Neuroprotective Effects Of Metformin Research Articles

Neuroprotective Effects of Metformin on Cerebral Ischemia-Reperfusion Injury: Modulation of JNK and p38 MAP Kinase Signaling Pathways.

Cerebral ischemia-reperfusion injury (CIRI) is a significant pathological process in stroke, characterized by neuronal cell death and neurological dysfunction. Metformin, commonly used for diabetes management, has been noted for its neuroprotective properties, though its effects on CIRI and the mechanisms involved remain unclear. This study explored the neuroprotective impact of metformin on CIRI, focusing on its potential to modulate the c-Jun N-terminal kinase (JNK) and p38 MAP kinase (p38) signaling pathways. Using in vitro models of oxygen-glucose deprivation/reperfusion (OGD/R) in neuronal cells and in vivo mouse models of middle cerebral artery occlusion (MCAO), the effects of metformin were assessed. Cell viability was measured with Cell Counting Kit-8 (CCK-8), protein expression via Western Blot (WB), and apoptosis through flow cytometry. The extent of brain injury in mice was evaluated using 2,3,5-triphenyltetrazolium chloride (TTC) staining, while JNK and p38 activation statuses were detected through WB and phospho-JNK (p-JNK) immunofluorescence staining. Results showed that metformin significantly improved the viability of HT22 cells post-OGD/R, reduced apoptosis, and decreased OGD/R-induced phosphorylation of JNK and p38 in vitro. In vivo, metformin treatment notably reduced brain infarct volume in MCAO mice, inhibited p-p38 and p-JNK expression, and enhanced neurological function. These findings suggest that metformin exerts neuroprotective effects against CIRI by modulating the JNK/p38 signaling pathway, highlighting its potential therapeutic value in treating cerebral ischemia-reperfusion injury and paving the way for clinical applications.

Insulin resistance and stroke: mechanisms and therapeutic approaches

The review analyzed literature data on the epidemio­logy, risk factors, and mechanisms of acute cerebrovascular accident (ACVA) in patients with diabetes mellitus. The role of insulin resistance and the effectiveness of therapeutic approaches to its correction in cerebral stroke are considered. Diabetes mellitus is recognized as an independent modifiable risk factor for ACVA. In people with diabetes of different age, the risk of stroke is increased by 2–6 times, and the indicators are especially high in patients of young working age. The presence of diabetes mellitus is associated with more severe symptoms, increased risk of complications, longer hospitalization, and higher mortality. Research results show that insulin resistance is one of the main triggers for the development of ischemic stroke due to embolism caused by oxidative stress, endothelial dysfunction and platelet hyperactivation, as well as due to atherosclerotic changes caused by inflammation, proliferation of smooth muscle cells of the vascular wall, dyslipidemia and hypertension on the background of hyperglycemia and hyperinsulinemia. It has been proven that insulin resistance not only provokes ACVA, but also negatively affects their prognosis. Metformin is a key drug for improving insulin sensitivity and is recognized as one of the most important first-line therapeutic agents to achieve and maintain treatment goals in patients with type 2 diabetes. The results of expe­rimental and clinical studies proved that this agent has a whole range of neuroprotective properties, which generally prevent the development of cerebral ischemia and reduce the negative consequences in case of its occurrence. Animals with experimental acute cerebral ischemia who have been treated with metformin had a better overall neurological score, significantly smaller infarct size, better coordination scores, and higher numbers of neurons and microglia. The neuroprotective effect of metformin in stroke is realized through the AMPK (5’AMP-activated protein kinase) signaling pathway with reduction of oxidative stress, neuroinflammation, stimulation of angiogenesis and neurogenesis, autophagy, and inhibition of apoptosis. According to data from cohort and randomized clinical trials, the use of metformin is associated with a significantly lower risk of developing ACVA. Long-term use of this drug in type 2 diabetes contributes to a milder course of stroke, is associated with better functional recovery, and a decrease in disability and mortality rates.

