Metformin pretreatment enhanced learning and memory in cerebral forebrain ischaemia: the role of the AMPK/BDNF/P70SK signalling pathway

The impact of pre-stroke metformin use on clinical outcomes after acute ischemic stroke: A systematic review and meta-analysis

OBJECTIVES

Stroke is a leading cause of mortality and disability globally, with limited treatment options available for acute ischemic stroke (AIS) patients. Type 2 diabetes mellitus (T2DM) is not only widespread but also a known risk factor for stroke. Our meta-analysis aims to assess the influence of pre-stroke metformin use on the clinical outcomes in AIS patients with T2DM.

MATERIALS AND METHODS

We conducted this study following PRISMA guidelines, searching the following databases: Medline, Embase, Scopus, Web of Science, and Cochrane Central Register of Controlled Trials up to February 29, 2024. All studies providing separate data on AIS patients using metformin were included, and statistical analysis was conducted using R software to pooled odds ratios (ORs) and their corresponding 95% confidence intervals (CI).

RESULTS

Out of 1051 studies, 7 met the inclusion criteria for our meta-analysis with a total of 11589 diabetic patients, including 5445 patients taking metformin and 6144 diabetic patients in the non-metformin group. Compared to the non-metformin group, the metformin group had a significantly higher rate of mRS 0-2 score at discharge (OR 1.56; 95% CI 1.25:1.95; p=< 0.01) and a lower rate of 90-day mortality (OR 0.51; 95% CI 0.42:0.61; p=< 0.01), with no significant difference in sICH (OR 0.88; 95% CI 0.47:1.64; p= 0.68) between the two groups.

CONCLUSIONS

Our meta-analysis demonstrated that pre-stroke metformin use is associated with higher functional independence and lower mortality in AIS patients with T2DM.

Promising use of metformin in treating neurological disorders: biomarker-guided therapies

Neurological disorders are a diverse group of conditions that affect the nervous system and include neurodegenerative diseases (Alzheimer's disease, multiple sclerosis, Parkinson's disease, Huntington's disease), cerebrovascular conditions (stroke), and neurodevelopmental disorders (autism spectrum disorder). Although they affect millions of individuals around the world, only a limited number of effective treatment options are available today. Since most neurological disorders express mitochondria-related metabolic perturbations, metformin, a biguanide type II antidiabetic drug, has attracted a lot of attention to be repurposed to treat neurological disorders by correcting their perturbed energy metabolism. However, controversial research emerges regarding the beneficial/detrimental effects of metformin on these neurological disorders. Given that most neurological disorders have complex etiology in their pathophysiology and are influenced by various risk factors such as aging, lifestyle, genetics, and environment, it is important to identify perturbed molecular functions that can be targeted by metformin in these neurological disorders. These molecules can then be used as biomarkers to stratify subpopulations of patients who show distinct molecular/pathological properties and can respond to metformin treatment, ultimately developing targeted therapy. In this review, we will discuss mitochondria-related metabolic perturbations and impaired molecular pathways in these neurological disorders and how these can be used as biomarkers to guide metformin-responsive treatment for the targeted therapy to treat neurological disorders.

Rhoa/ROCK, mTOR and Secretome-Based Treatments for Ischemic Stroke: New Perspectives

Ischemic stroke triggers a complex cascade of cellular and molecular events leading to neuronal damage and tissue injury. This review explores the potential therapeutic avenues targeting cellular signaling pathways implicated in stroke pathophysiology. Specifically, it focuses on the articles that highlight the roles of RhoA/ROCK and mTOR signaling pathways in ischemic brain injury and their therapeutic implications. The RhoA/ROCK pathway modulates various cellular processes, including cytoskeletal dynamics and inflammation, while mTOR signaling regulates cell growth, proliferation, and autophagy. Preclinical studies have demonstrated the neuroprotective effects of targeting these pathways in stroke models, offering insights into potential treatment strategies. However, challenges such as off-target effects and the need for tissue-specific targeting remain. Furthermore, emerging evidence suggests the therapeutic potential of MSC secretome in stroke treatment, highlighting the importance of exploring alternative approaches. Future research directions include elucidating the precise mechanisms of action, optimizing treatment protocols, and translating preclinical findings into clinical practice for improved stroke outcomes.

New insights on the potential anti-epileptic effect of metformin: Mechanistic pathway

Epilepsy is a chronic neurological disease characterized by recurrent seizures. Epilepsy is observed as a well-controlled disease by anti-epileptic agents (AEAs) in about 69%. However, 30%-40% of epileptic patients fail to respond to conventional AEAs leading to an increase in the risk of brain structural injury and mortality. Therefore, adding some FDA-approved drugs that have an anti-seizure activity to the anti-epileptic regimen is logical. The anti-diabetic agent metformin has anti-seizure activity. Nevertheless, the underlying mechanism of the anti-seizure activity of metformin was not entirely clarified. Henceforward, the objective of this review was to exemplify the mechanistic role of metformin in epilepsy. Metformin has anti-seizure activity by triggering adenosine monophosphate-activated protein kinase (AMPK) signalling and inhibiting the mechanistic target of rapamycin (mTOR) pathways which are dysregulated in epilepsy. In addition, metformin improves the expression of brain-derived neurotrophic factor (BDNF) which has a neuroprotective effect. Hence, metformin via induction of BDNF can reduce seizure progression and severity. Consequently, increasing neuronal progranulin by metformin may explain the anti-seizure mechanism of metformin. Also, metformin reduces α-synuclein and increases protein phosphatase 2A (PPA2) with modulation of neuroinflammation. In conclusion, metformin might be an adjuvant with AEAs in the management of refractory epilepsy. Preclinical and clinical studies are warranted in this regard.

Metformin treatment and acute ischemic stroke outcomes in patients with type 2 diabetes: a retrospective cohort study

BACKGROUND AND PURPOSE

Preclinical studies have shown that metformin has neuroprotective actions in stroke. However, the optimal treatment timing and duration remain unknown. Herein, we examined the efficacy of metformin treatment on prognosis in acute ischemic stroke (AIS) patients, and assessed the optimal treatment timing and duration.

METHODS

AIS patients with type 2 diabetes mellitus were retrospectively enrolled. Patients were grouped into those who never received metformin (MET - group), those who received metformin continuously before stroke and after admission (pre-stroke + /post-stroke + group), those who only received metformin before stroke onset (pre-stroke + /post-stroke - group), and those who only received metformin after admission (pre-stroke - /post-stroke + group). The all MET + group represents the sum of the three metformin treatment groups. The efficacy outcome was the 90-day modified Rankin Scale (mRS) score.

RESULTS

In total, 309 eligible patients were included (MET - [N = 130], pre-stroke + /post-stroke + [N = 94], pre-stroke + /post-stroke - [N = 30], pre-stroke - /post-stroke + [N = 55]; all MET + [N = 179]). The all MET + group had a trend toward a lower 90-day mRS score compared with that in the MET - group (1 [0-2] vs 1 [0-3], unadjusted odds ratio [OR] = 0.652, P = 0.041; adjusted OR = 0.752, P = 0.218). In the three metformin treatment groups, only the pre-stroke + /post-stroke + group had a significantly lower 90-day mRS score (1 [0-1] vs 1 [0-3], adjusted OR = 0.497, 95%CI = 0.289-0.854; P = 0.011) and higher proportion of mRS score 0-1 (78.7% vs. 61.5%, adjusted OR = 2.278, 95%CI = 1.108-4.680; P = 0.025) than the MET - group.

