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

Causal Association of Cytokines and Growth Factors with Stroke and Its Subtypes: a Mendelian Randomization Study

Cytokines and growth factors contribute to nerve growth and angiogenesis and are associated with the development of vascular disease. This Mendelian randomization (MR) study was designed to examine the causal relationship between factors associated with stem cell paracrine mechanisms and with stroke and its subtypes. We used pooled statistics on cytokine levels from three studies (INTERIAL, Olink Proseek CVD array, and KORA) encompassing 7795 participants in Europe. Data for stroke and its subtypes were pooled from these European populations (40,585 cases and 406,111 controls) in a multiprogenitor genome-wide association study (GWAS). MR was performed using established analytical methods, including inverse variance weighting (IVW), weighted median (WM), and MR-Egger. Genetically determined high IGF-1 levels were found to associate negatively with risk of stroke, ischemic stroke (large-artery atherosclerosis), and ischemic stroke (cardiogenic embolism). Meanwhile, high IL-13 levels had a positive causal relationship with ischemic stroke (large-artery atherosclerosis). An additional 27 cytokines were found to have a causal association with stroke or its subtypes. However, these results should be interpreted with caution given that the power efficacy was <80%. This MR study supports the concept of a causal relationship of 29 cytokines with stroke or its subtypes. Our genetic analysis provides new insights into stroke prevention and treatment by demonstrating an association of stem cell paracrine-related cytokines with stroke risk.

The Contribution of Type 2 Diabetes to Parkinson's Disease Aetiology

Type 2 diabetes (T2D) and Parkinson's disease (PD) are chronic disorders that have a significant health impact on a global scale. Epidemiological, preclinical, and clinical research underpins the assumption that insulin resistance and chronic inflammation contribute to the overlapping aetiologies of T2D and PD. This narrative review summarises the recent evidence on the contribution of T2D to the initiation and progression of PD brain pathology. It also briefly discusses the rationale and potential of alternative pharmacological interventions for PD treatment.

Artemisinin ameliorates cognitive decline by inhibiting hippocampal neuronal ferroptosis via Nrf2 activation in T2DM mice

BACKGROUND

Neuronal ferroptosis plays a critical role in the pathogenesis of cognitive deficits. The present study explored whether artemisinin protected type 2 diabetes mellitus (T2DM) mice from cognitive impairments by attenuating neuronal ferroptosis in the hippocampal CA1 region.

METHODS

STZ-induced T2DM mice were treated with artemisinin (40 mg/kg, i.p.), or cotreated with artemisinin and Nrf2 inhibitor MEL385 or ferroptosis inducer erastin for 4 weeks. Cognitive performance was determined by the Morris water maze and Y maze tests. Hippocampal ROS, MDA, GSH, and Fe2+ contents were detected by assay kits. Nrf2, p-Nrf2, HO-1, and GPX4 proteins in hippocampal CA1 were assessed by Western blotting. Hippocampal neuron injury and mitochondrial morphology were observed using H&E staining and a transmission electron microscope, respectively.

RESULTS

Artemisinin reversed diabetic cognitive impairments, decreased the concentrations of ROS, MDA and Fe2+, and increased the levels of p-Nr2, HO-1, GPX4 and GSH. Moreover, artemisinin alleviated neuronal loss and ferroptosis in the hippocampal CA1 region. However, these neuroprotective effects of artemisinin were abolished by Nrf2 inhibitor ML385 and ferroptosis inducer erastin.

CONCLUSION

Artemisinin effectively ameliorates neuropathological changes and learning and memory decline in T2DM mice; the underlying mechanism involves the activation of Nrf2 to inhibit neuronal ferroptosis in the hippocampus.

