S-9-PAHSA's neuroprotective effect mediated by CAIII suppresses apoptosis and oxidative stress in a mouse model of type 2 diabetes.

BACKGROUND: With the rapidly increasing prevalence of metabolic diseases such as type 2 diabetes mellitus (T2DM), neuronal complications associated with these diseases have resulted in significant burdens on healthcare systems. Meanwhile, effective therapies have remained insufficient. A novel fatty acid called S-9-PAHSA has been reported to provide metabolic benefits in T2DM by regulating glucose metabolism. However, whether S-9-PAHSA has a neuroprotective effect in mouse models of T2DM remains unclear. METHODS: This in vivo study in mice fed a high-fat diet (HFD) for 5 months used fasting blood glucose, glucose tolerance, and insulin tolerance tests to examine the effect of S-9-PAHSA on glucose metabolism. The Morris water maze test was also used to assess the impact of S-9-PAHSA on cognition in the mice, while the neuroprotective effect of S-9-PAHSA was evaluated by measuring the expression of proteins related to apoptosis and oxidative stress. In addition, an in vitro study in PC12 cells assessed apoptosis, oxidative stress, and mitochondrial membrane potential with or without CAIII knockdown to determine the role of CAIII in the neuroprotective effect of S-9-PAHSA. RESULTS: S-9-PAHSA reduced fasting blood glucose levels significantly, increased insulin sensitivity in the HFD mice and also suppressed apoptosis and oxidative stress in the cortex of the mice and PC12 cells in a diabetic setting. By suppressing oxidative stress and apoptosis, S-9-PAHSA protected both neuronal cells and microvascular endothelial cells in in vivo and in vitro diabetic environments. Interestingly, this protective effect of S-9-PAHSA was reduced significantly when CAIII was knocked down in the PC12 cells, suggesting that CAIII has a major role in the neuroprotective effect of S-9-PAHSA. However, overexpression of CAIII did not significantly enhance the protective effect of S-9-PAHSA. CONCLUSION: S-9-PAHSA mediated by CAIII has the potential to exert a neuroprotective effect by suppressing apoptosis and oxidative stress in neuronal cells exposed to diabetic conditions. Furthermore, S-9-PAHSA has the capability to reduce fasting blood glucose and LDL levels and enhance insulin sensitivity in mice fed with HFD.

Hydrothermal Growth of an Al-Doped α-Ga2O3 Nanorod Array and Its Application in Self-Powered Solar-Blind UV Photodetection Based on a Photoelectrochemical Cell.

Herein, we successfully fabricated an Al-doped α-Ga2O3 nanorod array on FTO using the hydrothermal and post-annealing processes. To the best of our knowledge, it is the first time that an Al-doped α-Ga2O3 nanorod array on FTO has been realized via a much simpler and cheaper way than that based on metal-organic chemical vapor deposition, magnetron sputtering, molecular beam epitaxy, and pulsed laser deposition. And, a self-powered Al-doped α-Ga2O3 nanorod array/FTO photodetector was also realized as a photoanode at 0 V (vs. Ag/AgCl) in a photoelectrochemical (PEC) cell, showing a peak responsivity of 1.46 mA/W at 260 nm. The response speed of the Al-doped device was 0.421 s for rise time, and 0.139 s for decay time under solar-blind UV (260 nm) illumination. Compared with the undoped device, the responsivity of the Al-doped device was ~5.84 times larger, and the response speed was relatively faster. When increasing the biases from 0 V to 1 V, the responsivity, quantum efficiency, and detectivity of the Al-doped device were enhanced from 1.46 mA/W to 2.02 mA/W, from ~0.7% to ~0.96%, and from ~6 × 109 Jones to ~1 × 1010 Jones, respectively, due to the enlarged depletion region. Therefore, Al doping may provide a route to enhance the self-powered photodetection performance of α-Ga2O3 nanorod arrays.

Wet-chemistry synthesis of two-dimensional Pt- and Pd-based intermetallic electrocatalysts for fuel cells.