CONCLUSION

AIS patients with type 2 diabetes mellitus who receive continuous metformin treatment before stroke onset and after admission have improved functional outcome at 90 days.

Metformin alleviates neurocognitive impairment in aging via activation of AMPK/BDNF/PI3K pathway

Slowing down age-related neurocognitive impairment has been a challenge. We evaluated the therapeutic effects of metformin in D-galactose-induced aging. Additionally, we studied the potential molecular mechanisms that could be responsible for metformin's anti-aging effects. Thirty male rats were equally divided into: 1-control group, which received saline solution, 2-D-galactose (D-gal) group, which received D-galactose (100 mg/kg/day) by gastric lavage for eight weeks, and 3-D-galactose + Metformin (D-gal + Met) treated group, which received D-galactose + metformin (200 mg/kg/day) by gastric lavage for eight weeks. Neurocognitive assessment was done. Measurement of inflammatory, oxidative stress, and BDNF biomarkers was performed. AMPK and PI3K genes expression were assessed. Hippocampal tissues were dissected for histopathological and immunohistochemical studies. D-gal resulted in neurocognitive impairments, elevation of inflammatory biomarkers, altered oxidative stress markers, decreased BDNF, decreased expression of synaptophysin and Bcl2 with increased expression of Caspase-3, and down-regulation of AMPK and PI3K genes. Neurodegenerative changes were present in the hippocampus. Metformin restored significantly D-gal induced neurodegenerative changes. We concluded that metformin could alleviate age-induced neurocognitive deficit via amelioration of neuroinflammation, attenuation of oxidative stress, reduction of apoptosis, as well as promotion of synaptic plasticity. These mechanisms could be mediated via the activation of the AMPK/BDNF/PI3K pathway.

Boosting amygdaloid GABAergic and neurotrophic machinery via dapagliflozin-enhanced LKB1/AMPK signaling in anxious demented rats

Anxiety is a neuropsychiatric disturbance that is commonly manifested in various dementia forms involving Alzheimer's disease (AD). The mechanisms underlying AD-associated anxiety haven't clearly recognized the role of energy metabolism in anxiety represented by the amygdala's autophagic sensors; liver kinase B1 (LKB1)/adenosine monophosphate kinase (AMPK). Dapagliflozin (DAPA), a SGLT2 inhibitor, acts as an autophagic activator through LKB1 activation in several diseases including AD. Herein, the propitious yet undetected anxiolytic potential of DAPA as an autophagic enhancer was investigated in AD animal model with emphasis on amygdala's GABAergic neurotransmission and brain-derived neurotrophic factor (BDNF). Alzheimer's disease was induced by ovariectomy (OVX) along with seventy-days-D-galactose (D-Gal) administration (150 mg/kg/day, i.p). On the 43rd day of D-Gal injection, OVX/D-Gal-subjected rats received DAPA (1 mg/kg/day, p.o) alone or with dorsomorphin the AMPK inhibitor (DORSO, 25 μg/rat, i.v.). In the amygdala, LKB1/AMPK were activated by DAPA inducing GABA_B2 receptor stimulation; an effect that was abrogated by DORSO. Dapagliflozin also replenished the amygdala GABA, NE, and 5-HT levels along with glutamate suppression. Moreover, DAPA triggered BDNF production with consequent activation of its receptor, TrkB through activating GABA_B2-related downstream phospholipase C/diacylglycerol/protein kinase C (PLC/DAG/PKC) signaling. This may promote GABA_A expression, verifying the crosstalk between GABA_A and GABA_B2. The DAPA's anxiolytic effect was visualized by improved behavioral traits in elevated plus maze together with amendment of amygdala' histopathological abnormalities. Thus, the present study highlighted DAPA's anxiolytic effect which was attributed to GABA_B2 activation and its function to induce BDNF/TrkB and GABA_A expression through PLC/DAG/PKC pathway in AMPK-dependent manner.

A Clinical Perspective of the Multifaceted Mechanism of Metformin in Diabetes, Infections, Cognitive Dysfunction, and Cancer

In type 2 diabetes, ecological and lifecourse factors may interact with the host microbiota to influence expression of his/her genomes causing perturbation of interconnecting biological pathways with diverse clinical course. Metformin is a plant-based or plant-derived medicinal product used for the treatment of type 2 diabetes for over 60 years and is an essential drug listed by the World Health Organization. By reducing mitochondrial oxidative phosphorylation and adenosine triphosphate (ATP) production, metformin increased AMP (adenosine monophosphate)-activated protein kinase (AMPK) activity and altered cellular redox state with reduced glucagon activity, endogenous glucose production, lipogenesis, and protein synthesis. Metformin modulated immune response by directly reducing neutrophil to lymphocyte ratio and improving the phagocytic function of immune cells. By increasing the relative abundance of mucin-producing and short-chain-fatty-acid-producing gut microbes, metformin further improved the host inflammatory and metabolic milieu. Experimentally, metformin promoted apoptosis and reduced proliferation of cancer cells by reducing their oxygen consumption and modulating the microenvironment. Both clinical and mechanistic studies support the pluripotent effects of metformin on reducing cardiovascular–renal events, infection, cancer, cognitive dysfunction, and all-cause death in type 2 diabetes, making this low-cost medication a fundamental therapy for individualization of other glucose-lowering drugs in type 2 diabetes. Further research into the effects of metformin on cognitive function, infection and cancer, especially in people without diabetes, will provide new insights into the therapeutic value of metformin in our pursuit of prevention and treatment of ageing-related as well as acute and chronic diseases beyond diabetes.

Mechanistic insight into the role of metformin in Alzheimer's disease

Alzheimer's disease (AD), a type of dementia, is characterized by progressive memory decline and cognition impairment. Despite the considerable body of evidence regarding AD pathophysiology, current therapies merely slow down the disease progression, and a comprehensive therapeutic approach is unavailable. Accordingly, finding an efficient multifunctional remedy is necessary to blunt the increasing rate of AD incidence in the upcoming years. AD shares pathophysiological similarities (e.g., impairment of cognitive functions, insulin sensitivity, and brain glucose metabolism) with noninsulin-dependent diabetes mellitus (NIDDM), which offers the utilization of metformin, a biguanide hypoglycemic agent, as an alternative therapeutic approach in AD therapy. Emerging evidence has revealed the impact of metformin in patients suffering from AD. It has been described that metformin employs multiple mechanisms to improve cognition and memory impairment in pre-clinical AD models, including reduction of hippocampal amyloid-beta (Aβ) plaque and neurofibrillary tangles (NFTs) load, suppression of inflammation, amelioration of mitochondrial dysfunction and oxidative stress, restriction of apoptotic neuronal death, and induction of neurogenesis. This review discusses the pre-clinical evidence, which may shed light on the role of metformin in AD and provide a more comprehensive mechanistic insight for future studies in this area of research.

