Can metformin use reduce the risk of stroke in diabetic patients? A systematic review and meta-analysis.

BACKGROUND AND AIM: Stroke and cardiovascular diseases are major causes of death and disability, especially among diabetic patients. Some studies have shown that metformin has been effective in preventing cardiovascular diseases. In this study, we aim to evaluate the effect of metformin on stroke in type 2 diabetic patients. METHODS: A comprehensive search was conducted in Medline, Embase, Scopus, and Web of Science databases from their inception till 1st July 2022. Randomized clinical trials (RCT) and cohort studies were included. Two independent researchers screened the records, extracted the data, and assessed the risk of bias and certainty of evidence. Findings were reported as risk ratio (RR) and 95% confidence interval (CI). All statistical analyses were performed using the STATA 17.0 software package. RESULTS: Analysis of 21 included studies with 1,392,809 patients demonstrated that metformin monotherapy was effective in reducing stroke risk in both RCTs (RR = 0.66, 95% CI: 0.50, 0.87 p = 0.004) and cohort studies (RR = 0.67, 95% CI: 0.55, 0.81, p < 0.0001). However, combined administration of metformin with other antihyperglycemic agents had no significant effect on stroke risk reduction in either the RCTs (RR = 0.92, 95% CI: 0.69, 1.22 p = 0.558) or the cohort studies (RR = 0.79, 95% CI: 0.59, 1.06, p = 0.122). CONCLUSION: Low to moderate level of evidence in RCTs showed that metformin monotherapy could reduce stroke risk in type 2 diabetic patients. However, the preventive effect of metformin in stroke was not observed in patients who received a combination of metformin plus other hypoglycemic agents.

Investigating the mechanism of antiepileptogenic effect of apigenin in kainate temporal lobe epilepsy: possible role of mTOR.

Clarifying the underlying mechanisms of epileptogenesis is important in preventing the progression of chronic epilepsy. In epilepsy, the mTOR (mammalian target of rapamycin) pathway plays a critical role in mediating the mechanism of epileptogenesis. In this study, we investigate whether apigenin can exert antiepileptogenic effects through the inhibition of mTOR in the kainate model of epilepsy. For assessing the antiepileptogenic effect of apigenin in kainic acid (KA)-induced temporal lobe epilepsy (TLE) model, apigenin at a dose of 50 mg/kg was administrated by gavage for 6 days. An intracranial electroencephalogram (iEEG) was performed to confirm the establishment of status epilepticus. BrdU was used to detect neurogenesis in the CA3, and dentate gyrus and mossy fiber sproutings were assessed by Timm staining. The expression of mTOR was quantified via western blot. We found that apigenin-pretreatment had a significant inhibitory effect on neural cell death, spontaneous seizure spikes, aberrant neurogenesis, mTOR hyperactivity, and aberrant mossy fiber sprouting. Overall, these results suggest that apigenin has an antiepileptogenic effect and may be a useful target for inhibiting mTOR hyperactivity in epilepsy.

Evaluation the cognition-improvement effects of N-acetyl cysteine in experimental temporal lobe epilepsy in rat.

Memory impairment is a critical issue in patients with temporal lobe epilepsy (TLE). Neuronal loss within the hippocampus and recurrent seizures may cause cognitive impairment in TLE. N -acetyl cysteine (NAC) is a sulfur-containing amino acid cysteine that is currently being investigated due to its protective effects on neurodegenerative disorders. NAC was orally administrated at a dose of 100 mg/kg for 8 days (7-day pretreatment and 1-day post-surgery). Neuronal viability, mTOR protein level, and spatial memory were detected in the kainite temporal epilepsy model via Nissl staining, western blot method, and Morris water maze task, respectively. Results showed that NAC delayed seizure activity and ameliorated memory deficit induced by Kainic acid. Histological analysis showed that NAC significantly increased the number of intact neurons in CA3 and hilar areas of the hippocampus following the induction of epilepsy. NAC also modulated the mTOR protein level 5 days after epilepsy compared to the KA-induced group. CONCLUSION: These results suggest that NAC improved memory impairment via anticonvulsant and neuroprotective activity and, in all probability, by lowering the level of mTOR.

Protective effect of N-acetyl cysteine on the mitochondrial dynamic imbalance in temporal lobe epilepsy: Possible role of mTOR.