Neuroprotective Effects of Metformin Through AMPK Activation in a Neurotoxin-Based Model of Cerebellar Ataxia.

Cerebellar ataxia is a heterogeneous group of neural disorders clinically characterized by cerebellar dysfunction. The diagnosis of patients with progressive cerebellar ataxia is complex due to the direct correlation with other neuron diseases. Although there is still no cure for this pathological condition, some metabolic, hereditary, inflammatory, and immunological factors affecting cerebellar ataxia are being studied and may become therapeutic targets. Advances in studying the neuroanatomy, pathophysiology, and molecular biology of the cerebellum (CE) contribute to a better understanding of the mechanisms behind the development of this disorder. In this study, Wistar rats aged 30 to 35 days were injected intraperitoneally with 3-acetylpyridine (3-AP) and/or metformin (for AMP-activated protein kinase (AMPK) enzyme activation) and euthanized in 24 hours and 4 days after injection. We analyzed the neuromodulatory role of the AMPK on cerebellar ataxia induced by the neurotoxin 3-AP in the brain stem (BS) and CE, after pre-treatment for 7 and 15 days with metformin, a pharmacological indirect activator of AMPK. The results shown here suggest that AMPK activation in the BS and CE leads to a significant reduction in neuroinflammation in these regions. AMPK was able to restore the changes in fatty acid composition and pro-inflammatory cytokines caused by 3-AP, suggesting that the action of AMPK seems to result in a possible neuroprotection on the cerebellar ataxia model.

Incident dementia risk among patients with type 2 diabetes receiving metformin versus alternative oral glucose-lowering therapy: an observational cohort study using UK primary healthcare records

Introduction4.2 million individuals in the UK have type 2 diabetes, a known risk factor for dementia and mild cognitive impairment (MCI). Diabetes treatment may modify this association, but existing evidence...

Metformin role in Parkinson's disease: a double-sword effect.

Parkinson's disease (PD) is a common neurodegenerative disease developed due to the degeneration of dopaminergic neurons in the substantia nigra. There is no single effective treatment in the management of PD. Therefore, repurposing effective and approved drugs like metformin could be an effective strategy for managing PD. However, the mechanistic role of metformin in PD neuropathology was not fully elucidated. Metformin is an insulin-sensitizing agent used as a first-line therapy in the management of type 2 diabetes mellitus (T2DM) and has the ability to reduce insulin resistance (IR). Metformin may have a beneficial effect on PD neuropathology. The neuroprotective effect of metformin is mainly mediated by activating adenosine monophosphate protein kinase (AMPK), which reduces mitochondrial dysfunction, oxidative stress, and α-synuclein aggregation. As well, metformin mitigates brain IR a hallmark of PD and other neurodegenerative diseases. However, metformin may harm PD neuropathology by inducing hyperhomocysteinemia and deficiency of folate and B12. Therefore, this review aimed to find the potential role of metformin regarding its protective and detrimental effects on the pathogenesis of PD. The mechanistic role of metformin in PD neuropathology was not fully elucidated. Most studies regarding metformin and its effectiveness in PD neuropathology were observed in preclinical studies, which are not fully translated into clinical settings. In addition, metformin effect on PD neuropathology was previously clarified in T2DM, potentially linked to an increasing PD risk. These limitations hinder the conclusion concerning the therapeutic efficacy of metformin and its beneficial and detrimental role in PD. Therefore, as metformin does not cause hypoglycemia and is a safe drug, it should be evaluated in non-diabetic patients concerning PD risk.

Metformin attenuates sevoflurane-induced neurogenesis damage and cognitive impairment: involvement of the Nrf2/G6PD pathway.

