kg body weight and nicotinamide at a dosage of 110 mg/kg body weight through intraperitoneal injection.

MATERIALS AND METHODS

Diabetic-induced rats were treated with 14-deoxy, 11, 12-didehydro andrographolide concentrations between 10 and 500 mg/kg body weight. The blood glucose level and body weight of the rats were periodically examined. The pancreas was isolated and the histopathological staining was performed after making fine sections of the pancreas using a microtome. The influence of 14-deoxy, 11, 12-didehydro andrographolide on the expression level of various insulin signaling cascades was determined with q-PCR and western blotting.

RESULTS

The blood glucose level of the diabetic-induced rats was significantly (p < 0.05) higher when compared with the control group and resulted in a drop in the blood glucose level of the diabetic rats. Oral glucose level was also reduced in the treatment group and no significant reduction was noted in the untreated. The lipid profiling revealed that the atherogenic index and cholesterol ratio was increased in the diabetic group over the control group. Upregulation of the insulin cascades like IRTK and GLUT4 was observed by the q-PCR and upregulation of GLUT4 and IR-β was observed by the western blot analysis.

CONCLUSION

Overall, the finding indicates that 14-deoxy, 11, 12-didehydro andrographolide exhibited antihyperglycemic activity by modulating the expression of insulin cascades.

Modulation of PPAR-γ, SREBP-1c and inflammatory mediators by luteolin ameliorates β-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 β-cells and kidneys to near normalcy.

CONCLUSION

Our study showed that luteolin ameliorated hyperglycemia and improved hypoinsulinemia, β-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.

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.

The Impact of Hydroxytyrosol on the Metallomic-Profile in an Animal Model of Alzheimer's Disease

It is undeniable that as people get older, they become progressively more susceptible to neurodegenerative illnesses such as Alzheimer's disease (AD). Memory loss is a prominent symptom of this condition and can be exacerbated by uneven levels of certain metals. This study used inductively coupled plasma mass spectrometry (ICP-MS) to examine the levels of metals in the blood plasma, frontal cortex, and hippocampus of Wistar rats with AD induced by streptozotocin (STZ). It also tested the effects of the antioxidant hydroxytyrosol (HT) on metal levels. The Barnes maze behavior test was used, and the STZ group showed less certainty and greater distance when exploring the Barnes maze than the control group. The results also indicated that the control group and the STZ + HT group exhibited enhanced learning curves during the Barnes maze training as compared to the STZ group. The ICP-MS analysis showed that the STZ group had lower levels of cobalt in their blood plasma than the control group, while the calcium levels in the frontal cortex of the STZ + HT group were higher than in the control group. The most important finding was that copper levels in the frontal cortex from STZ-treated animals were higher than in the control group, and that the STZ + HT group returned to equivalent levels to the control group. The antioxidant HT can restore copper levels to their basal physiological state. This finding may help explain HT's potential beneficial effect in AD-patients.

Neuroprotective Effects of Probiotic Lactobacillus reuteri GMNL-263 in the Hippocampus of Streptozotocin-Induced Diabetic Rats

Diabetes-related brain complications have been reported in clinical patients and experimental models. The objective of the present study was to investigate the neuroprotective mechanisms of Lactobacillus reuteri GMNL-263 in streptozotocin (STZ)-induced diabetic rats. In this study, three different groups, namely control group, STZ-induced (55 mg/kg streptozotocin intraperitoneally) diabetic rats (DM), and DM rats treated with Lactobacillus reuteri GMNL-263 (1 × 109 CFU/rat/day), were utilized to study the protective effect of GMNL-263 in the hippocampus of STZ-induced diabetic rats. The results demonstrated that GMNL-263 attenuated diabetes-induced hippocampal damage by enhancing the cell survival pathways and repressing both inflammatory and apoptotic pathways. Histopathological analysis revealed that GMNL-263 prevented structural changes in the hippocampus in the DM group and decreased the level of inflammation and apoptosis in the hippocampus of DM rats. The IGF1R cell survival signaling pathway also improved after GMNL-263 treatment. These results indicate that probiotic GMNL-263 exerts beneficial effects in the brain of diabetic rats and has potential ability for clinical application.

Ameliorative effect of Stevia rebaudiana Bertoni on sperm parameters, in vitro fertilization, and early embryo development in a streptozotocin-induced mouse model of diabetes

Diabetes mellitus (DM) is a common metabolic disease characterized by high blood sugar levels. It is well known that men with diabetes frequently experience reproductive disorders and sexual dysfunction. In fact, sperm quality has a significant effect on fertilization success and embryo development. The current study aimed to investigate the effect of Stevia rebaudiana hydroalcoholic extract on serum testosterone levels, sperm parameters, in vitro fertilization (IVF) success, and in vitro embryonic developmental potential to reach the blastocyst stage in a streptozotocin (STZ)-induced mouse model of diabetes. In this research, 30 male mice were distributed randomly into control, diabetic (streptozotocin 150 mg/kg) and diabetic + Stevia (400 mg/kg) groups. The results revealed a decrease in body and testis weight and elevated blood fasting blood sugar (FBS) levels in the diabetic group, compared with the control. However, Stevia treatment significantly increased body and testis weight, while serum FBS levels were decreased compared with the diabetic group. In addition, Stevia significantly increased blood testosterone levels compared with the diabetic group. Moreover, sperm parameters were improved considerably by Stevia treatment compared with the diabetic group. Furthermore, Stevia administration significantly promoted IVF success rate and in vitro development of fertilized oocytes compared with the diabetic group. In summary, our data indicated that Stevia enhanced sperm parameters, IVF success, and in vitro embryonic developmental competency in diabetic mice, probably because of its antioxidant effects. Therefore, Stevia could ameliorate sperm parameters that, in turn, increase fertilization outcomes in experimental-induced diabetes.

Açaí berry ameliorates cognitive impairment by inhibiting NLRP3/ASC/CASP axis in STZ-induced diabetic neuropathy in mice

Diabetes complications such as diabetic peripheral neuropathy (DPN) are linked to morbidity and mortality. Peripheral nerve damages in DPN are accompanied by discomfort, weakness, and sensory loss. Some drugs may demonstrate their therapeutic promise by reducing neuroinflammation, but they have side effects. Based on these considerations, the objective of this study was to examine the beneficial properties of açaí berry in a mouse model of DPN generated by injection of streptozotocin (STZ). Açaí berry was given orally to diabetic and control mice every day beginning 2 wk after STZ injection. The animals were euthanized after 16 wk, and tissues from the spinal cord and sciatic nerve and urine were taken. Our findings showed that daily treatment of açaí berry at a dose of 500 mg/kg was able to prevent behavioral changes as well as mast cell activation and nerve deterioration via NOD-like receptor family pyrin-domain-containing-3 (NLRP3)/apoptosis-associated speck-like protein containing a card (ASC)/caspase (CASP) regulation after diabetes induction.NEW & NOTEWORTHY Our research shows that açaí berry reduces mast cells degranulation and histological damage in diabetic neuropathy, improves physiological defense against reactive oxygen species, modulates the NLRP3/ASC/CASP axis, and ameliorates inflammation and oxidative stress. Diet could help treatment for diabetic peripheral neuropathy.

