Non-diabetic Animals Research Articles

Effects of Some Olive Fruits-Derived Products on Oxidative Stress and Cardiovascular Biomarkers on Experimental Diabetes Mellitus.

The aim of this study is to assess the possible effect of olive seed oil (OSO) and destoned and dehydrated olive oil (DDOO), in comparison with extra-virgin olive oil (EVOO), on some cardiovascular biomarkers in an experimental model of diabetes mellitus. Diabetic animals showed evident alterations in biomarkers involved in the evolution of diabetic vasculopathy, marked by increases in biomarkers that favor vascular damage, which was between 1.5 and five times as many as those in non-diabetic animals, and a smaller number of biomarkers that protect against such damage (25-75% less than in healthy controls) was observed. The three oils administered decreased the concentration of biomarkers of vascular damage (35-45% in the serum lipid profile, 15-40% in early biomarkers of vascular inflammation and 20-60% in platelet aggregation and in thromboxane/prostacyclin imbalance). The greatest effect was by the antioxidant, both in the inhibition of lipid peroxidation and in the increase of glutathione. DDOO showed a significantly greater effect on oxidative stress and on thromboxane/prostacyclin imbalance than those shown by OSO and EVOO. This greater effect may possibly be explained by its higher triterpenoid content (913 mg/kg, compared to 113 mg/kg in OSO and 75 mg/kg in EVOO). We conclude, in the light of the results of this study, that these oils meet two basic conditions: they could improve the yield of the olive industry, and they equal, and may even increase, the beneficial effects of EVOO on cardiovascular disease.

Establishment and characterization of a mouse model for studying kidney repair in diabetes.

The prognosis of acute kidney injury (AKI) is markedly worse in diabetic patients. Diabetes not only exaggerates the severity of AKI but may also prevent kidney repair or recovery from AKI. Little is known about the cellular and molecular basis of defective kidney repair in diabetes. One obstacle in studying kidney repair in diabetes is the lack of suitable animal models. Specifically, diabetes increases AKI severity, making it difficult to induce the same level of AKI in diabetic and non-diabetic animals to compare their kidney repair. Here, we have identified a time-window of 4 days immediately after the completion of streptozotocin (STZ) treatment in mice when blood glucose has yet to rise. Within this time-window, renal ischemia-reperfusion injury (IRI) induced the same level of AKI in STZ-treated mice [127.2±12.82 mg/dL blood urea nitrogen (BUN), 2.275±0.4728 serum creatinine] and vehicle solution-treated mice (128.6±11.83 mg/dL BUN, 2.087±0.4748 mg/dL serum creatinine]. By day 5-6, the post-AKI kidney entered into the phase of kidney repair when diabetic hyperglycemia started in STZ-treated mice, providing the opportunity to study the effect of diabetes on kidney repair without affecting initial AKI. In this model, kidney repair was indeed impaired by diabetes (116.5±8.052 mg/dL BUN and 1.382±0.2732 mg/dL serum creatinine in IR+vehicle group; 136.6±8.740 mg/dL BUN and 1.916±0.3756 mg/dL serum creatinine in IR+STZ group). The impairment was associated with decreased tubular cell proliferation and increased tubular cell senescence, peritubular capillary (PTC) rarefaction, inflammation, and 40.90% more interstitial fibrosis.

Characterization of sensory and motor dysfunction and morphological alterations in late stages of type 2 diabetic mice.