Evaluation of the effects of metformin as adenosine monophosphate-activated protein kinase activator on spatial learning and memory in a rat model of multiple sclerosis disease

In patients with multiple sclerosis (MS) disease, cognitive deficits have been detected because of destruction of hippocampus. Cognitive impairment is one of the common signs in MS. Recent studies showed that metformin (Met) has wide-ranging effects in the treatment of diseases. Here, we have tried to study the preservative effects of Met as adenosine monophosphate-activated protein kinase (AMPK) activator on the hippocampus dentate gyrus (DG) neuronal firing pattern, motor coordination, and learning & memory loss following MS induction. The MS induction was done by local ethidium bromide (EB) injection into the rat hippocampus. Then, rats were treated with Met (200 mg/kg) for two weeks. Spatial memory and learning status were assessed using Morris water maze. A neuronal single-unit recording was measured from hippocampus DG. After decapitation, the bilateral hippocampi separated to measure malondialdehyde (MDA). Treatment with Met ameliorated latency times and path lengths (P < 0.05, P < 0.01, P < 0.001 in 1th, 2th, 3th and 4th days) in the Met + MS group respectively. The percent of total time spent in goal quarter and the average number of spikes/bin were decreased significantly in MS rats compared with the sham group (p < 0.001) but significantly increased in the metformin-treated MS group (Met + MS), (p < 0.01, p < 0.001). Met treatment in rats with MS significantly reduced the concentration of MDA, which is an indicator of lipid peroxidation compared to untreated groups. These observations show that increase of neuronal activity, sensory-motor coordination, and improvement of spatial memory in MS rats treated with Met appears via an increment of AMPK.

Highlighting the protective or degenerative role of AMPK activators in dementia experimental models

AMP-activated protein kinase (AMPK) is a serine/threonine kinase and a driving or deterrent factor in the development of neurodegenerative diseases and dementia. AMPK affects intracellular proteins like the mammalian target of rapamycin (mTOR). Peroxisome proliferator-activated receptor-γ coactivator 1-α (among others) contributes to a wide range of intracellular activities based on its downstream molecules such as energy balancing (ATP synthesis), extracellular inflammation, cell growth, and neuronal cell death (such as apoptosis, necrosis, and necroptosis). Several studies have looked at the dual role of AMPK in neurodegenerative diseases such as Parkinson's disease (PD), Alzheimer's disease (AD), and Huntington disease (HD) but the exact effect of this enzyme on dementia, stroke, and motor neuron dysfunction disorders has not been elucidated yet. In this article, we review current research on the effects of AMPK on the brain to give an overview of the relationship. More specifically, we review the neuroprotective or neurodegenerative effects of AMPK or AMPK activators like metformin, resveratrol, and 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside on neurological diseases and dementia, which exert through the intracellular molecules involved in neuronal survival or death.

Pretreatment with bisoprolol and vitamin E alone or in combination provides neuroprotection against cerebral ischemia/reperfusion injury in rats

Global cerebral ischemia/reperfusion (I/R) induces selective neuronal injury in the hippocampus, leading to severe impairment in behavior, learning, and memory functions. This study aimed to evaluate the neuroprotective effects of bisoprolol (biso) and vitamin E (vit E) treatment alone or in combination on cerebral ischemia/reperfusion (I/R) injury. A total of 30 male rats were divided randomly into five groups (n = 6), sham, I/R, I/R + biso, I/R + vit E, and I/R + biso+vit E. Cerebral I/R group underwent global ischemia by bilateral common carotid artery occlusion for 20 min. Treatment groups received drugs once daily intraperitoneally for 7 days before the I/R induction. Locomotive and cognitive behaviors were utilized by open-field and Morris water maze tests. After behavioral testing, the brain was removed and processed to evaluate cerebral infarct size, histopathologic changes, myeloperoxidase (MPO) activity, and malondialdehyde (MDA) level. In I/R group tissue MDA and MPO levels and cerebral infarct size were significantly increased in comparison with the sham group. Furthermore, significant deficits were observed in locomotion and spatial memory after I/R. The areas of cerebral infarction, MPO, and MDA levels in biso, vit E, and combination group were significantly reduced compared with I/R group. Histopathological analysis demonstrated a significant reduction in leukocyte infiltration in all treated groups with the most profound reduction in the combination group. According to the behavioral tests, administration of biso and/or vit E protected locomotive ability and improved spatial memory after cerebral I/R. Our findings show that biso and vit E have beneficial effects against the I/R injury and due to their synergistic effects when administered in combination, may have a more pronounced protective effect on the cerebral I/R injury.

Repurposing metformin to treat age-related neurodegenerative disorders and ischemic stroke

Aging is a risk factor for major central nervous system (CNS) disorders. More specifically, aging can be inked to neurodegenerative diseases (NDs) because of its deteriorating impact on neurovascular unit (NVU). Metformin, a first line FDA-approved anti-diabetic drug, has gained increasing interest among researchers for its role in improving aging-related neurodegenerative disorders. Additionally, numerous studies have illustrated metformin's role in ischemic stroke, a cerebrovascular disorder in which the NVU becomes dysfunctional which can lead to permanent life-threatening disabilities. Considering metformin's beneficial preclinical actions on various disorders, and the drug's role in alleviating severity of these conditions through involvement in commonly characterized cellular pathways, we discuss the potential of metformin as a suitable drug candidate for repurposing in CNS disorders.

Blood-Brain Barrier Damage in Ischemic Stroke and Its Regulation by Endothelial Mechanotransduction

Ischemic stroke, a major cause of mortality in the United States, often contributes to disruption of the blood-brain barrier (BBB). The BBB along with its supportive cells, collectively referred to as the “neurovascular unit,” is the brain’s multicellular microvasculature that bi-directionally regulates the transport of blood, ions, oxygen, and cells from the circulation into the brain. It is thus vital for the maintenance of central nervous system homeostasis. BBB disruption, which is associated with the altered expression of tight junction proteins and BBB transporters, is believed to exacerbate brain injury caused by ischemic stroke and limits the therapeutic potential of current clinical therapies, such as recombinant tissue plasminogen activator. Accumulating evidence suggests that endothelial mechanobiology, the conversion of mechanical forces into biochemical signals, helps regulate function of the peripheral vasculature and may similarly maintain BBB integrity. For example, the endothelial glycocalyx (GCX), a glycoprotein-proteoglycan layer extending into the lumen of bloods vessel, is abundantly expressed on endothelial cells of the BBB and has been shown to regulate BBB permeability. In this review, we will focus on our understanding of the mechanisms underlying BBB damage after ischemic stroke, highlighting current and potential future novel pharmacological strategies for BBB protection and recovery. Finally, we will address the current knowledge of endothelial mechanotransduction in BBB maintenance, specifically focusing on a potential role of the endothelial GCX.

Activation of AMPK/aPKCζ/CREB pathway by metformin is associated with upregulation of GDNF and dopamine

Parkinson's disease (PD) is the second most common neurodegenerative disease, which is characterized by the progressive loss of dopaminergic neurons in the substantia nigra, leading to a decrease in striatal dopamine. There is no antiparkinsonian therapy that offers a true disease-modifying treatment till date and there is an urgent need for a safe and effective neuroprotective or neurorestorative therapy. Our previous study demonstrated that metformin upregulated dopamine in the mouse brain and provided significant neuroprotection in animal model of PD. Therefore, we designed this study to investigate the molecular mechanism underlying such pharmacological effect of metformin. Herein, we found that metformin enhanced the phosphorylation of tyrosine hydroxylase (TH) which was accompanied by increase in brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), and activation of their downstream signaling pathways in the mouse brain and SH-SY5Y cells. We further investigated the role of the neurotrophic factors in the activation of TH and observed that both BDNF and GDNF-induction were essential for metformin-induced TH activation. We found that the AMPK/aPKCζ/CREB pathway was essential for metformin-induced GDNF upregulation and TH activation. Thus, this study reveals the TH-activating property of metformin in the brain via induction of neurotrophic factors along with the signaling mechanism. These results potentiate the candidacy of metformin not only as a neuroprotective agent, but also as restorative therapy for the treatment of PD.

