Edaravone protects from memory impairment induced by chronic L-methionine administration

Development of Atomoxetine-Loaded NLC In Situ Gel for Nose-to-Brain Delivery: Optimization, In Vitro, and Preclinical Evaluation

The present study investigates the brain-targeted efficiency of atomoxetine (AXT)-loaded nanostructured lipid carrier (NLC)-laden thermosensitive in situ gel after intranasal administration. AXT-NLC was prepared by the melt emulsification ultrasonication method and optimized using the Box-Behnken design (BBD). The optimized formulation (AXT-NLC) exhibited particle size PDI, zeta potential, and entrapment efficiency (EE) of 108 nm, 0.271, -42.3 mV, and 84.12%, respectively. The morphology of AXT-NLC was found to be spherical, as confirmed by SEM analysis. DSC results displayed that the AXT was encapsulated within the NLC matrix. Further, optimized NLC (AXT-NLC13) was incorporated into a thermosensitive in situ gel using poloxamer 407 and carbopol gelling agent and evaluated for different parameters. The optimized in situ gel (AXT-NLC13G4) formulation showed excellent viscosity (2532 ± 18 Cps) at 37 °C and formed the gel at 28-34 °C. AXT-NLC13-G4 showed a sustained release of AXT (92.89 ± 3.98% in 12 h) compared to pure AXT (95.47 ± 2.76% in 4 h). The permeation flux through goat nasal mucosa of AXT from pure AXT and AXT-NLC13-G4 was 504.37 µg/cm²·h and 232.41 µg/cm²·h, respectively. AXT-NLC13-G4 intranasally displayed significantly higher absolute bioavailability of AXT (1.59-fold higher) than intravenous administration. AXT-NLC13-G4 intranasally showed 51.91% higher BTP than pure AXT (28.64%) when administered via the same route (intranasally). AXT-NLC13-G4 showed significantly higher BTE (207.92%) than pure AXT (140.14%) when administered intranasally, confirming that a high amount of the AXT reached the brain. With the disrupted performance induced by L-methionine, the AXT-NLC13-G4 showed significantly (p < 0.05) better activity than pure AXT as well as donepezil (standard). The finding concluded that NLC in situ gel is a novel carrier of AXT for improvement of brain delivery by the intranasal route and requires further investigation for more justification.

Epigenetic Mechanisms Involved in the Effects of Maternal Hyperhomocysteinemia on the Functional State of Placenta and Nervous System Plasticity in the Offspring

According to modern view, susceptibility to diseases, specifically to cognitive and neuropsychiatric disorders, can form during embryonic development. Adverse factors affecting mother during the pregnancy increase the risk of developing pathologies. Despite the association between elevated maternal blood homocysteine (Hcy) and fetal brain impairments, as well as cognitive deficits in the offspring, the role of brain plasticity in the development of these pathologies remains poorly studied. Here, we review the data on the negative impact of hyperhomocysteinemia (HHcy) on the neural plasticity, in particular, its possible influence on the offspring brain plasticity through epigenetic mechanisms, such as changes in intracellular methylation potential, activity of DNA methyltransferases, DNA methylation, histone modifications, and microRNA expression in brain cells. Since placenta plays a key role in the transport of nutrients and transmission of signals from mother to fetus, its dysfunction due to aberrant epigenetic regulation can affect the development of fetal CNS. The review also presents the data on the impact of maternal HHcy on the epigenetic regulation in the placenta. The data presented in the review are not only interesting from purely scientific point of view, but can help in understanding the role of HHcy and epigenetic mechanisms in the pathogenesis of diseases, such as pregnancy pathologies resulting in the delayed development of fetal brain, cognitive impairments in the offspring during childhood, and neuropsychiatric and neurodegenerative disorders later in life, as well as in the search for approaches for their prevention using neuroprotectors.

Exploring the effects of edaravone in rats with contrast-induced acute kidney injury

AIMS

Oxidative stress and inflammatory response play a vital role in the pathogenesis of contrast-induced acute kidney injury (CI-AKI). This study investigated the effects of edaravone in rats with CI-AKI.

MAIN METHODS

Male Sprague Dawley rats were randomly assigned into four groups (n = 11-14/group): control, edaravone (30 mg/kg/day intraperitoneally (IP)), CI-AKI, and edaravone with CI-AKI. The induction of CI-AKI was performed by dehydration and the administration of contrast media (iohexol) and inhibitors of prostaglandin (indomethacin) and nitric oxide synthesis (L-NAME: N-nitro L-arginine methyl ester). Edaravone was administered for two weeks before the induction of CI-AKI. Serum creatinine and urea, renal oxidative stress and inflammatory biomarkers, and histopathological alterations were evaluated after 48 h of contrast exposure.