Diabetic neuropathy is the most common complication of diabetes and lacks effective treatments. Although sensory dysfunction during the early stages of diabetes has been extensively studied in various animal models, the functional and morphological alterations in sensory and motor systems during late stages of diabetes remain largely unexplored. In the current work, we examined the influence of diabetes on sensory and motor function as well as morphological changes in late stages of diabetes. The obese diabetic Leprdb/db mice (db/db) were used for behavioral assessments and subsequent morphological examinations. The db/db mice exhibited severe sensory and motor behavioral defects at the age of 32 weeks, including significantly higher mechanical withdrawal threshold and thermal latency of hindpaws compared with age-matched nondiabetic control animals. The impaired response to noxious stimuli was mainly associated with the remarkable loss of epidermal sensory fibers, particularly CGRP-positive nociceptive fibers. Unexpectedly, the area of CGRP-positive terminals in the spinal dorsal horn was dramatically increased in diabetic mice, which was presumably associated with microglial activation. In addition, the db/db mice showed significantly more foot slips and took longer time during the beam-walking examination compared with controls. Meanwhile, the running duration in the rotarod test was markedly reduced in db/db mice. The observed sensorimotor deficits and motor dysfunction were largely attributed to abnormal sensory feedback and muscle atrophy as well as attenuated neuromuscular transmission in aged diabetic mice. Morphological analysis of neuromuscular junctions (NMJs) demonstrated partial denervation of NMJs and obvious fragmentation of acetylcholine receptors (AChRs). Intrafusal muscle atrophy and abnormal muscle spindle innervation were also detected in db/db mice. Additionally, the number of VGLUT1-positive excitatory boutons on motor neurons was profoundly increased in aged diabetic mice as compared to controls. Nevertheless, inhibitory synaptic inputs onto motor neurons were similar between the two groups. This excitation-inhibition imbalance in synaptic transmission might be implicated in the disturbed locomotion. Collectively, these results suggest that severe sensory and motor deficits are present in late stages of diabetes. This study contributes to our understanding of mechanisms underlying neurological dysfunction during diabetes progression and helps to identify novel therapeutic interventions for patients with diabetic neuropathy.

Amelioration of diabetic nephropathy in mice by a single intravenous injection of human mesenchymal stromal cells at early and later disease stages is associated with restoration of autophagy

Background and aimsMesenchymal stromal cells (MSCs) a potentially effective disease-modulating therapy for diabetic nephropathy (DN) but their clinical translation has been hampered by incomplete understanding of the optimal timing of administration and in vivo mechanisms of action. This study aimed to elucidate the reno-protective potency and associated mechanisms of single intravenous injections of human umbilical cord-derived MSCs (hUC-MSCs) following shorter and longer durations of diabetes.MethodsA streptozotocin (STZ)-induced model of diabetes and DN was established in C57BL/6 mice. In groups of diabetic animals, human (h)UC-MSCs or vehicle were injected intravenously at 8 or 16 weeks after STZ along with vehicle-injected non-diabetic animals. Diabetes-related kidney abnormalities was analyzed 2 weeks later by urine and serum biochemical assays, histology, transmission electron microscopy and immunohistochemistry. Serum concentrations of pro-inflammatory and pro-fibrotic cytokines were quantified by ELISA. The expression of autophagy-related proteins within the renal cortices was investigated by immunoblotting. Bio-distribution of hUC-MSCs in kidney and other organs was evaluated in diabetic mice by injection of fluorescent-labelled cells.ResultsCompared to non-diabetic controls, diabetic mice had increases in urine albumin creatinine ratio (uACR), mesangial matrix deposition, podocyte foot process effacement, glomerular basement membrane thickening and interstitial fibrosis as well as reduced podocyte numbers at both 10 and 18 weeks after STZ. Early (8 weeks) hUC-MSC injection was associated with reduced uACR and improvements in multiple glomerular and renal interstitial abnormalities as well as reduced serum IL-6, TNF-α, and TGF-β1 compared to vehicle-injected animals. Later (16 weeks) hUC-MSC injection also resulted in reduction of diabetes-associated renal abnormalities and serum TGF-β1 but not of serum IL-6 and TNF-α. At both time-points, the kidneys of vehicle-injected diabetic mice had higher ratio of p-mTOR to mTOR, increased abundance of p62, lower abundance of ULK1 and Atg12, and reduced ratio of LC3B to LC3A compared to non-diabetic animals, consistent with diabetes-associated suppression of autophagy. These changes were largely reversed in the kidneys of hUC-MSC-injected mice. In contrast, neither early nor later hUC-MSC injection had effects on blood glucose and body weight of diabetic animals. Small numbers of CM-Dil-labeled hUC-MSCs remained detectable in kidneys, lungs and liver of diabetic mice at 14 days after intravenous injection.ConclusionsSingle intravenous injections of hUC-MSCs ameliorated glomerular abnormalities and interstitial fibrosis in a mouse model of STZ-induced diabetes without affecting hyperglycemia, whether administered at relatively short or longer duration of diabetes. At both time-points, the reno-protective effects of hUC-MSCs were associated with reduced circulating TGF-β1 and restoration of intra-renal autophagy.Graphical abstract

