Streptozotocin-induced Diabetic Model Research Articles

The effect of Hydroxytyrosol on Spexin immunoreactivity in pancreatic islets and serum insulin levels in a Streptozotocin-induced experimental diabetes model in rats

Diabetes (DM), a major health problem worldwide, is associated with the loss of β cells in the pancreatic islets and decreased insulin secretion. Hydroxytyrosol (HxT) is a phenol found in high concentrations in olive oil. Spexin (SPX) plays a role in regulating many metabolisms such as glucose and energy. This study aimed to determine the effects of HxT on circulating insulin levels, histopathological changes in pancreatic islets, and SPX immunoreactivity in a Streptozotocin-induced experimental diabetes model (eDM) in rats. The 32 male rats used in the study were randomly divided into 4 groups (n: 8): Control, eDM, eDM+HxT, and HxT. After completing all applications in the experiment, the blood and pancreas tissues of the sacrificed rats were taken. Insulin levels were determined from the serum samples obtained. Histopathological changes and SPX immunoreactivities were evaluated in pancreatic tissues. While serum insulin levels decreased in eDM, histopathological changes in pancreatic islets increased. Additionally, SPX immunoreactivity in pancreatic islets was significantly reduced in eDM. On the other hand, HxT supplementation (eDM+HxT group) regulated eDM-related adverse effects. While HxT supplementation may have a curative and therapeutic effect in DM, it was concluded that SPX may be effective in regulating the endocrine functions of the pancreas.

Dosing time-dependent difference in the suppressive effect of empagliflozin on the development of mechanical pain hypersensitivity in diabetic mice.

A problem for patients with diabetes is the rise of complications, such as peripheral neuropathy, nephropathy and retinopathy. Among them, peripheral neuropathy, characterized by numbness and/or hypersensitivity to pain in the extremities, is likely to develop in the early stages of diabetes. Empagliflozin (EMPA), a sodium-glucose cotransporter-2 inhibitor, exerts hypoglycemic effects by preventing glucose reabsorption in proximal tubular cells. EMPA can improve cardiovascular and renal outcomes in diabetic patients, but its suppressive effect on the development of diabetic neuropathy remains unclear. In this study, we demonstrated that optimizing the dosing schedule of EMPA suppressed the development of pain hypersensitivity in streptozotocin (STZ)-induced diabetic model mice maintained under standardized light/dark cycle conditions. A single intraperitoneal administration of STZ to mice induced hyperglycemia accompanied by pain hypersensitivity. Although EMPA did not exert anti-hypersensitivity effect on STZ-induced diabetic mice after the establishment of neuropathic pain, the development of pain hypersensitivity in the diabetic mice was significantly suppressed by daily oral administration of EMPA at the beginning of the dark phase. On the other hand, the suppressive effect was not observed when EMPA was administered at the beginning of the light phase. The hypoglycemic effect of EMPA and its stimulatory effect on urinary glucose excretion were also enhanced by the administration of the drug at the beginning of the dark phase. Nocturnal mice consumed their food mainly during the dark phase. Our results support the notion that morning administration of EMPA may be effective in suppressing the development of peripheral neuropathy in diabetic patients. Significance Statement Empagliflozin, a sodium-glucose cotransporter-2 inhibitor suppressed the development of neuropathic pain hypersensitivity in streptozotocin-induced diabetic model mice in a dosing time-dependent manner.

Increased Diabetes Complications in a Mouse Model of Oxidative Stress Due to 'Mismatched' Mitochondrial DNA.

Associations between chronic diabetes complications and mitochondrial dysfunction represent a subject of major importance, given the diabetes pandemic and high personal and socioeconomic costs of diabetes and its complications. Modelling diabetes complications in inbred laboratory animals is challenging due to incomplete recapitulation of human features, but offer mechanistic insights and preclinical testing. As mitochondrial-based oxidative stress is implicated in human diabetic complications, herein we evaluate diabetes in a unique mouse model that harbors a mitochondrial DNA from a divergent mouse species (the 'xenomitochondrial mouse'), which has mild mitochondrial dysfunction and increased oxidative stress. We use the streptozotocin-induced diabetes model with insulin supplementation, with 20-weeks diabetes. We compare C57BL/6 mice and the 'xenomitochondrial' mouse, with measures of heart and kidney function, histology, and skin oxidative stress markers. Compared to C57BL/6 mice, the xenomitochondrial mouse has increased diabetic heart and kidney damage, with cardiac dysfunction, and increased cardiac and renal fibrosis. Our results show that mitochondrial oxidative stress consequent to divergent mtDNA can worsen diabetes complications. This has implications for novel therapeutics to counter diabetes complications, and for genetic studies of risk, as mtDNA genotypes may contribute to clinical outcomes.