Two-dimensional (2D) noble-metal-based nanomaterials have attracted tremendous attention and have widespread promising applications as a result of their unique physical, chemical, and electronic properties. Especially, 2D Pt- and Pd-based intermetallic nanoplates (IMNPs) and nanosheets (IMNSs) are widely studied for fuel cell (FC)-related reactions, including the cathodic oxygen reduction reaction (ORR) and anodic formic acid, methanol and ethanol oxidation reactions (FAOR, MOR and EOR). Wet-chemistry synthesis is a powerful strategy to prepare metallic nanocrystals with well-controlled dispersity, size, and composition. In this review, a fundamental understanding of the FC-related reactions is firstly elaborated. Subsequently, the current wet-chemistry synthesis pathways for 2D Pt- and Pd-based IMNPs and IMNSs are briefly summarized, as well as their electrocatalytic applications including in the ORR, FAOR, MOR, and EOR. Finally, we provide an overview of the opportunities and current challenges and give our perspectives on the development of high-performance 2D Pt- and Pd-based intermetallic electrocatalysts towards FCs. We hope this review offers timely information on the synthesis of 2D Pt- and Pd-based IMNPs and IMNSs and provides guidance for the efficient synthesis and application of them.

Intermetallic Nanocrystals: Seed-Mediated Synthesis and Applications in Electrocatalytic Reduction Reactions.

In recent years, intermetallic nanocrystals (IMNCs) have attracted extensive attention in the field of electrocatalysis. However, precise control over the size, shape, composition, structure, and exposed crystal facet of IMNCs seems to be a challenge to the traditional method of high-temperature annealing although these parameters have a significant effect on the electrocatalytic performance. Controllable synthesis of IMNCs by the wet chemistry method in the liquid phase shows great potential compared with the traditional high-temperature annealing method. In this Review, we attempt to summarize the preparation of IMNCs by the seed-mediated synthesis in the liquid phase, as well as their applications in electrocatalytic reduction reactions. Several representative examples are purposely selected for highlighting the huge potential of the seed-mediated synthesis approach in chemical synthesis. Specifically, we personally perceive the seed-mediated synthesis approach as a promising tool in the future for precise control over the size, shape, composition, structure, and exposed crystal facet of IMNCs.

High glucose and palmitic acid induces neuronal senescence by NRSF/REST elevation and the subsequent mTOR-related autophagy suppression.

Cell senescence is a basic aging mechanism. Previous studies have found that the cellular senescence in adipose tissue and other tissues, such as the pancreas, muscle and liver, is associated with the pathogenesis and progression of type 2 diabetes; however, strong evidence of whether diabetes directly causes neuronal senescence in the brain is still lacking. In this study, we constructed a high glucose and palmitic acid (HGP) environment on PC12 neuronal cells and primary mouse cortical neurons to simulate diabetes. Our results showed that after HGP exposure, neurons exhibited obvious senescence-like phenotypes, including increased NRSF/REST level, mTOR activation and cell autophagy suppression. Downregulation of NRSF/REST could remarkably alleviate p16, p21 and γH2A.X upregulations induced by HGP treatment, and enhance mTOR-autophagy of neurons. Our results suggested that the diabetic condition could directly induce neuronal senescence, which is mediated by the upregulation of NRSF/REST and subsequent reduction of mTOR-autophagy.

Knockdown of NRSF Alleviates Ischemic Brain Injury and Microvasculature Defects in Diabetic MCAO Mice.

Diabetes is one of the well-established risk factors of stroke and is associated with a poor outcome in patients with stroke. Previous studies have shown that the expression of neuron restrictive silencer factor (NRSF) is elevated in diabetes as well as ischemic stroke. However, the role of NRSF in regulating an outcome of diabetic ischemic stroke has not been completely understood. Here, we hypothesized that diabetes-induced NRSF elevation can aggravate brain injury and cognition impairment in ischemic stroke. The diabetic ischemic stroke mice model was established by 8 weeks of high-fat-diet feeding and 5 days of streptozotocin injection followed by 30 min of middle cerebral artery occlusion (MCAO). We found that diabetes enhanced the MCAO-induced elevation of NRSF in the hippocampus in accompany with an elevation of its corepressors, HDAC1, and mSin3A, and decrease of ß-TrCP. By using histological/immunofluorescence staining and neurobehavioral testing, our results showed that the brain damage and learning/memory impairment were aggravated in diabetic ischemic mice but significantly attenuated after stereotaxic injection of NRSF-shRNA. Meanwhile, by performing whole-brain clearing with PEGASOS, microvascular reconstruction, western blotting, and ELISA, we found that NRSF-shRNA markedly alleviated the vasculature disorders and rescued the suppression of NRP-1, VEGF, and VEGFR2 in the hippocampus of diabetic ischemic mice. Therefore, our results demonstrated for the first time that the elevation of hippocampal NRSF plays an important role in alleviating brain injury and cognitive disabilities in diabetic ischemic mice, potentially via the reduction of NRP-1/VEGF signaling.

