High-Fat Diet/Low-Dose Streptozotocin-Induced Type 2 Diabetes in Rats Impacts Osteogenesis and Wnt Signaling in Bone Marrow Stromal Cells

Effects of Zinc Combined with Metformin on Zinc Homeostasis, Blood-Epididymal Barrier, and Epididymal Absorption in Male Diabetic Mice

Diabetes increases the likelihood of germ cell damage, hypogonadism, and male infertility. Diabetes leads to lower zinc (Zn) levels, an important micronutrient for maintaining male fertility, and zinc deficiency can lead to decreased male fertility through multiple mechanisms. The aim of this study was to investigate the effect of combined metformin and zinc administration on epididymis in diabetic mice; 10 of 50 male mice were randomly selected as the control group (group C), and the remaining 40 mice were randomly divided into untreated diabetes group (group D), diabetes + zinc group (group Z), diabetes + metformin group (group M), and diabetes + metformin + zinc group (group ZM) with 10 mice each. Diabetic mice in group Z received oral zinc (10 mg/kg) once daily for 4 weeks; diabetic mice in group M received oral metformin (200 mg/kg) once daily for 4 weeks; diabetic mice in group ZM received oral metformin and zinc once daily for 4 weeks; and groups C and D received the same amount of sterile water by gavage. Overnight fasted mice were sacrificed, and blood samples, mouse epididymides, and sperm were collected for further experiments. In group D, fasting blood glucose and insulin resistance index increased significantly, semen quality, serum insulin, and testosterone decreased, and epididymal structure was disordered. In group D, epididymal tissue zinc, free zinc ions in the caput, and cauda of epididymis and zinc transporter (ZnT2) decreased significantly, while ZIP12, metallothionein (MT), and metal transcription factor (MTF1) increased significantly. In addition, the expressions of blood-epididymal barrier (BEB)-related molecules (including ZO-1 β-catenin and N-cadherin) and aquaporins (AQPs, including AQP3, AQP9, and AQP11) in the epididymis of mice in group D were significantly decreased. In addition, compared with groups D, Z, and M, in the ZM group, the expression of BEB-related molecules (including ZO-1, β-catenin, and N-cadherin) and aquaporins (AQP3, AQP9, and AQP11) in epididymis tissue were significantly increased, and sperm motility and serum testosterone were significantly increased. It was concluded that male diabetic mice have a disturbed epididymal structure and decreased semen quality by causing an imbalance in epididymal zinc homeostasis, BEB, and impaired absorptive function. The combination of zinc and metformin is an effective and safe alternative treatment and provides additional benefits over metformin alone.

The impact of gut microbial dysbiosis on the atrophy of the hippocampus and abnormal metabolism of N-acetyl aspartate in type 2 diabetic rats

Rationale and objectives

This study aimed to investigate the effect of intestinal dysbiosis on the hippocampal volume using proton magnetic resonance spectroscopy (1H-MRS) in a type 2 diabetes mellitus (T2DM) rat model.

Materials and methods

We established a T2DM animal model with high-fat diet and streptozotocin (HFD/STZ) administration to Sprague-Dawley rats. Short-term ceftriaxone sodium administration was used to establish a T2DM intestinal dysbiosis (T2DM-ID) model. After establishing the model, fecal microbiota were detected using 16S rRNA sequencing. The models were then subjected to magnetic resonance imaging (MRI). Associations between MRI findings and fecal microbiota were evaluated.

Results

Magnetic resonance imaging (MRI) showed that the bilateral hippocampal voxel value and N-acetylaspartate (NAA) level were lower in the experimental group than in the normal control (NC) group (p < 0.05) and that NAA/creatine in the left hippocampus was lower in the T2DM-ID group than in the NC group (p < 0.05). α and β diversities differed significantly among the three groups (p < 0.05). In the T2DM and T2DM-ID groups, the abundance of bacteria in the phylum Proteobacteria increased significantly, whereas that of bacteria in the phylum Firmicutes decreased. The relative abundance of Actinobacteria was significantly increased in the T2DM-ID group. The Chao1 index (r = 0.33, p < 0.05) and relative abundance of Firmicutes (r = 0.48, p < 0.05) were positively correlated with the left hippocampal voxel, while the relative abundance of Proteobacteria was negatively correlated with the left hippocampal voxel (r = -0.44, p < 0.05). NAA levels, bilateral hippocampal voxels, and the relative abundance of Lactobacillus, Clostridia_UCG_014, and other genera were correlated positively (r = 0.34-0.70, p < 0.05). NAA levels and the relative abundances of Blautia and Enterococcus were correlated negatively (r = -0.32-0.44, p < 0.05).

Conclusion

The T2DM-ID rat model showed hippocampal volume atrophy and decreased levels of neuronal markers (such as NAA). The abnormal content of specific gut microorganisms may be a key biomarker of T2DM-associated brain damage.

A Novel Diabetic Arthritic Model in Rats Induced by Streptozotocin, High-Fat Diet, and Complete Freund's Adjuvant

Introduction

Ankle arthrodesis is one of the treatments of choice, particularly in late-stage and unstable diabetic Charcot arthropathy. Unfortunately, poor healing capacity might play a role in the high nonunion rate (10-40%). The advancement in regenerative medicine opens a new horizon for enhancing fusion after ankle arthrodesis in patients with poor healing capacity. However, a suitable small animal model is warranted to study the effectivity of these regenerative medicine approaches. Streptozotocin (STZ)-induced diabetes models and adjuvant-induced arthritis models with complete Freund's adjuvant are two established models. However, no study has combined those two models to make a diabetic arthritic model that more closely resembles the condition in Charcot arthropathy.

Methods

Twenty male Sprague-Dawley rats were assigned into five groups, consisting of one control group, and four diabetic groups which were induced by STZ injection and a high-fat diet. Among these diabetic rats, two groups received complete Freund's adjuvant (CFA) injections to the left ankle of the hind limb. The control group, one of the diabetic-only groups, and one of the arthritic-diabetic-induced groups were euthanized at 4 weeks after STZ induction, and the remainder were euthanized 6 weeks after STZ induction. Clinical, radiological, and histological examinations were then compared in all five groups.

Results

Diabetic status was successfully achieved in the model, which was maintained until the completion of the study. The CFA-induced ankles were significantly larger than the contralateral ankles in all groups (p<0.05). Histopathological evaluation confirmed arthritic changes in the CFA-induced group with less variability after 4 weeks of arthritis induction.

Conclusion

This rat model of arthritic diabetic mimics the progressive and chronic nature of Charcot arthropathy in humans. This model can be further use to study treatments that might enhance the fusion rate in ankle arthrodesis in healing-defective patients such as those with diabetes.

Level of Clinical Evidence

5.

A Model of Immediate Implant Placement to Evaluate Early Osseointegration in 129/Sv Diabetic Mice

PURPOSE

To analyze the process of early oral osseointegration of titanium (Ti) implants in diabetic 129/Sv mice through microCT and histologic and immunohistochemical analysis.

MATERIALS AND METHODS

A group of 30 male 129/Sv mice was equally subdivided into two groups: (1) nondiabetic (ND), in which mice did not undergo systemic alterations and received a standard diet, and (2) diabetic (D), in which mice were provided a high-fat diet from the age of 6 weeks until the conclusion of the study and received two intraperitoneal (IP) injections of streptozotocin (STZ) at a concentration of 100 mg/Kg each. Each mouse underwent extraction of a maxillary first molar, and customized Ti screws (0.50 mm diameter, 1.5 mm length) were placed in the residual alveolar sockets of the palatal roots. At 7 and 21 days after implant placement, the animals were euthanized for maxilla and pancreas collection. Maxillae containing Ti implants were analyzed with microCT, histology, and immunohistochemistry for cells that were positive for F4/80, CD146, runt-related transcription factor 2 (Runx2), and proliferating cell nuclear antigen (PCNA). Pancreata were histologically analyzed. Quantitative data were statistically analyzed with a significance level at 5% (P < .05).

RESULTS

ND mice presented successful healing and osseointegration, with a significantly higher fraction of bone volume compared to D mice, both at the alveolar sockets (53.39 ± 5.93 and 46.08 ± 3.18, respectively) and at the implant sites (68.88 ± 7.07 and 44.40 ± 6.98, respectively) 21 days after implant placement. Histologic evaluation revealed that the ND mice showed a significant decrease in inflammatory infiltrate and a significant increase in newly formed bone matrix at 21 days, whereas peri-implant sites in the D mice were predominantly encapsulated by fibrous tissue and chronic inflammatory infiltrate. Immunohistochemical characterization revealed higher Runx2 osteoblast differentiation and higher cell proliferation activity in the ND mice at 7 days, while higher amounts of macrophages were present in D mice at 7 and 21 days. Interestingly, no differences were found in CD146-positive cells when comparing ND and D mice.

CONCLUSIONS

This study evaluated the effects of immediate dental implant placement in 129/Sv diabetic mice by using specific healing markers to identify changes in cellular events involved in early oral osseointegration. This approach may serve as tool to evaluate new materials and surface coatings to improve osseointegration in diabetic patients.

SATB1 promotes osteogenic differentiation of diabetic rat BMSCs through MAPK signalling activation

OBJECTIVE

Special AT-rich binding protein 1 (SATB1), a chromatin organizer and global transcriptional regulator, plays an important role in tumorigenesis and immune response. However, its function in the osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) remains unknown. Therefore, this study aimed to explore the role of SATB1 in osteogenesis.

METHODS

BMSCs were collected from the type 2 diabetes rat model and the protein and gene expression of SATB1 and osteospecific genes were evaluated post osteogenic induction.