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).

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. 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). 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. 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. 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.

Cardioprotective and Hypolipidemic Effect of Cardamom Oil-Loaded Lipid Carrier Nanoparticles in a Rat Model of Streptozotocin-Induced Diabetes

Background: Diabetic cardiomyopathy (DCM) is a serious complication of poorly managed diabetes. Inflammation, hyperglycemia, oxidative stress, hyperlipidemia, and other factors all play a role in DCM pathogenesis. Objective: To investigate the cardioprotective effects of cardamom oil-loaded lipid carrier nanoparticles (CEO-LC NPs) on streptozotocin (STZ)-induced diabetes in rats. Methods: Twenty-four male rats were randomly divided into four groups of six each. STZ (50 mg/kg) caused diabetes in all groups but the negative control. The diabetic control group (G1) received a normal saline solution. For 28 days, group G2 received CEO-LC NPs (600 mg/kg), group G3 received empagliflozin (10 mg/kg), and group G4 (no diabetes) received normal saline as a negative control. On day 29, blood samples were taken to determine blood glucose, cholesterol, LDL, HDL, and triglyceride levels, as well as oxidative stress markers. Additionally, atherogenic indices were calculated. Heart tissue was sent for histopathological examination. Results: In diabetic rats treated with CEO-LC NPs, serum glucose, cholesterol, LDL, and triglyceride levels were significantly reduced, while HDL levels increased. The CEO-LC NP treatment also reduced oxidative stress by increasing total antioxidant capacity while decreasing malondialdehyde (MDA). Furthermore, diabetic rats treated with CEO-LC NP had significantly lower AIP, CRI-I, and CRI-II ratios. Conclusions: CEO-LC NPs improve cardioprotection in STZ-induced diabetic rats by lowering plasma lipid levels and oxidative stress.

Evaluation of the Antidiabetic Activities of the Fruit of Parquetina nigrescens (Afzel.) Bullock and In Silico Identification of Its Antidiabetic Agent.

The study investigated the antidiabetic potentials of the fruit extract of Parquetina nigrescens with the aim of justifying its folkloric antidiabetic usage in some part of Nigeria. Acute toxicity test of the plant extract was assessed using Lorke's method. Its antidiabetic activities were assayed in α-amylase, α-glucosidase, glucose, and streptozotocin-induced diabetic rats' models at various doses with acarbose and glibenclamide (5 mg/kg) as positive controls. Molecular docking studies were performed to identify the antidiabetic constituent of the extract and elucidate its possible mechanism of action. The estimated median lethal dose (LD50) of the extract was above 5000 mg/kg. In the α-amylase, α-glucosidase study, the extract elicited concentration-dependent activity similar to acarbose. In the glucose-induced hyperglycaemic model, 200 mg/kg of the extract was the most effective dose with comparable (P > .05) antihyperglycaemic activity to glibenclamide (5 mg kg) at 1 to 4 h. Also in the streptozotocin-induced diabetic rats model, 100 and 200 mg/kg of the extract gave comparable (P > 0.05) activity on days 4 to 14 that were significantly better than that of glibenclamide on days 4 to 7. The n-hexane and ethylacetate fractions of the extract, both at 200 mg/kg were the most active with comparable activity to glibenclamide at all time points. The molecular docking studies identified isorhoifolin as the best binder against alpha amylase with binding energy (-9.1 kcal/mol), alpha glucosidase (-9.4 kcal/mol), sodium-glucose cotransporter-2 (-9.5 kcal/mol), peroxisome proliferator activated receptor gamma (-10.3 kcal/mol), 11β-Hydroxysteroid dehydrogenase (-10.8 kcal/mol), and dipeptidyl peptidase IV (-9.4 kcal/mol). The results of the antidiabetic study of P nigrescence fruit extract justified its usage in ethnomedicne in diabetes management.