9-PAHSA Improves Cardiovascular Complications by Promoting Autophagic Flux and Reducing Myocardial Hypertrophy in Db/Db Mice.

Atherosclerotic cardiovascular disease is a common and severe complication of diabetes. There is a large need to identify the effective and safety strategies on diabetic cardiovascular disease (DCVD). 9-PAHSA is a novel endogenous fatty acid, and has been reported to reduce blood glucose levels and attenuate inflammation. We aim to evaluate the effects of 9-PAHSA on DCVD and investigate the possible mechanisms underlying it. Firstly, serum 9-PAHSA levels in human were detected by HPLC-MS/MS analysis. Then 9-PAHSA was synthesized and purified. The synthesized 9-PAHSA was gavaged to db/db mice with 50 mg/kg for 4 weeks. The carotid arterial plaque and cardiac structure was assessed by ultrasound. Cardiac autophagy was tested by western blot analysis, electron microscope and iTRAQ. The results showed that 9-PAHSA, in patients with type 2 diabetes mellitus (T2DM), was significantly lower than that in non-diabetic subjects. Administration of 9-PAHSA for 2 weeks reduced blood glucose levels. Ultrasound observed that continue administration of 9-PAHSA for 4 weeks ameliorated carotid vascular calcification, and attenuated myocardial hypertrophy and dysfunction in db/db mice. Electron microscopy showed continue 9-PAHSA treatment significantly increased autolysosomes, while dramatically decreased greases in the myocardial cells of the db/db mice. Moreover, iTRAQ analysis exhibited that continue 9-PAHSA treatment upregulated BAG3 and HSPB8. Furthermore, western blot analysis confirmed that 9-PAHSA down-regulated Akt/mTOR and activated PI3KIII/BECN1 complex in diabetic myocardium. Thus, 9-PAHSA benefits DCVD in diabetic mice by ameliorating carotid vascular calcification, promoting autophagic flux and reducing myocardial hypertrophy.

The role of carbonic anhydrase III and autophagy in type 2 diabetes with cardio-cerebrovascular disease.

Type 2 diabetes mellitus (T2DM) is one of the most common chronic diseases among the elderly people. The T2DM increases the risk of cardio-cerebrovascular disease (CCD), and the main pathological change of the CCD is atherosclerosis (AS). Meanwhile, the carbonic anhydrases (CAs) are involved in the formation and progression of plaques in AS. However, the exact physiological mechanism of carbonic anhydrase III (CAIII) has not been clear yet, and there are also no correlation study between CAIII protein and T2DM with CCD. The 8-week old diabetic mice (db/db-/- mice) and wild-type mice (wt mice) were feed by a normal diet till 32 weeks, and detected the carotid artery vascular opening angle using the method of biomechanics; The changes of cerebral cortex and myocardium were watched by the ultrastructure, and the autophagy were observed by electron microscope; The tissue structure, inflammation and cell injury were observed by Hematoxylin and eosin (HE) staining; The apoptosis of cells were observed by TUNEL staining; The protein levels of CAIII, IL-17, p53 were detected by immunohistochemical and Western Blot, and the Beclin-1, LC3, NF-κB were detected by Western Blot. All statistical analysis is performed using PRISM software. Compared with wt mice, db/db-/- mice' carotid artery open angle increased significantly. Electron microscope results indicated that autophagy in db/db-/- mice cerebral cortex and heart tissue decreased and intracellular organelle ultrastructure were damaged. HE staining indicated that, db/db-/- mice' cerebral cortex and heart tissue stained lighter, inflammatory cells infiltration, cell edema were obvious, myocardial fibers were disorder, and myocardial cells showed different degrees of degeneration. Compared with wt mice, TUNEL staining showed that there was obviously increase in db/db-/- mice cortex and heart tissue cell apoptosis. The results of immunohistochemistry and Western Blot indicated that CAIII, Beclin-1 and LC3II/I expression levels conspicuously decreased in cortex and heart tissue of db/db-/- mice, and the expression level of IL-17, NF-κB and p53 obviously increased. The carotid artery' vascular stiffness was increased and which was probably related with formation of AS in diabetic mice. And the autophagy participated in the occurrence and development of diabetic CCD. CAIII protein might somehow be involved in the regulation of autophagy probably through affecting cell apoptosis and inflammation, but the underlying mechanism remains to be further studied.