RESULTS

SATB1 protein expression significantly decreased in diabetic rat BMSCs whereas it increased in BMSCs following osteogenic induction. SATB1 knockdown significantly suppressed the expression of osteospecific genes, including alkaline phosphatase (Alp), runt-related transcription factor 2, and osteocalcin, and reduced the number of mineral deposits and ALP activity, whereas SATB1 overexpression yielded the opposite results. Moreover, SATB1 knockdown suppressed activation of the MAPK signalling pathway (phosphorylation of p38 and ERK), and MAPK pathway inhibitors could reverse the inhibitory effect of SATB1 knockdown on osteogenic differentiation of BMSCs.

CONCLUSION

SATB1 plays a key role in the osteogenic differentiation of BMSCs via the p38 MAPK and ERK MAPK signalling pathways. These findings may provide a new strategy for the application of BMSCs in bone regeneration.

Ursolic acid enhances the effect of exercise training on vascular aging by reducing oxidative stress in aged type 2 diabetic rats

Ursolic acid (UA) mediates the vasorelaxant activity via nitric oxide (NO) release, and upregulation of endothelial nitric oxide synthase (eNOS) in endothelial cells (ECs) in disease conditions with increased oxidative stress (OS). The present study aimed to reflect on the impact of 8 weeks of a combination of UA supplementation and resistance/endurance training in old male Wistar rats having a high-fat diet and/or low-dose streptozotocin-induced type 2 diabetes (HFD/STZ-induced T2D), with an emphasis on Sirtuin 1 (SIRT1)-endothelial nitric oxide synthase (eNOS) axis and OS indices in their aortic tissues. A total number of56 21-month-old male Wistar rats with HFD/STZ-induced T2D were randomized into seven groups (n = eight animals per group): (1) sedentary old nondiabetic (Control [C]); (2) sedentary HFD/STZ-induced T2D (Diabetic [D]); (3) sedentary HFD/STZ-induced T2D plus UA (Diabetic + Ursolic Acid [DU]); (4) endurance-trained HFD/STZ-induced T2D (Diabetic + Endurance Training [DE]); (5) resistance-trained HFD/STZ-induced T2D (Diabetic + Resistance Training [DR]); (6) endurance-trained HFD/STZ-induced T2D plus UA (Diabetic + Endurance Training + Ursolic Acid [DEU]); and (7) resistance-trained STZ-diabetic plus UA (Diabetic + Resistance Training + Ursolic Acid [DRU]) rats. The ladder-based resistance training group performed the ladder resistance training at 60% of the maximum voluntary carrying capacity (MVCC), 14-20 climbs in each session, with a one-min rest between each two trials, 5 days a week. The treadmill-based endurance exercise training protocol consisted of repeated bouts of high- and low-intensity training with 60-75% maximal running speed and 30%-40% maximal running speed in the course of 8 weeks, respectively. The animals in the supplement groups also took 500 mg of UA/kg of high-fat diet/day, resulting in a daily UA intake of approximately 250 mg UA per kg of body weight rat/day. The resistance/endurance training plus the UA consumption could partially reverse the levels of malondialdehyde (MDA), nitric oxide (NO), as well as total antioxidant capacity (TAC). It was concluded that oral 0.5% UA supplementation can prevent vascular aging biomarkers in a HFD/STZ-induced T2D model. Further studies are also required to clarify how chronic consumption of UA with/without training protocols reverses vascular aging process.

Bone-muscle crosstalk following exercise plus Ursolic acid by myomiR-133a/Cx43-Runx2 axis in aged type 2 diabetes rat models

Natural bioactive compound, Ursolic acid (UA), plus different types of exercise may exert the action on glycemic control, leading to clinical benefits in the prevention and treatment of aging/diabetes-associated complications. So, this study examined the effects of eight weeks combination of 250 mg of UA per day per kilogram of body weight of rat as well as resistance/endurance training on miR-133a expression across serum, bone marrow, skeletal muscle, and Connexin 43 (Cx43)-Runt-related transcription factor 2 (Runx2) signaling axis in high-fat diet and low-dose streptozotocin-induced T2D (here, HFD/STZ-induced T2D). The study was conducted on 56 male Wistar rats (427 ± 44 g, 21 months old), having HFD/STZ-induced T2D randomly assigned into 7 groups of 8 including (1) sedentary non-diabetic old rats (C); (2) sedentary type 2 diabetes animal model (D); (3) sedentary type 2 diabetes animal model + UA (DU); (4) endurance-trained type 2 diabetes animal model (DE); (5) resistance-trained type 2 diabetes animal model (DR); (6) endurance-trained type 2 diabetes animal model + UA (DEU); and (7) resistance-trained type 2 diabetes animal model + UA (DRU). Resistance training included a model of eight weeks of ladder resistance training at 60-80% maximal voluntary carrying capacity (MVCC) for five days/week. Treadmill endurance exercise protocol included eight weeks of repetitive bouts of low-/high-intensity training with 30%-40% and 60%-75% maximal running speed for five days/week, respectively. UA Supplementary groups were treated with 500 mg of UA per kg of high-fat diet per day. The results revealed significant supplement and exercise interaction effects for the BM miR-133a (p = 0.001), the bone marrow Runx2 (p = 0.002), but not the serum miR-133a (p = 0.517), the skeletal muscle miR-133a (p = 0.097) and the Cx43 (p = 0.632). In conclusion, only eight weeks of resistance-type exercise could affect miR-133a profile in muscles and osteoblast differentiation biomarker RUNX2 in aged T2D model of rats. 250 mg of UA per kilogram of body weight rat per day was administered orally, less than the sufficient dose for biological and physiological impacts on osteoblast differentiation biomarkers in aged T2D model of rats following eight weeks.

Effect of resistance and endurance training with ursolic acid on oxidative stress and cognitive impairment in hippocampal tissue in HFD/STZ-induced aged diabetic rats

Objectives

The increase in age-related cognitive impairment (CIs) and diabetes mellitus is a global health concern. Exercise training has been reported to activate the Nrf2/Keap1/ARE signaling and enhance the antioxidant defense pathways in some animal models. This study aimed to investigate the effects of ursolic acid (UA) associated with resistance or endurance training on antioxidant markers, and the Nrf2/Keap1/ARE pathway in the brain of older diabetic rats.

Materials and Methods

23-month-aged diabetes induced male Wistar rats were randomly assigned to seven groups (n=8). UA supplementation (250 mg/kg, daily) was administered along with resistance (60% maximum capacity of voluntary carrying [MVCC], 14-20 climbs) or endurance training (60-75% velocity at maximal oxygen uptake [vVO2max]), five days/week for eight weeks. Cognitive-motor functioning was assessed through open-field and passive avoidance response tests. Nrf2, Keap1, and antioxidant markers including SOD, CAT, GPx, and GSH were measured in the hippocampus tissue.

Results

The results showed positive effect of resistance training (P≤0.001) on Nrf2. There was endurance training with supplementation main effect (P=0.018) on Keap1 concentration. SOD revealed a significant endurance/resistance training by supplementation interaction effect (P≤0.05); however, there was no main training or UA supplementation effects on CAT, GPx, and GSH, despite improving spatial memory changes in exercise or UA groups.

Conclusion

It appears that UA treatment with resistance or endurance exercise has some beneficial effects on Nrf2 and some antioxidant markers. However, more research is needed to elucidate UA's interaction effects and exercise interventions in diabetic situations.

Investigation of the Chemical Composition, Antihyperglycemic and Antilipidemic Effects of Bassia eriophora and Its Derived Constituent, Umbelliferone on High-Fat Diet and Streptozotocin-Induced Diabetic Rats

This study was designed to investigate the chemical profile, antihyperglycemic and antilipidemic effect of total methanolic extract (TME) of Bassia eriophora and isolated pure compound umbelliferone (UFN) in high-fat diet (HFD)- and streptozotocin (STZ)- induced diabetic rats. TME was subjected to various techniques of chromatography to yield UFN. Diabetes was induced after eight weeks of HFD by administration of STZ (40 mg/kg) intraperitoneally, and experimental subjects were divided into five groups. The diabetic control showed an increase in levels of blood glucose throughout the experiment. Treatments were initiated in the other four groups with glibenclamide (GLB) (6 mg/kg), TME (200 mg/kg and 400 mg/kg) and isolated UFN (50 mg/kg) orally. The effect on blood glucose, lipid profile and histology of the pancreatic and adipose tissues was assessed. Both 200 and 400 mg/kg of TME produced a comparably significant decrease in blood glucose levels and an increase in insulin levels with GLB. UFN began to show a better blood sugar-lowering effect after 14 days of treatment, comparatively. However, both 400 mg/kg TME and UFN significantly returned blood glucose levels in diabetic rats compared to normal rats. Analysis of the lipid profile showed that while HFD + STZ increased all lipid profile parameters, TME administration produced a significant decrease in their levels. Histopathological examinations showed that treatment with TME and UFN revealed an improved cellular architecture, with the healthy islets of Langerhans and compact glandular cells for pancreatic cells distinct from damaged cells in non-treated groups. Conversely, the adipose tissue displayed apparently normal polygonal fat cells. Therefore, these results suggest that TME has the potential to ameliorate hyperglycemia conditions and control lipid profiles in HFD + STZ-induced diabetic rats.

miR-153-3p inhibits osteogenic differentiation of BMSCs by down-regulating the expression of RUNX2 in a high glucose environment

To study the effect of miR-153-3p on the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) in a high glucose environment and its potential mechanism. The results showed that high glucose inhibited the osteogenic differentiation of BMSCs, and the expression of miR-153-3p increased during osteogenic differentiation. Further experiments found that in BMSCs induced by high glucose, overexpression of miR-153-3p inhibited the osteogenic differentiation of BMSCs, and the expressions of osteogenesis-related genes bone sialoprotein, Collagen I and alkaline phosphatase were down-regulated, while silencing of miR-153-3p alleviated the inhibition effect. The dual-luciferase reporter gene assay confirmed that the 3'-untranslated region (3'-UTR) of runt related transcription factor 2 (RUNX2) had a targeted binding site with miR-153-3p and a negative regulatory effect. Molecular studies further confirmed that miR-153-3p inhibited the osteogenic differentiation of BMSCs by targeting the 3'-UTR of RUNX2. In conclusion, our study found that as one key regulator of high glucose affecting the osteogenic differentiation of BMSCs, miR-153-3p may play a negative regulatory role by inhibiting the expression of RUNX2.