Moricandia sinaica (Boiss.): A Potent Source of Hypoglycaemic and Antidiabetic Remedy

Here, we evaluated the antidiabetic and hypoglycaemic activities of Moricandia sinaica, a species of the Brassicaceae family, for the first time. The hypoglycaemic and antidiabetic activities of the M. sinaica shoot’s methanol extract (MOR-1), butanol fraction (MOR-2), and aqueous fraction (MOR-3) were examined against streptozotocin-induced diabetes model in albino Swiss mice. The mice were divided into eight groups (each group consisted of 6 mice). MOR-1 (100 and 200 mg/kg), MOR-2 (100 and 200 mg/kg), and MOR-3 (100 and 200 mg/kg) were administered to groups III, IV, V, VI, VII, and VIII, respectively, for 15 days (daily). The blood samples were haematologically and biochemically assessed at 0 days, 7 days, and 15 days. Mice in group I were kept untreated as control while group II was treated with glibenclamide as standard. Antidiabetic effects increased with MOR-1 and MOR-2 doses in a dose-dependent manner. MOR-2 treatment (200 mg/kg) yielded the best results (29.56% and 40.07% after 7 and 15 days, respectively) compared to the results obtained at zero days. MOR-2 (200 mg/kg) showed the greatest decline in glucose levels (27.67% and 41.13% after 7 and 15 days, respectively). The results concluded that M. sinaica exhibited potential hypoglycaemic activity.

Advantages and Limitations of Diabetic Bone Healing in Mouse Models: A Narrative Review.

Diabetes represents a major risk factor for impaired fracture healing. Type 2 diabetes mellitus is a growing epidemic worldwide, hence an increase in diabetes-related complications in fracture healing can be expected. However, the underlying mechanisms are not yet completely understood. Different mouse models are used in preclinical trauma research for fracture healing under diabetic conditions. The present review elucidates and evaluates the characteristics of state-of-the-art murine diabetic fracture healing models. Three major categories of murine models were identified: Streptozotocin-induced diabetes models, diet-induced diabetes models, and transgenic diabetes models. They all have specific advantages and limitations and affect bone physiology and fracture healing differently. The studies differed widely in their diabetic and fracture healing models and the chosen models were evaluated and discussed, raising concerns in the comparability of the current literature. Researchers should be aware of the presented advantages and limitations when choosing a murine diabetes model. Given the rapid increase in type II diabetics worldwide, our review found that there are a lack of models that sufficiently mimic the development of type II diabetes in adult patients over the years. We suggest that a model with a high-fat diet that accounts for 60% of the daily calorie intake over a period of at least 12 weeks provides the most accurate representation.

GMFB/AKT/TGF-β3 in Müller cells mediated early retinal degeneration in a streptozotocin-induced rat diabetes model.

Retinal degeneration, characterized by Müller cell gliosis and photoreceptor apoptosis, is considered an early event in diabetic retinopathy (DR). Our previous study proposed that GMFB may mediate diabetic retinal degeneration. This study identified GMFB as a sensitive and functional gliosis marker for DR. Compared to the wild type (WT) group, Gmfb knockout (KO) significantly improved visual function, attenuated gliosis, reduced the apoptosis of neurons, and decreased the mRNA levels of tumor necrosis factor α (Tnf-α) and interleukin-1β (Il-1β) in diabetic retinas. Tgf-β3 was enriched by hub genes using RNA sequencing in primary WT and KO Müller cells. Gmfb KO significantly upregulated the transforming growth factor (TGF)-β3 protein level via the AKT pathway. The protective effect of TGF-β3 in the vitreous resulted in significantly improved visual function and decreased the number of apoptotic cells in the diabetic retina. The protection of Gmfb KO in primary Müller cells against high glucose (HG)-induced photoreceptor apoptosis was partially counteracted by TGF-β3 antibody and administration of TGFBR1/2 inhibitors. Nuclear receptor subfamily 3 group C member 1 (NR3C1) binds to the promoter region of Gmfb and regulates Gmfb mRNA at the transcriptional level. NR3C1 was increased in the retinas of early diabetic rats but decreased in the retinas of late diabetic rats. N'-[(1E)-(3-Methoxyphenyl)Methylene]-3-Methyl-1H-Pyrazole-5-Carbohydrazide (DS-5) was identified as an inhibitor of GMFB, having a protective role in DR. We demonstrated that GMFB/AKT/TGF-β3 mediated early diabetic retinal degeneration in diabetic rats. This study provides a novel therapeutic strategy for treating retinal degeneration in patients with DR.