Long-term metformin therapy improves neurobehavioral functions and antioxidative activity after cerebral ischemia/reperfusion injury in rats

Metformin (MET),an antidiabetic drug, has shown antioxidative and neuroprotective effects. In the present investigation, we aimed to study the probable effects of MET on cerebral ischemia/reperfusion in rats. Rats underwent cerebral ischemia/reperfusion and MET was administered orally at doses of 100 and 200 mg/kg for 56 days. Anxiety- and depressive-like behaviors were evaluated by elevated plus-maze or forced swimming tests, respectively. was assessed by. Cognitive functions were assessed by Y-maze continuous alternation task and morris water maze. The activity of SOD and the level of BDNF were measured in brains samples. Our results showed that administration of 200 mg/kg MET reduced the percent of brain edema (84.00 ± 2.13) in comparison with the ischemic animals (91.25 ± 2.25) (p < 0.05). Administration of 200 mg/kg MET in ischemic animals improved anxiety-like behavior by increasing the percentage of the open arms entries (46.51 ± 3.13) and the percentage of the open arms time (32.70 ± 2.49) in comparison with the cerebral ischemia group (26.35 ± 7.02 and 15.32 ± 5.78, respectively) (all p < 0.001). MET treatment (200 mg/kg) increased the cognition index of correct alternations (90.20 ± 4.95) in comparison with the cerebral ischemia group (59.50 ± 8.01) (p < 0.05). MET at the both doses reduced escape latency compared to the cerebral ischemia animals (all p < 0.05). In addition, 200 mg/kg MET increased the time spent in the target quadrant (16.06 ± 0.58) in comparison with the ischemic animals (9.84 ± 0.92) (p < 0.001) and the both doses of the drug increased the number of crossing (5.42 ± 0.36 and 6.5 ± 0.42, respectively) compared to the cerebral ischemia group (3.75 ± 0.31) (p < 0.05 and p < 0.001, respectively). Moreover, 200 mg/kg MET reduced the immobility time (47.50 ± 9.00) in comparison with the cerebral ischemia group (93.43 ± 8.28) (p < 0.001). Furthermore, the both doses of MET increased the BDNF levels (4590 ± 197.6 and 4767 ± 44.10, respectively) in comparison with the ischemic animals (3807 ± 42.56) (p < 0.01 and p < 0.001, respectively). Also, the both doses of the drug increased the SOD activity of brain (52.67 ± 0.33 and 55.00 ± 0.57, respectively) compared to the ischemic animals (49.33 ± 0.33) (p < 0.01 and p < 0.001, respectively). Based on our data, long-term MET therapy may improve behavioral disorders following cerebral ischemia/reperfusion and can be considered as a novel therapeutic approach for the treatment of brain ischemic conditions.

The Modulatory Effect of Metformin on Ethanol-Induced Anxiety, Redox Imbalance, and Extracellular Matrix Levels in the Brains of Wistar Rats

The study investigated the potential neuroprotective effects of metformin (MET) on alcohol-induced neurotoxicity in adult Wistar rats. The animals were randomized in four groups (n = 10): control, alcohol (ALC), ALC + MET, and MET. ALC (2 g/kg b.w.) and MET (200 mg/kg b.w.) were orally administered for 21 days, once daily. For the ALC + MET group, MET was administered 2 h after ALC treatment. On day 22, the open field test (OFT) and elevated plus maze (EPM) were performed. MET improved global activity and increased the time spent in unprotected open arms, decreased oxidative stress, both in the frontal lobe and in the hippocampus, and increased neuroglobin expression in the frontal cortex. Histopathologically, an increased neurosecretory activity in the frontal cortex in the ALC + MET group was noticed. Thus, our findings suggest that metformin has antioxidant and anxiolytic effects and may partially reverse the neurotoxic effects induced by ethanol.

Could metformin be therapeutically useful in Huntington's disease?

Emerging evidence suggest that dimethylbiguanide (metformin), a first-line drug for type 2 diabetes mellitus, could be neuroprotective in a range of brain pathologies, which include neurodegenerative diseases and brain injury. However, there are also contraindications that associate metformin treatment with cognitive impairment as well as adverse outcomes in Alzheimer's disease and Parkinson's disease animal models. Recently, a beneficial effect of metformin in animal models of Huntington's disease (HD) has been strengthened by multiple reports. In this brief review, the findings associated with the effects of metformin in attenuating neurodegenerative diseases are discussed, focusing on HD-associated pathology and the potential underlying mechanisms highlighted by these studies. The mechanism of action of metformin is complex, and its therapeutic efficacy is therefore expected to be dependent on the disease context. The key metabolic pathways that are effectively affected by metformin, such as AMP-activated protein kinase activation, may be altered in the later decades of the human lifespan. In this regard, metformin may nonetheless be therapeutically useful for neurological diseases with early pathological onsets, such as HD.

Effects of metformin on recognition memory and hippocampal neuroplasticity in rats with metabolic syndrome

Metabolic syndrome (MS) is a health problem that is characterized by body fat accumulation, hypertension, dyslipidemia, and hyperglycemia; recently, it has been demonstrated that MS also damages memory processes. The first-line drug in the treatment of MS and type 2 diabetes mellitus is metformin, which is an antihyperglycemic agent. This drug has been shown to produce neuroprotection and to improve memory processes. However, the mechanism involved in this neuroprotection is unknown. A 90-day administration of metformin improved the cognitive processes of rats with MS as evaluated by the novel object recognition test, and this finding could be explained by an increase in the neuronal spine density and spine length. We also found that metformin increased the immunoreactivity of synaptophysin, sirtuin-1, AMP-activated protein kinase, and brain-derived neuronal factor, which are important plasticity markers. We conclude that metformin is an important therapeutic agent that increases neural plasticity and protects cognitive processes. The use of this drug is important in the minimization of the damage caused by MS.

Metformin and cognition from the perspectives of sex, age, and disease

Metformin is the safest and the most widely prescribed first-line therapy for managing hyperglycemia due to different underlying causes, primarily type 2 diabetes mellitus. In addition to its euglycemic properties, metformin has stimulated a wave of clinical trials to investigate benefits on aging-related diseases and longevity. Such an impact on the lifespan extension would undoubtedly expand the therapeutic utility of metformin regardless of glycemic status. However, there is a scarcity of studies evaluating whether metformin has differential cognitive effects across age, sex, glycemic status, metformin dose, and duration of metformin treatment and associated pathological conditions. By scrutinizing the available literature on animal and human studies for metformin and brain function, we expect to shed light on the potential impact of metformin on cognition across age, sex, and pathological conditions. This review aims to provide readers with a broader insight of (a) how metformin differentially affects cognition and (b) why there is a need for more translational and clinical studies examining multifactorial interactions. The outcomes of such comprehensive studies will streamline precision medicine practices, avoiding "fit for all" approach, and optimizing metformin use for longevity benefit irrespective of hyperglycemia.