Understanding the underlying molecular mechanisms involved in epilepsy is critical for the development of more effective therapies. It is believed that mTOR (Mechanistic Target of Rapamycin kinases) activity and the mitochondrial dynamic balance change during epilepsy. mTOR affects mitochondrial fission by stimulating the translation of mitochondrial fission process 1 (MTFP1). In This study, the protective role of N-acetylcysteine was studied in temporal lobe epilepsy (TLE) through the regulation of mTOR and mitochondrial dynamic proteins. Rats received N-acetylcysteine (oral administration) seven days before induction of epilepsy, followed by one day after epilepsy. TLE was induced by microinjection of kainite into the left lateral ventricle. The total mTOR and Drp1 levels in the hippocampus were evaluated by western blotting. MFN1 was assessed using immunohistochemistry, and the expression of Fis.1 and MTFP1 (fission-related proteins) and OPA (fusion-related protein) were detected by real-time PCR. The mitochondrial membrane potential was measured by Rhodamin 123. The results showed that 72 h after induction of epilepsy, the mTOR protein level increased, and the balance of the mitochondrial dynamic was disturbed; however, oral administration of NAC decreased the mTOR protein level and improved the mitochondrial dynamic. These findings indicate that NAC plays a neuroprotective role in temporal lobe epilepsy, probably through decreasing the mTOR protein level, which can improve the imbalance in the mitochondrial dynamic.

The plasma level of glutamic acid decarboxylase 65 (GAD65) increased in severely autistic Iranian children.

INTRODUCTION: Autism spectrum disorder (ASD) is a neurodevelopmental disorder. The major etiological mechanism lies in glutamatergic/GABAergic imbalance. The aim of this study was to evaluate the plasma levels of glutamic acid decarboxylase 65 (GAD65) protein in mildly and severely autistic patients, and also to compare plasma GAD65 concentration in mild and severe autism. METHOD: In total, 62 autistic patients (aged 6-9 years) and 17 age-matched neurotypically healthy controls were included in the study. The diagnosis, as well as the level of autism, was assessed by applying the Gilliam Autism Rating Scale. Plasma GAD65 protein level was determined using an enzyme-linked immunosorbent assay (ELISA) kit for GAD65. RESULTS: Our findings showed no remarkable alteration in plasma GAD65 concentration in patients with mild autism as compared to healthy subjects, while patients with severe autism showed an increased plasma level of GAD65 as compared to healthy controls and mildly autistic patients. CONCLUSION: Our findings suggest the level of plasma GAD65 to be considered a potential diagnostic biomarker for the severity of autism (Fig. 2, Ref. 40).

GSK-3ß as a target for apigenin-induced neuroprotection against Aß 25-35 in a rat model of Alzheimer's disease.

Glycogen synthase kinase-3 (GSK-3) is a critical molecule in Alzheimer's disease (AD) that modulates two histopathological hallmarks of AD: Amyloid beta (Aß) plaques and neurofibrillary tangles composed of aberrant hyper-phosphorylation of tau protein. This study was performed to investigate the protective effect of flavone apigenin through inhibition of GSK-3 and the involvement of this kinase in the inhibition of BACE1 expression and hyperphosphorylation of tau protein in an AD rat model. 15 nM of aggregated amyloid-beta 25-35 was microinjected into the left lateral ventricle of an AD rat. Apigenin (50 mg/kg) was administered orally 45 min before the Aß injection and continued daily for three weeks. Immunohistochemistry and western blot analysis showed that apigenin significantly reduced the hyperphosphorylation of tau levels in the hippocampus. Real-time PCR analysis revealed significant inhibition of the mRNA level of ß secretase (BACE1) and GSK-3ß, but Apigenin had no effect on the level of GSK-3α. The results demonstrate that apigenin has a protective effect against amyloid-beta 25-35 by decreasing the expression of GSK-3ß with the consequence of lowering the hyperphosphorylation of tau protein and suppressing BACE1 expression.

Protective effect of orexin-A on 6-hydroxydopamine-induced neurotoxicity in SH-SY5Y human dopaminergic neuroblastoma cells.

Parkinson's disease (PD) is a progressive neurodegenerative disease characterized by progressive and selective death of midbrain dopaminergic neurons. Pharmacologic treatment of PD can be divided into symptomatic and neuroprotective therapies. Orexin-A (hypocretin-1) is a hypothalamic peptide that exerts its biological effects by stimulation of two specific, membrane-bound orexin receptors. Recent studies have shown that orexin-A has a protective role during neuronal damage. Here, we investigated the effects of orexin-A on 6-OHDA-induced neurotoxicity in human neuroblastoma SH-SY5Y cell line as an in vitro model of Parkinson's disease. Cell damage was induced by 150µM 6-OHDA and the cells viability was examined by MTT assay. Intracellular reactive oxygen species (ROS) was determined by fluorescence spectrophotometry method. Immunoblotting and DNA analysis were also employed to determine the levels of biochemical markers of apoptosis in the cells. The data showed that 6-OHDA could decrease the viability of the cells. In addition, intracellular ROS, activated caspase 3, Bax/Bcl-2 ratio, cytochrome c as well as DNA fragmentation were significantly increased in 6-OHDA-treated cells. Pretreatment of cells with orexin-A (80pM) elicited protective effect and reduced biochemical markers of cell death. The results suggest that orexin-A has protective effects against 6-OHDA-induced neurotoxicity and its protective effects are accompanied by its antioxidant and anti-apoptotic properties and contribute to our knowledge of the pharmacology of orexin-A.