State of peroxidation in the brain and liver in experimental diabetes and its correction possibility with niacin-oxyethylendiphosphonatogermanate

The development of pharmacological methods to control oxidant stress manifestations in diabetes can be achieved using organic complex germanium compounds. One of the promising compounds is niacin-oxyethylenediphosphonategermanate (MIGU-4), which is an effective corrector of lipid metabolism and a stabilizer of the lipid layer of erythrocyte and hepatocyte membranes in the streptozotocin-induced diabetic model. The aim of the work is to determine the dynamics of the malondialdehyde (MDA) content, the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPO) in the brain tissue, as well as the diene conjugate (DC) content, lipid hydroperoxides (LHP), reduced glutathione (GSH) in the liver mitochondria, the serum activities of aspartate and alanine aminotransferases (AST and ALT) in experimental diabetes mellitus with the correction using a complex compound of germanium with nicotinic acid – MIGU-4 and insulin, insulin alone as well as in comparison with effectiveness of vitamin E supplementation. Materials and methods. Diabetes was induced in male Wistar rats by intraperitoneal injection of streptozotocin (60.0 mg/kg). MIGU-4 was administered intraperitoneally at a dose of ED50 that was 25.0 mg/kg. Mitochondrial membranes were obtained by differential centrifugation of the liver tissue. In rats with confirmed diabetes, parameters of peroxidation and antioxidant protection were studied by generally accepted biochemical and biophysical methods. Results. Glucose levels were 29.4 % lower in rats treated with MIGU-4 (25.0 mg/kg) after 8 weeks of streptozotocin-induced diabetes than those in untreated diabetic rats (p < 0.05), while a decrease was 39.0 % (p < 0.05) upon insulin treatment, and 47.2 % (p < 0.05) – with combined use of the drugs. The MDA content in the brain tissue was 3.48 times higher than that in the control (p < 0.05). At the same time, the activities of SOD and CAT were decreased by 46.4 % and 32.0 %, respectively, the activity of GPO was decreased by half (p < 0.05). In the liver mitochondria, the DC content exceeded that in the control by 53.5 % (p < 0.05), and the MDA and LHP levels were 2.48 times and 31.7 % higher (p < 0.05), respectively. AST activity was almost doubled, ALT activity was 5.48 times increased. Insulin and the biologically active substance MIGU-4 used alone exerted a moderate corrective effect. The combined use of the drugs caused definite therapeutic and preventive effects as the brain content of MDA was 2.4 times decreased, the activity of SOD, CAT and GPO was increased by 45.6 %, 35.2 % and 67.3 % (p < 0.05), respectively. In the liver mitochondria, the DC, MDA, and LHP contents were decreased by 41.0 %, 53.3 %, and 28.4 %, respectively, compared to those in rats with diabetes (p < 0.05). The activity of SOD and CAT as well as GSH content were increased by 2.7 times, 51.9 %, and 23.0 % (p < 0.05), respectively. AST and ALT activities were 42.2 % and 74.3 % (p < 0.05) reduced, respectively. The combined use of MIGU-4 (25.0 mg/kg) and vitamin E (250.0 mg/kg) caused a decrease in the brain MDA content by 70.1 % (p < 0.05) in experimental rats. The combination of MIGU-4 and vitamin E increased the activity of GPO by 58.3 % (p < 0.05) as compared to rats with diabetes, indicating cumulative effects of these drugs. Conclusions. The use of MIGU-4 prevents the occurrence of oxidant stress manifestations in the brain tissue and liver mitochondria in streptozotocin-induced diabetes. The corrective effect size of MIGU-4 (25.0 mg/kg) corresponds to that of vitamin E (250.0 mg/kg).

The construction of long-acting exendin-4 analog and its hypoglycemic effect in diabetic mice

Exendin-4 is a glucagon-like polypeptide-1 (GLP-1) analog derived from lizard venom, but its short half-life affects drug administration compliance. An anti-HSA nanobody with a smaller size to guide the peptide coupling to Human Serum Albumin(HSA) in vivo may be a feasible strategy for constructing inexpensive, long-acting exendin-4 analogs. For this purpose, a fusion protein (exendin-4-(G4S)3-sdAbHSA), in which a humanized anti-HSA nanobody to the C-terminal of exendin-4 through the (Gly4Ser)3 flexible joint, was constructed. The target gene was designed according to the preferred codons and cloned into expression vector pET21b of Escherichia coli. The fusion protein could be efficiently expressed as a soluble protein, and purified to a purity over 98% by two steps of chromatography columns. In the streptozotocin-induced mouse diabetes model, the purified product had similar hypoglycemic activity as exendin-4, but dropped to the lowest value from 1 to 2 h to more than 8–10 h. The results show that this construction form does not interfere with the binding of exendin-4 to GLP-1 receptor, and can significantly prolong its half-life in vivo. This study has important reference value for constructing long-acting exendin-4 analogs and establishing efficient and green production process.