Neuromodulatory effects of anti-diabetes medications: A mechanistic review

Diabetes mellitus is a potent upstream event in the molecular pathophysiology which gives rise to various diabetes-related complications. There are several classes of anti-diabetic medications that have been developed to normalize blood glucose concentrations through a variety of molecular mechanisms. Beyond glucose-lowering effects, these agents may also provide further therapeutic potential. For instance, there is a high incidence of diabetes-induced neuronal disorders among patients with diabetes, who may also develop neurodegenerative and psychological complications. If anti-diabetic agents can modify the molecular mechanisms involved in the pathophysiology of neuronal comorbidities, this could potentially be translated to reducing the risk of other neurological conditions such as Alzheimer's disease, Parkinson's disease, depression, memory deficits and cognition impairments among patients with diabetes. This review aimed to shed light on some of the potentially beneficial aspects of anti-diabetic agents in lowering the risk or treating neuronal disorders by reviewing the molecular mechanisms by which these agents can potentially modulate neuronal behaviors.

Metformin-induced AMPK activation stimulates remyelination through induction of neurotrophic factors, downregulation of NogoA and recruitment of Olig2+ precursor cells in the cuprizone murine model of multiple sclerosis

PURPOSE

Oligodendrocytes (OLGs) damage and myelin distraction is considered as a critical step in many neurological disorders especially multiple sclerosis (MS). Cuprizone (cup) animal model of MS targets OLGs degeneration and frequently used to the mechanistic understanding of de- and remyelination. The aim of this study was exploring the effects of metformin on the OLGs regeneration, myelin repair and profile of neurotrophic factors in the mice brain after cup-induced acute demyelination.

METHODS

Mice (C57BL/6 J) were fed with chow containing 0.2% cup for 5 weeks to induce specific OLGs degeneration and acute demyelination. Next, the cup was withdrawn to allow one-week recovery (spontaneous remyelination). At the end of this period, mature OLGs markers, myelin-associated neurite outgrowth inhibitor protein A (NogoA), premature specific OLGs transcription factor (Olig2), anti-apoptosis marker (survivin), neurotrophic factors, and AMPK activation were monitored in the presence or absence of metformin (50 mg/kg body weight/day) in the corpus callosum (CC).

RESULTS

Our finding indicated that consumption of metformin during the recovery period potentially induced an active form of AMPK (p-AMPK) and promoted repopulation of mature OLGs (MOG⁺ cells, MBP⁺ cells) in CC through up-regulation of BDNF, CNTF, and NGF as well as down-regulation of NogoA and recruitment of Olig2⁺ precursor cells.

CONCLUSIONS

This study for the first time reveals that metformin-induced AMPK, a master regulator of energy homeostasis, activation following toxic demyelination could potentially accelerate regeneration and supports spontaneous demyelination. These findings suggest the development of new therapeutic strategies based on AMPK activation for MS in the near future. Graphical abstract An overview of the possible molecular mechanisms of action of metformin-mediated remyelinationa.

Would Colloidal Gold Nanocarriers Present An Effective Diagnosis Or Treatment For Ischemic Stroke?

INTRODUCTION

This study was conducted to evaluate OX26-PEG-coated gold nanoparticles (GNPs) (OX26@GNPs) as a novel targeted nanoparticulate system on cell survival after ischemic stroke.

MATERIALS AND METHODS

Dynamic light scattering (DLS), zeta sizer, and transmission electron microscopy (TEM) were performed to characterize the OX26@GNPs. The effect of OX26@GNPs on infarct volume, neuronal loss, and necroptosis was evaluated 24 h after reperfusion using 2, 3,5-Triphenyltetrazolium chloride (TTC) staining, Nissl staining and Western blot assay, respectively.

RESULTS

Conjugation of OX26-PEG to the surface of the 25 nm colloidal gold particles increased their size to 32±2 nm, while a zeta potential change of -40.4 to 3.40 mV remarkably increased the stability of the nanoparticles. Most importantly, OX26@GNPs significantly increased the infarcted brain tissue, while bare GNPs and PEGylated GNPs had no effect on the infarct volume. However, our results indicated an extension of necroptotic cell death, followed by cell membrane damage.

CONCLUSION

Collectively, our results showed that the presently formulated OX26@GNPs are not suitable nanocarriers nor contrast agents under oxidative stress for the diagnosis and treatment of ischemic stroke. Moreover, our findings suggest that the cytotoxicity of GNPs in the brain is significantly associated with their surface charge.

The influence of chromosome 4 on metabolism and spatial memory in SHR and SLA16 rat strains

The Spontaneously Hypertensive Rat (SHR) has been proposed as a good model to study the pathways related to neurodegenerative diseases and glucose intolerance. Our research group developed the SLA16 (SHR.LEW-Anxrr16) congenic strain, which is genetically identical to the SHR strain, except for a locus on chromosome 4 (DGR). We applied in silico analysis on DGR to evaluate the association of their genes with neurobiological and metabolic pathways. After, we characterized cholesterol, triglycerides, metabolism of glucose and the behavioral performance of young (2 months old) and adult (8 months old) SHR and SLA16 rats in the open field, object location and water maze tasks. Finally, naïve young rats were repeatedly treated with metformin (200 mg/kg; v.o.) and evaluated in the same tests. Bioinformatics analysis showed that DGR presents genes related to glucose metabolism, oxidative damage and neurodegenerative diseases. Young SLA16 presented higher cholesterol, triglycerides, glucose and locomotion in the open field than SHR rats. In adulthood, SLA16 rats presented high triglycerides and locomotion in the open field and impairment on spatial learning and memory. Finally, the treatment with metformin decreased the glucose tolerance curve and also improved long-term memory in SLA16 rats. These results indicate that DGR presents genes associated with metabolic pathways and neurobiological processes that may produce alterations in glucose metabolism and spatial learning/memory. Therefore, we suggest that SHR and SLA16 strains could be important for the study of genes and subsequent mechanisms that produce metabolic glucose alterations and age-related cognitive deficits.

Pro-neurocognitive and anti-sarcopenic benefits of one-year metformin therapy in ovariectomized aged mice

Health promotion and healthy nutrition significantly increased life expectancy around the world. Aging is associated with an increase in age-related diseases. The use of metformin (Met) as an anti-aging drug has recently been proposed based on its widespread use in clinical practice. Reports have shown that Met acts as an anti-aging agent. In this study, the effects of long-term, 1 year, Met administration on aging-related behaviors and longevity in ovariectomized mice was studied. Met (1 and 10 mg/kg, daily) was administered orally in ovariectomized mice. The anxiety-like behavior, working memory, and physical strength were measured through elevated plus maze, Y-maze, vertical grid holding, and the obligatory swimming capacity tests. Brains were harvested to measure brain-derived neurotrophic factor (BDNF) level. Also, the Kaplan-Meier survival curves were used to show differences and similarities in survival patterns. Met (10 mg/kg) decreased anxiety-like behaviors as well as increased muscle strength and working memory in the ovariectomized mice. Moreover, Met increased the physical strength and longevity as well as the level of BDNF in the ovariectomized mice. Our results indicate that Met administration can be an effective strategy for having a healthy aging in the absence of female gonadal hormones and reverses deleterious effects of ovariectomy-induced aging possibly through BDNF.