Effect of Perfluorooctanoic Acid on Kidney Function in Diabetic and Non-‎‎Diabetic Male Guinea Pigs

Perfluorooctanoic acid (PFOA) is a synthetic fluor-surfactant chemical used widely in ‎products that resist oil, heat, grease, stains, and water. It is also used in producing other ‎fluoropolymers. The main sources of exposure to PFOA are water, soil, and animal-‎origin food (meat, fish, and dairy products). The aim of this study to evaluate the renal ‎function following oral gavage of sub-lethal dose of PFOA in diabetic and non-diabetic ‎guinea pigs. The experiment run for 4 weeks, total of 40 male guinea pigs, ‎‎(Cavia porcellus), were randomly selected and grouped into four equal groups. The first ‎group (G1) served as the negative control; 2nd group (G2) alloxan induced diabetic, 3rd ‎group (G3) non-diabetic was exposed to PFOA at 100 mg/kg BW orally/daily and 4th ‎Group (G4) was diabetic guinea pig exposed to PFOA at 100 mg/kg BW orally/daily. ‎Serum creatinine and histopathological alterations in the kidney tissue were evaluated. ‎Serum creatinine concentrations were significantly increased (P<0.05) in G3 and G4 ‎exposed to PFOA. High serum creatinine levels were suggesting impairment in kidney ‎function. Impaired kidney function was confirmed through histopathological changes ‎such as glomerular atrophy, severe necrosis, and degeneration of renal tubular epithelium ‎in guinea pigs that received PFOA in G3 and G4. In conclusion, the results confirmed ‎that PFOA was associated with renal damage and elevated creatinine concentrations in ‎diabetic and non-diabetic animals since PFOA itself can contribute to diabetes‎‎‎.

Revolutionizing fracture fixation in diabetic and non-diabetic rats: High mobility group box 1-based coating for enhanced osseointegration.

Chronic inflammation and hyperglycemia in diabetic patients increase the risk of implant failure and impaired fracture healing. We previously developed and characterized a titanium (Ti) coating strategy using an imidazolium-based ionic liquid (IonL) with a fully reduced, non-oxidizable High Mobility Group Box 1 (HMGB1) isoform (Ti-IonL-HMGB1) to immunomodulate tissue healing. In this study, we used an open reduction fracture fixation (ORIF) model in non-diabetic (ND) and diabetic (D) rats to further investigate the effectiveness of this Ti-IonL-HMGB1 coating on orthopedic applications. Ninety male Lewis rats (12-15weeks) were divided into D (n=45) and ND (n=45) groups that were distributed into three subgroups based on the type of local treatment received: Ti (uncoated Ti), Ti-IonL, and Ti-IonL-HMGB1 implants. Fracture healing and osseointegration were evaluated using microtomographic, histological, and immunohistochemical analysis of proliferating cell nuclear antigen (PCNA), Runt-related transcription factor 2 (RUNX2), and HMGB1 markers at 2, 10, and 21days post-ORIF. Scanning Electron Microscopy verified the coating stability after placement. Microtomographic and histological analysis demonstrated increased fracture healing and osseointegration for ND rats in all treatment groups at 10days, with impaired healing for D rats. Immunohistochemical analysis exhibited elevated PCNA+ and RUNX2+ cells for D animals treated with Ti-IonL-HMGB1 at 21days compared to all other groups. The immunohistochemical marker HMGB1 was elevated at all time points for D animals in comparison to ND animals, yet was lowered for D tissues near the Ti-IonL-HMGB1 treated implant. Improved osseous healing was demonstrated in D animals with Ti-IonL-HMGB1 treatment by 21days, compared to D animals with other treatments. To the best of our knowledge, this is the first study analyzing Ti-IonL-HMGB1 implantation in an injury site through ORIF procedures in ND and D rats. This surface approach has potential for improving implanted biomaterials in diabetic environments.