Dose-dependent progression of multiple low-dose streptozotocin-induced diabetes in mice

This study investigated the effects of different multiple low doses of streptozotocin (STZ), namely 35 and 55 mg/kg, on the onset and progression of diabetes in mice. Both doses are commonly used in research, and although both induced a loss of beta cell mass, they had distinct effects on whole glucose tolerance, beta cell function, and gene transcription. Mice treated with 55 mg/kg became rapidly glucose intolerant, whereas those treated with 35 mg/kg had a slower onset and remained glucose tolerant for up to a week before becoming equally glucose intolerant as the 55 mg/kg group. Beta cell mass loss was similar between the two groups, but the 35 mg/kg-treated mice had improved glucose-stimulated insulin secretion in gold-standard hyperglycemic clamp studies. Transcriptomic analysis revealed that the 55 mg/kg dose caused disruptions in nearly five times as many genes as the 35 mg/kg dose in isolated pancreatic islets. Pathways that were downregulated in both doses were more downregulated in the 55 mg/kg-treated mice, whereas pathways that were upregulated in both doses were more upregulated in the 35 mg/kg-treated mice. Moreover, we observed a differential downregulation in the 55 mg/kg-treated islets of beta cell characteristic pathways, such as exocytosis or hormone secretion. On the other hand, apoptosis was differentially upregulated in 35 mg/kg-treated islets, suggesting different transcriptional mechanisms in the onset of STZ-induced damage in the islets. This study demonstrates that the two STZ doses induce distinctly mechanistic progressions for the loss of functional beta cell mass.

Effects of thymoquinone and memantine alone and in combination on memory and hippocampal morphology in rats with streptozotocin-induced Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is a progressive neurodegenerative disease. Thymoquinone (TQ) has broad biological functions, including antiinflammatory, antioxidant, neuroprotective properties. Memantine (MEM) is indicated for the symptomatic treatment of moderate to severe AD. We aimed to evaluate the effect of TQ alone or in combination with MEM on memory and hippocampal morphology in an STZ-induced rat AD model.

METHODS

Thirty male rats were included in this study. The AD model was created by giving ICV STZ. The rats were divided into 5 groups (n = 6 each). Group 1 (control group): The rats received only ICV-STZ 3 mg/kg for 2 weeks. Group 2 (sham group): In addition to ICV STZ, 9% NaCl, 1 mL/day i.p. for 2 weeks of injection, was applied. Group 3 (TQ group): In addition to ICV STZ, rats received TQ 10 mg/kg i.p. for 2 weeks. Group 4 (MEM group): In addition to ICV STZ, rats were given MEM at a dose of 5 mg/kg for two weeks. Group 5 (TQ+MEM group): In addition to ICV STZ, this group was given TQ (10 mg/kg/day, i.p.) and MEM (5 mg/kg/day, i.p.) for 2 weeks. On the 15th day, passive avoidance learning (PAL) was applied to all groups. Then, rats were sacrificed, neurons in the hippocampal CA1, CA2, CA3 regions were evaluated.

RESULTS

Groups 3, 4, 5 had longer latency periods than groups 1 and 2. The neuron density in the CA1, CA2, CA3 regions had decreased in groups 1 and 2 compared to groups 3, 4, 5. There were significantly more neurons in groups 3, 4, 5 than in groups 1 and 2.

DISCUSSION

We found that TQ alone and in combination with MEM showed ameliorative effects on memory and hippocampal morphology. TQ may offer a promising treatment strategy for AD.

Characterization of a S1PR2 specific 11C-labeled radiotracer in streptozotocin-induced diabetic murine model

BACKGROUND

Diabetes mellitus is a chronic progressive metabolic disorder that affects millions of people worldwide. Emerging evidence suggests the important roles of sphingolipid metabolism in diabetes. In particular, sphingosine-1-phosphate (S1P) and S1P receptor 2 (S1PR2) have important metabolic functions and are involved in several metabolic diseases. In diabetes, S1PR2 can effectively preserve β cells and improve glucose/insulin tolerance in high-fat diet induced and streptozotocin (STZ)-induced diabetic mouse models. We previously developed a group of potent and selective S1PR2 ligands and radioligands.

METHODS

In this study, we continued our efforts and characterized our leading S1PR2 radioligand, [11C]TZ34125, in a STZ-induced diabetic mouse model. [11C]TZ34125 was radiosynthesized in an automated synthesis module and in vitro saturation binding assay was performed using recombinant human S1PR2 membrane. In vitro saturation autoradiography analysis was also performed to determine the binding affinity of [11C]TZ34125 against mouse tissues. Type-1 diabetic mouse model was developed following a single high dose of STZ in C57BL/6 mice. Ex vivo biodistribution was performed to evaluate the distribution and amount of [11C]TZ34125 in tissues. In vitro autoradiography analysis was performed to compare the uptake of [11C]TZ34125 between diabetic and control animals in mouse spleen and pancreas.

RESULTS

Our in vitro saturation binding assay using [11C]TZ34125 confirmed [11C]TZ34125 is a potent radioligand to recombinant human S1PR2 membrane with a Kd value of 0.9 nM. Saturation autoradiographic analysis showed [11C]TZ34125 has a Kd of 67.5, 45.9, and 25.0 nM to mouse kidney, spleen, and liver tissues respectively. Biodistribution study in STZ-induced diabetic mice showed the uptake of [11C]TZ34125 was significantly elevated in the spleen (~2 fold higher) and pancreas (~1.4 fold higher) compared to normal controls. The increased uptake of [11C]TZ34125 was further confirmed using autoradiographic analysis in the spleen and pancreases of STZ-induced diabetic mice, indicating S1PR2 can potentially act as a biomarker of diabetes in pancreases and inflammation in spleen. Future mechanistic analysis and in vivo quantitative assessment using non-invasive PET imaging in large animal model of diabetes is worthwhile.

CONCLUSIONS

Overall, our data showed an increased uptake of our lead S1PR2-specific radioligand, [11C]TZ34125, in the spleen and pancreases of STZ-induced diabetic mice, and demonstrated [11C]TZ34125 has a great potential for preclinical and clinical usage for assessment of S1PR2 in diabetes and inflammation.

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 N^G-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.