Hemp (Cannabis sativa L.) Seed Protein-EGCG Conjugates: Covalent Bonding and Functional Research.

In order to make HPI have a wide application prospect in the food industry, we used EGCG to modify HPI. In this study, we prepared different concentrations (1, 2, 3, 4, and 5 mM) of (-)-epigallocatechin gallate (EGCG) covalently linked to HPI and use methods such as particle size analysis, circular dichroism (CD), and three-dimensional fluorescence spectroscopy to study the changes in the structure and functional properties of HPI after being covalently combined with EGCG. The particle size data indicated that the covalent HPI-EGCG complex was larger than native HPI, and the particle size was mainly distributed at about 200 µm. CD and three-dimensional fluorescence spectroscopy analyses showed that the conformation of the protein was changed by conjugation with EGCG. The ß-sheet content decreased from 82.79% to 66.67% after EGCG bound to the protein, and the hydrophobic groups inside the protein were exposed, which increased the hydrophobicity of the protein and changed its conformation. After HPI and 1 mM of EGCG were covalently bonded, the solubility and emulsifying properties of the covalent complex were improved compared with native HPI. These results indicated that HPI-EGCG conjugates can be added in some foods.

Serum Heparanase: A New Clinical Biomarker Involved in Senile Metabolic Inflammatory Syndrome.

AIM: Metabolic inflammation syndrome (MIS) can lead to a series of complications, but its exact inflammatory mechanism is still unclear. The aim of this study was to explore the correlation between heparanase (HPA) and MIS, and the close relationship between HPA and other chronic low-grade inflammation index, such as C-reactive protein (CRP) and interleukin-6 (IL-6). METHODS: A total of 105 patients with MIS in the physical examination population of Huashan Hospital affiliated to Fudan University from May to June 2018 were selected as the MIS group, and 52 patients who were relatively healthy during the same period were used as the control group. The basic clinical data of the selected candidates were collected, the levels of serum HPA, CRP and IL-6 were measured by ELISA, and the levels of blood glucose and blood lipids were also detected. RESULTS: Compared with the control group, the levels of HPA, CRP, IL-6, FBG, HbA1C, and TG of MIS group were all significantly elevated (all P<0.05), and HDL-C levels were considerably reduced (P<0.05). Correlation analysis showed that there was a noticeably positive correlation between serum HPA level and CRP, IL-6 levels (P<0.05). CONCLUSION: Higher HPA levels might play a certain role in the occurrence and development of MIS. There was a certain close correlation between serum HPA level and CRP and IL-6 levels, and which indicated that HPA was involved in the chronic low-grade inflammatory reaction process of MIS.

Template-Directed Rapid Synthesis of Pd-Based Ultrathin Porous Intermetallic Nanosheets for Efficient Oxygen Reduction.

Atomically ordered intermetallic nanoparticles exhibit improved catalytic activity and durability relative to random alloy counterparts. However, conventional methods with time-consuming and high-temperature syntheses only have rudimentary capability in controlling the structure of intermetallic nanoparticles, hindering advances of intermetallic nanocatalysts. We report a template-directed strategy for rapid synthesis of Pd-based (PdM, M=Pb, Sn and Cd) ultrathin porous intermetallic nanosheets (UPINs) with tunable sizes. This strategy uses preformed seeds, which act as the template to control the deposition of foreign atoms and the subsequent interatomic diffusion. Using the oxygen reduction reaction (ORR) as a model reaction, the as-synthesized Pd3 Pb UPINs exhibit superior activity, durability, and methanol tolerance. The favored geometrical structure and interatomic interaction between Pd and Pb in Pd3 Pb UPINs are concluded to account for the enhanced ORR performance.