Bee gomogenat enhances the healing process of diabetic wounds by orchestrating the connexin-pannexin gap junction proteins in streptozotocin-induced diabetic mice

Delay in wound healing remains one of diabetes's worse side effects, which increases mortality. The proposed study sought to scrutinize the implications of bee gomogenat (BG) on diabetic's wound closure in a streptozotocin-(STZ)-enhanced type-1 diabetes model’s rodents. We used 3 different mice groups: group 1 non-diabetic rodents "serving as control", group 2 diabetic rodents, and group3 BG-treated diabetic rodents. We noticed that diabetic rodents experience a delayed wound closure, which emerged as a significant (*P < 0.05) decline in the deposition of collagen as compared to control non-diabetic animals. We noticed that diabetic rodents have a delayed wound closure characterized by a significant (*P < 0.05) decrease in the CD31 expression (indicator for wound angiogenesis and neovascularization) and an apparent elevation in the expression of such markers of inflammation as MCP-1 and HSP-70 as compared to control animals. Moreover, diabetic animals displayed a significant (*P < 0.05) increase in the expression of gap junction proteins Cx43 and a significant decrease in the expression of Panx3 in the wounded skin tissues when compared to the controls. Intriguingly, topical application with BG on the diabetic wounded skin tissues contributes to a significant (#P < 0.05) enhancing in the collagen deposition, up-regulating the level of CD31 expression and a significant (#P < 0.05) down-regulation in the MCP-1 and HSP-70 expressions as compared to diabetic non-treated animals. The expression's levels of Cx43 and Panx3 were significantly (#P < 0.05) retrieved in diabetic rodents after BG treatment. Taken together, our findings showed for the first time that BG promotes the recovering process and accelerated the closure of diabetic related wounds.

Abstract 19069: Empagliflozin Improves Right Ventricular Remodeling and Right Ventricular Systolic Function in Non-Diabetic Hfref: Insights From Porcine and Human Studies

Background On top of improving heart failure outcomes, we and others have demonstrated that SGLT2 inhibitors induce reverse cardiac remodeling in HFrEF. However, these studies have focused on the left ventricle, while no information is available on the potential benefits of SGLT2i on the right ventricle (RV). Therefore, our objective is to investigate the effect of empagliflozin on RV remodeling and RV systolic function in non-diabetic HFrEF Methods Animal study: HFrEF was induced by means of proximal LAD occlusions for 2 hours in non-diabetic pigs. Pigs were then randomized to empagliflozin 10mg daily or placebo for 2 months (8/group). Pigs were evaluated with cardiac MRI. We previously reported that empagliflozin reduces LV volumes and improve LVEF (Santos-Gallego, JACC 2019) Human study : The EMPATROPISM clinical trial ((NCT03485222) randomized non-diabetic HFrEF patients to empagliflozin 10mg daily or placebo. All patients were evaluated with MRI. We previously reported that empagliflozin reduces LV volumes, while also improving peakVO2, LVEF, and quality of life (Santos-Gallego, JACC 2021) Results Animal study: Both groups were similar at baseline (RVESV 16.1±3.2 vs 15.8±2.1mL; RVEF 51.9±5.6 vs 52.7±4.7%; p=NS). Cardiac MRI showed that empagliflozin-treated pigs exhibited smaller RVEDV and RVESV at 2 months compared with control. Also treated animals exhibited better RVEF and better right ventriculoarterial coupling (Ees/Ea) vs control (Table) Human study: Both groups were similar at baseline (RVESV 87.4±35.6 vs 76.4±32.4 mL; RVEF 47.1±7.9 vs 49.2±9.1%; p=NS). Cardiac MRI showed that empagliflozin-treated patients experienced a reduction in RVESV vs placebo. Furthermore, empagliflozin-treated patients exhibited improvement in RVEF and in right ventriculoarterial coupling (Ees/Ea) vs control (Table) Conclusions Empagliflozin improves right ventricular remodeling and right ventricular systolic function in non-diabetic HFrEF

Repurposing Metformin for periodontal disease management as a form of oral-systemic preventive medicine