Hyperglycaemia, pregnancy outcomes and maternal metabolic disease risk during pregnancy and lactation in a lean gestational diabetes mouse model

Hyperglycaemia in pregnancy (HIP) is a pregnancy complication characterized by mild to moderate hyperglycaemia that negatively impacts short- and long-term health of mother and child. However, relationships between severity and timing of pregnancy hyperglycaemia and postpartum outcomes have not been systemically investigated. We investigated the impact of hyperglycaemia developing during pregnancy (gestational diabetes mellitus, GDM) or already present pre-mating (pre-gestational diabetes mellitus, PDM) on maternal health and pregnancy outcomes. GDM and PDM were induced in C57BL/6NTac mice by combined 60% high fat diet (HF) and low dose streptozotocin (STZ). Animals were screened for PDM prior to mating, and all underwent an oral glucose tolerance test on gestational day (GD)15. Tissues were collected at GD18 or at postnatal day (PN)15. Among HFSTZ-treated dams, 34% developed PDM and 66% developed GDM, characterized by impaired glucose-induced insulin release and inadequate suppression of endogenous glucose production. No increased adiposity or overt insulin resistance was observed. Furthermore, markers of non-alcoholic fatty liver disease (NAFLD) were significantly increased in PDM at GD18 and were positively correlated with basal glucose levels at GD18 in GDM dams. By PN15, NAFLD markers were also increased in GDM dams. Only PDM affected pregnancy outcomes such as litter size. Our findings indicate that GDM and PDM, resulting in disturbances of maternal glucose homeostasis, increase the risk of postpartum NAFLD development, related to the onset and severity of pregnancy hyperglycaemia. These findings signal a need for earlier monitoring of maternal glycaemia and more rigorous follow-up of maternal health after GDM and PDM pregnancy in humans. KEY POINTS: We studied the impact of high-fat diet/streptozotocin induced hyperglycaemia in pregnancy in mice and found that this impaired glucose tolerance and insulin release. Litter size and embryo survival were compromised by pre-gestational, but not by gestational, diabetes. Despite postpartum recovery from hyperglycaemia in a majority of dams, liver disease markers were further elevated by postnatal day 15. Maternal liver disease markers were associated with the severity of hyperglycaemia at gestational day 18. The association between hyperglycaemic exposure and non-alcoholic fatty liver disease signals a need for more rigorous monitoring and follow-up of maternal glycaemia and health in diabetic pregnancy in humans.

TXNIP overexpression in mice enhances streptozotocin-induced diabetes severity

Thioredoxin-interacting protein (TXNIP) is a key player in the endocrine pancreas; it induces beta cell apoptosis, such that TXNIP deficiency promotes beta cell survival. To study its function in more detail, we generated transgenic mice with ubiquitous overexpression of TXNIP. CBA^TXNIP/+ mice were investigated under basal conditions and after being challenged in diet-induced obesity (DIO) and streptozotocin-induced type 1 diabetes mellitus (T1DM) models. TXNIP overexpression caused no effect in the DIO model, contrasting to the already reported TXNIP-deficient mice. However, in the T1DM background, CBA^TXNIP/+ animals showed significantly enhanced blood glucose and increased glucose levels in a glucose tolerance test. Finally, the beta cell mass of CBA^TXNIP/+ transgenic animals in the T1DM model was significantly reduced compared to control littermates. Our study demonstrates that overexpression of TXNIP doesn't affect blood glucose parameters under basal conditions. However, overexpression of TXNIP in a T1DM model enhances the severity of the disease.

The Emerging Importance of Cirsimaritin in Type 2 Diabetes Treatment

Cirsimaritin is a dimethoxy flavon that has different biological activities such as antiproliferative, antimicrobial, and antioxidant activities. This study aims to investigate the anti-diabetic effects of cirsimaritin in a high-fat diet and streptozotocin-(HFD/STZ)-induced rat model of type 2 diabetes mellitus (T2D). Rats were fed HFD, followed by a single low dose of STZ (40 mg/kg). HFD/STZ diabetic rats were treated orally with cirsimaritin (50 mg/kg) or metformin (200 mg/kg) for 10 days before terminating the experiment and collecting plasma, soleus muscle, adipose tissue, and liver for further downstream analysis. Cirsimaritin reduced the elevated levels of serum glucose in diabetic rats compared to the vehicle control group (p < 0.001). Cirsimaritin abrogated the increase in serum insulin in the treated diabetic group compared to the vehicle control rats (p < 0.01). The homeostasis model assessment of insulin resistance (HOMA-IR) was decreased in the diabetic rats treated with cirsimaritin compared to the vehicle controls. The skeletal muscle and adipose tissue protein contents of GLUT4 (p < 0.01 and p < 0.05, respectively) and pAMPK-α1 (p < 0.05) were upregulated following treatment with cirsimaritin. Cirsimaritin was able to upregulate GLUT2 and AMPK protein expression in the liver (p < 0.01, <0.05, respectively). LDL, triglyceride, and cholesterol were reduced in diabetic rats treated with cirsimaritin compared to the vehicle controls (p < 0.001). Cirsimaritin reduced MDA, and IL-6 levels (p < 0.001), increased GSH levels (p < 0.001), and reduced GSSG levels (p < 0.001) in diabetic rats compared to the vehicle control. Cirsimaritin could represent a promising therapeutic agent to treat T2D.

Wound healing activity of Salvia huberi ethanolic extract in streptozocin-induced diabetic rats

Objective: The aim of this study was to examine the in vivo wound healing potential of Salvia huberi Hedge (endemic to Turkey) on excision and incision wound models in diabetic rats. Method: Male Wistar albino rats, 3-4 months old and weighing 180-240g were used. The animals were randomly divided into five groups including Control, Vehicle and Fito reference, and two different concentrations (0.5% and 1% weight/weight (w/w)) of ethanol extract of Salvia huberi were investigated in both wound models on streptozocin-induced diabetic rats using macroscopic, biomechanical, biochemical, histopathological, genotoxic and gene expression methods over both seven and 14 days. Fito cream (Tripharma Drug Industry and Trade Inc., Turkey) was used as the reference drug. Results: A total of 60 rats were used in this study. Salvia huberi ointments at 0.5% and 1% (w/w) concentrations and Fito cream showed 99.3%, 99.4% and 99.1% contraction for excision wounds, and 99.9%, 97.0% and 99% contraction for incision wounds, respectively. In Salvia huberi ointments and Fito cream groups, re-epithelialisation increased dramatically by both day 7 and day 14 (p<0.05). By day 14, low hydroxyproline and malondialdehyde (MDA) levels, and high glutathione (GSH) levels were observed in the Salvia huberi ointment groups. After two application periods, damaged cell percent and genetic damage index values and micronucleus frequency of Salvia huberi ointment treatment groups were lower than Control and Vehicle groups (p<0.001). A growth factor expression reached a high level by day 7 in the Control group; in Salvia huberi-treated groups it was decreased. Conclusion: The study showed that application of Salvia huberi ointments ameliorated the healing process in diabetic rats with excisional and incisional wounds and may serve as a potent healing agent.

Wound healing activity of Salvia huberi ethanolic extract in streptozocin-induced diabetic rats

Objective: The aim of this study was to examine the in vivo wound healing potential of Salvia huberi Hedge (endemic to Turkey) on excision and incision wound models in diabetic rats. Method: Male Wistar albino rats, 3-4 months old and weighing 180-240g were used. The animals were randomly divided into five groups including Control, Vehicle and Fito reference, and two different concentrations (0.5% and 1% weight/weight (w/w)) of ethanol extract of Salvia huberi were investigated in both wound models on streptozocin-induced diabetic rats using macroscopic, biomechanical, biochemical, histopathological, genotoxic and gene expression methods over both seven and 14 days. Fito cream (Tripharma Drug Industry and Trade Inc., Turkey) was used as the reference drug. Results: A total of 60 rats were used in this study. Salvia huberi ointments at 0.5% and 1% (w/w) concentrations and Fito cream showed 99.3%, 99.4% and 99.1% contraction for excision wounds, and 99.9%, 97.0% and 99% contraction for incision wounds, respectively. In Salvia huberi ointments and Fito cream groups, re-epithelialisation increased dramatically by both day 7 and day 14 (p<0.05). By day 14, low hydroxyproline and malondialdehyde (MDA) levels, and high glutathione (GSH) levels were observed in the Salvia huberi ointment groups. After two application periods, damaged cell percent and genetic damage index values and micronucleus frequency of Salvia huberi ointment treatment groups were lower than Control and Vehicle groups (p<0.001). A growth factor expression reached a high level by day 7 in the Control group; in Salvia huberi-treated groups it was decreased. Conclusion: The study showed that application of Salvia huberi ointments ameliorated the healing process in diabetic rats with excisional and incisional wounds and may serve as a potent healing agent.