A novel palmitic acid hydroxy stearic acid (5-PAHSA) plays a neuroprotective role by inhibiting phosphorylation of the m-TOR-ULK1 pathway and regulating autophagy.

AIMS: Type 2 diabetes mellitus (T2DM) can lead to brain dysfunction and a series of neurological complications. Previous research demonstrated that a novel palmitic acid (5-PAHSA) exerts effect on glucose tolerance and chronic inflammation. Autophagy was important in diabetic-related neurodegeneration. The aim of the present study was to investigate whether 5-PAHSA has specific therapeutic effects on neurological dysfunction in diabetics, particularly with regard to autophagy. METHODS: 5-PAHSA was successfully synthesized according to a previously described protocol. We then carried out a series of in vitro and in vivo experiments using PC12 cells under diabetic conditions, and DB/DB mice, respectively. PC12 cells were treated with 5-PAHSA for 24 h, while mice were administered with 5-PAHSA for 30 days. At the end of each experiment, we analyzed glucolipid metabolism, autophagy, apoptosis, oxidative stress, cognition, and a range of inflammatory factors. RESULTS: Although there was no significant improvement in glucose metabolism in mice administered with 5-PAHSA, ox-LDL decreased significantly following the administration of 5-PAHSA in serum of DB/DB mice (p < 0.0001). We also found that the phosphorylation of m-TOR and ULK-1 was suppressed in both PC12 cells and DB/DB mice following the administration of 5-PAHSA (p < 0.05 and p < 0.01), although increased levels of autophagy were only observed in vitro (p < 0.05). Following the administration of 5-PAHSA, the concentration of ROS decreased in PC12 cells and the levels of CRP increased in high-dose group of 5-PAHSA (p < 0.01). There were no significant changes in terms of apoptosis, other inflammatory factors, or cognition in DB/DB mice following the administration of 5-PAHSA. CONCLUSION: We found that 5-PAHSA can enhance autophagy in PC12 cells under diabetic conditions. Our data demonstrated that 5-PAHSA inhibits phosphorylation of the m-TOR-ULK1 pathway and suppressed oxidative stress in PC12 cells, and exerted influence on lipid metabolism in DB/DB mice.

Strain-Stabilized Metastable Face-Centered Tetragonal Gold Overlayer for Efficient CO2 Electroreduction.

Synthesis of the unconventional phase of noble metal nanocrystals may create new opportunities in exploring intriguing physicochemical properties but remains challenging. In the research field of thin film growth, the interface strain offers a general driving force to stabilize the metastable phase of epitaxial film. Herein we extend this concept to the field of noble metal nanocrystals and report the solution synthesis of metastable face-centered tetragonal Au that has not been discovered before. The successful synthesis relies on the formation of intermetallic AuCu3@Au core-shell structure, where the interface strain stabilizes the metastable fct Au overlayer. Compared with the face-centered cubic Au counterpart, the metastable fct Au shows greatly improved catalytic activity toward CO2 reduction to CO. The density functional theory calculations and spectroscopic studies reveal that the metastable fct Au upshifts the d-band center, which lowers the energy barrier of key intermediate COOH* formation and thus facilitates the reaction kinetics.

Corrigendum: 9-PAHSA Improves Cardiovascular Complications by Promoting Autophagic Flux and Reducing Myocardial Hypertrophy in Db/Db Mice.

[This corrects the article DOI: 10.3389/fphar.2021.754387.].

Effect of 9 - PAHSA on cognitive dysfunction in diabetic mice and its possible mechanism.

Diabetes mellitus (DM) is currently a major global health problem, which is associated with the development of cognitive dysfunction. However, although numerous clinical drugs for hyperglycemia have been used at present, safer and more effective therapeutic intervention strategies for diabetic cognitive impairments are still a huge challenge. Recently, several studies have indicated that a novel class of branched palmitic acid esters of hydroxyl stearic acids (PAHSAs) may have anti-diabetes and anti-inflammatory effects in insulin-resistant mice. Herein, whether the 9-PAHSA that one of the PAHSAs can attenuates DM-associated cognitive impairment in a mouse model of type 2 diabetes has been investigated. Our results showed that 9-PAHSA mildly prevented deficits of spatial working memory in Y-maze test while reversed the preference bias toward novel mice in Social choice test. Furthermore, the effect of REST on cognitive impairment of diabetes was explored for the first time. It was found that the expression of REST in diabetic mice increased, and the expression of target protein BDNF (Brain-derived neurotrophic factor) was decreased. After administration of 9-PAHSA, the situation was reversed. In summary, we conclude that exogenous supplement of 9-PAHSA can improve DM-related cognitive impairment to some extent, and the protective effect may be associated with decreased REST/NRSF (repressor element-1 silencing transcription factor/neuron-restrictive silence factor) and upregulated BDNF expression in frontal cortex.