Potential mechanisms underlying the association between type II diabetes mellitus and cognitive dysfunction in rats: a link between miRNA-21 and Resveratrol's neuroprotective action

Cognitive impairment is considered as a typical feature of neurodegenerative diseases in diabetes mellitus (DM). However, the exact link between cognitive dysfunction and diabetes mellitus is still vague. This study aims to investigate some of the mechanisms underlying cognitive impairment that associates diabetes mellitus and insulin resistance. We investigated the role of resveratrol as well on cognitive function in experimentally induced type 2 diabetes highlighting on its influence on the expression of brain miRNA 21. Resveratrol is a naturally occurring, biologically active compound that has numerous significant impacts on the body. Type 2 diabetes mellitus was induced by high fat diet followed a single dose of streptozotocin. Diabetic rats were treated with resveratrol for four weeks. Rats were sacrificed after neurobehavioral testing. Hippocampal tissues were used to assess expression of miRNA 21, GSK and oxidative stress markers. Serum samples were obtained to determine glucose levels, lipid profile and insulin levels. Hippocampal and serum AGEs were measured as well and HOMA IR was calculated. We detected memory impairment and disturbed insulin signaling in diabetic rats. These derangements were reversed by resveratrol treatment partially due to increased expression of miRNA-21. Our study pins the role of miRNA-21 in modulating brain insulin signaling and hence alleviating cognitive dysfunction accompanying diabetes mellitus.

Improved fatigue properties, bone microstructure and blood glucose in type 2 diabetic rats with verapamil treatment

BACKGROUND

Type 2 diabetes mellitus is a global epidemic disease, which leads to a severe complication named increased bone fracture risk. This study aimed to explore if verapamil treatment could improve bone quality of type 2 diabetes mellitus.

METHODS

Rat models of control, diabetes and verapamil treatment with 4/12/24/48 mg/kg/d were established, respectively. Blood glucose was monitored during 12-week treatment, and bilateral tibiae were collected. Microstructural images of bilateral metaphyseal cancellous bone and high-resolution images of cortical bone of left tibial shafts were obtained by micro-computed tomography. Fatigue properties of bone were evaluated via cyclic compressive tests of right tibial shafts.

FINDINGS

Verapamil treatment had no significant effect on blood glucose, but blood glucose tended to decline with the increase of verapamil-treated time and dose. Compared with controls, osteocyte lacunar and canal porosities in diabetes and verapamil-treated groups were significantly decreased (P < 0.05), trabecular separation and degree of anisotropy were significantly increased (P < 0.05), while trabecular tissue mineral density, trabecular bone volume fraction and trabecular number in verapamil-treated (48 mg/kg/d) group were significantly higher than those in diabetes (P < 0.05). Compared with diabetes, initial compressive elastic moduli in verapamil-treated (12/24/48 mg/kg/d) groups were significantly increased (P < 0.05), while secant modulus degradations in verapamil-treated (24/48 mg/kg/d) groups were significantly decreased (P < 0.05).

INTERPRETATION

Verapamil could improve bone microstructure and fatigue properties in type 2 diabetic rats; and high-dose verapamil presented a significant effect on improving bone quality. These findings provided a new possibility for preventing the high bone fracture risk of type 2 diabetes mellitus in clinics.

The effect of resistance and endurance training with ursolic acid on atrophy-related biomarkers in muscle tissue of diabetic male rats induced by streptozotocin and a high-fat diet

In this study, the effect of resistance and endurance training with/without ursolic acid supplementation was evaluated to identify atrophy-related biomarkers in elderly rats induced by diabetes and a high-fat diet (HFD) based on in silico analysis algorithms and pharmaceutical methods. The visualizer software found differential gene expression levels in skeletal muscle atrophy via computed hub gene network parameters. Also, the impact of ursolic acid, as a potent inducer of the Trp53 protein in ameliorating decreased muscle mass, was analyzed in diabetic rats. Fifty-six-old male Wistar rats were randomly assigned into seven groups, including healthy control (Control), diabetic control (DM), Ursolic acid supplementation (UA), resistance training (RT), endurance training (ET), resistance training+ Ursolic acid supplementation (RT + U), and endurance training in combination with Ursolic acid supplementation (ET + U). Exercise intervention included 8 weeks of resistance or endurance training programs. Biomedical informatic outputs determined the P53 signaling pathway as a remarkable causative factor in the pathomechanism of atrophy. In addition, the results demonstrated that exercise and supplementation of UA impeded the interactions among p53/ATF4/p21. Moreover, ET and ursolic acid had a synergetic effect on the signaling pathway of p53/ATF4/p21 and probably could inhibit the aging process and modulate the p53/ATF4/p21 molecular pathway. The interaction between UA and endurance exercise significantly modified the activity of the p53/ATF4/p21 signaling pathway. Based on in silico studies, the p53/ATF4/p21 pathway plays an essential role in aging, and the inhibition of this pathway would be beneficial in decelerating the aging process. PRACTICAL APPLICATIONS: Ursolic acid (UA) is a natural pentacyclic triterpenoid carboxylic acid found in apples (a major compound of apple wax) and other fruits; it is known to improve skeletal muscle function and reduce the muscular atrophy pathways. We indicated that p53/ATF4/p21 signaling is an essential factor in aging, and the suppression of this pathway could be beneficial in the deceleration of the aging process. Therefore, this work would shed light on understanding the effect of exercise and nutrition interventions on preventing atrophy markers of skeletal muscle in diabetic rats. Further studies are needed to seek the precise mechanism of the synergism between UA and exercise in ameliorating atrophy markers.

Brain Energy Metabolism in Ischemic Stroke: Effects of Smoking and Diabetes

Proper regulation of energy metabolism in the brain is crucial for maintaining brain activity in physiological and different pathophysiological conditions. Ischemic stroke has a complex pathophysiology which includes perturbations in the brain energy metabolism processes which can contribute to worsening of brain injury and stroke outcome. Smoking and diabetes are common risk factors and comorbid conditions for ischemic stroke which have also been associated with disruptions in brain energy metabolism. Simultaneous presence of these conditions may further alter energy metabolism in the brain leading to a poor clinical prognosis after an ischemic stroke event. In this review, we discuss the possible effects of smoking and/or diabetes on brain glucose utilization and mitochondrial energy metabolism which, when present concurrently, may exacerbate energy metabolism in the ischemic brain. More research is needed to investigate brain glucose utilization and mitochondrial oxidative metabolism in ischemic stroke in the presence of smoking and/or diabetes, which would provide further insights on the pathophysiology of these comorbid conditions and facilitate the development of therapeutic interventions.

Pulsed electromagnetic fields inhibit mandibular bone deterioration depending on the Wnt3a/β-catenin signaling activation in type 2 diabetic db/db mice

Type 2 diabetes mellitus (T2DM) patients have compromised mandibular bone architecture/quality, which markedly increase the risks of tooth loosening, tooth loss, and failure of dental implantation. However, it remains lacks effective and safe countermeasures against T2DM-related mandibular bone deterioration. Herein, we studied the effects of pulsed electromagnetic fields (PEMF) on mandibular bone microstructure/quality and relevant regulatory mechanisms in T2DM db/db mice. PEMF exposure (20 Gs, 15 Hz) for 12 weeks preserved trabecular bone architecture, increased cortical bone thickness, improved material properties and stimulated bone anabolism in mandibles of db/db mice. PEMF also upregulated the expression of canonical Wnt3a ligand (but not Wnt1 or Wnt5a) and its downstream β-catenin. PEMF improved the viability and differentiation of primary osteoblasts isolated from the db/db mouse mandible, and stimulated the specific activation of Wnt3a/β-catenin signaling. These positive effects of PEMF on mandibular osteoblasts of db/db mice were almost totally abolished after Wnt3a silencing in vitro, which were equivalent to the effects following blockade of canonical Wnt signaling using the broad-spectrum antagonist DKK1. Injection with Wnt3a siRNA abrogated the therapeutic effects of PEMF on mandibular bone quantity/quality and bone anabolism in db/db mice. Our study indicates that PEMF might become a non-invasive and safe treatment alternative resisting mandibular bone deterioration in T2DM patients, which is helpful for protecting teeth from loosening/loss and securing the dental implant stability.