Gemfibrozil Alleviates Cognitive Impairment by Inhibiting Ferroptosis of Astrocytes via Restoring the Iron Metabolism and Promoting Antioxidant Capacity in Type 2 Diabetes

Diabetes-associated cognitive dysfunction (DACD) is considered a significant complication of diabetes and manifests as cognitive impairment. Astrocytes are vital to the brain energy metabolism and cerebral antioxidant status. Ferroptosis has been implicated in cognitive impairment, but it is unclear whether the ferroptosis of astrocytes is involved in the progression of DACD. PPARA/PPARα (peroxisome proliferator-activated receptor alpha) is a transcription factor that regulates glucose and lipid metabolism in the brain. In this study, we demonstrated that high glucose promoted ferroptosis of astrocytes by disrupting iron metabolism and suppressing the xCT/GPX4-regulated pathway in diabetic mice and astrocytes cultured in high glucose. Administration of gemfibrozil, a known PPARα agonist, inhibited ferroptosis and improved memory impairment in db/db mice. Gemfibrozil also prevented the accumulation of lipid peroxidation products and lethal reactive oxygen species induced by iron deposition in astrocytes and substantially reduced neuronal and synaptic loss. Our findings demonstrated that ferroptosis of astrocytes is a novel mechanism in the development of DACD. Additionally, our study revealed the therapeutic effect of gemfibrozil in preventing and treating DACD by inhibiting ferroptosis.

The role of autophagy in the treatment of type II diabetes and its complications: a review

Type II diabetes mellitus (T2DM) is a chronic metabolic disease characterized by prolonged hyperglycemia and insulin resistance (IR). Its incidence is increasing annually, posing a significant threat to human life and health. Consequently, there is an urgent requirement to discover effective drugs and investigate the pathogenesis of T2DM. Autophagy plays a crucial role in maintaining normal islet structure. However, in a state of high glucose, autophagy is inhibited, resulting in impaired islet function, insulin resistance, and complications. Studies have shown that modulating autophagy through activation or inhibition can have a positive impact on the treatment of T2DM and its complications. However, it is important to note that the specific regulatory mechanisms vary depending on the target organ. This review explores the role of autophagy in the pathogenesis of T2DM, taking into account both genetic and external factors. It also provides a summary of reported chemical drugs and traditional Chinese medicine that target the autophagic pathway for the treatment of T2DM and its complications.

The protective effects of melatonin in high glucose environment by alleviating autophagy and apoptosis on primary cortical neurons

Cognitive dysfunction has been regarded as a complication of diabetes. Melatonin (MLT) shows a neuroprotective effect on various neurological diseases. However, its protective effect on cortical neurons in high glucose environment has not been reported. Our present study aims to observe the protective effect of melatonin on rat cortical neurons and its relationship with autophagy in high glucose environment. The rat primary cortical neurons injury model was induced by high glucose. The CCK-8, flow cytometry, Western blot and immunofluorescence methods were used to examine the cell viability, apoptosis rate and proteins expression. Our results showed that there were no differences in cell viability, apoptosis rate, and protein expression among the control, MLT and mannitol group. The cell viability of the glucose group was significantly lower than that of the control group, and the apoptosis rate of the glucose group was significantly higher than that of the control group. Compared with the glucose group, the glucose + melatonin group showed a significant increase in cell viability and a notable decrease in apoptosis rate. Melatonin concentration of 0.1-1 mmol/L can significantly alleviate the injury of cortical neurons caused by high glucose. Compared with the control group, the glucose group showed a significant reduction of B-cell lymphoma 2 (Bcl-2) protein expression, while remarkable elevations of Bcl2-associated X protein (Bax), cleaved Caspase-3, coiled-coil, myosin-like Bcl2-interacting protein (Beclin-1) and microtubule-associated protein 1 light chain-3B type II (LC3B-II) levels. The neurons pre-administered with melatonin obtained significantly reversed these changes induced by high glucose. The phosphorylation levels of protein kinase B (Akt), mechanistic target of rapamycin kinase (mTOR) and Unc-51 like autophagy activating kinase 1(ULK1) were decreased in the glucose group compared with the control group, whereas significant increase were observed in the glucose + MLT group, compared with the glucose group. These data indicated that melatonin has a neuroprotective effect on cortical neurons under high glucose environment, which may work by activating Akt/mTOR/ULK1 pathway and may be deeply associated with the downregulation of autophagy.