"Multiomics" Analyses Combined with Systems Pharmacology Reveal the Renoprotection of Mangiferin Monosodium Salt in Rats with Diabetic Nephropathy: Focus on Improvements in Renal Ferroptosis, Renal Inflammation, and Podocyte Insulin Resistance

We explored the protection of mangiferin monosodium salt (MGM) on kidney injury in rats with streptozotocin (STZ)-induced diabetic nephropathy (DN) by "multiomics" analysis combined with systems pharmacology, with a specific focus on ferroptosis, inflammation, and podocyte insulin resistance (IR) signaling events in kidneys. MGM treatment afforded renoprotective effects on rats with STZ-induced DN by alleviating systemic IR-induced renal inflammation and podocyte IR. These mechanisms were correlated mainly with the MGM treatment-induced inhibition of the mitogen-activated protein kinase/nuclear factor-kappa B axis and activation of the phosphorylated insulin receptor substrate 1(Tyr608)/phosphorylated phosphatidylinositol 3-kinase/phosphorylated protein kinase B axis in the kidneys of DN rats. MGM had an ameliorative function in renal ferroptosis in rats with STZ-induced DN by upregulating mevalonate-mediated antioxidant capacities (glutathione peroxidase 4 and ferroptosis suppressor protein 1/coenzyme Q10 axis) and weakening acyl-CoA synthetase long-chain family member 4-mediated proferroptotic generation of lipid drivers in kidneys. MGM may be a promising alternative strategy for the treatment of DN.

Streptozotocin-Induced Type 1 and 2 Diabetes Mellitus Mouse Models Show Different Functional, Cellular and Molecular Patterns of Diabetic Cardiomyopathy

The main cause of morbidity and mortality in diabetes mellitus (DM) is cardiovascular complications. Diabetic cardiomyopathy (DCM) remains incompletely understood. Animal models have been crucial in exploring DCM pathophysiology while identifying potential therapeutic targets. Streptozotocin (STZ) has been widely used to produce experimental models of both type 1 and type 2 DM (T1DM and T2DM). Here, we compared these two models for their effects on cardiac structure, function and transcriptome. Different doses of STZ and diet chows were used to generate T1DM and T2DM in C57BL/6J mice. Normal euglycemic and nonobese sex- and age-matched mice served as controls (CTRL). Immunohistochemistry, RT-PCR and RNA-seq were employed to compare hearts from the three animal groups. STZ-induced T1DM and T2DM affected left ventricular function and myocardial performance differently. T1DM displayed exaggerated apoptotic cardiomyocyte (CM) death and reactive hypertrophy and fibrosis, along with increased cardiac oxidative stress, CM DNA damage and senescence, when compared to T2DM in mice. T1DM and T2DM affected the whole cardiac transcriptome differently. In conclusion, the STZ-induced T1DM and T2DM mouse models showed significant differences in cardiac remodeling, function and the whole transcriptome. These differences could be of key relevance when choosing an animal model to study specific features of DCM.

Dimethyl Fumarate Alleviates Adult Neurogenesis Disruption in Hippocampus and Olfactory Bulb and Spatial Cognitive Deficits Induced by Intracerebroventricular Streptozotocin Injection in Young and Aged Rats

The disorder of adult neurogenesis is considered an important mechanism underlying the learning and memory impairment observed in Alzheimer's disease (AD). The sporadic nonhereditary form of AD (sAD) affects over 95% of AD patients and is related to interactions between genetic and environmental factors. An intracerebroventricular injection of streptozotocin (STZ-ICV) is a representative and well-established method to induce sAD-like pathology. Dimethyl fumarate (DMF) has antioxidant and anti-inflammatory properties and is used for multiple sclerosis treatment. The present study determines whether a 26-day DMF therapy ameliorates the disruption of adult neurogenesis and BDNF-related neuroprotection in the hippocampus and olfactory bulb (OB) in an STZ-ICV rat model of sAD. Considering age as an important risk factor for developing AD, this study was performed using 3-month-old (the young group) and 22-month-old (the aged group) male Wistar rats. Spatial cognitive functions were evaluated with the Morris water maze task. Immunofluorescent labelling was used to assess the parameters of adult neurogenesis and BDNF-related neuroprotection in the hippocampus and OB. Our results showed that the STZ-ICV evoked spatial learning and memory impairment and disturbances in adult neurogenesis and BDNF expression in both examined brain structures. In the aged animals, the deficits were more severe. We found that the DMF treatment significantly alleviated STZ-ICV-induced behavioural and neuronal disorders in both age groups of the rats. Our findings suggest that DMF, due to its beneficial effect on the formation of new neurons and BDNF-related neuroprotection, may be considered as a promising new therapeutic agent in human sAD.

Abietic acid ameliorates nephropathy progression via mitigating renal oxidative stress, inflammation, fibrosis and apoptosis in high fat diet and low dose streptozotocin-induced diabetic rats

BACKGROUND

Abietic acid (AA) has been reported to exhibit anti-inflammatory activity, however its protective effect against inflammation and its trigger factor i.e., oxidative stress and the related sequelae i.e., apoptosis and fibrosis in the kidney in diabetes mellitus (DM) is unknown.

PURPOSE

To identify the ability of AA to mitigate the inflammatory and inflammation-related insults to the kidney in DM.

METHODS & STUDY DESIGN

Adult male rats were induced type-2 DM by feeding with a high-fat diet for twelve weeks followed by injection with a single dose of streptozotocin (STZ) (30 mg/kg/bw) intraperitoneally at twelve weeks. Following DM confirmation, AA (10 and 20 mg/kg/day) was given orally for another four weeks. Then the fasting blood glucose (FBG) and renal profile were determined and oral glucose tolerance test (OGTT) and insulin tolerance test (ITT) tests were performed. A day after the last treatment, rats were sacrificed and kidneys were harvested and subjected for histopathological and molecular biological analysis.

RESULTS

AA treatment was found to reduce the FBG, serum urea and creatinine levels (p < 0.05) while improving the OGTT and ITT (p < 0.05) in diabetic rats. Besides, AA treatment also mitigated kidney histopathological changes, reduces kidney oxidative stress as reflected by reduced levels of RAGE and Keap1 but increased levels of kidney antioxidants Nrf2, SOD, CAT, GPX, HO-1 & NQO-1 (p < 0.05). Additionally, AA treatment also decreases kidney inflammation (NF-kB p65, IL-1β, IL-6, TNF-α and iNOS) and fibrosis (TGF-β1 and GSK-3β) (p < 0/05). Kidney apoptosis decreased as reflected by decreased levels of Bax, caspase-3 and caspase-9 while its anti-apoptosis Bcl-2 protein levels increased (p < 0.05).