BackgroundDespite the improvements in treatment over the last decades, periodontal disease (PD) affects millions of people around the world and the only treatment available is based on controlling microbial load. Diabetes is known to increase the risk of PD establishment and progression, and recently, glucose metabolism modulation by pharmaceutical or dietarian means has been emphasised as a significant modulator of non-communicable disease development.MethodsThe impact of pharmaceutically controlling glucose metabolism in non-diabetic animals and humans (REBEC, UTN code: U1111-1276-1942) was investigated by repurposing Metformin, as a mean to manage periodontal disease and its associated systemic risk factors.ResultsWe found that glucose metabolism control via use of Metformin aimed at PD management resulted in significant prevention of bone loss during induced periodontal disease and age-related bone loss in vivo. Metformin also influenced the bacterial species present in the oral environment and impacted the metabolic epithelial and stromal responses to bacterial dysbiosis at a single cell level. Systemically, Metformin controlled blood glucose levels and age-related weight gain when used long-term. Translationally, our pilot randomized control trial indicated that systemic Metformin was safe to use in non-diabetic patients and affected the periodontal tissues. During the medication window, patients showed stable levels of systemic blood glucose, lower circulating hsCRP and lower insulin levels after periodontal treatment when compared to placebo. Finally, patients treated with Metformin had improved periodontal parameters when compared to placebo treated patients.ConclusionThis is the first study to demonstrate that systemic interventions using Metformin in non-diabetic individuals aimed at PD prevention have oral-systemic effects constituting a possible novel form of preventive medicine for oral-systemic disease management.

Effects of advanced glycation end-products, diabetes and metformin on the osteoblastic transdifferentiation capacity of vascular smooth muscle cells: In vivo and in vitro studies

AimsOur objective was to study the vascular smooth muscle cells (VSMC) osteoblastic transdifferentiation in AGE exposed cells or those from diabetic animals, and its response to metformin treatment. MethodsVSMC were obtained from non-diabetic rats, grown with or without AGE; while VSMC of in vivo-ex vivo studies were obtained from non-diabetic control animals (C), diabetic (D), C treated with metformin (M) and D treated with metformin (D-M). We studied the osteoblastic differentiation by evaluating alkaline phosphatase (ALP), type I collagen (Col) and mineral deposit. ResultsIn vitro, AGE increased proliferation, migration, and osteoblastic differentiation of VSMC. Metformin cotreatment prevented the AGE induced proliferation and migration. Both AGE and metformin stimulated the expression of ALP and Col. AGE induced mineralization was prevented by metformin. VSMC from D expressed a higher production of Col and ALP. Those from D-M showed an ALP increase vs C and M, and a partial decrease vs D. Cultured in osteogenic medium, ALP, Col and mineralization increased in D vs C, remained unchanged in M, and were prevented in D-M animals. ConclusionBoth AGE and DM favor VSMC differentiation towards the osteogenic phenotype and this effect can be prevented by metformin.

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.

A Model Study to Evaluate Osseointegration and Fracture Healing Following Open Reduction and Internal Fixation (ORIF) in Diabetic Lewis Rats

There is a higher risk of implant osseointegration failure after open reduction and internal fixation (ORIF) in patients with diabetes due to increased inflammatory conditions, associated metallic corrosion and infection. While it is possible to avoid elective osseous surgery in patients with diabetes, it may not be the case in nonelective cases, such as ORIF ankle fractures. A total of 30 male Lewis rats (12-15 weeks old) were distributed into diabetic (D) and nondiabetic (ND) groups. Fracture healing and osseointegration were evaluated at 2-, 10-, and 21-day time points. Microtomographic and histological analysis depicted distinct differences in fracture healing and osseointegration between D and ND animals. Immunohistochemical analysis exhibited elevated proliferation (PCNA) and osteogenic (Runx2) cells for ND animals, while HMGB1 (inflammatory marker) was elevated for D animals during healing. Bone resorption marker CTX-1 was elevated in the plasma of D animals at 2 days, while bone formation marker P1NP was higher for ND animals at 10 days. Overall, this model resulted in delayed implant osseointegration and fracture healing in diabetic animals, highlighting the importance of developing new biomaterials or implant coatings that can improve bone healing outcomes in this patient population.

The Effects of Prolonged Treatment with Cemtirestat on Bone Parameters Reflecting Bone Quality in Non-Diabetic and Streptozotocin-Induced Diabetic Rats.