Type 2 Diabetes and Parkinson's Disease: A Focused Review of Current Concepts

Highly reproducible epidemiological evidence shows that type 2 diabetes (T2D) increases the risk and rate of progression of Parkinson's disease (PD), and crucially, the repurposing of certain antidiabetic medications for the treatment of PD has shown early promise in clinical trials, suggesting that the effects of T2D on PD pathogenesis may be modifiable. The high prevalence of T2D means that a significant proportion of patients with PD may benefit from personalized antidiabetic treatment approaches that also confer neuroprotective benefits. Therefore, there is an immediate need to better understand the mechanistic relation between these conditions and the specific molecular pathways affected by T2D in the brain. Although there is considerable evidence that processes such as insulin signaling, mitochondrial function, autophagy, and inflammation are involved in the pathogenesis of both PD and T2D, the primary aim of this review is to highlight the evidence showing that T2D-associated dysregulation of these pathways occurs not only in the periphery but also in the brain and how this may facilitate neurodegeneration in PD. We also discuss the challenges involved in disentangling the complex relationship between T2D, insulin resistance, and PD, as well as important questions for further research. © 2022 International Parkinson and Movement Disorder Society.

Huang-Lian-Jie-Du decoction attenuates cognitive dysfunction of rats with type 2 diabetes by regulating autophagy and NLRP3 inflammasome activation

ETHNOPHARMACOLOGICAL RELEVANCE

Huang-Lian-Jie-Du decoction (HLJDD) is a traditional Chinese formula that is efficacious in treating diabetes mellitus, Alzheimer's disease, and diabetic encephalopathy; the underlying mechanisms of HLJDD in diabetes-associated cognitive dysfunction remain unclear.

AIM OF THE STUDY

This study investigated the neuroprotective effects of HLJDD on cognitive function, and the possible underlying mechanisms in type 2 diabetes mellitus (T2DM) in a rat model of cognitive impairment.

MATERIALS AND METHODS

Twelve active ingredients in HLJDD were detected using high-performance liquid chromatography analysis. An animal model of cognitive dysfunction in T2DM was induced via a high-sugar and high-fat diet combined with a low dose of streptozotocin. Sprague-Dawley rats were randomly divided into six groups: control, T2DM, metformin (0.34 g/kg/day), and HLJDD groups (3, 1.5, and 0.75 g/kg/day). All treatments were intragastrically administrated for nine continuous weeks after the development of T2DM. Body weight, food and water intake, fasting blood glucose, insulin sensitivity, and blood lipid levels were measured. Spatial learning and memory of the rats were assessed using the Morris water maze test. Hematoxylin and eosin and Nissl staining were performed to evaluate neuronal morphology and vitality. Glutathione, malondialdehyde, and superoxide dismutase levels were measured to determine the level of oxidative stress in the hippocampus. Transmission electron microscopy was performed to observe the synaptic morphology and structure of hippocampal neurons. IL-1β levels in the hippocampus and cerebrospinal fluid were determined. The protein expression of NLRP3, cleaved caspase-1, mature IL-1β, ATG7, P62, LC3, and brain-derived neurotrophic factor (BDNF) was determined using western blotting and immunofluorescence analysis.

RESULTS

HLJDD attenuated cognitive dysfunction in rats with T2DM as shown by the decreased escape latency, increased times crossing the platform and time spent in the target quadrant in the Morris water maze test (P < 0.05), improvement in hippocampal histopathological changes, and an elevated level of cell vitality. HLJDD treatment also reduced blood glucose and lipid levels, ameliorated oxidative stress, and downregulated IL-1β expression in the hippocampus and cerebrospinal fluid (P < 0.05). Moreover, HLJDD enhanced BDNF, ATG7, and LC3 protein expression and significantly inhibited the expression of P62, NLRP3, cleaved caspase-1, and mature IL-1β in the hippocampal CA1 region (P < 0.05). Immunofluorescence results further confirmed that the fluorescence intensity of NLRP3 and P62 in the hippocampus decreased after HLJDD intervention (P < 0.05).