EGb761 improves the cognitive function of elderly db/db-/- diabetic mice by regulating the beclin-1 and NF-κB signaling pathways.

To assess whether EGb761 could protect elderly diabetic mice with cognitive disorders and explore the role of beclin-1-mediated autophagy in these protective effects. Two-month-old male db/db-/- mice and wild-type C57/BL6 mice were randomly divided into six groups: db/db-/- control, db/db-/- 50 mg, db/db-/- 100 mg, wild-type (WT) control, WT 50 mg, and WT 100 mg. EGb761 (50 mg/kg or 100 mg/kg of bodyweight) was given by gavage once a day for 1 month from the age of 6 months. Y-maze and social choice tests were performed at 8th months. The blood pressure was measured. The imaging changes in the brain were measured using magnetic resonance imaging (MRI). The expression and distribution of beclin-1, LC3, and NF-κB were detected using immunohistochemistry staining and western blotting. Ultrastructure alterations in the hippocampus were observed using transmission electron microscopy. Compared with WT mice, the learning ability, memory and overall cognitive function of db/db-/- mice decreased (P < 0.05), and EGb761 could significantly improve the learning and memory function of db/db-/- mice (P < 0.05). EGb761 significantly improved systolic blood pressure in db/db-/- mice (P < 0.01). In addition, fMRI-bold showed a decline in the hippocampus of mice in the db/db-/- group compared with WT. EGb761 could improve these above changes. Immunohistochemistry staining and western blotting confirmed that EGb761 significantly increased beclin-1 and reduced LC3-II/I levels in the brains of db/db-/- mice (P < 0.05). NF-κB levels were obviously higher in the db/db-/- group than that in the WT group, and EGb761 significantly reduced NF-κB levels in db/db-/- mice (P < 0.05). There was a trend of increased autophagosomes in db/db-/- mice, but EGb761 did not change obviously the number of autophagosomes. Compared with normal aged WT mice, aging db/db-/- mice had more common complications of cerebral small vessel disease and cognitive dysfunction. EGb761 could significantly improve the cognitive function of aging db/db-/- mice via a mechanism that may involve the regulation of beclin-1, LC3, and NF-κB.

Elongator promotes the migration and invasion of hepatocellular carcinoma cell by the phosphorylation of AKT.

The Elongator is a complex with multiple subunits (Elp1-Elp6) which promotes transcript elongation and protein translation. In this study, we investigated the effects of Elongator on the migration and invasion of HCC cells as well as the underlying mechanisms. We showed that overexpression of Elp3 or Elp4 promoted the migration and invasion of HCC cells, which was abolished when either Elp3 or Elp4 was silenced. The expression of matrix metalloproteinase-2 (MMP-2) and MMP-9 were enhanced by phosphorylation of AKT. Elongator-driven migration and invasion and the expression of MMP-2 and MMP-9 were reduced in HCC cells treated with AKT inhibitor LY294002. Depletion of Elp3 also reduced the phosphorylation of AKT induced by growth factors. In vivo assay of lung metastasis in mice demonstrated that overexpression of Elp3 increased tumor nodules metastatic to lung. Importantly, Elp3 was up-regulated in human HCC tissues, which was correlated with the phosphorylation of AKT and expression of MMP-2. Collectively, these results suggested that Elongator activated migration and invasion of HCC cells by promoting the expression of MMP-2 and MMP-9 through the PI3K/AKT signaling pathway. Our work suggests that Elongator might be a potential marker which promotes the metastasis of HCC.

Prolonged DADLE exposure epigenetically promotes Bcl-2 expression and elicits neuroprotection in primary rat cortical neurons via the PI3K/Akt/NF-κB pathway.