CONCLUSION

AA helps to mitigate nephropathy development in DM via counteracting oxidative stress, inflammation and apoptosis.

Long-term follow-up of intracerebroventricular injection of streptozotocin-inducing pain sensitization

Age is known to be the major risk factor for both pain sensation and sporadic Alzheimer's disease (sAD). Pain management in AD is a critical health condition. However, assessing pain in sAD patients is challenging. The intracerebroventricularly injected streptozotocin (icv-STZ) rat model of sAD has been brought to the fore as a hopefully suitable model that could mimic some features of sAD. However, the exact mechanism by which this agent may induce AD-like pathology is largely unknown. In some studies, analgesic drugs have been suggested as possible prevention of AD and icv-STZ-induced AD-like pathology. Therefore, this study used formalin and tail-flick tests to investigate whether different doses of icv-STZ injections could affect acute and inflammatory pain sensation and edema volume over time. Behavioral responses were observed at four testing time points (1, 2.5, 3.5, and 6 months postinjection). The results indicate that icv-STZ was able to significantly decrease the animals' formalin pain threshold in both a time- and dose-dependent manner. Formalin-induced acute and chronic pain scores of animals treated with streptozotocin 3 mg/kg (STZ3) increased dramatically 2.5 months after injection and persisted thereafter. The augmentation in pain score induced by streptozotocin 1 mg/kg (STZ1) was observed from 3.5 months after STZ injection. However, the effect of streptozotocin 0.5 mg/kg (STZ0.5) was NS until 6 months after injection. However, formalin-induced paw edema occurred with a longer delay and was not detectable in STZ0.5-treated animals. In addition, only STZ3-treated animals significantly reduced the thermal pain threshold of animals 6 months after injection. These observations indicate that icv-STZ can sensitize central and/or peripheral receptors to pain. The effect of STZ is dose- and time-dependent. AD-like pathology induced by icv-STZ could be partially activated via pain processing pathways. Therefore, anti-inflammatory agents could alleviate AD-like symptoms via pain treatments.

Recurrent hypoglycemia increases hepatic gluconeogenesis without affecting glycogen metabolism or systemic lipolysis in rat

INTRODUCTION

Recurrent hypoglycemia (RH) impairs secretion of counterregulatory hormones. Whether and how RH affects responses within metabolically important peripheral organs to counterregulatory hormones are poorly understood.

OBJECTIVE

To study the effects of RH on metabolic pathways associated with glucose counterregulation within liver, white adipose tissue and skeletal muscle.

METHODS

Using a widely adopted rodent model of 3-day recurrent hypoglycemia, we first checked expression of counterregulatory hormone G-protein coupled receptors (GPCRs), their inhibitory regulators and downstream enzymes catalyzing glycogen metabolism, gluconeogenesis and lipolysis by qPCR and western blot. Then, we examined epinephrine-induced phosphorylation of PKA substrates to validate adrenergic sensitivity in each organ. Next, we measured hepatic and skeletal glycogen content, degree of breakdown by epinephrine and abundance of phosphorylated glycogen phosphorylase under hypoglycemia and that of phosphorylated glycogen synthase during recovery to evaluate glycogen turnover. Further, we performed pyruvate and lactate tolerance tests to assess gluconeogenesis. Additionally, we measured circulating FFA and glycerol to check lipolysis. The abovementioned studies were repeated in streptozotocin-induced diabetic rat model. Finally, we conducted epinephrine tolerance test to investigate systemic glycemic excursions to counterregulatory hormones. Saline-injected rats served as controls.

RESULTS

RH increased counterregulatory hormone GPCR signaling in liver and epidydimal white adipose tissue (eWAT), but not in skeletal muscle. For glycogen metabolism, RH did not affect total content or epinephrine-stimulated breakdown in liver and skeletal muscle. Although RH decreased expression of phosphorylated glycogen synthase 2, it did not affect hepatic glycogen biosynthesis during recovery from hypoglycemia or after fasting-refeeding. For gluconeogenesis, RH upregulated fructose 1,6-bisphosphatase 1 and monocarboxylic acid transporter 1 that imports lactate as precursor, resulting in a lower blood lactate profile during hypoglycemia. In agreement, RH elevated fasting blood glucose and caused higher glycemic excursions during pyruvate tolerance test. For lipolysis, RH did not affect circulating levels of FFA and glycerol after overnight fasting or upon epinephrine stimulation. Interestingly, RH upregulated the trophic fatty acid transporter FATP1 and glucose transporter GLUT4 to increase lipogenesis in eWAT. These aforementioned changes of gluconeogenesis, lipolysis and lipogenesis were validated in streptozotocin-diabetic rats. Finally, RH increased insulin sensitivity to accelerate glucose disposal, which was attributable to upregulated visceral adipose GLUT4.

CONCLUSIONS

RH caused metabolic adaptations related to counterregulation within peripheral organs. Specifically, adrenergic signaling was enhanced in liver and visceral fat, but not in skeletal muscle. Glycogen metabolism remained unchanged. Hepatic gluconeogenesis was augmented. Systemic lipolysis was unaffected, but visceral lipogenesis was enhanced. Insulin sensitivity was increased. These findings provided insights into mechanisms underlying clinical problems associated with intensive insulin therapy, such as high gluconeogenic flux and body weight gain.

Patchouli alcohol ameliorates the learning and memory impairments in an animal model of Alzheimer's disease via modulating SIRT1

BACKGROUND

Alzheimer's disease (AD) is one of the most prevalent neurodegenerative diseases. Patchouli alcohol (PA), a major active ingredient isolated from Pogostemonis Herba, exhibits extensive bioactivity in the central nervous system (CNS) and exerts neuroprotective effects.

PURPOSE

This study aimed to investigate the anti-AD effects of PA in an animal model of AD and to elucidate the underlying molecular mechanisms.

METHODS

The gas chromatography (GC) was used to determine the ability of PA to pass the blood-brain barrier (BBB) in rats after oral administration. The sporadic AD rat model was established by intracerebroventricularly (ICV) injection with streptozotocin (STZ). PA (25 and 50 mg/kg) was given to rat orally once daily for 42 consecutive days. Morris water maze (MWM) test was performed to determine the learning and memory functions of the STZ-induced AD rats. EX527, a silent information regulator 1 (SIRT1) selective inhibitor, was used to investigate the involvement of SIRT1 in the anti-AD effects of PA in rats.

RESULTS

PA could penetrate the BBB. MWM test results showed that PA could significantly ameliorate the learning and memory deficits induced by STZ in rats. Meanwhile, PA enhanced the expression of SIRT1, and markedly alleviated the tau pathology by inhibiting the hyperacetylation (at the site of Lys174) and hyperphosphorylation (at the sites of Thr181, Thr205, Ser396 and Ser404) of tau protein. PA also efficiently suppressed the activation of microglia and astrocytes, and the beta-amyloid (Aβ) expression and the deacetylation of nuclear factor-kappa B (NF-κB) at Lys 310 (K310) in the STZ-treated AD rats. EX527, a SIRT1 selective inhibitor, could partially abolish the cognitive deficits improving effect of PA and inhibit the down-regulation of acetylated tau and acetylated NF-κB p65, suggesting that PA exhibited neuroprotective effects against AD via upregulating SIRT1.