Envisioning the neuroprotective effect of Metformin in experimental epilepsy: A portrait of molecular crosstalk

Epilepsy is a neurological disorder characterized by an enduring predisposition to generate and aggravate epileptic seizures affecting around 1% of global population making it a serious health concern. Despite the recent advances in epilepsy research, no disease-modifying treatment able to terminate epileptogenesis have been reported yet reflecting the complexity in understanding the disease pathogenesis. To overcome the current treatment gap against epilepsy, one effective approach is to explore anti-epileptic effects from a drug that are approved to treat non-epileptic diseases. In this regard, Metformin emerged as an ideal candidate which is a first line treatment option for type 2 diabetes mellitus (T2DM), has conferred neuroprotection in several in vivo neurological disorders such as Alzheimer's diseases (AD), Parkinson's disease (PD), Stroke, Huntington's diseases (HD) including epilepsy. In addition, Metformin has ameliorated cognitive alteration, learning and memory induced by epilepsy as well as in animal model of AD. Herein, we review the promising findings demonstrated upon Metformin treatment against animal model of epilepsy however, the precise underlying mechanism of anti-epileptic potential of Metformin is not well understood. However, there is a growing understanding that Metformin demonstrates its anti-epileptic effect mainly via ameliorating brain oxidative damage, activation of AMPK, inhibition of mTOR pathway, downregulation of α-synuclein, reducing apoptosis, downregulation of BDNF and TrkB level. These reflects that Metformin being non-anti-epileptic drug (AED) has a potential to ameliorate the cellular pathways that were impaired in epilepsy reflecting its therapeutical potential against epileptic seizure that might plausibly overcome the limitations of today epilepsy treatment.

The beneficial roles of metformin on the brain with cerebral ischaemia/reperfusion injury

Cerebral ischaemia/reperfusion (I/R) injury is the transient loss, followed by rapid return, of blood flow to the brain. This condition is often caused by strokes and heart attacks. The underlying mechanisms resulting in brain damage during cerebral I/R injury include mitochondrial dysregulation, increased oxidative stress/reactive oxygen species, blood-brain-barrier breakdown, inflammation of the brain, and increased neuronal apoptosis. Metformin is the first-line antidiabetic drug which has recently been shown to be capable of acting through the aforementioned pathways to improve recovery following cerebral I/R injury. However, some studies have suggested that metformin therapy may have no effect or even worsen recovery following cerebral I/R injury. The present review will compile and examine the available in vivo, in vitro, and clinical data concerning the neuroprotective effects of metformin following cerebral I/R injury. Any contradictory evidence will also be assessed and presented to determine the actual effectiveness of metformin treatment in stroke recovery.

Targeting necroptotic cell death pathway by high-intensity interval training (HIIT) decreases development of post-ischemic adverse remodelling after myocardial ischemia / reperfusion injury

Regulated necrosis (necroptosis) plays a pivotal role in the extent of cardiomyocyte loss and the development of post-ischemic adverse remodelling and cardiac dysfunction following myocardial I/R injury. Although HIIT has been reported to give rise to cardioprotection against MI, but the detailed knowledge of its molecular targets for treatment of MI is still not available. The LAD of Male Wistar rats was occluded to induce MI for 30 min and reperfusion for eight weeks. We investigated the effect of long-term HIIT for eight weeks on lipid peroxidation, SOD activity and GSH content using ELISA assay. Cardiac function, fibrosis, and infarct size were assessed by echocardiography, Masson's trichrome and Evans Blue/TTC dual staining respectively. The expressions of gene markers of myocardial hypertrophy, fibrosis and key mediators of necroptosis were measured using RT-PCR and western blotting assay respectively. The results indicated that HIIT reduced lipid peroxidation, infarct size and improved endogenous antioxidant system and heart function. Significant decreases in mRNA levels of procollagen α1(I), α1(III), and fibronectin1were observed following HIIT. Moreover, that HIIT significantly decreased the expression of key mediators of necroptosis induced by MI (P < 0.05). There were no significant differences in β-MHC mRNA level in different groups. The findings of study suggest that HIIT might exert cardioprotective effects against post-ischemic adverse remodeling through targeting necroptosis process. Likewise, cardioprotective effects of HIIT in coping with myocardial I/R injury may be associated with RIP1-RIP3-MLKL axis. These findings establish a critical foundation for higher efficiency of exercise-based cardiac rehabilitation post-MI and future research.

Metformin exerts antidepressant effects by regulated DNA hydroxymethylation

Aim: We aim to study the antidepressant mechanism of metformin. Materials & methods: Tail suspension test and forced swimming test were used to detect the depression-like behavior; the expressions of target protein were examined by western blot; the levels of target genes were tested by quantitative PCR; the content of α-ketoglutarate and 5hmC were detected by ELISA kit. Results: We showed that metformin can improve the depression-like behavior in spatial restraint stress model; then we found that metformin through AMPK/Tet2 pathway increasing the expression of BDNF to antidepression. Conclusion: Our study provided evidences that metformin plays a role of antidepressant effects through the AMPK/Tet2/BDNF pathway.

Serum levels of interleukin-6, interleukin-8, interleukin-10, and tumor necrosis factor-α, renal function biochemical parameters and clinical outcomes in pediatric cardiopulmonary bypass surgery

BACKGROUND

Cardiopulmonary bypass causes detrimental effects on remote organs due to inflammatory response. One of these organs is kidney that is frequently affected by cardiac surgery. Acute kidney injury is a post-cardiopulmonary bypass complication, which may result in increased post-operative morbidity and mortality. Post-cardiopulmonary bypass inflammatory response may contribute to remote organ dysfunction. In the present study, we investigated the relation between cytokines including interleukin-6, interleukin-8, interleukin-10, and tumor necrosis factor-α, and renal function tests such as creatinine and blood urea nitrogen (BUN).

METHODS

In total, 91 patients between the ages of 4 and 60 months were enrolled for elective cardiac surgery with cardiopulmonary bypass after informed consent. Data regarding renal function tests and clinical outcomes were carefully recorded until 24 hours after admission to intensive care unit and analyzed.

RESULTS

Our findings support that there is a direct correlation between cytokines including interleukin-6, interleukin-8, interleukin-10, and tumor necrosis factor-α and cardiopulmonary bypass time, duration of operation, and intensive care unit stay. Longer cardiopulmonary bypass time was associated with higher interleukin-8 at cross-clamp removal and 24 hours post- intensive care unit as well as higher interleukin-10 at declamp time. Higher interleukin-6 at declamp time was directly correlated with higher post-operative BUN. Interleukin-8 level after anesthesia induction was directly correlated with intensive care unit stay duration. Higher blood interleukin-6 and tumor necrosis factor-α levels following 24 hours of admission to intensive care unit were associated with longer mechanical ventilation time.

CONCLUSION

Higher circulatory pro-inflammatory cytokine level is associated with adverse outcomes such as increased intensive care unit stay and longer mechanical ventilation time in pediatric patients. It is also correlated with unfavorable biochemical parameter of renal function, BUN. Findings hint that proper control of the inflammatory response is vital for the control of unfavorable clinical and pathological outcomes.