Anesthetics such as sevoflurane are commonly administered to infants and children. However, the possible neurotoxicity caused by prolonged or repetitive exposure to it should be a concern. The neuroprotective effects of metformin are observed in many models of neurological disorders. In this study, we investigated whether metformin could reduce the developmental neurotoxicity induced by sevoflurane exposure in neonatal rats and the potential mechanism. Postnatal day 7 (PND 7) Sprague-Dawley rats and neural stem cells (NSCs) were treated with normal saline or metformin before sevoflurane exposure. The Morris water maze (MWM) was used to observe spatial memory and learning at PND 35-42. Immunofluorescence staining was used to detect neurogenesis in the subventricular zone (SVZ) of the lateral ventricle and the subgranular zone (SGZ) of the dentate gyrus at PND 14. MTT assays, immunofluorescence staining, and TUNEL staining were used to assess the viability, proliferation, differentiation, and apoptosis of NSCs. Western blotting and ELISA were used to assess the protein expression of cleaved caspase-3, nuclear factor erythroid 2-related factor 2 (Nrf2), and glucose-6-phosphate dehydrogenase (G6PD) pathway-related molecules. Exposure to sevoflurane resulted in late cognitive defects, impaired neurogenesis in both the SVZ and SGZ, reduced NSC viability and proliferation, increased NSC apoptosis, and decreased protein expression of G6PD in vitro. Metformin pretreatment attenuated sevoflurane-induced cognitive functional decline and neurogenesis inhibition. Metformin pretreatment also increased the protein expression of Nrf2 and G6PD. However, treatment with the Nrf2 inhibitor, ML385 or the G6PD inhibitor, dehydroepiandrosterone (DHEA) reversed the protective effect of metformin on sevoflurane-induced NSC damage in vitro. Our findings suggested that metformin could reduce sevoflurane-induced neurogenesis damage and neurocognitive defects in the developing rat brain by influencing the Nrf2/G6PD signaling pathways.

Protective Effect of Metformin Alone or in Combination with Valproic acid on Pentylenetetrazole-Induced Seizures in Mice

Abstract Objective: The aim of this study was to investigate the effects of metformin on pentylenetetrazole (PTZ)-induced seizures and the neuroprotective effect of metformin on neuronal damage after pentylenetetrazole administration. Material and Methods: Thirty-five (35) Male BALB-c Albino mice weighing 35-38 g were divided randomly into five groups: Control group (1), Saline+PTZ group (2), Valproic Acid (VPA, 200 mg/kg intraperitoneal-i.p.)+PTZ group (3), Metformin (200 mg/kg i.p.)+PTZ group (4), and VPA+Metformin+PTZ group (5). The PTZ (60 mg/kg, i.p.) was injected 30 min after drugs injection to induce seizures and seizure stages and behavioral scoring were evaluated. After completing procedure, brain tissues were removed and analyzed with biochemical and histopathological procedures. The hippocampal Cornu Ammonis (CA) 1, CA2, CA3 and DG (dentate gyrus) regions were histopathologically evaluated and oxidative stress markers (total antioxidant status (TAS), total oxidant status (TOS)) were measured. Results: Compare to Saline+PTZ group, metformin administration alone did not affect the onset time of the first myoclonic jerk (FMJ), but combination of VPA and metformin significantly increased FMJ onset time (p<0.05). Additionally, the treatment of metformin with or without VPA reduced the brain oxidative stress (p<0.05). Furthermore, histopathological assessment demonstrated that metformin administration and the combination of VPA and metformin decreased dark neuron formation in the hippocampal CA1, CA2, CA3, and DG areas (p<0.05). Conclusion: Metformin was found to be significantly effective in reducing epileptic seizures, brain oxidative stress, and preventing neural damage after PTZ-induced seizure

Neuroprotective effects of metformin on cerebral ischemia-reperfusion injury by regulating PI3K/Akt pathway.