Enhanced diabetic wound healing using platelet-derived extracellular vesicles and reduced graphene oxide in polymer-coordinated hydrogels

Impaired wound healing is a significant complication of diabetes. Platelet-derived extracellular vesicles (pEVs), rich in growth factors and cytokines, show promise as a powerful biotherapy to modulate cellular proliferation, angiogenesis, immunomodulation, and inflammation. For practical home-based wound therapy, however, pEVs should be incorporated into wound bandages with careful attention to delivery strategies. In this work, a gelatin-alginate hydrogel (GelAlg) loaded with reduced graphene oxide (rGO) was fabricated, and its potential as a diabetic wound dressing was investigated. The GelAlg@rGO-pEV gel exhibited excellent mechanical stability and biocompatibility in vitro, with promising macrophage polarization and reactive oxygen species (ROS)-scavenging capability. In vitro cell migration experiments were complemented by in vivo investigations using a streptozotocin-induced diabetic rat wound model. When exposed to near-infrared light at 2 W cm− 2, the GelAlg@rGO-pEV hydrogel effectively decreased the expression of inflammatory biomarkers, regulated immune response, promoted angiogenesis, and enhanced diabetic wound healing. Interestingly, the GelAlg@rGO-pEV hydrogel also increased the expression of heat shock proteins involved in cellular protective pathways. These findings suggest that the engineered GelAlg@rGO-pEV hydrogel has the potential to serve as a wound dressing that can modulate immune responses, inflammation, angiogenesis, and follicle regeneration in diabetic wounds, potentially leading to accelerated healing of chronic wounds.

Compare the effectiveness of extracorporeal shockwave and hyperbaric oxygen therapy on enhancing wound healing in a streptozotocin-induced diabetic rodent model.

Studies have revealed that both extracorporeal shock-wave therapy (ESWT) and hyperbaric oxygen therapy (HBOT) can accelerate wound healing. This study aimed to compare the effectiveness of ESWT and HBOT in enhancing diabetic wound healing. A dorsal skin defect in a streptozotocin-induced diabetes rodent model was used. Postoperative wound healing was assessed once every 3 days. Histologic examination was performed with hematoxylin and eosin staining. Proliferation marker protein Ki-67 (Ki-67), endothelial nitric oxide synthase (eNOS), vascular endothelial growth factor (VEGF), and 8-hydroxy-2-deoxyguanosine (8-OHdG) were evaluated with immunohistochemical (IHC) staining. The wound area was significantly reduced in the ESWT and HBOT groups compared to that in the diabetic controls. However, the wound healing time was significantly increased in the HBOT group compared to the ESWT group. Histological findings showed a statistical increase in neovascularization and suppression of the inflammatory response by both HBOT and ESWT compared to the controls. IHC staining revealed a significant increase in Ki-67, VEGF, and eNOS but suppressed 8-OHdG expression in the ESWT group compared to the HBOT group. ESWT facilitated diabetic wound healing more effectively than HBOT by suppressing the inflammatory response and enhancing cellular proliferation and neovascularization and tissue regeneration.

ANTIDIABETIC EFFECT OF A NEW ORIGINAL NT-3 DIPEPTIDE MIMETIC

It was previously established that the original dipeptide mimetic of the 4th loop of NT-3, hexamethylenediamide bis-(N-monosuccinyl-L-asparaginyl-L-asparagine) (GTS-301), has a pronounced neuroprotective effect in vitro at concentrations of 10–5–10–12 М. In the present study, experiments on the streptozotocin-induced diabetes model in C57Bl/6 mice showed that GTS-301, administered intraperitoneally for 32 days at doses of 0.1 and 0.5 mg/kg, has antidiabetic activity manifested in the reduction of hyperglycemia, polydipsia, and in the increase of animal survival. The results obtained confirm the concept of the similarity of neurochemical mechanisms underlying the regulation of neurons and β-cells functions.