Cemtirestat, a bifunctional drug acting as an aldose reductase inhibitor with antioxidant ability, is considered a promising candidate for the treatment of diabetic neuropathy. Our study firstly examined the effects of prolonged cemtirestat treatment on bone parameters reflecting bone quality in non-diabetic rats and rats with streptozotocin (STZ)-induced diabetes. Experimental animals were assigned to four groups: non-diabetic rats, non-diabetic rats treated with cemtirestat, diabetic rats, and diabetic rats treated with cemtirestat. Higher levels of plasma glucose, triglycerides, cholesterol, glycated hemoglobin, magnesium, reduced femoral weight and length, bone mineral density and content, parameters characterizing trabecular bone mass and microarchitecture, cortical microarchitecture and geometry, and bone mechanical properties were determined in STZ-induced diabetic versus non-diabetic rats. Treatment with cemtirestat did not affect all aforementioned parameters in non-diabetic animals, suggesting that this drug is safe. In diabetic rats, cemtirestat supplementation reduced plasma triglyceride levels, increased the Haversian canal area and slightly, but insignificantly, improved bone mineral content. Nevertheless, the insufficient effect of cemtirestat treatment on diabetic bone disease does not support its use in the therapy of this complication of type 1 diabetes mellitus.

The influence of high glucose conditions on macrophages and its effect on the autophagy pathway.

Macrophages are central cells in mediating the inflammatory response. We evaluated the effect of high glucose conditions on the inflammatory profile and the autophagy pathway in Bone-Marrow Derived Macrophages (BMDM) from diabetic (D-BMDM) (alloxan: 60mg/kg, i.v.) and non-diabetic (ND-BMDM) C57BL/6 mice. BMDM were cultured in medium with normal glucose (5.5 mM), or high glucose (25 mM) concentration and were primed with Nigericin (20µM) stimulated with LPS (100 ng/mL) at times of 30 minutes; 2; 4; 6 and 24 hours, with the measurement of IL-6, IL-1β and TNF-α cytokines. We have further identified changes in the secretion of pro-inflammatory cytokines IL-6, IL-1β and TNF-α, where BMDM showed increased secretion of these cytokines after LPS + Nigericin stimulation. In addition, changes were observed in the autophagy pathway, where the increase in the autophagic protein LC3b and Beclin-1 occurred by macrophages of non-diabetic animals in hyperglycemic medium, without LPS stimulation. D-BMDM showed a reduction on the expression of LC3b and Beclin-1, suggesting an impaired autophagic process in these cells. The results suggest that hyperglycemia alters the inflammatory pathways in macrophages stimulated by LPS, playing an important role in the inflammatory response of diabetic individuals.

Enhanced Vulnerability of Diabetic Mice to Hypervirulent Streptococcus agalactiae ST-17 Infection.

Streptococcus agalactiae (Group B Streptococcus, GBS) is the leading cause of neonatal sepsis and meningitis but has been recently isolated from non-pregnant adults with underlying medical conditions like diabetes. Despite diabetes being a key risk factor for invasive disease, the pathological consequences during GBS infection remain poorly characterized. Here, we demonstrate the pathogenicity of the GBS90356-ST17 and COH1-ST17 strains in streptozotocin-induced diabetic mice. We show that GBS can spread through the bloodstream and colonize several tissues, presenting a higher bacterial count in diabetic-infected mice when compared to non-diabetic-infected mice. Histological sections of the lungs showed inflammatory cell infiltration, collapsed septa, and red blood cell extravasation in the diabetic-infected group. A significant increase in collagen deposition and elastic fibers were also observed in the lungs. Moreover, the diabetic group presented red blood cells that adhered to the valve wall and disorganized cardiac muscle fibers. An increased expression of KC protein, IL-1β, genes encoding immune cell markers, and ROS (reactive oxygen species) production was observed in diabetic-infected mice, suggesting GBS promotes high levels of inflammation when compared to non-diabetic animals. Our data indicate that efforts to reverse the epidemic of diabetes could considerably reduce the incidence of invasive infection, morbidity and mortality due to GBS.

Chronic hyperglycaemia increases the vulnerability of the hippocampus to oxidative damage induced during post-hypoglycaemic hyperglycaemia in a mouse model of chemically induced type 1 diabetes