Selenium nanoparticles for targeted stroke therapy through modulation of inflammatory and metabolic signaling

Ischemic cerebral stroke is a major cause of death and morbidity. Currently, no neuroprotective agents have been shown to impact the clinical outcomes in cerebral stroke cases. Here, we report therapeutic effects of Se nanoparticles on ischemic stroke in a murine model. Anti-transferrin receptor monoclonal antibody (OX26)-PEGylated Se nanoparticles (OX26-PEG-Se NPs) were designed and synthesized and their neuroprotective effects were measured using in vitro and in vivo approaches. We demonstrate that administration of the biodegradable nanoparticles leads to resolution of brain edema, protection of axons in hippocampus region, and myelination of hippocampal area after cerebral ischemic stroke. Our nanoparticle design ensures efficient targeting and minimal side effects. Hematological and biochemical analyses revealed no undesired NP-induced changes. To gain mechanistic insights into the therapeutic effects of these particles, we characterized the changes to the relevant inflammatory and metabolic signaling pathways. We assessed metabolic regulator mTOR and related signaling pathways such as hippo, Ubiquitin-proteasome system (ERK5), Tsc1/Tsc2 complex, FoxO1, wnt/β-catenine signaling pathway. Moreover, we examined the activity of jak2/stat3 signaling pathways and Adamts1, which are critically involved in inflammation. Together, our study provides a promising treatment strategy for cerebral stroke based on Se NP induced suppression of excessive inflammation and oxidative metabolism.

Hesperidin improves the follicular development in 3D culture of isolated preantral ovarian follicles of mice

IMPACT STATEMENT

It has been stated that hesperidin has many pharmacological effects, such as anti-inflammatory and antioxidant effects, antimicrobial activity, and anti-carcinogenic activity; but hesperidin and its derivatives have been under investigation as anti-fertility factors for a very long time. However, our results show that hesperidin can improve mice follicular growth and maturation during in vitro 3D culture. Hesperidin as an antioxidant factor could enhance the mRNA expression levels of two important genes involved in folliculogenesis, PCNA, and FSH-R. Our results prove for the first time that hesperidin not only has deleterious effects on follicular development but can also increase rates of in vitro fertilization and embryo development.

Mesenchymal stem cells from human amniotic membrane differentiate into cardiomyocytes and endothelial-like cells without improving cardiac function after surgical administration in rat model of chronic heart failure

Introduction: Human amnion-derived mesenchymal stem cells (hAMSCs) have been used in the treatment of acute myocardial infarction. In the current study, we investigated the efficacy of hAMSCs for the treatment of chronic model of myocardial ischemia and heart failure (HF) in rats. Methods: Male Wistar rats weighing between 250 to 350 g were randomized into three groups: sham, HF control and HF+hAMSCs. For HF induction, animals were anesthetized and underwent left anterior descending artery ligation. In HF+hAMSCs group, 2×106 cells were injected into the left ventricular muscle four weeks post ischemia in the border zone of the ischemic area. Cardiac function was studied using echocardiography. Masson's trichrome staining was used for studying tissue fibrosis. Cells were transduced with green fluorescent protein (GFP) coding lentiviral vector. Immunohistochemistry was used for detecting GFP, vascular-endothelial growth factor (VEGF) and troponin T markers in the tissue sections. Results: Assessment of the cardiac function revealed no improvement in the myocardial function compared to the control HF group. Moreover, tissue fibrosis was similar in two groups. Immunohistochemical study revealed the homing of the injected hAMSCs to the myocardium. Cells were stained positive for VEGF and troponin T markers. Conclusion: injection of hAMSCs 4 weeks after ischemia does not improve cardiac function and cardiac muscle fibrosis, although the cells show markers of differentiation into vascular endothelial cells and cardiomyocytes. In sum, it appears that hAMSCs are effective in the early phases of myocardial ischemia and does not offer a significant advantage in patients with chronic HF.

Combined Fluoxetine and Metformin Treatment Potentiates Antidepressant Efficacy Increasing IGF2 Expression in the Dorsal Hippocampus

An increasing number of studies show that selective serotonin reuptake inhibitors (SSRIs) exert their therapeutic action, at least in part, by amplifying the influence of the living environment on mood. As a consequence, when administered in a favorable environment, SSRIs lead to a reduction of symptoms, but in stressful conditions, they show limited efficacy. Therefore, novel therapeutic approaches able to neutralize the influence of the stressful environment on treatment are needed. The aim of our study was to test whether, in a mouse model of depression, the combined administration of SSRI fluoxetine and metformin, a drug able to improve the metabolic profile, counteracts the limited efficacy of fluoxetine alone when administered in stressful conditions. Indeed, metabolic alterations are associated to both the onset of major depression and the antidepressant efficacy. To this goal, adult C57BL/6 male mice were exposed to stress for 6 weeks; the first two weeks was aimed at generating a mouse model of depression. During the remaining 4 weeks, mice received one of the following treatments: vehicle, fluoxetine, metformin, or a combination of fluoxetine and metformin. We measured liking- and wanting-type anhedonia as behavioral phenotypes of depression and assessed the expression levels of selected genes involved in major depressive disorder and antidepressant response in the dorsal and ventral hippocampus, which are differently involved in the depressive symptomatology. The combined treatment was more effective than fluoxetine alone in ameliorating the depressive phenotype after one week of treatment. This was associated to an increase in IGF2 mRNA expression and enhanced long-term potentiation, specifically in the dorsal hippocampus, at the end of treatment. Overall, the present results show that, when administered in stressful conditions, the combined fluoxetine and metformin treatment may represent a more effective approach than fluoxetine alone in a short term. Finally, our findings highlight the relevance of polypharmacological strategy as effective interventions to increase the efficacy of the antidepressant drugs currently available.

Three-Dimensional Graphene Foams: Synthesis, Properties, Biocompatibility, Biodegradability, and Applications in Tissue Engineering

Presently, clinical nanomedicine and nanobiotechnology have impressively demanded the generation of new organic/inorganic analogues of graphene (as one of the intriguing biomedical research targets) for stem-cell-based tissue engineering. Among different shapes of graphene, three-dimensional (3D) graphene foams (GFs) are highly promising candidates to provide conditions for mimicking in vivo environments, affording effective cell attachment, proliferation,and differentiation due to their unique properties. These include the highest biocompatibility among nanostructures, high surface-to-volume ratio, 3D porous structure (to provide a homogeneous/isotropic growth of tissues), highly favorable mechanical characteristics, and rapid mass and electron transport kinetics (which are required for chemical/physical stimulation of differentiated cells). This review aims to describe recent and rapid advances in the fabrication of 3D GFs, together with their use in tissue engineering and regenerative nanomedicine applications. Moreover, we have summarized a broad range of recent studies about the behaviors, biocompatibility/toxicity,and biodegradability of these materials, both in vitro and in vivo. Finally, the highlights and challenges of these 3D porous structures, compared to the current polymeric scaffold competitors, are discussed.

Lavender oil (Lavandula angustifolia) attenuates renal ischemia/reperfusion injury in rats through suppression of inflammation, oxidative stress and apoptosis

Renal ischemia/reperfusion (I/R) injury following kidney transplantation has been found to be a great clinical problem owing to initiation of acute inflammatory responses and subsequently rapid loss of kidney function. It is well known that lavender oil exhibits an extensive spectrum of pharmacological and biochemical activities. The purpose of this study was to clarify molecular targets of lavender in treatment of this disease. Male Wistar rats weighing 200-250 g were divided into three major groups: sham, I/R, and I/R + different doses of lavender oil (L1:50 mg/kg, L2: 100 mg/kg, and L3: 200 mg/kg). A rat model of renal I/R (45 min ischemia and 24 h reperfusion) was created and lavender was administrated at 1 h after the beginning of reperfusion (i.p). Activities of antioxidant enzymes such as SOD, GPX, and CAT, and lipid peroxidation were evaluated. The expression of inflammatory cytokines such as TNFα, IL1β, and IL10 was determined by IHC and ELISA assay. Apoptosis activity and tissue damage were evaluated by TUNEL and H & E staining, respectively. Our results showed that lavender oil markedly restored activities of antioxidant enzymes and reduced lipid peroxidation (P < 0.05). Lavender significantly decreased levels of TNFα and IL1β and increased level of IL10 in a dose-dependent manner (P < 0.05). Lavender reduced TUNEL positive cells in a dose-dependent manner. However, lavender reduced damage to peritubular capillaries and contributed to preservation of normal morphology of renal cells. In sum, our findings establish a fundamental foundation for future drug industry to decrease the rates of rejection in kidney transplant patients.