Ameliorative Effect of Ocimum forskolei Benth on Diabetic, Apoptotic, and Adipogenic Biomarkers of Diabetic Rats and 3T3-L1 Fibroblasts Assisted by In Silico Approach

Diabetes mellitus (DM) is a complicated condition that is accompanied by a plethora of metabolic symptoms, including disturbed serum glucose and lipid profiles. Several herbs are reputed as traditional medicine to improve DM. The current study was designed to explore the chemical composition and possible ameliorative effects of Ocimum forskolei on blood glucose and lipid profile in high-fat diet/streptozotocin-induced diabetic rats and in 3T3-L1 cell lines as a first report of its bioactivity. Histopathological study of pancreatic and adipose tissues was performed in control and treatment groups, along with quantification of glucose and lipid profiles and the assessment of NF-κB, cleaved caspase-3, BAX, and BCL2 markers in rat pancreatic tissue. Glucose uptake, adipogenic markers, DGAT1, CEBP/α, and PPARγ levels were evaluated in the 3T3-L1 cell line. Hesperidin was isolated from total methanol extract (TME). TME and hesperidin significantly controlled the glucose and lipid profile in DM rats. Glibenclamide was used as a positive control. Histopathological assessment showed that TME and hesperidin averted necrosis and infiltration in pancreatic tissues, and led to a substantial improvement in the cellular structure of adipose tissue. TME and hesperidin distinctly diminished the mRNA and protein expression of NF-κB, cleaved caspase-3, and BAX, and increased BCL2 expression (reflecting its protective and antiapoptotic actions). Interestingly, TME and hesperidin reduced glucose uptake and oxidative lipid accumulation in the 3T3-L1 cell line. TME and hesperidin reduced DGAT1, CEBP/α, and PPARγ mRNA and protein expression in 3T3-L1 cells. Moreover, docking studies supported the results via deep interaction of hesperidin with the tested biomarkers. Taken together, the current study demonstrates Ocimum forskolei and hesperidin as possible candidates for treating diabetes mellitus.

The Role of Zinc in Bone Mesenchymal Stem Cell Differentiation

Zinc is an essential trace element for bone growth and bone homeostasis in the human body. Bone mesenchymal stem cells (BMSCs) are multipotent progenitors existing in the bone marrow stroma with the capability of differentiating along multiple lineage pathways. Zinc plays a paramount role in BMSCs, which can be spurred differentiating into osteoblasts, chondrocytes, or adipocytes, and modulates the formation and activity of osteoclasts. The expression of related genes also changed during the differentiation of various cell phenotypes. Based on the important role of zinc in BMSC differentiation, using zinc as a therapeutic approach for bone remodeling will be a promising method. This review explores the role of zinc ion in the differentiation of BMSCs into various cell phenotypes and outlines the existing research on their molecular mechanism.

Clinically relevant experimental rodent models of diabetic foot ulcer

Chronic wounds are a substantial clinical problem in diabetes and nearly 6% of diabetics suffer from foot disease including ulceration, infection, and tissue necrosis. Wound healing in diabetes is impaired and delayed and is augmented by diabetic complications. Wound healing involves complex cellular, molecular, and biochemical processes and animal models are the most suitable prototype to investigate and understand the underlying pathological changes in the process of wound healing. Animal models are also useful in evaluating the safety and efficacy of newer therapeutic agents and improving the clinical approaches for human patients with chronic ulcers. The wound healing strategies get more complicated in the presence of diabetes and its associated complication. Despite the advancement in methods of wound healing, the healing of the chronic diabetic foot ulcer (DFU) remains an important clinical problem resulting in costly and prolonged treatment and poses a risk for major amputation. Saying that it is important to elucidate the newer therapeutic targets and strategies via an in-depth understanding of the complicated cascade of the chronic DFU. A major challenge in translating lab findings to clinics is the lack of an optimal preclinical model capable of properly recapitulating human wounds. Both small and large animal models of wound healing involving rodents, rabbits, and pigs have been discussed. Mouse and rats as small animal models and pig as large animal models have been discussed in association with the diabetic wound but there are advantages and limitations for each model. In this review, we critically reviewed the pros and cons of experimental models of diabetic wound healing with a focus on type II diabetes rodent models.

Therapeutic role of Azadirachta indica leaves ethanolic extract against diabetic nephropathy in rats neonatally induced by streptozotocin

Diabetic nephropathy (DN) is manifested by chronic loss of renal function due to damage of glomeruli and renal tubules. Therefore, this study is mainly designed to evaluate the therapeutic role of Azadiracta indica (neem) leaves extract as a novel approach for treatment of DN in rats neonatally induced by streptozotocin (STZ). For this study, 40 offspring were selected after parturition and categorized into four groups (n = 10). Group1: control group, group 2: neem leaves extract supplemented group, group 3: diabetic group that injected with a single dose of STZ and group 4: diabetic group treated with neem extract. The results revealed deleterious histological and ultrstructural changes in the renal tissues of diabetic rats. Such changes included atrophied glomeruli, dilated renal cortical tubules and scattered hemorrhage spots, thickening of glomerular basement membrane, expansion of mesangial matrix and pyknotic podocyte. Additionally, the proximal convoluted tubule and distal tubule showed cytoplasmic vacuolation, vacuolated mitochondria, scattered lipid droplets, lost microvilli and disrupted basal lamina and basal infoldings. Moreover, significant decreased levels of serum antioxidants (SOD&CAT) and significant increased levels of serum MDA, urea and creatinine were noticed in diabetic rats. Neem leaves extract successfully alleviated the histological and ultrastructural as well as biochemical changes induced by diabetes.

Strontium-incorporated titanium implant surfaces treated by hydrothermal treatment enhance rapid osseointegration in diabetes: A preclinical vivo experimental study

OBJECTIVES

The aim of the current study was to explore effects of strontium-incorporated titanium implant surfaces by hydrothermal treatment on osseointegration in diabetic rats.

MATERIALS AND METHODS

The surface characteristics of SLA and SLA-Sr surfaces were detected by related instruments. Thirty-six male Sprague-Dawley rats were induced into diabetes, and thirty-six rats were normal. SLA and SLA-Sr implants were, respectively, inserted into bilateral tibial metaphysis of each rat. Percentage of bone-to-implant contact (BIC%) and percentage of bone area (BA%) were analyzed at 4 and 8 weeks after implantation. Immunohistochemistry of osteoprotegerin (OPG) and Wnt5a were conducted at 1 and 4 weeks. Gene expression levels of inflammatory cytokines and related signaling molecules in peri-implant bone tissue were detected at 3 and 7 days.

RESULTS

Strontium was uniformly distributed on SLA-Sr surfaces, and it was released in an effective concentration range. SLA-Sr surfaces showed significantly higher BIC% in diabetic rats at 4 (p < .05) and 8 weeks (p < .05). Besides, it displayed higher BIC% at 4 weeks (p < .05) in normal rats. Also, SLA-Sr surfaces upregulated expression of OPG at 4 weeks (p < .05) in diabetic rats. What's more, SLA-Sr surfaces downregulated inflammation (TNF-α, IL-1β, and IL-6; p < .01) in diabetic rats at 3 days. In addition, expression of Wnt5a and ROR2 was upregulated (p < .05) at 7 days after implantation under diabetes.

CONCLUSION

It is suggested that strontium-incorporated titanium implant surfaces by hydrothermal treatment could enhance implant osseointegration as compared with SLA implant surfaces in diabetic rats.

Cinacalcet as a surrogate therapy for diabetic cardiomyopathy in rats through AMPK-mediated promotion of mitochondrial and autophagic function

Decreased activity of AMP-activated protein kinase (AMPK) is implicated in the pathogenesis of diabetic cardiomyopathy (DCM). Recent evidence suggests a crosstalk between cinacalcet and AMPK activation. This study investigated the effects of cinacalcet on cardiac remodeling and dysfunction in type 2 diabetic rats (T2DM). High fat diet for 4 weeks combined with single intraperitoneal injection of streptozotocin (30 mg/kg) was used to induce type 2 diabetes in rats. Diabetic rats were either orally treated with vehicle, 5 or 10 mg/kg cinacalcet for 4 weeks. Control rats were fed standard chow diet and intraperitoneally injected with citrate buffer. T2DM rats showed lower body weight (BW), hyperglycemia and dyslipidemia, along with increased heart weight (HW) and HW/BW ratio. Masson's trichrome stained cardiac sections revealed massive fibrosis in T2DM rats. There were increased TGF-β1 and hydroxyproline levels, coupled with up-regulation of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) in hearts of T2DM rats. These alterations were associated with redox imbalance and impaired cardiac functions. Decreased phosphorylation of AMPK at threonine172 residue was found in T2DM hearts. Cinacalcet for 4 weeks significantly activated AMPK and alleviated cardiac remodeling and dysfunction in a dose-dependent manner, without affecting blood glucose, serum calcium and phosphorus levels. Cinacalcet increased the mitochondrial DNA content, and expressions of PGC-1α, UCP-3, beclin-1 and LC3-II/LC3-I ratio. Cinacalcet decreased the pro-apoptotic Bax, while increased the anti-apoptotic Bcl-2 in cardiac tissue of T2DM rats. These findings might highlight cinacalcet as an alternative therapy to combat the development and progression of DCM.

Analysis of jejunum microbiota of HFD/STZ diabetic rats

Currently, several studies propose that the dominant intestinal bacteria are core flora. Besides keeping the homeostasis of the intestinal environment, the intestinal microflora also plays a role in body metabolism, production of some vitamins, and control of barrier function. The study aimed to investigate the jejunum microbiota in diabetic rats as well as it's the relationship with Ceftriaxone sodium-mediated gut dysbiosis, diabetic parameters, and intestinal permeability. Thirty-two Wistar rats (Male) were enrolled and divided into four groups (A, B, C, and D; N = 8). Subsequently, T2DM was induced in C and D groups by HFD/STZ model and then gut dysbiosis in B and D groups via intragastric administration of Ceftriaxone sodium for two weeks. The food-water intake, body weight, fasting blood glucose, plasma insulin, HOMA-IR, intestinal permeability, and jejunum microbiota and it's histology were investigated. In this study, T2DM was associated with a significant decrease in the richness and diversity of jejunum microbiota, elevation in the intestinal permeability, and higher abundance of some opportunistic pathogens. Ceftriaxone sodium-induced gut dysbiosis declined food-water intake, damagedthe villi of jejunum tissue, increased intestinal permeability, and affected the diversity of jejunum microbiota. In diabetic rats, Ceftriaxone sodium-mediated gut dysbiosis also declined the abundance of someSCFAs bacteria and raised the abundant of some opportunistic bacteria such as Staphylococcus_sciuri. Interestingly, we found that several bacteria were negatively correlated with HOMA-IR, fasting blood glucose, body weight, and intestinal permeability. Overall, the study highlighted the jejunum microflora alterations in HFD/STZ diabetic rats and assessed the effect of Ceftriaxone sodium-induced gut dysbiosis on diabetic parameters, jejunum microbiota and histology, and intestinal permeability, which are of potential for further studies.