Aims/hypothesisChronic hyperglycaemia and recurrent hypoglycaemia are independently associated with accelerated cognitive decline in type 1 diabetes. Recurrent hypoglycaemia in rodent models of chemically induced (streptozotocin [STZ]) diabetes leads to cognitive impairment in memory-related tasks associated with hippocampal oxidative damage. This study examined the hypothesis that post-hypoglycaemic hyperglycaemia in STZ-diabetes exacerbates hippocampal oxidative stress and explored potential contributory mechanisms.MethodsThe hyperinsulinaemic glucose clamp technique was used to induce equivalent hypoglycaemia and to control post-hypoglycaemic glucose levels in mice with and without STZ-diabetes and Nrf2−/− mice (lacking Nrf2 [also known as Nfe2l2]). Subsequently, quantitative proteomics based on stable isotope labelling by amino acids in cell culture and biochemical approaches were used to assess oxidative damage and explore contributory pathways.ResultsEvidence of hippocampal oxidative damage was most marked in mice with STZ-diabetes exposed to post-hypoglycaemic hyperglycaemia; these mice also showed induction of Nrf2 and the Nrf2 transcriptional targets Sod2 and Hmox-1. In this group, hypoglycaemia induced a significant upregulation of proteins involved in alternative fuel provision, reductive biosynthesis and degradation of damaged proteins, and a significant downregulation of proteins mediating the stress response. Key differences emerged between mice with and without STZ-diabetes following recovery from hypoglycaemia in proteins mediating the stress response and reductive biosynthesis.Conclusions/interpretationThere is a disruption of the cellular response to a hypoglycaemic challenge in mice with STZ-induced diabetes that is not seen in wild-type non-diabetic animals. The chronic hyperglycaemia of diabetes and post-hypoglycaemic hyperglycaemia act synergistically to induce oxidative stress and damage in the hippocampus, possibly leading to irreversible damage/modification to proteins or synapses between cells. In conclusion, recurrent hypoglycaemia in sub-optimally controlled diabetes may contribute, at least in part, to accelerated cognitive decline through amplifying oxidative damage in key brain regions, such as the hippocampus.Data availabilityThe datasets generated during and/or analysed during the current study are available in ProteomeXchange, accession no. 1-20220824-173727 (www.proteomexchange.org). Additional datasets generated during and/or analysed during the present study are available from the corresponding author upon reasonable request.Graphical abstract

Cannabidiol modulates contextual fear memory consolidation in animals with experimentally induced type-1 diabetes mellitus.

In view of the neuroprotective characteristic of cannabidiol (CBD) and its beneficial action on aversive memory in non-diabetic animals, we aimed to investigate in animals with experimentally induced type-1 diabetes mellitus (T1DM) whether CBD treatment would be able to impair the contextual fear memory consolidation, its generalisation and whether the effect would be lasting. We also investigated the CBD effect on anxiety-like responses. After T1DM induction, animals received single or more prolonged treatment with CBD and were submitted to the contextual fear conditioning test. As expression of activity-regulated cytoskeletal-associated (Arc) protein is necessary for memory consolidation, we evaluated its expression in the dorsal hippocampus (DH). For evaluating anxiety-related responses, animals were submitted to the elevated plus maze test (EPMT), in which the time and number of entries in the open arms were used as anxiety index. A single injection of CBD impaired the contextual fear memory consolidation and its generalisation, which was evaluated by exposing the animal in a neutral context. This single injection was able to reduce the elevated expression of Arc in the DH from these animals. Interestingly, more prolonged treatment with CBD also impaired the persistence of context-conditioned fear memory and induced an anxiolytic-like effect, as the treated group spent more time in the open arms of the EPMT. CBD interferes with contextual fear memory and the dosage regimen of treatment seems to be important. Moreover, we cannot rule out the involvement of emotional aspects in these processes related to fear memory.

The Effects of Metformin Treatment on Diabetic Albino Rats' Pancreas, Liver, and Kidney Histology.

Metformin, an oral hypoglycemic drug, has traditionally been considered the standard therapy for hyperglycemia. Metformin's several modes of action include inhibition of hepatic gluconeogenesis, anti-glucagon activity, and insulin-sensitizing effect. This study aims to assess the effectiveness of Metformin on the liver, pancreatic, and kidney tissues of alloxan-induced diabetic albino rats. Twenty mature albino white male rats were allocated at random into two groups. Intraperitoneal injections of alloxan monohydrate were utilised to induce diabetic Mellitus type II in the first ten rats. The second group of rats were injected intraperitoneally with normal saline. Both groups were then separated into four subgroups: Group 1 consisted of non-diabetic rats that were only administered distilled water (control), Group 2 consisted of non-diabetic rats that were administered metformin at a dose of 1000 mg/kg/day, and Group 3 consisted of diabetic control animals that were administered alloxan intravenously and distilled water orally, but were not given any medications. After seven days of DM induction, diabetic rats were administered Metformin at a dose of 1000 mg/kg/day orally. After one month of therapy, the animals were slaughtered and their organs were harvested. Compared to the control group, the histological results of pancreatic tissue were normal in the treatment groups. In contrast, liver and kidney sections from non-diabetic control, non-diabetic, and diabetic animals given 1000 mg/kg/day of Metformin had normal histology. Still, both tissues of untreated diabetic control mice exhibited lymphocyte infiltration. Metformin has been found to have significant blood glucose lowering properties and the capacity to protect several organs from the negative consequences of diabetes.