CONCLUSIONS

HLJDD ameliorated cognitive dysfunction in T2DM rats. The neuroprotective effect is exerted via the modulation of glucose and lipid metabolism, upregulation of autophagy, and inhibition of NLRP3 inflammasome signaling pathway.

Autophagy and Diabetic Encephalopathy: Mechanistic Insights and Potential Therapeutic Implications

Diabetic Encephalopathy (DE) is one of the complications of diabetes mellitus (DM) in the central nervous system. Up to now, the mechanisms of DE are not fully discussed by the field. Autophagy is an intracellular degradation pathway crucial to maintain cellular homeostasis by clearing damaged organelles, pathogens, and unwanted protein aggregates. Increasing evidence has demonstrated that autophagy might play an essential role in DE progress. In this review, we summarize the current evidence on autophagy dysfunction under the condition of DE, and provide novel insights of possibly biological mechanisms linking autophagy impairment to DE, as well as discuss autophagy-targeted therapies as potential treatments for DE.

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.

Treatment with Autophagy Inducer Trehalose Alleviates Memory and Behavioral Impairments and Neuroinflammatory Brain Processes in db/db Mice

Autophagy attenuation has been found in neurodegenerative diseases, aging, diabetes mellitus, and atherosclerosis. In experimental models of neurodegenerative diseases, the correction of autophagy in the brain reverses neuronal and behavioral deficits and hence seems to be a promising therapy for neuropathologies. Our aim was to study the effect of an autophagy inducer, trehalose, on brain autophagy and behavior in a genetic model of diabetes with signs of neuronal damage (db/db mice). A 2% trehalose solution was administered as drinking water during 24 days of the experiment. Expressions of markers of autophagy (LC3-II), neuroinflammation (IBA1), redox state (NOS), and neuronal density (NeuN) in the brain were assessed by immunohistochemical analysis. For behavioral phenotyping, the open field, elevated plus-maze, tail suspension, pre-pulse inhibition, and passive avoidance tests were used. Trehalose caused a slight reduction in increased blood glucose concentration, considerable autophagy activation, and a decrease in the neuroinflammatory response in the brain along with improvements of exploration, locomotor activity, anxiety, depressive-like behavior, and fear learning and memory in db/db mice. Trehalose exerted some beneficial peripheral and systemic effects and partially reversed behavioral alterations in db/db mice. Thus, trehalose as an inducer of mTOR-independent autophagy is effective at alleviating neuronal and behavioral disturbances accompanying experimental diabetes.