Streptozotocin-induced type 1 and 2 diabetes in rodents: a model for studying diabetic cardiac autonomic neuropathy

Background

Several animal models are continually being developed to study diabetic complication. Several conflicting regimen for diabetes induction exist in the literature with varying dose strength and regimen for different study interest in diabetes. This study aims to show the effect of high dose streptozotocin (STZ) on the one hand compared with multiple low doses after high fat diet induction on diabetic cardiac autonomic neuropathy (DCAN).

Methodology

Eighty-four Wistar rats were used to demonstrate DCAN induction using 2 approaches one for T1DM (STZ 50mg/kg) and the other for T2DM (HFD for 8 weeks with STZ 25mg/Kg daily for five days). DCAN features were assessed using invasive biomarkers, histology patterns and cardiac nerve densities.

Results

Diabetes induction rate was 76% and 89% in T1DM and T2DM model respectively. T1DM group had significant weight loss, reduced c-peptide, and insulin level post induction. The T2DM additionally showed significantly higher total cholesterol and Homeostatic model assessment (HOMA) compared with control. Serum levels of catecholamine, choactase, nerve growth factor and cardiac nerve density confirms development of DCAN.

Conclusion

High single dose of STZ and HFD with multiple low doses of STZ may be recommended for DCAN study in T1DM and T2DM rat model respectively.

Features of a simvastatin-loaded multi-layered co-electrospun barrier membrane for guided bone regeneration

A novel tri-layer membrane consisting of polycaprolactone (PCL) fibrous sheets and structured nanofibers with a gelatin (Gt) shell and a simvastatin-containing PCL core (PCL-Gt/PCL-simvastatin membrane) was prepared. The soft external layer comprised of Gt/PCL-simvastatin, the external layer of PCL and the middle layer of both microfilaments, interwoven together. The membrane was designed to promote osteoinduction and act as a barrier against cells but not against water and molecules in order to promote guided bone regeneration. The structure of the membrane was characterized by scanning electronic microscopy. The in vitro release rates of simvastatin over 32 days were determined by high-performance liquid chromatography. For in vitro biological assays, bone marrow mesenchymal stem cells and human fibroblasts were cultured on the different surfaces of the membrane. Cell adhesion, proliferation, distribution, and differentiation were examined. For in vivo testing, cranial defects were created in rabbits to assess the amount of new bone formed for each membrane. The results revealed that membranes with multi-layered structures showed good cell viability and effective osteoinductive and barrier properties. These results suggest that the novel multi-layered PCL-Gt/PCL-simvastatin membranes have great potential for bone tissue engineering.

The synergistic promotion of osseointegration by nanostructure design and silicon substitution of hydroxyapatite coatings in a diabetic model

Accumulating evidence indicates much higher failure rates for biomedical titanium implants in diabetic patients. This phenomenon is attributed to impaired osteoblastic function, suppressed angiogenesis capacity, and abnormal osteoclast activation in diabetic patients. Our previous study demonstrated that titanium implants coated with highly crystalline nanostructured hydroxyapatite (nHA) promoted the osteogenic differentiation of bone marrow stromal cells (BMSCs) and bone-implant osseointegration under healthy conditions. Furthermore, recent studies showed that silicon-substituted biomaterials exhibited excellent osteogenesis and angiogenesis performance while repressing osteoclastogenesis. Hence, we proposed that a combination of nanostructural modification and Si substitution might produce synergetic effects to mitigate the impaired osseointegration of bone implants under diabetes mellitus (DM) conditions. To confirm this hypothesis, titanium implants coated with highly crystalline Si-substituted nHA (Si-nHA) were successfully fabricated via atmospheric plasma spraying combined with hydrothermal treatment. An in vitro study demonstrated that compared to the original HA coating, the nHA coating improved osteogenic and angiogenic differentiation and altered the OPG/RANKL ratio of DM-BMSCs. In addition, the Si-nHA coating further enhanced cell proliferation, improved osteogenic and angiogenic differentiation, and repressed osteoclastogenesis in DM-BMSCs. An in vivo study confirmed that the titanium implants coated with nHA or Si-nHA effectively promoted bone formation and bone-implant osseointegration in a diabetic rabbit model, with the Si-nHA coating exhibiting the best stimulatory effect. Collectively, the results suggest that the nanostructured topography and Si substitution act synergistically to ameliorate the poor bone regeneration and osseointegration associated with DM. Thus, the results provide a promising coating method for dental and orthopedic applications under diabetic conditions.

Total flavonoids of Rhizoma drynariae ameliorate steroid‑induced avascular necrosis of the femoral head via the PI3K/AKT pathway

Steroid-induced avascular necrosis of the femoral head (SANFH) is a common orthopaedic disease that is difficult to treat. The present study investigated the effects of total flavonoids of Rhizoma drynariae (TFRD) on SANFH and explored its underlying mechanisms. The SANFH rat model was induced by intramuscular injection of lipopolysaccharides and methylprednisolone. Osteoblasts were isolated from the calvariae of neonatal rats and then cultured with dexamethasone (Dex). TFRD was used in vitro and in vivo, respectively. Haematoxylin and eosin staining was used to assess the pathological changes in the femoral head. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labelling assay and flow cytometry were conducted to detect apoptosis of osteoblasts. The 2,7-dichlorofluorescein-diacetate staining method was used to detect reactive oxygen species (ROS) levels in osteoblasts and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was used to detect osteoblast proliferation. The expression of caspase-3, Bax, Bcl-2, VEGF, runt-related transcription factor 2 (RUNX2), osteoprotegerin (OPG), osteocalcin (OCN), receptor activator of nuclear factor κB ligand (RANKL) and phosphoinositide 3-kinase (PI3K)/AKT pathway related-proteins were detected via western blotting. It was found that TFRD reduced the pathological changes, inhibited apoptosis, increased the expression of VEGF, RUNX2, OPG and OCN, decreased RANKL expression and activated the PI3K/AKT pathway in SANFH rats. TFRD promoted proliferation, inhibited apoptosis and reduced ROS levels by activating the PI3K/AKT pathway in osteoblasts. In conclusion, TFRD protected against SANFH in a rat model. In addition, TFRD protected osteoblasts from Dex-induced damage through the PI3K/AKT pathway. The findings of the present study may contribute to find an effective treatment for the management of SANFH.

Effects of Obesity and Diabetes on Sperm Cell Proteomics in Rats

Infertility caused by male factors is potentially associated with metabolic disorders such as obesity and/or diabetes. This experimental study was conducted in a male rodent model to assess the effects of different diseases on semen quality and sperm proteomics. Ten Wistar rats were used for each treatment. Rats were fed commercial food provided controllably to the control group and the diabetic group, and a hypercaloric diet supplemented with 5% sucrose in water was provided ad libitum to the obese group for 38 weeks. Diabetes was induced with 35 mg/kg streptozotocin. After euthanasia, testicles, spermatozoa, fat, and blood (serum) samples were collected. Spermatozoa were evaluated for quality and subjected to proteomics analyses. Histology and cytology of the testis, and serum leptin, adiponectin, interleukin 8 (IL-8), blood glucose, and testosterone levels, were also assessed. Body weight, retroperitoneal and testicular fat, and the Lee index were also measured. Obesity and diabetes were induced. The diabetic group showed noticeable changes in spermatogenesis and sperm quality. The mass spectrometry proteomics data have been deposited in Mendeley Data (doi: 10.17632/rfp7kfjcsd.5). Fifteen proteins varied in abundance between groups, especially proteins related to energy production and structural function of the spermatozoa, suggesting disturbances in energy production with a subsequent alteration in sperm motility in both groups, but with a compensatory response in the obese group.

Catalpol Protects Against High Glucose-Induced Bone Loss by Regulating Osteoblast Function

Objective: The overall objective of this study was to investigate the effects of catalpol on bone remodeling of diabetic osteoporosis by regulating osteoblast differentiation and migration.

Method: Using a murine model of diabetic osteoporosis, to detect the protective effects of catalpol on bone loss, architectural deterioration of trabecular bone and bone metabolism biomarkers were tested. A model of MC3T3-E1 cells was established by treatment with high glucose; the regulatory role of catalpol in the differentiation and migration was tested by Western blot, ALP staining, and Alizarin Red staining.

Results: Catalpol treatment markedly ameliorated trabecular bone deterioration by reducing degenerative changes of the trabecular structure by improving the bone formation marker levels of ALP, osteopontin, type I collagen, and osteocalcin, as well as the level of OPG/RANKL. Catalpol enhanced cell motility and scattering following gap formation of MC3T3-E1 cells.

Conclusion: The results indicated that catalpol exhibits a protective effect against diabetic osteoporosis by regulating the differentiation and migration of osteoblast.