CONCLUSION

This study reported for the first time that PA could penetrate the BBB to exert its protective effects on the brain after a single-dose oral administration. The current experimental findings also amply demonstrated that PA could improve the cognitive and memory impairments in the STZ-induced AD rat model. The underlying mechanisms involve the alleviations of neuroinflammation, tau pathology and Aβ deposition via modulating of SIRT1 and NF-κB pathways. All these findings strongly suggest that PA is a promising naturally occurring compound worthy of further development into an anti-AD pharmaceutical.

KLF9 Aggravates Streptozotocin-Induced Diabetic Cardiomyopathy by Inhibiting PPARγ/NRF2 Signalling

AIMS

Krüppel-like Factor 9 (KLF9) is a transcription factor that regulates multiple disease processes. Studies have focused on the role of KLF9 in the redox system. In this study, we aimed to explore the effect of KLF9 on diabetic cardiomyopathy.

METHODS AND RESULTS

Cardiac-specific overexpression or silencing of KLF9 in C57BL/6 J mice was induced with an adeno-associated virus 9 (AAV9) delivery system. Mice were also subjected to streptozotocin injection to establish a diabetic cardiomyopathy model. In addition, neonatal rat cardiomyocytes were used to assess the possible role of KLF9 in vitro by incubation with KLF9 adenovirus or small interfering RNA against KLF9. To clarify the involvement of peroxisome proliferator-activated receptors (PPARγ), mice were subjected to GW9662 injection to inhibit PPARγ. KLF9 was upregulated in the hearts of mice with diabetic cardiomyopathy and in cardiomyocytes. In addition, KLF9 overexpression in the heart deteriorated cardiac function and aggravated hypertrophic fibrosis, the inflammatory response and oxidative stress in mice with diabetic cardiomyopathy. Conversely, cardiac-specific silencing of KLF9 ameliorated cardiac dysfunction and alleviated hypertrophy, fibrosis, the cardiac inflammatory response and oxidative stress. In vitro, KLF9 silencing in cardiomyocytes enhanced inflammatory cytokine release and oxidative stress; KLF9 overexpression increased these detrimental responses. Moreover, KLF9 was found to regulate the transcription of PPARγ, which suppressed the expression and nuclear translocation of nuclear Factor E2-related Factor 2 (NRF2). In mice injected with a PPARγ inhibitor, the protective effects of KLF9 knockdown on diabetic cardiomyopathy were counteracted by GW9662 injection.

CONCLUSIONS

KLF9 aggravates cardiac dysfunction, the inflammatory response and oxidative stress in mice with diabetic cardiomyopathy. KLF9 may become a therapeutic target for diabetic cardiomyopathy.

The Nicotinamide/Streptozotocin Rodent Model of Type 2 Diabetes: Renal Pathophysiology and Redox Imbalance Features

Diabetic nephropathy (DN) is a common complication of diabetes mellitus. While there has been a great advance in our understanding of the pathogenesis of DN, no effective managements of this chronic kidney disease are currently available. Therefore, continuing to elucidate the underlying biochemical and molecular mechanisms of DN remains a constant need. In this regard, animal models of diabetes are indispensable tools. This review article highlights a widely used rodent model of non-obese type 2 diabetes induced by nicotinamide (NA) and streptozotocin (STZ). The mechanism underlying diabetes induction by combining the two chemicals involves blunting the toxic effect of STZ by NA so that only a percentage of β cells are destroyed and the remaining viable β cells can still respond to glucose stimulation. This NA-STZ animal model, as a platform for the testing of numerous antidiabetic and renoprotective materials, is also discussed. In comparison with other type 2 diabetic animal models, such as high-fat-diet/STZ models and genetically engineered rodent models, the NA-STZ model is non-obese and is less time-consuming and less expensive to create. Given that this unique model mimics certain pathological features of human DN, this model should continue to find its applications in the field of diabetes research.

The effect of tropisetron on peripheral diabetic neuropathy: possible protective actions against inflammation and apoptosis

Diabetic peripheral neuropathy (DPN) is a common nerve disorder of diabetes. The aim of this study was to explore the protective effects of tropisetron in DPN. Type 1 diabetes was created by a single injection of streptozotocin (50 mg/kg, ip). Tropisetron (3 mg/kg, ip) was administered daily for 2 weeks. Our analysis showed that nerve fibers and their myelin sheaths were thinned with decreased myelinated fiber number in diabetic animals. The intensity of Bcl-2 staining decreased and the intensity of Bax staining increased in the sciatic nerves of diabetic rats by using immunohistochemical staining. Furthermore, diabetes significantly increased tumor necrosis factor-alpha, interleukin 1-β (TNFα and IL-1β) and Bax/Bcl-2 ratio in sciatic nerves of rats. However, intraperitoneal injection of tropisetron significantly reversed these alterations induced by diabetes. These findings suggest that tropisetron attenuates diabetes-induced peripheral nerve injury through its anti-inflammatory and anti-apoptotic effects, and may provide a novel therapeutic strategy to ameliorate the process of peripheral neuropathy in diabetes.

Protective Effects of the Bilobalide on Retinal Oxidative Stress and Inflammation in Streptozotocin-Induced Diabetic Rats

Diabetic retinopathy (DR) is a diabetes mellitus (DM) complication that causes visual acuity impairment and loss of sight in the working population, mainly in developed countries. According to the WHO, DR accounts for 5% of the world's 37 million blind people. The prevalence of diabetic retinopathy was highest in Africa, followed by North America and the Caribbean and South and Central America. Hyperglycemia can generate excessive ROS that activates multiple pathways, which can damage the cells. Oxidative stress and inflammatory process are intricate in the DR pathological mechanism. Bilobalide is the main bioactive compound isolated from the Ginkgo biloba, a plant utilized in folklore medicine. Bilobalide, a sesquiterpene trilactone, exhibits excellent antioxidant activity. But the molecular mechanisms associated with such effects, especially the antioxidant-related mechanism, have not been documented. Hence, this investigation explored whether bilobalide may attenuate DR in streptozotocin (STZ)-prompted diabetic rats. The effects of bilobalide on parameters of antioxidant content, oxidative stress, and inflammatory factors in the retinal tissues were evaluated by ELISA, RT-PCR, and immunohistochemistry methods. Bilobalide improved caloric management by reducing food consumption and increasing body weight. Furthermore, the administration of bilobalide decreases the blood glucose level and glycosylated (HbA1c) hemoglobin. The anti-retinopathy activity of bilobalide was established by the increase in the total retina thickness (TRT), inner nuclear layer (INL), and outer nuclear layer (ONL) in diabetic rats. Additionally, the serum level of MDA was decreased. In contrast, the antioxidant enzyme (SOD and CAT) levels were increased with TAC plus lower Keap1 and higher Nrf2 expression in the retina when associated with the DM rats. Moreover, bilobalide increased the nuclear factor erythroid 2-related factor 2 (Nrf2) and Heme oxygenase-1 (HO-1) expression level and inflammatory mediators (NF-κβ p65, TNF-α, IL-1β, and VEGF), thus inhibiting oxidative stress. Bilobalide can be effective against DR, and the possible mechanism may be relatively elucidated by decreasing oxidative stress and anti-inflammatory activities. But the further investigation should be directed to expose the precise mechanism.