Both in vivo and in vitro studies have shown the beneficial effects of the delta-opioid receptor (DOR) on neurodegeneration in hypoxia/ischemia. We previously reported that DOR stimulation with [(D-Ala2, D-Leu5) enkephalin] (DADLE), a potent DOR agonist, for both a short (minutes) and long (days) time has notable protective effects against sodium azide (NaN3)-induced cell injury in primary cultured rat cortical neurons. We further demonstrated that short-term DADLE stimulation increased neuronal survival through the PKC-mitochondrial ERK pathway. However, the mechanisms underlying long-term neuroprotection by DADLE remain unclear. Here, we showed that DOR stimulation with DADLE (0.1 µmol/L) for 2 d selectively activates the PI3K/Akt/NF-κB pathway in NaN3-treated neurons; this activation increased Bcl-2 expression, attenuated Cyto c release and promoted neuronal survival. Further investigation revealed that sustained DADLE stimulation increased Bcl-2 expression by enhancing NF-κB binding to the Bcl-2 promoter and upregulating the histone acetylation levels of the Bcl-2 promoter. Our results demonstrate that prolonged DADLE exposure epigenetically promotes Bcl-2 expression and elicits neuroprotective effects in the NaN3 model via the PI3K/Akt/NF-κB pathway.

G-CSF and cognitive dysfunction in elderly diabetic mice with cerebral small vessel disease: Preventive intervention effects and underlying mechanisms.

AIMS: Although cognitive dysfunction is a common neurological complication in elderly patients with diabetes, the mechanisms underlying this relationship remain unclear, and effective preventive interventions have yet to be developed. Thus, this study investigated the preventive effects and mechanisms of action associated with granulocyte colony-stimulating factor (G-CSF) on cognitive dysfunction in elderly diabetic mice with cerebral small vessel disease. METHODS: This study included 40 male db/db diabetic and wild-type (WT) mice that were categorized into the following four groups at the age of 3 weeks: db/db group (DG), db/db+G-CSF group (DGG), WT group (WG), and WT+G-CSF group (WGG). The mice were fed normal diets for 4 months and then given G-CSF (75 µg/kg) via intraperitoneal injections for 1 month. At 7.5 months of age, the cognitive abilities of the mice were assessed with the Y-maze test and the Social Choice Test; body weight, blood pressure (BP), and blood glucose measurements were obtained throughout the study. Brain imaging and blood oxygen level-dependent (BOLD) contrast imaging analyses were performed with a small animal magnetic resonance imaging (MRI) system, autophagosome levels were detected with a transmission electron microscope (TEM), hippocampal neurons were assessed with hematoxylin and eosin (HE) staining, and protein expressions and distributions were evaluated using immunohistochemistry and Western blot analyses. RESULTS: (i) The body weight and blood glucose levels of the DG and DGG mice were significantly higher than those of the WG and WGG mice; (ii) social choice and spatial memory capabilities were significantly reduced in DG mice but were recovered by G-CSF in DGG mice; (iii) the MRI scans revealed multiple lacunar lesions and apparent hippocampal atrophy in the brains of DG mice, but G-CSF reduced the number of lacunar lesions and ameliorated hippocampal atrophy; (iv) the MRI-BOLD scans showed a downward trend in whole-brain activity and reductions in the connectivities of the hippocampus and amygdala with subcortical structures in DG mice, but G-CSF clearly improved the altered brain activity as well as the connectivity of the hippocampus in DGG mice; (v) HE staining revealed fewer neurons in the hippocampus in DG mice; (vi) TEM analyses revealed significantly fewer autophagosomes in the hippocampi of DG mice, but G-CSF did not increase these numbers; (vii) there were significant reductions in mechanistic target of rapamycin (mTOR) and LC3-phosphatidylethanolamine conjugate (LC3)-II/I levels in the hippocampi of DG mice, whereas p62 was upregulated, and G-CSF significantly enhanced the levels of Beclin1, mTOR, and LC-II/I in DGG mice; and (viii) G-CSF significantly reversed increases in nuclear factor κB (NF-κB) protein levels in DG but not in WG mice. CONCLUSIONS: In this study, aged diabetic mice were prone to cognitive dysfunction and cerebral small vessel disease. However, administration of G-CSF significantly improved cognitive function in elderly db/db diabetic mice, and this change was likely related to the regulation of autophagy and NF-κB signaling pathways.