Metformin (Met) is a commonly used drug in the treatment of type 2 diabetes. Currently, it has been found that Met can effectively reduce the incidence of stroke and exert anti‐inflammatory effects. However, its role in ischemia‐reperfusion (I/R)‐induced nerve injury remains unclear. This study aims to investigate the neuroprotective effects of Met in I/R‐induced neuron injury as well as the underlying mechanism. A middle cerebral artery occlusion (MCAO) model was established in Sprague Dawley (SD) rats, which were then treated with different doses of Met. Neurological deficits of rats were measured at different times post‐surgery. TTC staining was done to observe the volume of cerebral infarction. HE staining was performed to observe pathological changes of brain tissues. Immunohistochemistry was performed to observe the expression of inflammatory factors in the cerebral tissues. qRT‐PCR method was used to detect the relative expression of PI3K, Akt mRNA in cells after 24 h of drug action. Western blot method was used to detect the expression of PI3K, p‐PI3K, Akt, and p‐Akt in hippocampus. What is more, in vitro experiments were performed on BV2 microglia to verify the role of Met against oxygen‐glucose deprivation (OGD). As a result, Met dose‐dependently attenuated neurological deficits and neuronal apoptosis. Besides, Met administration also significantly reduced BV2 cells apoptosis and inflammatory response. Mechanistically, Met inactivated PI3K/Akt pathway induced by I/R and OGD, while it upregulated PI3K. In conclusion, Met protected rats from cerebral I/R injury via reducing neuronal apoptosis and microglial inflammation through PI3K/Akt pathway.

Механізми дії метформіну за діабету та пов’язаних із діабетом патологій

Метформін (МФ) — основний пероральний препарат, який використовується в клініці для лікування пацієнтів із цукровим діабетом 2-го типу (ЦД2) понад 60 років. Предіабет — метаболічний стан, що характеризується резистентністю до інсуліну та первинною або вторинною дисфункцією β-клітин, що збільшує ризик ЦД2. Отримані дані підтверджують роль МФ у запобіганні ЦД2 в людей із предіабетом. Його ефективність для затримки або запобігання виникненню діабету доведено у великих, добре обгрунтованих і спланованих ран- домізованих дослідженнях. За діабету МФ знижує гіперглікемію, пригнічуючи глюконеогенез у печінці через активацію шляху LKB/AMPK, а також підвищує чутливість до інсуліну — ефект, що підсилює опосередковану інсуліном супресію продукції глюкози в печінці й утилізацію глюкози в скелетних м’язах. Дію МФ пов’язано з руйнуванням мітохондріального комплексу I і зменшенням продукції АТР, посиленням автофагії та іншими механізмами. Отримані дані надійно свідчать про зв’язок ЦД із порушеннями когнітивних здібностей людини. За діабету відбуваються структурні та функціональні зміни в нервовій системі та її кровоносних судинах. ЦД прискорює розвиток хвороби Альцгеймера, стимулюючи утворення сенильних бляшок і нейрофібрилярних клубочків. Хворі на діабет, які приймають МФ, меншою мірою схильні до когнітивних розладів. МФ запобігає апоптозу в первинних нейронах, ефективно посилює споживання глюкози в інсулінорезистентних клітинах. Нейропротекторні ефекти МФ, мабуть, пов’язано з його цукрознижуючими, антиоксидантними й антиапоптотичними властивостями. Відомо, що хворі на ЦД характеризуються підвищеним ризиком канцерогенезу, а в разі захворювання на рак їхня здатність до виживання є нижчою, ніж у недіабетичних пацієнтів. Антидіабетична терапія гальмує клітинний ріст, проліферацію та метаболізм і, як наслідок, впливає на потенціал онкогенезу. Гіперінсулінемія та гіперглікемія є добре встановленими чинниками ризику канцерогенезу, тому зниження їх рівня є важливим моментом у запобіганні злоякісній трансформації клітин. МФ має протипухлиннівластивості та може пригнічувати онкогенез за допомогою системних і клітинних механізмів. Цей препарат справляє пряму, спрямовану на ракові клітини, та непряму дію, впливаючи на системну інсулінемію та глікемію.