Recovering the osteoblastic differentiation potential of mesenchymal stem cells derived from diabetic rats by photobiomodulation therapy

Autologous cell-based therapy for bone regeneration might be impaired by diabetes mellitus (DM) due to the negative effects on mesenchymal stem cells (MSCs) differentiation. Strategies to recover their osteogenic potential could optimize the results. We aimed to evaluate the effect of photobiomodulation (PBM) therapy on osteoblast differentiation of rats with induced DM. Bone marrow MSCs of healthy and diabetic rats were isolated and differentiated into osteoblasts (OB and dOB, respectively). dOB were treated with PBM therapy every 72 hour (660 nm; 0.14 J; 20 mW; 0.714 W/cm² , and 5 J/cm² ). Cell morphology, viability, gene and protein expression of osteoblastic markers, alkaline phosphatase (ALP) activity, and the mineralized matrix production of dOB-PBM were compared to dOB. PBM therapy improved viability of dOB, increased the gene and protein expression of bone markers, the ALP activity and the mineralized matrix production. PBM therapy represents an innovative therapeutic approach to optimize the treatment of bone defects in diabetic patients.

A Newly Developed Synbiotic Yogurt Prevents Diabetes by Improving the Microbiome-Intestine-Pancreas Axis

The prevalence of type 2 diabetes mellitus (T2D) is increasing worldwide, and there are no long-term preventive strategies to stop this growth. Emerging research shows that perturbations in the gut microbiome significantly contribute to the development of T2D, while microbiome modulators may be beneficial for T2D prevention. However, microbiome modulators that are effective, safe, affordable, and able to be administered daily are not yet available. Based on our previous pro- and prebiotic studies, we developed a novel synbiotic yogurt comprised of human-origin probiotics and plant-based prebiotics and investigated its impact on diet- and streptozotocin-induced T2D in mice. We compared the effects of our synbiotic yogurt to those of a commercially available yogurt (control yogurt). Interestingly, we found that the feeding of the synbiotic yogurt significantly reduced the development of hyperglycemia (diabetes) in response to high-fat diet feeding and streptozotocin compared to milk-fed controls. Surprisingly, the control yogurt exacerbated diabetes progression. Synbiotic yogurt beneficially modulated the gut microbiota composition compared to milk, while the control yogurt negatively modulated it by significantly increasing the abundance of detrimental bacteria such as Proteobacteria and Enterobacteriaceae. In addition, the synbiotic yogurt protected pancreatic islet morphology compared to the milk control, while the control yogurt demonstrated worse effects on islets. These results suggest that our newly developed synbiotic yogurt protects against diabetes in mice and can be used as a therapeutic to prevent diabetes progression.

Diabetes impairs periosteal progenitor regenerative potential

Diabetics are at increased risk for fracture, and experience severely impaired skeletal healing characterized by delayed union or nonunion of the bone. The periosteum harbors osteochondral progenitors that can differentiate into chondrocytes and osteoblasts, and this connective tissue layer is required for efficient fracture healing. While bone marrow-derived stromal cells have been studied extensively in the context of diabetic skeletal repair and osteogenesis, the effect of diabetes on the periosteum and its ability to contribute to bone regeneration has not yet been explicitly evaluated. Within this study, we utilized an established murine model of type I diabetes to evaluate periosteal cell differentiation capacity, proliferation, and availability under the effect of a diabetic environment. Periosteal cells from diabetic mice were deficient in osteogenic differentiation ability in vitro, and diabetic mice had reduced periosteal populations of mesenchymal progenitors with a corresponding reduction in proliferation capacity following injury. Additionally, fracture callus mineralization and mature osteoblast activity during periosteum-mediated healing was impaired in diabetic mice compared to controls. We propose that the effect of diabetes on periosteal progenitors and their ability to aid in skeletal repair directly impairs fracture healing.

L-carnitine improves metabolic disorders and regulates apelin and apelin receptor genes expression in adipose tissue in diabetic rats

Apelin is a new adipocytokine that acts as an endogenous hormone in various tissues through its receptor (APJ). This study aimed to investigate the effects of oral administration of L-carnitine (LC) on the expression of Apelin and APJ in adipose tissue of experimentally induced insulin-resistant and type 2 diabetic rats. In this experimental study, 60 male rats fed with high fat/high carbohydrate (HF/HC) diet. After 50 mg/kg intraperitoneally injection of streptozotocin (STZ) and confirmation of diabetes (FBS higher than 126 mg/dl), the animals were daily treated with 300 mg/kg LC for 28 days. At days 7, 14, and 28 of posttreatment, the expression of apelin and APJ in adipose tissue were determined using qPCR in diabetic, diabetic + LC treated, control, and control + LC treated groups. Apelin, insulin, TNF-α, and IL1-β were measured by the ELISA method. Results demonstrated that the rats fed with the HF/HC diet for 5 weeks were hyperinsulinemic and normoglycemic, while after STZ injection, they showed hyperinsulinemia and hyperglycemia with higher levels of HOMA-IR. Apelin serum level, APJ and apelin gene expression in adipose tissue increased significantly with the development of diabetes compared to the control group. Treatment with LC for 14 days caused a reduction in apelin and APJ expressions in adipose tissue of diabetic rats. TNF-α and IL1-β levels were reduced in diabetic rats 14 days after their treatment with LC. The study results show that L-carnitine could act as a new regulator in apelin gene expression in adipose tissue, improving the metabolic disorders in diabetic patients.

Population pharmacokinetics of gabapentin in patients with neuropathic pain: Lack of effect of diabetes or glycaemic control

AIMS

Gabapentin (GBP) is widely used to treat neuropathic pain, including diabetic neuropathic pain. Our objective was to evaluate the role of diabetes and glycaemic control on GBP population pharmacokinetics.

METHODS

A clinical trial was conducted in patients with neuropathic pain (n = 29) due to type 2 diabetes (n = 19) or lumbar/cervical disc herniation (n = 10). All participants were treated with a single oral dose GBP. Blood was sampled up to 24 hours after GBP administration. Data were analysed with a population approach using the stochastic approximation expectation maximization algorithm. Weight, body mass index, sex, biomarkers of renal function and diabetes, and genotypes for the main genetic polymorphisms of SLC22A2 (rs316019) and SLC22A4 (rs1050152), the genes encoding the transporters for organic cations OCT2 and OCTN1, were tested as potential covariates.

RESULTS

GBP drug disposition was described by a 1-compartment model with lag-time, first-order absorption and linear elimination. The total clearance was dependent on estimated glomerular filtration rate. Population estimates (between-subject variability in percentage) for lag time, first-order absorption rate, apparent volume of distribution and total clearance were 0.316 h (10.6%), 1.12 h^-1 (10.7%), 140 L (7.7%) and 14.7 L/h (6.97%), respectively. No significant association was observed with hyperglycaemia, glycated haemoglobin, diabetes diagnosis, age, sex, weight, body mass index, SLC22A2 or SLC22A4 genotypes.

CONCLUSION

This population pharmacokinetics model accurately estimated GBP concentrations in patients with neuropathic pain, using estimated glomerular filtrationrate as a covariate for total clearance. The distribution and excretion processes of GBP were not affected by hyperglycaemia or diabetes.

miR-124-3p promotes BMSC osteogenesis via suppressing the GSK-3β/β-catenin signaling pathway in diabetic osteoporosis rats

The purpose of this study is to investigate miRNAs' effects, targeting the Wnt signaling pathway, on osteogenic differentiation to provide new targets for diabetic osteoporosis treatments. Twelve male rats were divided into a normal rat group (NOR group) and a model rat group (MOD group). Cluster analysis of differentially expressed miRNAs and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were performed. Primary rat bone marrow mesenchymal stem cells (BMSCs) were divided into a high-glucose group and a low-glucose group, and osteogenic differentiation was induced. Alkaline phosphatase (ALP) staining and Alizarin Red staining were used for pathological analysis of the cells. Western blot analysis was used to measure GSK-3β, β-catenin, p-β-catenin, c-Myc, and CyclinD1 expression. Immunofluorescence (IF) was used to analyze the effect of GSK-3β inhibitor (CHIR99021) on β-catenin and CyclinD1 expressions levels in BMSCs. A total of 428 differentially expressed miRNAs were found between the NOR and MOD groups. KEGG analysis showed that the target genes were mostly enriched in signaling pathways, including PI3K-Akt, focal adhesion, AGE-RAGE, HIF-1, and Wnt. qPCR verification demonstrated that miR-124-3p exhibited the greatest difference in expression level. In BMSCs, miR-124-3p overexpression could reverse the inhibited expression of BMSC osteogenic markers, including Alpl, Bglap, and Runx2, induced by high glucose. Western blot analysis revealed that the transfection of miR-124-3p mimics could further reverse the upregulated p-β-catenin and GSK-3β levels and the downregulated c-Myc and CyclinD1 levels induced by high glucose. IF results revealed that BMSCs treated CHIR99021 under high glucose showed the reduced GSK-3β and increased β-catenin and CyclinD1 expression levels. Our research highlighted miRNAs' important roles in regulating the Wnt pathway and provided new information for the diagnosis and treatment of diabetic osteoporosis.

Targeting Oxidative Stress Reduction and Inhibition of HDAC1, MECP2, and NF-kB Pathways in Rats With Experimentally Induced Hyperglycemia by Administration of Thymus marshallianus Willd. Extracts

The effects of two lyophilized extracts obtained from the aerial parts of Thymus marschallianus Willd. and harvested from wild flora (TMW) and obtained from culture (TMC) were evaluated in Wistar rats with experimentally induced hyperglycemia. The hyperglycemia was induced by streptozotocin (STZ) administration and the obtained results were evaluated in comparison for TMW and TMC. The polyphenolic composition of extracts was evaluated by spectrophotometrical and LC-MS methods. In vitro antioxidant capacity assays (DPPH, FRAP, EPR) were performed in order to preliminary establish the ability of tested samples to protect against free radical induced damage. Afterwards, the effects of these extracts were assessed in vivo on rats with experimental-induced hyperglycemia. Oxidative stress biomarkers (e.g. malondialdehyde-MDA), phosphorylated transcription factor subunit of nuclear kappaB (NF-kB) p65, methyl CpG binding protein (MECP) 2 and histone deacetylase 1 (HDAC1) expressions in hippocampus and frontal lobe were assessed. Open Field Test (OFT) and Elevated Plus Maze (EPM) were conducted on tested animals. Malondialdehyde (MDA) levels and HDAC1and MeCP2 expressions increased significantly in hippocampus (p<0.05) and frontal lobe (p<0.001) of diabetes group compared to the control group in parallel with decreasing of GSH/GSSG ratio. TMW and TMC administration reduced blood glucose levels and diminished lipid peroxidation, HDAC1 expression and enhanced antioxidant capacity in frontal lobe. TMW improved central locomotion of rats, increased phospho-NFkB p65 and diminished MECP2 expressions in hippocampus. Both tested samples exerted a beneficial effect by increasing the antioxidant defense. Our findings indicate that the administration of these extracts might represent a good option in the treatment of diabetes and its complications.