The effect of the anti-diabetic drug metformin on behavioral manifestations associated with ovariectomy in mice

The aim of this study was to evaluate the anti-diabetic drug metformin (Met) effects on the anxiety and cognitive impairment in ovariectomized mice. Thirty-two female adult mice were distributed into four groups: control, sham ovariectomy, ovariectomy + Met 7 mg/kg and ovariectomy + Met 15 mg/kg. The vaginal cytology was used to confirm the ovariectomy surgery. Anxiety was monitored using elevated plus maze test and cognitive function was assessed by novel object recognition task. Animal's brains were analyzed for the brain-derived neurotrophic factor (BDNF). Our results demonstrated that ovariectomy caused cognitive impairments and anxiety, as well as decreased BDNF levels. Moreover, administration of Met improves ovariectomy-related disorders such as cognitive impairments and anxiety, as well as increased BDNF levels. The results of the present study suggest that Met could be used as a novel therapeutic strategy for the treatment of ovariectomy-related conditions.

The protective effect of betulinic acid on microvascular responsivity and protein expression in alzheimer disease induced by cerebral micro-injection of beta-amyloid and streptozotocin

OBJECTIVE

Alzheimer's disease (AD) is mainly caused by accumulation of β-amyloid (Aβ) in vessels or parenchyma of the brain. Accordingly, natural compounds such as betulinic acid (BA) might improve the AD signs by increase in blood flow and through reduction in amyloid plaques.

METHODS

Intra-hippocampal injection of BA (0.2 and 0.4 μmol/L /10 μL DMSO /rat) was done at intervals of 180 and 10 min before co-microinjection of 0.1 μmol/L Aβ dissolved in PBS (5 μL/rat, hippocampi) and 1.5 mg/kg Streptozotocin dissolved in aCSF (10 μL/rat, lateral ventricles). Cerebro-vascular responsivity tested by Laser Doppler, BBB leakage, Elisa assays of cytokines (TNF-α and IL-10), and Western blot analysis of proteins (BDNF and AchE) in the hippocampus were assessed 1 month after the injections.

RESULTS

Microvascular reaction and BBB function were significantly impaired in AD rats, which were improved via BA pretreatment. BA could increase BDNF expression and decrease cytokine levels in the hippocampus of AD rats (especially 0.1 μmol/L Aβ: 0.4 μmol/L BA); however, no significant changes were detected in the blotting of AchE among the groups.

CONCLUSIONS

Betulinic acid could have a role in AD through protecting microcirculation, alleviating inflammation, and up-regulating BDNF expression which is clearer toward 1:4 molar ratios of Aβ to BA.

The membrane mesenchymal stem cell derived conditioned medium exerts neuroprotection against focal cerebral ischemia by targeting apoptosis

OBJECTIVE

The mesenchymal stem cells derived from human amniotic membrane have the ability to secrete and release some factors that can promote the repair of damaged tissues. This secretome contains proteins and factors that reduce apoptosis and increase angiogenesis in the ischemia/reperfusion models. The present study was conducted to determine whether this secretome provides protection against transient focal cerebral ischemia.

MATERIALS AND METHODS

A rat model of focal cerebral ischemia was established through middle cerebral artery occlusion (MCAO) for 60 min and 24 h reperfusion. The amniotic mesenchymal stem cells-conditioned medium (AMSC-CM) at the dose of 0.5 μl was injected intracerebroventriculary (ICV) 30 min after reperfusion. Infarct volume, brain edema, neurobehavioral functions, and blood brain barrier (BBB) integrity were assessed 24 h after reperfusion. Neuronal loss and expression of caspase-3, Bax and Bcl-2 in motor cortex were evaluated by nissl staining and immunohistochemistry assay respectively.

RESULTS

ICV administration of AMSC-CM markedly reduced infarct volume, brain edema and the evans blue penetration rate compared with MCAO group (P < 0.05). Additionally, post-treatment with AMSC-CM significantly reduced neuronal loss, neurological motor disorders and expression of caspase-3, Bax and Bcl-2 in motor cortex compared with MCAO group (P < 0.05).

CONCLUSION

The results of this study indicate that treatment with AMSC-CM improves the pathological effects in the acute phase of cerebral ischemia. These findings establish a substantial foundation for stroke therapy and future research.

Natural lavender oil (Lavandula angustifolia) exerts cardioprotective effects against myocardial infarction by targeting inflammation and oxidative stress

BACKGROUND

The study was conducted to examine therapeutic effects of lavender oil (LO) against myocardial infarction (MI) and its potential mechanisms.

METHODS

A rat model of MI was established and LO (100, 200 and 300 mg/kg) was intraperitoneally administrated immediately after ischemia. Anti-inflammatory and antioxidant activity of LO were evaluated by immunohistochemical assay and measurement of SOD, GSH, and MDA. The myocardial injury markers, apoptotic activity and infarct volume were examined by ELISA, TUNEL and TTC staining, respectively.

RESULTS

Compared with the control I/R-Vehicle, the expression of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) significantly reduced 8 h after reperfusion and expression of interleukin-10 (IL-10) elevated 48 h after reperfusion in LO-treated rats (P < 0.05). Likewise, significant decreases in apoptotic activity, infarct volume and significant restoration of antioxidant endogenous defenses were observed in LO-treated rats (P < 0.05).

CONCLUSION

Collectively, these findings confirm that LO can be a good candidate to reduce injury after MI.

Pre-Treatment with Metformin in Comparison with Post-Treatment Reduces Cerebral Ischemia Reperfusion Induced Injuries in Rats

Objective

To explore the effects of pre versus post ischemic treatment with metformin after global cerebral ischemia in rats.

Methods

Male Wister rats underwent forebrain ischemia by bilateral common carotid artery occlusion for 17 min. Metformin (200 mg/kg) or vehicle was given orally by gavage for 7-14 days. Rats were divided into: control, metformin pre-treatment, metformin post-treatment and metformin pre and post continuous treatment groups. Cerebral infarct size, histopathology, myeloperoxidase and serum malondialdehyde were measured 7 days after ischemia.

Results

Histopathological analysis showed that metformin pre-treatment significantly decreased leukocyte infiltration, myeloperoxidase activity and also malondialdehyde level. Metformin pre-treatment and metformin post-treatment reduced infarct size compared with the control group, but it was not significant in the pre and post continuous treatment group.

Conclusion

Our findings suggest that pre-treatment with metformin in comparison with post-treatment in experimental stroke can reduce the extent of brain damage and is more neuroprotective at least in part by inhibiting oxidative stress and inflammation.