Metformin protects rotenone-induced dopaminergic neurodegeneration by reducing lipid peroxidation.

Metformin, a widely prescribed antidiabetic drug, has been suggested to have a neuroprotective effect on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity in mice. In this study, we investigated the neuroprotective potential of metformin against rotenone-induced dopaminergic neuron damage and its underlying mechanisms. C57BL/6 mice were given saline or rotenone (2.5mg/kg/day, ip) injection for 10days. Metformin treatment (300mg/kg/day, ip) was started concurrently with rotenone administration and continued for 10days. The neuroprotective effect of metformin on rotenone-induced dopaminergic toxicity was assessed by tyrosine hydroxylase (TH), cleaved caspase-3 and α-synuclein immunohistochemistry in substantia nigra (SN). SN tissues were extracted for biochemical analysis. Malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) protein levels were measured by spectrophotometric assay. We found that metformin treatment attenuated the rotenone-induced loss of TH+ neurons in the SN. Additionally, metformin significantly decreased the rotenone-induced increase of cleaved caspase-3 and α-synuclein accumulation in the SN; however, there was no difference in motor behaviours between the experimental groups. Meanwhile, the levels of MDA and 4-HNE in SN were significantly reduced in the rotenone-metformin group compared to the rotenone group. Results showed that metformin treatment attenuated dopaminergic neuron loss in SN induced by rotenone by decreasing lipid peroxidation.

Possible involvement of metformin in downregulation of neuroinflammation and associated behavioural changes in mice.

Metformin (MET), a biguanide oral hypoglycaemic agent, recently has been shown to be effective in various conditions other than type-2 diabetes including cancer, stroke, weight reduction, and polycystic ovarian syndrome, to name a few. MET has also possessed antioxidant and antiinflammatory properties by activation of AMPK . This study was aimed at evaluating the effects of MET on lipopolysaccharide (LPS)-induced systemic and neuroinflammation, oxidative stress, and behavioural changes. The study consisted of six groups, where three selected doses of MET (100, 200, and 300mg/kg) were employed in male Swiss albino mice, with one group of imipramine (IMI), saline, and LPS each. Systemic inflammation was induced by injecting LPS (1.5mg/kg) by intraperitoneal route. A battery of behavioural tests including open field, forced swim, and tail suspension tests were employed to assess the impact of systemic inflammation on exploratory behaviour and learned helplessness. LPS induced significant immobility with profound symptoms of sickness behaviour. Furthermore, LPS led to significant increase in serum and brain proinflammatory cytokines TNF-α and IL-6; and also increased lipid peroxidation with reduced glutathione levels. Pretreatment of the animals with 100 and 200mg/kg of MET significantly reduced both systemic and central inflammatory markers along with protecting against LPS-induced oxidative stress. The higher dose, 300mg/kg of MET was not effective against most of LPS-induced biochemical changes. Our preliminary results from this study suggest the antiinflammatory and neuroprotective effects of MET in LPS-induced model of sickness behaviour and neuroinflammation.

Rescue of Retinal Degeneration in rd1 Mice by Intravitreally Injected Metformin.

Retinitis pigmentosa (RP) is a progressive hereditary retinal degenerative disease in which photoreceptor cells undergo degeneration and apoptosis, eventually resulting in irreversible loss of visual function. Currently, no effective treatment exists for this disease. Neuroprotection and inflammation suppression have been reported to delay the development of RP. Metformin is a well-tested drug used to treat type 2 diabetes, and it has been reported to exert beneficial effects in neurodegenerative diseases, such as Parkinson’s disease and Alzheimer’s disease. In the present study, we used immunofluorescence staining, electroretinogram (ERG) recordings and RNA-Seq to explore the effects of metformin on photoreceptor degeneration and its mechanism in rd1 mice. We found that metformin significantly reduced apoptosis in photoreceptors and delayed the degeneration of photoreceptors and rod bipolar cells in rd1 mice, thus markedly improving the visual function of rd1 mice at P14, P18, and P22 when tested with a light/dark transition test and ERG. Microglial activation in the outer nuclear layer (ONL) of the retina of rd1 mice was significantly suppressed by metformin. RNA-Seq showed that metformin markedly downregulated inflammatory genes and upregulated the expression of crystallin proteins, which have been demonstrated to be important neuroprotective molecules in the retina, revealing the therapeutic potential of metformin for RP treatment. αA-crystallin proteins were further confirmed to be involved in the neuroprotective effects of metformin in a Ca2+ ionophore-damaged 661W photoreceptor-like cell line. These data suggest that metformin exerts a protective effect in rd1 mice via both immunoregulatory and new neuroprotective mechanisms.