Enhanced Levels of Glycosphingolipid GM3 Delay the Progression of Diabetic Nephropathy.

We recently found that albuminuria levels in patients with minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS) inversely correlate with glycosphingolipid GM3 expression levels in glomerular podocytes. Moreover, we showed enhanced expression of GM3 via activation of the GM3 synthase gene upon administration of valproic acid (VPA) is effective in suppressing albuminuria and podocyte injury in mice with anti-nephrin antibody-induced podocytopathy. However, the therapeutic effect of GM3 on diabetic nephropathy, which is the most common underlying disease in patients undergoing dialysis and with podocyte injury, remains unclear. Here, we investigated the therapeutic effect of enhanced GM3 expression via VPA on podocyte injury using streptozotocin-induced diabetic nephropathy model mice. Administration of VPA clearly decreased levels of albuminuria and glomerular lesions and inhibited the loss of podocytes and expansion in the mesangial area. Furthermore, we found that albuminuria levels in patients with diabetic nephropathy inversely correlate with the expression of GM3 in podocytes. These results indicate that maintaining GM3 expression in podocytes by administration of VPA may be effective in treating not only podocyte injury, such as MCD and FSGS, but also the late stage of diabetic nephropathy.

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

BackgroundDiabetes 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. MethodsIn 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. ResultsOur 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. ConclusionsOverall, 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.

The impact of nutritional immunity on Group B streptococcal pathogenesis during wound infection.

Group B Streptococcus (GBS) is a Gram-positive pathobiont that can cause adverse health outcomes in neonates and vulnerable adult populations. GBS is one of the most frequently isolated bacteria from diabetic (Db) wound infections but is rarely found in the non-diabetic (nDb) wound environment. Previously, RNA sequencing of wound tissue from Db wound infections in leprdb diabetic mice showed increased expression of neutrophil factors, and genes involved in GBS metal transport such as the zinc (Zn), manganese (Mn), and putative nickel (Ni) import systems. Here, we develop a Streptozotocin-induced diabetic wound model to evaluate the pathogenesis of two invasive strains of GBS, serotypes Ia and V. We observe an increase in metal chelators such as calprotectin (CP) and lipocalin-2 during diabetic wound infections compared to nDb. We find that CP limits GBS survival in wounds of non-diabetic mice but does not impact survival in diabetic wounds. Additionally, we utilize GBS metal transporter mutants and determine that the Zn, Mn, and putative Ni transporters in GBS are dispensable in diabetic wound infection but contributed to bacterial persistence in non-diabetic animals. Collectively, these data suggest that in non-diabetic mice, functional nutritional immunity mediated by CP is effective at mitigating GBS infection, whereas in diabetic mice, the presence of CP is not sufficient to control GBS wound persistence. IMPORTANCE Diabetic wound infections are difficult to treat and often become chronic due to an impaired immune response as well as the presence of bacterial species that establish persistent infections. Group B Streptococcus (GBS) is one of the most frequently isolated bacterial species in diabetic wound infections and, as a result, is one of the leading causes of death from skin and subcutaneous infection. However, GBS is notoriously absent in non-diabetic wounds, and little is known about why this species thrives in diabetic infection. The work herein investigates how alterations in diabetic host immunity may contribute to GBS success during diabetic wound infection.

Antidiabetic and antioxidant effect of magnetic and noble metal nanoparticles of Clitoria ternatea

Diabetes is a chronic metabolic endocrine disorder associated with diabetic complications that result in microvascular and macrovascular complications due to oxidative stress, neurodegeneration, and peripheral cell damage. Oxidative stress is characterized by the development of reactive oxygen species (ROS) which progresses by hampering antioxidant enzyme activities. Phytomolecules from different plant sources like leaves, flowers, fruits, etc are reported to possess super-antioxidant properties. Hence these phytomolecules can be good leads in the treatment and management of diabetes. Metal nanoparticles have evolved to increase the potency, efficacy, and safety of different drug delivery systems owing to their superior physicochemical properties. This research work is designed for the synthesis of magnetic and noble metal nanoparticles by green synthesis of fresh flower aqueous extract of Clitoria ternatea. A mechanistic evaluation of the magnetic (cobalt oxide) and noble metal (gold) nanoparticles has been designed by in-vitro and in-vivo models of a streptozotocin-induced diabetes model. The cobalt oxide and gold nanoparticles showed a significant (p < 0.05) decrease in the diabetic enzyme levels (α-amylase, α-glucosidase, and xanthine oxidase). In vitro and in vivo studies of the antioxidant activity of both nanoparticles also revealed the increased potential of antioxidant activity. In-vivo studies of both nanoparticles exhibited anti-diabetic properties by significantly enhancing the level of insulin. The cholesterol profiling of both nanoparticles proved the reduction of levels of serum cholesterol, triglycerides, HDL, VLDL, LDL, and creatinine content signifying the decreasing risk of macrovascular complications associated with diabetes. However, gold nanoparticles produced a more protective effect as compared to cobalt oxide nanoparticles. The study concludes that the magnetic and gold nanoparticles conjugated with Clitoria ternatea exhibited potential anti-diabetic and antioxidant activities in a streptozotocin-induced diabetic rat model.