Functional chicken-liver hydrolysates ameliorate insulin resistance and cognitive decline in streptozotocin-induced diabetic mice

As part of the slaughtering processing in Taiwan, approximately 10,000 metric tons of broiler livers are produced yearly. However, these livers are regarded as waste. Our team has successfully developed a functional chicken-liver hydrolysate (CLH) with several useful activities. It has been reported that there is a positive relationship between diabetes mellitus (DM) patients and cognitive decline. To maximize broiler-livers' utilization and add value, we investigated the modulative effects of the CLHs on glucose homeostasis and cognitive decline in streptozotocin (STZ) induced diabetic mice. After a 9-wk experiment, CLH supplementation lowered blood glucose by increasing GLUT4 protein expressions in the brains, livers, and muscles of STZ-induced mice (P < 0.05). CLHs also enhanced antioxidant capacities in the livers and brains of STZ-induced mice. Amended memory and alternation behavior were tested by using water and Y-maze assays (P < 0.05). Besides, STZ-induced mice with CLH supplementation had less contracted neuron bodies in the hippocampus and lower (P < 0.05) Aβ depositions in the dentate gyrus area. Less AGE accumulation and apoptosis-related proteins (RAGE, JNK, and activated Caspase 3) in the brains of STZ-induced mice were also detected by supplementing CLHs (P < 0.05). In conclusion, the results from this study offer not only scientific evidence on the amelioration of insulin resistance and cognitive decline in hyperglycemia but also add value to this byproduct.

NAG-1/GDF15 protects against streptozotocin-induced type 1 diabetes by inhibiting apoptosis, preserving beta-cell function, and suppressing inflammation in pancreatic islets

The loss of functional insulin-producing β-cells is a hallmark of type 1 diabetes mellitus (T1DM). Previously, we reported that the non-steroidal anti-inflammatory drug activated gene-1, or growth differentiation factor-15 (NAG-1/GDF15) inhibits obesity and improves insulin sensitivity in both genetic and dietary-induced obese mice. However, the regulatory role of NAG-1/GDF15 in the structure and function of β-cells and the prevention of T1DM is largely unknown. In the current study, we reported that NAG-1/GDF15 transgenic (Tg) mice are resistant to diabetogenesis induced by multiple low-dose streptozotocin (MLD-STZ) treatment. NAG-1/GDF15 overexpression significantly reduced diabetes incidence, alleviated symptoms of T1DM, and improved MLD-STZ-induced glucose intolerance and insulin resistance. Both the mass and function of pancreatic β cells were preserved in the NAG-1/GDF15 Tg mice as evidenced by significantly increased islet area and insulin production. The mechanistic study revealed that NAG-1/GDF15 significantly inhibited STZ-induced apoptosis and preserved the reduction of proliferation in the islets of the Tg mice as compared to the wild-type (WT) mice upon MLD-STZ treatment. Additionally, NAG-1/GDF15 significantly reduced both the serum and islet levels of the inflammatory cytokines (IL-1β, IL-6, and TNFα), and reduced the expression of NF-κB expression and immune cells infiltration in the islets. Collectively, these results indicate that NAG-1/GDF15 is effective in improving STZ-induced glucose intolerance, probably was mediated via suppressing inflammation, inhibiting apoptosis, and preserving β-cell mass and function.

Anti-obesity and Anti-diabetic Effect of Ursolic Acid against Streptozotocin/High Fat Induced Obese in Diabetic Rats

Obesity is occurring due to continue taken high fat diet; this is the fast-growing problem reaching epidemic proportion globally. Ursolic acid altered the abnormal glucose metabolism in diabetic rats. In this experimental protocol, we examine ursolic acid (UA) anti-obesity effect against streptozotocin (STZ) and high-fat diet-induced obesity in rats. Orally administered the ursolic acid (2.5, 5 and 10 mg/kg) dose to the hyperglycemic rats for 8 weeks and estimated the blood glucose level at different time intervals. Biochemical, hepatic, lipid, renal and antioxidant parameters were estimated. Traf-4, Mapk-8, Traf-6 and genes such as Ins-1, ngn-3 and Pdx-1 mRNA expression were estimated using qRT-PCR to scrutinize the molecular mechanism in MAPK downstream JNK cascade and insulin pathway signalling pathways. Ursolic acid significantly (p<0.001) down-regulated the blood glucose level at dose dependent manner. Its also reduced the plasma insulin level, non-essential fatty acid and increased the level of adiponectin as compared to obese control group rats. Ursolic acid treated group rats reduced the level of total cholesterol and triglycerides. Ursolic-acid-treated rats have been shown to decrease oxidative stress in pancreatic tissue by restoring the free radical effect of scavenging, suppress the Traf-6, Mapk-8 and Traf-4 mRNA expression, enhance the expression of Pdx-1, Ins-1 and Ngn-3 and ensure the regeneration of pancreas β cells and therefore pancreas insulin. The current result suggested the anti-obese effect of ursolic acid against high fat diet (HFD) induced obese rats via alteration of insulin and JNK signaling pathway.

Cannabidiol Treatment Improves Glucose Metabolism and Memory in Streptozotocin-Induced Alzheimer’s Disease Rat Model: A Proof-of-Concept Study

An early and persistent sign of Alzheimer’s disease (AD) is glucose hypometabolism, which can be evaluated by positron emission tomography (PET) with ¹⁸F-2-fluoro-2-deoxy-D-glucose ([¹⁸F]FDG). Cannabidiol has demonstrated neuroprotective and anti-inflammatory properties but has not been evaluated by PET imaging in an AD model. Intracerebroventricular (icv) injection of streptozotocin (STZ) is a validated model for hypometabolism observed in AD. This proof-of-concept study evaluated the effect of cannabidiol treatment in the brain glucose metabolism of an icv-STZ AD model by PET imaging. Wistar male rats received 3 mg/kg of STZ and [¹⁸F]FDG PET images were acquired before and 7 days after STZ injection. Animals were treated with intraperitoneal cannabidiol (20 mg/kg—STZ–cannabidiol) or saline (STZ–saline) for one week. Novel object recognition was performed to evaluate short-term and long-term memory. [¹⁸F]FDG uptake in the whole brain was significantly lower in the STZ–saline group. Voxel-based analysis revealed a hypometabolism cluster close to the lateral ventricle, which was smaller in STZ–cannabidiol animals. The brain regions with more evident hypometabolism were the striatum, motor cortex, hippocampus, and thalamus, which was not observed in STZ–cannabidiol animals. In addition, STZ–cannabidiol animals revealed no changes in memory index. Thus, this study suggests that cannabidiol could be an early treatment for the neurodegenerative process observed in AD.