Protective role of metformin against methamphetamine induced anxiety, depression, cognition impairment and neurodegeneration in rat: The role of CREB/BDNF and Akt/GSK3 signaling pathways

BackgroundMethamphetamine is a neuro-stimulant with neurodegenerative effects, and ambiguous mechanism of action. Metformin is an antidiabetic agent with neuroprotective properties but not fully understood mechanisms. The present study investigated the molecular basis of metformin neuroprotection against methamphetamine-induced neurodegeneration. Brief methodSixty adult male rats were randomly divided into six groups: group 1 (received normal saline), group 2 (received 10 mg/kg of methamphetamine) and groups 3, 4, 5 and 6 [received methamphetamine (10 mg/kg) plus metformin (50, 75, 100 and 150 mg/kg) respectively]. Elevated Plus Maze (EPM), Open Field Test (OFT), Forced Swim Test (FST), Tail Suspension Test (TST) and Morris Water Maze (MWM) were used to assess the level of anxiety, depression and cognition in experimental animals. Also animals’ hippocampus were isolated and oxidative stress and inflammatory parameters and expression of total and phosphorylated forms of cAMP response element binding (CREB), brain-derived neurotrophic factor (BDNF), protein kinase B (Akt) and glycogen synthase kinase 3 (GSK3) proteins were evaluated by ELISA method. ResultsAccording to the data obtained, methamphetamine caused significant depression, anxiety, motor activity disturbances and cognition impairment in experimental animals. Metformin, in all used doses, decreased methamphetamine induced behavioral disturbances. Also chronic administration of methamphetamine could increase malondialdehyde (MDA), tumor necrosis factor-Alpha (TNF-α) and interleukine-1 beta (IL-1β) in rats, while caused reduction of superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GR) activities. Metformin, especially in high doses, could prevent these malicious effects of methamphetamine. Also Metformin could activate CREB (both forms), BDNF and Akt (both forms) proteins’ expression and inhibited GSK3 (both forms) protein expression in methamphetamine treated rats. SignificanceAccording to obtained data, metformin could protect the brain against methamphetamine-induced neurodegeneration probably by mediation of CREB/BDNF or Akt/GSK3 signaling pathways. These data suggested that CREB/BDNF or Akt/GSK3 signaling pathways may have a critical role in methamphetamine induced neurotoxicity and/or neuroprotective effects of metformin.

Metformin protects PC12 cells against oxygen-glucose deprivation/reperfusion injury

Oxidative stress has a causative role in ischemic reperfusion-induced cell death. Evidence has shown that metformin is capable to reduce ischemic reperfusion injuries. The current study investigated the effect of metformin on ischemia/reperfusion-induced apoptosis in PC12 cells by evaluation of Bcl-2 family proteins expression. Cells were exposed to a time-dependent in vitro oxygen-glucose deprivation/reoxygenation (OGD/R) injury and then treated with metformin. The intracellular reactive oxygen species (ROS) levels were measured. Western blotting was used to examine the expression of anti- and pro-apoptotic proteins. Moreover, the number of apoptotic cell death was evaluated by TUNEL assay. Our results showed that metformin attenuated ROS generation, downregulated pro-apoptotic BAX expression, and upregulated expression of the Bcl-2 protein in the PC12 cells. Moreover, metformin reduced cell death under OGD/R condition which was confirmed by lower apoptotic cell death in the TUNEL assay. These findings suggest that neuroprotective effect of metformin on OGD/R-induced cell death is possibly mediated by inhibition of ROS-induced apoptosis pathway.