Sodium-glucose cotransporter 2 inhibition does not improve the acute pressure natriuresis response in rats with type 1 diabetes.

What is the central question of this study? Sodium-glucose cotransporter 2 (SGLT2) inhibitors reduce cardiovascular risk in patients with both diabetic and non-diabetic kidney disease: can SGLT2 inhibition improve renal pressure natriuresis (PN), an important mechanism for long-term blood pressure control, which is impaired in type 1 diabetes mellitus (T1DM)? What is the main finding and its importance? The SGLT2 inhibitor dapagliflozin did not enhance the acute in vivo PN response in either healthy or T1DM Sprague-Dawley rats. The data suggest that the mechanism underpinning the clinical benefits of SGLT2 inhibitors on health is unlikely to be due to an enhanced natriuretic response to increased blood pressure. Type 1 diabetes mellitus (T1DM) leads to serious complications including premature cardiovascular and kidney disease. Hypertension contributes importantly to these adverse outcomes. The renal pressure natriuresis (PN) response, a key regulator of blood pressure (BP), is impaired in rats with T1DM as tubular sodium reabsorption fails to down-regulate with increasing BP. We hypothesised that sodium-glucose cotransporter 2 (SGLT2) inhibitors, which reduce cardiovascular risk in kidney disease, would augment the PN response in T1DM rats. Non-diabetic or T1DM (35-50mg/kg streptozotocin i.p.) adult male Sprague-Dawley rats were anaesthetised (thiopental 50mg/kg i.p.) and randomised to receive either dapagliflozin (1mg/kg i.v.) or vehicle. Baseline sodium excretion was measured and then BP was increased by sequential arterial ligations to induce the PN response. In non-diabetic animals, the natriuretic and diuretic responses to increasing BP were not augmented by dapagliflozin. Dapagliflozin induced glycosuria, but this was not influenced by BP. In T1DM rats the PN response was impaired. Dapagliflozin again increased urinary glucose excretion but did not enhance PN. Inhibition of SGLT2 does not enhance the PN response in rats, either with or without T1DM. SGLT2 makes only a minor contribution to tubular sodium reabsorption and does not contribute to the impaired PN response in T1DM.

Local zinc treatment enhances fracture callus properties in diabetic rats.

The effects of locally applied zinc chloride (ZnCl2 ) on early and late-stage parameters of fracture healing were evaluated in a diabetic rat model. Type 1 Diabetes has been shown to negatively impact mechanical parameters of bone as well as biologic markers associated with bone healing. Zinc treatments have been shown to reverse those outcomes in tests of nondiabetic and diabetic animals. This study is the first to assess the efficacy of a noncarrier mediated ZnCl2 on bony healing in diabetic animals. This is a promising basic science approach which may lead to benefits for diabetic patients in the future. Treatment and healing were assessed through quantification of callus zinc, radiographic scoring, microcomputed tomography (µCT), histomorphometry, and mechanical testing. Local ZnCl2 treatment increased callus zinc levels at 1 and 3 days after fracture (p ≤ 0.025). Femur fractures treated with ZnCl2 showed increased mechanical properties after 4 and 6 weeks of healing. Histomorphometry of the ZnCl2 -treated fractures found increased callus cartilage area at Day 7 (p = 0.033) and increased callus bone area at Day 10 (p = 0.038). In contrast, callus cartilage area was decreased (p < 0.01) after 14 days in the ZnCl2 -treated rats. µCT analysis showed increased bone volume in the fracture callus of ZnCl2 -treated rats at 6 weeks (p = 0.0012) with an associated increase in the proportion of µCT voxel axial projections (Z-rays) spanning the fracture site. The results suggest that local ZnCl2 administration improves callus chondrogenesis leading to greater callus bone formation and improved fracture healing in diabetic rats.