Randomized trial of granulocyte colony-stimulating factor for spinal cord injury

Attenuation of the secondary injury of spinal cord injury (SCI) can suppress the spread of spinal cord tissue damage, possibly resulting in spinal cord sparing that can improve functional prognoses. Granulocyte colony-stimulating factor (G-CSF) is a haematological cytokine commonly used to treat neutropenia. Previous reports have shown that G-CSF promotes functional recovery in rodent models of SCI. Based on preclinical results, we conducted early phase clinical trials, showing safety/feasibility and suggestive efficacy. These lines of evidence demonstrate that G-CSF might have therapeutic benefits for acute SCI in humans. To confirm this efficacy and to obtain strong evidence for pharmaceutical approval of G-CSF therapy for SCI, we conducted a phase 3 clinical trial designed as a prospective, randomized, double-blinded and placebo-controlled comparative trial. The current trial included cervical SCI [severity of American Spinal Injury Association (ASIA) Impairment Scale (AIS) B or C] within 48 h after injury. Patients are randomly assigned to G-CSF and placebo groups. The G-CSF group was administered 400 μg/m²/day × 5 days of G-CSF in normal saline via intravenous infusion for five consecutive days. The placebo group was similarly administered a placebo. Allocation was concealed between blinded evaluators of efficacy/safety and those for laboratory data, as G-CSF markedly increases white blood cell counts that can reveal patient treatment. Efficacy and safety were evaluated by blinded observer. Our primary end point was changes in ASIA motor scores from baseline to 3 months after drug administration. Each group includes 44 patients (88 total patients). Our protocol was approved by the Pharmaceuticals and Medical Device Agency in Japan and this trial is funded by the Center for Clinical Trials, Japan Medical Association. There was no significant difference in the primary end point between the G-CSF and the placebo control groups. In contrast, one of the secondary end points showed that the ASIA motor score 6 months (P = 0.062) and 1 year (P = 0.073) after drug administration tend to be higher in the G-CSF group compared with the placebo control group. The present trial failed to show a significant effect of G-CSF in primary end point.

Bulbocodin D ameliorate cognitive impairment in APP/PS1 transgenic mice by modulating amyloid-beta burden, oxidative status and neuroinflammation

RATIONALE

Amyloid β peptide (Aβ) triggers a series of pathological events including microglial activation, oxidative stress, and inflammation-causing neuronal death and typical pathological changes in Alzheimer's disease (AD).

OBJECTIVES

This study aimed to investigate the therapeutic effects and mechanism of bulbocodin D for AD in vivo.

METHODS

In this study, Morris water maze (MWM) analysis was used to detect the cognitive ability of APP/PS1 mice after gavage with bulbocodin D for 2 months. Levels of Aβ40, Aβ42, IL-1β, and TNF-α were evaluated by ELISA. Aβ plaques and biomarkers of neuroinflammation were also investigated through histological analysis.

RESULTS

We established that bulbocodin D significantly improved cognitive deficits in APP/PS1 transgenic mice and reduced the levels of amyloid plaque, Aβ40, and Aβ42. Bulbocodin D also reduced levels of microglial markers IbA1, GFAP, and antioxidant enzymes and reduced the products of lipid peroxidation and proinflammatory cytokines.

CONCLUSION

In summary, the present study provides preclinical evidence that oral bulbocodin D can reduce AD pathology.

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.

Targeting hepcidin improves cognitive impairment and reduces iron deposition in a diabetic rat model

Cognitive impairment is a common complication of type 2 diabetes mellitus (T2DM) that may be related to iron deposition in the brain. Hepcidin is expressed in the brain and has the ability to regulate iron. Therefore, this study explored the role of hepcidin in hippocampal iron deposition and cognitive impairment in T2DM. The effects of a recombinant adeno-associated virus targeting hepcidin (AAV-hepcidin) for hippocampal iron content and cognitive function were investigated in a T2DM rat model induced by streptozotocin and a high-fat diet. Adult male rats (n = 32) were categorized as either C-saline (normal control), M-saline (T2DM), M-blank (AAV-blank + T2DM), or M-hepcidin (AAV-hepcidin + T2DM). Hippocampal iron content was assessed using quantitative susceptibility mapping. Morris water maze (MWM) testing was used to assess the cognitive function. Magnetic resonance imaging indicated that hippocampal susceptibility values were significantly increased bilaterally in T2DM rats compared with controls (P = 0.044, P = 0.043). Compared with the M-blank group, the M-hepcidin group exhibited significantly decreased hippocampal susceptibility values bilaterally (P = 0.007, P = 0.030). Compared with the M-saline group, susceptibility values from left hippocampus in the M-hepcidin group were significantly reduced (P = 0.002). MWM results showed that the performance of T2DM rats was significantly decreased from that of control rats. Compared with the M-saline and M-blank groups, the performance of the M-hepcidin group was significantly increased. These studies demonstrate that T2DM rats developed cognitive impairment and iron deposits in the hippocampus, both of which were improved by AAV-hepcidin administration.