Urinary levels of pro-fibrotic transglutaminase 2 (TG2) may help predict progression of chronic kidney disease

Renal clinical chemistry only detects kidney dysfunction after considerable damage has occurred and is imperfect in predicting long term outcomes. Consequently, more sensitive markers of early damage and better predictors of progression are being urgently sought, to better support clinical decisions and support shorter clinical trials. Transglutaminase 2 (TG2) is strongly implicated in the fibrotic remodeling that drives chronic kidney disease (CKD). We hypothesized that urinary TG2 and its ε-(γ-glutamyl)-lysine crosslink product could be useful biomarkers of kidney fibrosis and progression. Animal models: a rat 4-month 5/6th subtotal nephrectomy model of CKD and a rat 8-month streptozotocin model of diabetic kidney disease had 24-hour collection of urine, made using a metabolic cage, at regular periods throughout disease development. Patients: Urine samples from patients with CKD (n = 290) and healthy volunteers (n = 33) were collected prospectively, and progression tracked for 3 years. An estimated glomerular filtration rate (eGFR) loss of 2–5 mL/min/year was considered progressive, with rapid progression defined as > 5 mL/min/year. Assays: TG2 was measured in human and rat urine samples by enzyme-linked immunosorbent assay (ELISA) and ε-(γ-glutamyl)-lysine by exhaustive proteolytic digestion and amino acid analysis. Urinary TG2 and ε-(γ-glutamyl)-lysine increased with the development of fibrosis in both animal model systems. Urinary TG2 was 41-fold higher in patients with CKD than HVs, with levels elevated 17-fold by CKD stage 2. The urinary TG2:creatinine ratio (UTCR) was 9 ng/mmol in HV compared with 114 ng/mmol in non-progressive CKD, 1244 ng/mmol in progressive CKD and 1898 ng/mmol in rapidly progressive CKD. Both urinary TG2 and ε-(γ-glutamyl)-lysine were significantly associated with speed of progression in univariate logistic regression models. In a multivariate model adjusted for urinary TG2, ε-(γ-glutamyl)-lysine, age, sex, urinary albumin:creatinine ratio (UACR), urinary protein:creatinine ratio (UPCR), and CKD stage, only TG2 remained statistically significant. Receiver operating characteristic (ROC) curve analysis determined an 86.4% accuracy of prediction of progression for UTCR compared with 73.5% for UACR. Urinary TG2 and ε-(γ-glutamyl)-lysine are increased in CKD. In this pilot investigation, UTCR was a better predictor of progression in patients with CKD than UACR. Larger studies are now warranted to fully evaluate UTCR value in predicting patient outcomes.

Krill Oil Inhibits NLRP3 Inflammasome Activation in the Prevention of the Pathological Injuries of Diabetic Cardiomyopathy

Diabetic cardiomyopathy (DCM) is a common complication of diabetes mellitus (DM), resulting in high mortality. Myocardial fibrosis, cardiomyocyte apoptosis and inflammatory cell infiltration are hallmarks of DCM, leading to cardiac dysfunction. To date, few effective approaches have been developed for the intervention of DCM. In the present study, we investigate the effect of krill oil (KO) on the prevention of DCM using a mouse model of DM induced by streptozotocin and a high-fat diet. The diabetic mice developed pathological features, including cardiac fibrosis, apoptosis and inflammatory cell infiltration, the effects of which were remarkably prevented by KO. Mechanistically, KO reversed the DM-induced cardiac expression of profibrotic and proinflammatory genes and attenuated DM-enhanced cardiac oxidative stress. Notably, KO exhibited a potent inhibitory effect on NLR family pyrin domain containing 3 (NLRP3) inflammasome that plays an important role in DCM. Further investigation showed that KO significantly upregulated the expression of Sirtuin 3 (SIRT3) and peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α), which are negative regulators of NLRP3. The present study reports for the first time the preventive effect of KO on the pathological injuries of DCM, providing SIRT3, PGC-1α and NLRP3 as molecular targets of KO. This work suggests that KO supplementation may be a viable approach in clinical prevention of DCM.

MORPHOLOGICAL CHARACTERISTICS OF DIABETIC GLOSSITIS

OBJECTIVE

The aim: To identify characteristic features of structural change of the dorsal part of the mucous membrane of the tongue (MMT) in experimental streptozotocin-induced diabetes (ESID).

PATIENTS AND METHODS

Materials and methods: The study included 20 adult white male rats of Vistar line (body weight 180-200 g), which were equally divided into 2 groups: experimental (simulated streptozotocin diabetes mellitus) and control ones.

RESULTS

Results: 8 weeks after the beginning of ESID modeling, the changes in MMT are particularly pronounced. A large number of lamellar structures and keratin conglomerates are found on the surface of MMT. This phenomenon is closely correlated (r=0.70) with a decrease in the absorption capacity of superficial epitheliocytes and an increase in the number of heterogeneous microflora on the impression smear with low activity of leukocyte elements. The number of epitheliocytes of differentiation stages I-III continues to increase, and the number of epitheliocytes of differentiation stages IV-VI diminishes, which leads to a significant decrease in the index of cell differentiation and an increase in the nuclear-cytoplasmic ratio. Such changes in MMT impression smears indicate active processes of epithelial desquamation with increasing duration of ESID.

CONCLUSION

Conclusions: Thus, the morphological changes of MMT in ESID are characterized by a diverse combination of atrophic and hyperplastic processes, resulting in uneven thickening of multilayered squamous epithelium. There are pronounced dystrophic changes in the epitheliocytes of the stratum corneum (dyskeratosis, parakeratosis) in the area of the taste buds. All areas of MMT are inflamed which indicates the development of diabetic glossitis.

Antihyperglycemic, Antihyperlipidemic, and Antioxidant Effects of Salvia tingitana in Streptozotocin-Induced Diabetic Rats

AIMS

The study aimed to assess the antidiabetic effect of Salvia tingitana (S. tingitana).

BACKGROUND

S. tingitana is an aromatic plant that belongs to the Lamiaceae family. Phytochemical analysis of the aerial parts of S. tingitana revealed the existence of terpenoids and flavonoids. In addition, S. tingitana possesses antimicrobial activity.

OBJECTIVE

The goal of the study was to obtain information about the antihyperglycemic, antihyperlipidemic, antioxidant abilities of S. tingitana aqueous extract.

METHODS

The effect of an acute and sub-chronic administration of S. tingitana aqueous extract (AEST) at the doses of 60 and 80 mg/kg on glucose, lipid profile, and lipoprotein profile was examined in normoglycemic and hyperglycemic rats. Additionally, a preliminary phytochemical screening and the antioxidant activity using DPPH assay were carried out.

RESULTS

Rats treated with AEST at a dose of 60 mg/kg showed a significant decrease in the serum glucose levels during the single oral administration at the 4th and 6th hour of treatment in both normal and streptozotocin(STZ)-induced hyperglycemic rats. Interestingly, a dose of 80 mg/kg AEST produced a significant lowering effect on blood glucose levels at the 2nd, 4th, and 6th hour of treatment after a single oral administration in both diabetic and normal rats. Both doses of AEST (60 and 80 mg/kg) revealed a significant amelioration of lipid and lipoprotein profile. In addition, the qualitative and quantitative phytochemical analysis proved the presence of polyphenols compounds, flavonoids, and tannins. Results suggest that S. tingitana contains some secondary metabolites like alkaloids, phenols, flavonoids, and saponins. Importantly, the study revealed that the aqueous extract of S. tingitana has a very interesting antioxidant activity (IC50 = 553.21 μg/ml).

CONCLUSION

The study illustrates the beneficial action of the aqueous extract of S. tingitana as an antihyperglycemic and antihyperlipidemic agent.