Targeting Anti-Inflammatory Pathways to Treat Diabetes-Induced Neuropathy by 6-Hydroxyflavanone.

It is evident that inflammation and metabolic syndrome instigated by diabetes mellitus can precipitate diabetes-induced neuropathy (DIN) and pain. In order to find an effective therapeutic method for diabetes-related problems, a multi-target-directed ligand model was used. 6-Hydroxyflavanone (6-HF) carrying anti-inflammatory and anti-neuropathic pain potential due to its quadruplicate mechanisms, targeting cyclooxygenase-2 (COX-2), 5-lipoxygenase (5-LOX), and opioid and GABA-A receptors was investigated. The anti-inflammatory potential of the test drug was confirmed utilizing in silico, in vitro, and in vivo tests. A molecular simulation approach was utilized to observe the interaction of 6-HF with the inflammatory enzyme COX-2 as well as opioid and GABA-A receptors. The same was confirmed via in vitro COX-2 and 5-LOX inhibitory assays. In vivo tests were performed to analyze the thermal anti-nociception in the hot-plate analgesiometer and anti-inflammatory action in the carrageenan-induced paw edema model in rodents. The potential anti-nociceptive effect of 6-HF was evaluated in the DIN model in rats. The Naloxone and Pentylenetetrazole (PTZ) antagonists were used to confirm the underlying mechanism of 6-HF. The molecular modeling studies revealed a favorable interaction of 6-HF with the identified protein molecules. In vitro inhibitory studies revealed that 6-HF inhibited the COX-2 and 5-LOX enzymes significantly. The 6-HF at dosages of 15, 30, and 60 mg/kg substantially reduced heat nociception in a hot plate analgesiometer as well as carrageenan-induced paw edema in rodent models. The authors discovered that 6-HF had anti-nociception properties in a streptozotocin-induced diabetic neuropathy model. According to the findings of this study, 6-HF was demonstrated to diminish inflammation caused by diabetes as well as its anti-nociception effect in DIN.

Bone morphogenetic protein-7 attenuates pancreatic damage under diabetic conditions and prevents progression to diabetic nephropathy via inhibition of ferroptosis.

Approximately 30% of diabetic patients develop diabetic nephropathy, a representative microvascular complication. Although the etiological mechanism has not yet been fully elucidated, renal tubular damage by hyperglycemia-induced expression of transforming growth factor-β (TGF-β) is known to be involved. Recently, a new type of cell death by iron metabolism called ferroptosis was reported to be involved in kidney damage in animal models of diabetic nephropathy, which could be induced by TGF-β. Bone morphogenetic protein-7 (BMP7) is a well-known antagonist of TGF-β inhibiting TGF-β-induced fibrosis in many organs. Further, BMP7 has been reported to play a role in the regeneration of pancreatic beta cells in diabetic animal models. We used protein transduction domain (PTD)-fused BMP7 in micelles (mPTD-BMP7) for long-lasting in vivo effects and effective in vitro transduction and secretion. mPTD-BMP7 successfully accelerated the regeneration of diabetic pancreas and impeded progression to diabetic nephropathy. With the administration of mPTD-BMP7, clinical parameters and representative markers of pancreatic damage were alleviated in a mouse model of streptozotocin-induced diabetes. It not only inhibited the downstream genes of TGF-β but also attenuated ferroptosis in the kidney of the diabetic mouse and TGF-β-stimulated rat kidney tubular cells. BMP7 impedes the progression of diabetic nephropathy by inhibiting the canonical TGF-β pathway, attenuating ferroptosis, and helping regenerate diabetic pancreas.