Protective effects of resveratrol on random-pattern skin flap survival: an experimental study

Random-pattern skin flap transplantation is a common procedure in plastic surgery, but its distal area usually incurs ischemia and necrosis. Resveratrol (Rev), a natural polyphenol primarily found in peanuts, grapes, and red wine, which exerts multi-bioactivity. In this study, forty-eight rats with the modified "McFarlane flap" model were divided into Control and Rev groups, which were treated with vehicle Control and Rev, respectively. After 7 days of continuous treatment and observation, ischemic flap tissues were harvested to evaluate angiogenesis, apoptosis, oxidative stress, and autophagy. It was observed a greater survival area of flaps, accompanied with reduced water content and stronger blood supply, in the Rev group than in the Control group. In addition, Rev upregulated the expression of MMP9, VEGF, and Cadherin5, indicating that Rev promotes angiogenesis in ischemic flaps. Moreover, Rev decreased the levels of Bax, CYC, and Caspase3, suggesting that it inhibits apoptosis. Besides, Rev increased the expression of SOD1, eNOS, HO1, the activities of SOD and GSH, and reduced the levels of MDA, which uncovers that it depresses oxidative stress in ischemic flaps. Finally, it increased the expression of Beclin1, LC3II, VPS34, and CTSD, and decreased SQSTM1/p62 levels, which reveals that it activates autophagy in the flaps. These results suggest that Rev promotes random skin flap survival through proangiogenic, antiapoptotic, and antioxidative effects; moreover, autophagy is activated in the process, which might be another underlying mechanism for the flap survival.

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.

Liraglutide improves cognitive impairment via the AMPK and PI3K/Akt signaling pathways in type 2 diabetic rats

Liraglutide is a type of glucagon‑like‑peptide 1 receptor agonist, which has been reported as a novel type of antidiabetic agent with numerous benefits, including cardiovascular and neuroprotective effects. To the best of our knowledge, few studies to date have reported the potential mechanism underlying the neuroprotective effects of liraglutide on rats with type 2 diabetes mellitus (T2DM). The present study aimed to investigate the neuroprotective actions of liraglutide in diabetic rats and to determine the mechanisms underlying these effects. A total of 30 male T2DM Goto‑Kakizaki (GK) rats (age, 32 weeks; weight, 300‑350 g) and 10 male Wistar rats (age, 32 weeks; weight, 300‑350 g) were used in the present study. Wistar rats received vehicle treatment, and GK rats randomly received treatment with vehicle, low dose of liraglutide (75 µg/kg) or high dose of liraglutide (200 µg/kg) for 28 days. Cognitive deficits were evaluated using the Morris water maze test. The expression levels of phosphoinositide 3‑kinase (PI3K), protein kinase B (Akt), phosphorylated (p)‑Akt, AMP‑activated protein kinase (AMPK), mammalian target of rapamycin (mTOR), Beclin‑1, microtubule‑associated protein light chain 3 (LC)‑3 II, caspase‑3, B‑cell lymphoma 2 (Bcl‑2)‑associated X protein and Bcl‑2 were assessed by western blot analysis. The results demonstrated that diabetic GK rats exhibited cognitive dysfunction, whereas treatment with liraglutide alleviated the learning and memory deficits, particularly in the high‑dose liraglutide group. The expression levels of Beclin‑1 and LC‑3 II were decreased in GK rats; however, this decrease was alleviated in the presence of liraglutide. Liraglutide also reversed T2DM model‑induced increases in mTOR, and decreases in p‑AMPK, PI3K and p‑Akt expression, and modulated the expression of apoptosis‑associated proteins. Furthermore, the administration of liraglutide inhibited apoptosis and exerted a protective effect against cognitive deficits via the activation of autophagy. In conclusion, the protective effects of liraglutide may be associated with increased mTOR expression via activation of the AMPK and PI3K/Akt signaling pathways.

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.