Biological properties of bone marrow stem cells and adipose-derived stem cells derived from T2DM rats: a comparative study

Background

Patients with type 2 diabetes mellitus (T2DM), especially those with poor glycemic control, are characterized by low bone mass and destruction of bone microstructure. Nowadays, autologous mesenchymal stem cells (auto-MSCs) have been used to repair defects and promote tissue regeneration due to handy source, low immunogenicity and self-renewing and multi-differentiating potential. However, T2DM changed the biological properties of auto-MSCs, and investigating the most suitable auto-MSCs for T2DM patients becomes a focus in tissue engineering.

Results

In this research, we compared the biological characteristics of adipose-derived stem cells (ASCs) and bone marrow stem cells (BMSCs) derived from T2DM rats. These results demonstrated that ASCs had a higher proliferation rate, colony-formation and cell-sheet forming ability, while BMSCs got better osteogenesis-related staining, expression of osteogenesis-related genes and proteins, and osteogenic capacity in vitro.

Conclusions

As it turned out, ASCs from T2DM had a higher proliferation, while BMSCs had significantly higher osteogenetic ability no matter in vitro and in vivo. Therefore, we should take into account the specific and dominated properties of MSC according to different needs to optimize the protocols and improve clinical outcomes for tissue regeneration of T2DM patients.

Protective role of Convolvulus pluricaulis on lipid abnormalities in high-fat diet with low dose streptozotocin-induced experimental rat model

BACKGROUND

The methanolic extract of Convolvulus pluricaulis had earlier shown lipid lowering activity in Triton induced reversible hyperlipidemia model, but, the hypolipidemic activity in irreversible models and hypoglycaemic activity are not investigated so far.

OBJECTIVE

This study was designed to validate the lipid and glucose-lowering actions of C. pluricaulis methanolic extract (CPME) by using ingredients from the Indian diet for induction of hyperlipidemia and diabetes on experimental rats.

MATERIALS AND METHODS

Experimental animals were divided into four groups having six animals in each group (n = 6). Animals of Group I II, III and IV received - no treatment, 0.9% NaCl, Glipizide (GPZ) 5 mg/kg and CPME 400 mg/kg once daily for two weeks respectively. Animals of all groups except group I were fed a high fat-based Indian diet for 21 days followed by a single STZ (35 mg/kg) i.p. administration in model induction phase. Afterwards, animals were sacrificed, and the pancreas was dissected for histological changes, and blood was collected for measuring lipid parameters, FBS, insulin levels, and HOMA scores.

RESULTS

CPME significantly ameliorate the lipid abnormalities in HFD-STZ-treated experimental model (p < 0.001) but fails to reverse the hyperglycaemia developed in diabetic rats with no protective effect on islet architecture (p > 0.05) as compared to experimental group while, GPZ showed protective effect on both lipid abnormalities and hyperglycemia by modulating the levels of lipid parameters and insulin respectively.

CONCLUSION

In conclusion, the study confirm that CPME possesses significant hypolipidemic activity but fails to reverse the hyperglycaemia developed in diabetic rats.

Influence of nano-hydroxyapatite coating implants on gene expression of osteogenic markers and micro-CT parameters. An in vivo study in diabetic rats

This study evaluated the response of a nano-hydroxyapatite coating implant through gene expression analysis (runt-related transcription factor 2 (Runx2), alkaline phosphatase (Alp), osteopontin (Opn), osteocalcin (Oc), receptor activator of nuclear factor-kappa B (Rank), receptor activator of nuclear factor-kappa B ligand (Rank-L), and osteoprotegerin (Opg)). Three-dimensional evaluation (percent bone volume (BV/TV); percent intersection surface (BIC); bone surface/volume ratio (BS/BV); and total porosity (To.Po)) were also analyzed. Mini implants were surgically placed in tibias of both healthy and diabetic rats. The animals were euthanized at 7 and 30 days. Evaluating all factors the relative expression of Rank showed that NANO surface presented the best results at 7 days (diabetic rats). Furthermore the levels of Runx2, Alp, Oc, and Opn suggest an increase in osteoblasts proliferation, especially in early stages of osseointegration. %BIC in healthy and diabetic (7 days) depicted statistically significant differences for NANO group. BV/TV, BS/BV and To.Po demonstrated higher values for NANO group in all evaluated time point and irrespective of systemic condition, but BS/BV 30 days (healthy rat) and 7 and 30 days (diabetic rat). Microtomographic and gene expression analyses have shown the benefits of nano-hydroxyapatite coated implants in promoting new bone formation in diabetic rats.

Anti-hyperglycemic activity of myricetin, through inhibition of DPP-4 and enhanced GLP-1 levels, is attenuated by co-ingestion with lectin-rich protein

Dipeptidyl peptidase-4 (DPP-4) is a proteolytic enzyme responsible for the rapid degradation of Glucagon-like peptide 1 (GLP-1) that is required for the secretion of insulin. DPP-4 also influences activation of node like receptor family, pyrin domain containing 3 (NLRP3) inflammasome under diabetic conditions. Although several polyphenols are reported for various bioactivities, they are consumed as part of the food matrix and not in isolation. Horsegram (Macrotyloma uniflorum) is a rich source of myricetin (Myr) (35 μg/g flour), reported for its anti-hyperglycemic effect. In this investigation, we aimed to study the effect of Myr, singly, and in the presence of co-nutrient horsegram protein (HP) on DPP-4 activity and its consequential impact on GLP-1, insulin, and NLRP3 inflammasome in high-fat diet and single low dose streptozotocin (STZ)-induced diabetic male Wistar rats. In diabetic control (DC), the activity of DPP-4 and its expression were higher compared to treated groups. The consequential decrease in the circulating GLP-1 levels in the DC group, but not treated groups, further indicated the effectiveness of our test molecules under diabetic conditions. Specifically, Myr decreased DPP-4 activity and its expression levels with enhanced circulating GLP-1 and insulin levels. Myr administration also resulted in a lessening of diabetes-induced NLRP3 inflammasome activation and enhanced antioxidant enzyme activities. HP also proved to be efficient in reducing elevated blood glucose levels and enhancing antioxidant enzyme activities. However, Myr, in the presence of HP as a co-nutrient, had diminished capacity to inhibit DPP-4 and, consequently, reduced potential in ameliorating diabetic conditions. Myr proved to be a potent inhibitor of DPP-4 in vitro and in vivo, resulting in enhanced circulating GLP-1 and insulin levels, thereby improving diabetic conditions. Though Myr and HP, individually ameliorate diabetic conditions, their dietary combination had reduced efficiency.

Anti‑glycolipid disorder effect of epigallocatechin‑3‑gallate on high‑fat diet and STZ‑induced T2DM in mice

Epigallocatechin-3-gallate (EGCG) is beneficial for inhibiting dyslipidemia and reducing hyperlipidemic risk. The purpose of the present study was to investigate the glycolipid regulatory effects and potential mechanisms of EGCG in a high-fat diet and streptozotocin-induced type 2 diabetes mellitus (T2DM) mouse model. The results demonstrated that EGCG can decrease blood glucose levels and increase insulin resistance in T2DM mice. In addition, EGCG can regulate serum lipid levels, including those of total cholesterol, triglyceride and low-density lipoprotein receptor (LDL-r), and reduce lipid deposition in vascular endothelial cells in a dose-dependent manner. In addition, the gene and protein expression of related scavenger receptors, including cluster of differentiation 36, sterol regulatory element binding protein 2 (SREBP), SREBP cleavage-activating protein and LDL-r, were downregulated in a dose-dependent manner. The present study noted that EGCG possesses potential as a natural product for preventing and treating metabolic hyperlipidemia syndrome, probably by reducing the blood lipid levels, alleviating vascular endothelial cell damage, maintaining normal lipid metabolism in blood vessels and ameliorating glycolipid disorders.

Hypermethylation in Calca Promoter Inhibited ASC Osteogenic Differentiation in Rats with Type 2 Diabetic Mellitus

The abnormal environment of type 2 diabetes mellitus (T2DM) leads to a substantial decrease in osteogenic function of stem cells. However, the gene sequence does not vary before and after disease for the patient. This phenomenon may be related to changes in osteogenesis-related gene expression caused by DNA methylation. In this study, we established T2DM models to extract adipose-derived stem cells (ASCs) for different gene identifications through DNA methylation sequencing. Specific fragments of methylation changes in the target gene (Calca) were identified by IGV analysis. CGRP was applied to compare the effects on ASCs-T2DM morphology via phalloidin staining, proliferation through CCK-8 assay, and osteogenic differentiation with osteogenic staining, qPCR, and repair of calvarial defect. Furthermore, 5-azacytidine (5-az) was used to intervene ASCs-T2DM to verify the relationship between the methylation level of the target fragment and expression of Calca. We found that the DNA methylation level of target fragment of Calca in ASCs-T2DM was higher than that in ASCs-C. CGRP intervention showed that it did not change the morphology of ASCs-T2DM but could improve proliferation within a certain range. Meanwhile, it could significantly enhance the formation of ALP and calcium nodules in ASCs-T2DM, increase the expression of osteogenesis-related genes in vitro, and promote the healing of calvarial defects of T2DM rat in a concentration-dependent manner. 5-az intervention indicated that the reduction of the methylation level in Calca target fragment of ASCs-T2DM indeed escalated the gene expression, which may be related to DNMT1. Taken together, the environment of T2DM could upregulate the methylation level in the promoter region of Calca and then decrease the Calca expression. The coding product of Calca revealed a promoting role for osteogenic differentiation of ASCs-T2DM. This result provides an implication for us to understand the mechanism of the decreased osteogenic ability of ASCs-T2DM and improve its osteogenic capacity.