Antidiabetic Drug Metformin Protects Neuronal Cells against Quinolinic Acid-Induced Excitotoxicity by Decreasing Intracellular Calcium.

The antidiabetic drug metformin has been found to have beneficial effects in various neurological disorders; however, the molecular mechanisms underlying these effects remain unclear. Here we report that metformin protects neuronal cells from quinolinic acid (QUIN)-induced excitotoxicity. For this, we pretreated N18D3 neuronal cells with metformin prior to QUIN for 24 h. We found that pretreating the cells with metformin significantly improved cell survival rate in a concentration-dependent manner and reduced apoptotic cell death, as revealed by a MTT assay and DAPI staining, respectively. Calcium imaging using fluo-4 showed that metformin (100 µM) inhibited the intracellular calcium increase that was induced by QUIN. In addition, mRNA expression of pro-apoptotic genes, p21 and Bax, was decreased and of anti-apoptotic genes, Bcl-2 and Bcl-xl, was increased with metformin treatment compared to QUIN-induced cells. The immunoreactivity of phosphorylated ERK1/2 was elevated in cells treated with metformin, indicating the ERK1/2 signaling pathway in the neuroprotective effects of metformin in QUIN-induced cell death. Collectively, our data demonstrates that metformin exerts its neuroprotective effects by inhibiting intracellular calcium increases, allowing it to regulate ERK1/2 signaling and modulate cell survival and death genes.

Neuroprotective effects of metformin against Aβ-mediated inhibition of long-term potentiation in rats fed a high-fat diet

Metformin (Met) is used to treat neurodegenerative disorders such as Alzheimer's disease (AD). Conversely, high-fat diets (HFD) have been shown to increase AD risk. In this study, we investigated the neuroprotective effects of Met on β-amyloid (Aβ)-induced impairments in hippocampal synaptic plasticity in AD model rats that were fed a HFD. In this study, 32 adult male Wistar rats were randomly assigned to four groups: group I (control group, regular diet); group II (HFD+vehicle); group III (HFD+Aβ); or group IV (Met+HFD+Aβ). Rats fed a HFD were injected with Aβ to induce AD, allowed to recover, and treated with Met for 8 weeks. The rats were then anesthetized with intraperitoneal injections of urethane and placed in a stereotaxic apparatus for surgery, electrode implantation, and field potential recording. In vivo electrophysiological recordings were then performed to measure population spike (PS) amplitude and excitatory postsynaptic potential (EPSP) slope in the hippocampal dentate gyrus. Long-term potentiation (LTP) was induced by high-frequency stimulation of the perforant pathway. Blood samples were then collected to measure plasma levels of triglycerides, low-density lipoproteins, very low-density lipoprotein, and cholesterol. After induction of LTP, PS amplitude and EPSP slope were significantly decreased in Aβ-injected rats fed a HFD compared to vehicle-injected animals or untreated animals that were fed a normal diet. Met treatment of Aβ-injected rats significantly attenuated these decreases, suggesting that Met decreased the effects of Aβ on LTP. These findings suggest that Met treatment is neuroprotective against the detrimental effects of Aβ and HFDs on hippocampal synaptic plasticity.