Trifolium pratense (Red Clover) Improve SIRT1 Expression and Glycogen Content in High Fat Diet-Streptozotocin Induced Type 2 Diabetes in Rats

Flowering tops of Trifolium pratense L. (Fabaceae) are known for its traditional medicinal values. In present study, our aim was to investigate effect of standardized aqueous extract of flowering tops of Trifolium pratense L. on insulin resistance and SIRT1 expression in type 2 diabetic rats. Type 2 diabetes was induced by feeding high fat diet and administering low dose of streptozotocin. Diabetic animals were treated with standardized aqueous extract at three different doses. Parameters such as blood glucose, lipid profile, glycohemoglobin, insulin sensitivity, HOMA-IR and liver glycogen content were measured. Changes in morphology and expression of SIRT1 in pancreatic tissue were measured in histopathological and immunohistological studies. Aqueous extract treatment showed reduction in hyperglycemia and improved insulin sensitivity. Extract treatment also showed reduction in formation of glycated hemoglobin and improved liver glycogen level. Histopathological study revealed protecting effect of extract in pancreatic tissue against hyperglycemia induced damage. Treatment increased expression of SIRT1 in rat pancreatic tissue. Results indicate that the aqueous extract of Trifolium pratense had beneficial role in improving insulin sensitivity and SIRT1 expression.

Swim training affects bone canonical Wnt pathway in type 2 diabetes induced by high fat diet and low dose of streptozotocin in male rats

Objective: Susceptibility to diabetes-induced bone complication has been linked to Wnt signaling, which plays an important role in bone development and remodeling. In this study, the effect of swim training on Wnt pathway in T2DM was investigated. Materials and methods: Forty male rats were assigned to groups: control (C), diabetic (D), exercised control (E) and diabetic exercised (DE). One week after the induction of diabetes, animals were subjected to swim. At the end of training, bone gene and protein levels of SOST, RUNX2 and RANKL/OPG ratio were measured. Results: Diabetes could significantly increase bone sclerostin expression levels, while decreased RUNX2 mRNA and protein. Bone RANKL/OPG ratio was significantly lower in diabetic rats compared to control group. Swim training significantly increased this ratio in DE compared to D group. Conclusion: Swim training could partially compensate the diabetes-associated changes of Wnt pathway possibly by moderating sclerostin or blood sugar.

Teriparatide Improves Bone and Lipid Metabolism in a Male Rat Model of Type 2 Diabetes Mellitus

Osteoporosis is a complication of diabetes mellitus (DM). The pathology of diabetic osteoporosis is distinct from postmenopausal osteoporosis, and there are no specific treatment guidelines for diabetic osteoporosis. In the current study, this issue was addressed by evaluating the effect of osteoporosis medications, such as the anabolic agent PTH [teriparatide (TPTD)] and the antiresorptive agents calcitonin [elcatonin (ECT)] and bisphosphonate [risedronate (RIS)], on bone metabolism as well as on glucose and lipid metabolism in spontaneously diabetic Torii (SDT) fatty rats, which are a model of type 2 DM (T2DM). The medicines were injected subcutaneously into 8-week-old male SDT fatty rats three times weekly for 8 weeks. TPTD treatment in SDT fatty rats increased the osteoblast number and function on trabecular bone in vertebrae, and increased the trabecular bone mass, bone mineral density (BMD), and mechanical strength of vertebrae. Additionally, TPTD improved cortical bone structure and increased BMD. RIS decreased the osteoclast number and function, which led to an increase in vertebral bone mineral content and BMD in the femoral diaphysis, and mechanical strength was increased in the vertebrae. ECT showed no clear effects on bone mass or metabolism. Similar to diabetic lesions, all of the drugs had no effects on hyperglycemia, pancreas morphology, or serum insulin and glucagon levels. However, triglyceride levels and lipid droplets in fatty liver were decreased in the TPTD group. These results suggest that TPTD may be useful for treating fatty liver in addition to osteoporosis in T2DM.

Cinaciguat in combination with insulin induces a favorable effect on implant osseointegration in type 2 diabetic rats

The osseointegration process of implant is seriously impaired in type 2 diabetes mellitus (T2DM) that causes high failure rate, and insufficiency exists in current insulin therapy, creating a demand for new bone-synergistic agent. Cinaciguat, a novel type of soluble guanylate cyclase (sGC) activator, plays a vital role in glucose metabolism, inflammation control and bone regeneration. We hypothesized that the combined application of cinaciguat and insulin could reverse poor implant osseointegration in diabetes. To test this hypothesis, streptozotocin-induced diabetic rats were placed implants in the femur, and divided into five groups: control, T2DM, cinaciguat-treated T2DM (7 μg/kg), insulin-treated T2DM (12 IU/kg), cinaciguat plus insulin combination-treated T2DM (7 μg/kg and 12 IU/kg respectively), according to different treatment received. The weight and glucose levels of rats were evaluated at fixed times, and plasma level of cyclic guanosine monophosphate (cGMP) was determined before euthanasia. Three months after therapy, the femurs were isolated for pull-out test, environmental scanning electron microscope observation, microscopic computerized tomography evaluation and various histology analysis. Results revealed that diabetic rats showed the highest blood glucose level and lowest cGMP content, which led to the worst structural damage and least osseointegration. Combined treatment could attenuate the diabetes induced hyperglycemia to be normal, restore the cGMP content, protein kinase G II (PKG II) expression, phosphodiesterase-5 (PDE5) activity and ameliorate the mechanical strength, the impaired bone microarchitecture and osseointegration to the highest level. Meanwhile, monotreatment (insulin or cinaciguat) also showed restorative effect, but less. Our findings demonstrated that the cGMP/PKG II signaling pathway activated by cinaciguat mediated the favorable effects of the combined application on improving implant fixation under T2DM condition.

Changes in the levels of 12/15-lipoxygenase, apoptosis-related proteins and inflammatory factors in the cortex of diabetic rats and the neuroprotection of baicalein

This study was designed to investigate the neuroprotective effects of baicalein and the effect of the cortical 12/15-lipoxygenase (12/15-LOX) pathway on diabetic cognitive dysfunction. Our results showed that spatial learning and memory ability, as well as cortex neurons, were significantly impaired after the onset of diabetes. The fasting blood glucose and random blood glucose levels in the model group were significantly higher than those in the normal group. The levels of TG and TC in the plasma of the model group were significantly increased, but there was no significant difference in the LDL level. The insulin content in the plasma of diabetic rats was significantly lower than that of the normal group. The levels of inflammatory factors and 12(S)-HETE were significantly increased in diabetic rats, as were the protein expression levels of cPLA2, 12/15-LOX, p38MAPK, phospho-p38MAPK, caspase-3, caspase-9 and Aβ_1-42; by contrast, protein expression of Bcl-2 was significantly decreased. Administration of baicalein was shown to improve the spatial learning and memory ability and significantly decrease the levels of inflammatory cytokines. However, baicalein did not significantly influence the levels of blood glucose, lipids or insulin in rats. Baicalein treatment significantly protected diabetes rats from neuron death; significantly attenuated the overexpression of cPLA2, 12/15-LOX, p38MAPK, phospho-p38MAPK, caspase-3, caspase-9 and Aβ_1-42; and upregulated the expression of Bcl-2. These findings suggest that baicalein improves the cognitive function of diabetic rats by directly acting in the brain rather than by regulating the levels of blood glucose, lipids or insulin. In addition, baicalein can protect rat cortical neurons from damage caused by diabetes via inhibiting the 12/15-LOX pathway and relieving inflammation and apoptosis of the central nervous system.

Type 2 diabetes is associated with suppression of autophagy and lipid accumulation in β-cells

Both type 2 diabetes (T2D) and obesity are characterized by excessive hyperlipidaemia and subsequent lipid droplet (LD) accumulation in adipose tissue. To investigate whether LDs also accumulate in β-cells of T2D patients, we assessed the expression of PLIN2, a LD-associated protein, in non-diabetic (ND) and T2D pancreata. We observed an up-regulation of PLIN2 mRNA and protein in β-cells of T2D patients, along with significant changes in the expression of lipid metabolism, apoptosis and oxidative stress genes. The increased LD buildup in T2D β-cells was accompanied by inhibition of nuclear translocation of TFEB, a master regulator of autophagy and by down-regulation of lysosomal biomarker LAMP2. To investigate whether LD accumulation and autophagy were influenced by diabetic conditions, we used rat INS-1 cells to model the effects of hyperglycaemia and hyperlipidaemia on autophagy and metabolic gene expression. Consistent with human tissue, both LD formation and PLIN2 expression were enhanced in INS-1 cells under hyperglycaemia, whereas TFEB activation and autophagy gene expression were significantly reduced. Collectively, these results suggest that lipid clearance and overall homeostasis is markedly disrupted in β-cells under hyperglycaemic conditions and interventions ameliorating lipid clearance could be beneficial in reducing functional impairments in islets caused by glucolipotoxicity.