Abstract WP305: Impact Of Metformin on Survival Following Ischemic Stroke in Patients With Diabetes: The Greater Cincinnati Northern/Kentucky Stroke Study (GCNKSS)

Introduction: Metformin, an oral antidiabetic drug, is associated with reduced risk of diabetic related endpoints, including stroke. Evidence from animal studies show neuroprotective properties of metformin via the AMP-activated protein kinase pathway. We examined if these neuroprotective effects of metformin may extend into improved survival among stroke patients. Methods: All stroke patients within the Greater Cincinnati/Northern Kentucky catchment area of ∼ 1.3 million were identified using ICD-9 discharge codes (430-436) in 2005 and 2010. Cases were abstracted by study nurses and verified by physician review. Patients surviving to hospital discharge with a history of diabetes or diagnosed with diabetes during hospitalization (DM) were categorized into four groups based on recorded medication use: metformin monotherapy, metformin combotherapy, other antidiabetic drug therapy, and no antidiabetic medications. The primary outcome was all cause case fatality at 3 years following stroke. Covariates considered were age at onset, sex, race, BMI, baseline NIHSS and mRS, smoking status, history of comorbidities, and glucose level on admission. Cox proportional hazard models were used to estimate the risk of case fatality. Results: Overall, 37% (1,471) of the 4,015 ischemic stroke patients (>= 20 years of age) met criteria for DM. Patients with DM (vs non DM) were 65 (vs 66) years of age, 55% (vs 56%) female, and 27% (vs 18%) black. Of patients with DM, 10% were on metformin monotherapy, 28% metformin combotherapy, 50% other antidiabetic drugs, and 13% no antidiabetic drugs. In adjusted analysis, at 3 years post stroke, patients on metformin monotherapy or combotherapy had similar risk of case fatality compared with non-DM and had lower risk of case fatality compared with DM on no drug therapy (Table). Conclusions: Use of metformin, either alone or in combination with other antidiabetic drugs may provide a long term survival benefit among stroke patients with diabetes.

Beneficial Effect of Metformin on Nerve Regeneration and Functional Recovery After Sciatic Nerve Crush Injury in Diabetic Rats.

Neuroprotective effects of metformin have been increasingly recognized in both diabetic and non-diabetic conditions. Thus far, no information has been available on the potential beneficial effects of metformin on peripheral nerve regeneration in diabetes mellitus. The present study was designed to investigate such a possibility. Diabetes was established by a single injection of streptozotocin at 50mg/kg in rats. After sciatic nerve crush injury, the diabetic rats were intraperitoneally administrated daily for 4weeks with metformin (30, 200 and 500mg/kg), or normal saline, respectively. The axonal regeneration was investigated by morphometric analysis and retrograde labeling. The functional recovery was evaluated by electrophysiological studies and behavioral analysis. It was found that metformin significantly enhanced axonal regeneration and functional recovery compared to saline after sciatic nerve injury in diabetic rats. In addition, metformin at 200 and 500mg/kg showed better performance than that at 30mg/kg. Taken together, metformin is capable of promoting nerve regeneration after sciatic nerve injuries in diabetes mellitus, highlighting its therapeutic values for peripheral nerve injury repair in diabetes mellitus.

RETRACTED: Neuroprotective and neurotrophic effects of Apigenin and Luteolin in MPTP induced parkinsonism in mice

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editor-in-Chief. It has been highlighted that there is image manipulation. Fig. 6 b), e) ad f) are the same images from Fig 5 a), b), c) from Patil, S.P., Jain, P.D., Ghumatkar, P.J., Tambe, R., Sathaye, S., 2014. Neuroprotective effect of metformin in MPTP-induced Parkinson’s disease in mice. Neuroscience 277, 747–754 and used to describe different drug doses and treatments in the paper. Fig. 8 d), e) and f) are the same image manipulated to be results for different drug treatments. Fig. 10a), b) and h) are the same images as Fig. 7 B) in the paper Patil, S.P., Jain, P.D., Ghumatkar, P.J., Tambe, R., Sathaye, S., 2014. Neuroprotective effect of metformin in MPTP-induced Parkinson’s disease in mice. Neuroscience 277, 747–754 and used to describe different drug treatments. The authors acknowledge there are serious errors and agree with the retraction of this paper.