KEY FINDINGS

Rats with CI-AKI showed a significant increase in serum creatinine and urea. The levels of antioxidant biomarkers including glutathione peroxidase, superoxide dismutase and reduced glutathione were significantly decreased in CI-AKI group versus control. Pre-treatment of rats with edaravone normalized kidney function and protected the kidney from oxidative damage as demonstrated by normalization of previous biomarkers. Furthermore, edaravone partially ameliorated renal histopathological alterations relative to the CI-AKI group, notably in the nephrons. No changes were observed in inflammatory biomarkers including tumour necrosis factor-alpha and interleukin-6 among all groups.

SIGNIFICANCE

The current findings suggest that edaravone could be a potential strategy to ameliorate developing CI-AKI possibly by improving renal antioxidant capacity. Further studies are warranted to expand the current understanding of the use of edaravone in the various models of AKI.

Sitagliptin Attenuates the Cognitive Deficits in L-Methionine-Induced Vascular Dementia in Rats

Vascular dementia (VaD) is the second most prevalent type of dementia characterized by progressive cognitive deficits and is a major risk factor for the development of Alzheimer's disease and other neurodegenerative disorders. This study is aimed at determining the potential neuroprotective effect of sitagliptin (STG) on cognitive deficits in L-methionine-induced VaD in rats and the possible underlying mechanisms. 30 adult male Wistar albino rats were divided equally (n = 10) into three groups: control, VaD, and VaD + STG groups. The cognitive performance of the animals was conducted by open field, elevated plus maze, Y-maze, novel object recognition, and Morris water maze tests. Serum homocysteine, TNF-α, IL-6, IL-10, total cholesterol, and triglycerides levels were assessed together with hippocampal MDA, SOD, and BDNF. Histopathological and immunohistochemical assessments of the thoracic aorta and hippocampus (CA1 region) were also performed. Chronic L-methionine administration impaired memory and learning and induced anxiety. On the other hand, STG protected against cognitive deficits through improving oxidative stress biomarkers, inflammatory mediators, lipid profiles, and hippocampus level of BDNF as well as decreasing caspase-3 and GFAP and increasing Ki-67 immunoreactions in the hippocampus. Also, STG improved the endothelial dysfunction via upregulation of aortic eNOS immunoreaction. STG improved the cognitive deficits of L-methionine-induced VaD by its antioxidant, anti-inflammatory, antiapoptotic, and neurotrophic effects. These findings suggest that STG may be a promising future agent for protection against VaD.

Methionine as a double-edged sword in health and disease: Current perspective and future challenges

Methionine is one of the essential amino acids and plays a vital role in various cellular processes. Reports advocate that methionine restriction and supplementation provide promising outcomes, and its regulation is critical for maintaining a healthy life. Dietary methionine restriction in houseflies and rodents has been proven to extend lifespan. Contrary to these findings, long-term dietary restriction of methionine leads to adverse events such as bone-related disorders, stunted growth, and hyperhomocysteinemia. Conversely, dietary supplementation of methionine improves hepatic steatosis, insulin resistance, inflammation, fibrosis, and bone health. However, a high level of methionine intake shows adverse effects such as hyperhomocysteinemia, reduced body weight, and increased cholesterol levels. Therefore, dietary methionine in a safe dose could have medicinal values. Hence, this review is aimed to provide a snapshot of the dietary role and regulation of methionine in the modulation of health and age-related diseases.

Hyperhomocysteinemia: Metabolic Role and Animal Studies with a Focus on Cognitive Performance and Decline-A Review

Disturbances in the one-carbon metabolism are often indicated by altered levels of the endogenous amino acid homocysteine (HCys), which is additionally discussed to causally contribute to diverse pathologies. In the first part of the present review, we profoundly and critically discuss the metabolic role and pathomechanisms of HCys, as well as its potential impact on different human disorders. The use of adequate animal models can aid in unravelling the complex pathological processes underlying the role of hyperhomocysteinemia (HHCys). Therefore, in the second part, we systematically searched PubMed/Medline for animal studies regarding HHCys and focused on the potential impact on cognitive performance and decline. The majority of reviewed studies reported a significant effect of HHCys on the investigated behavioral outcomes. Despite of persistent controversial discussions about equivocal findings, especially in clinical studies, the present evaluation of preclinical evidence indicates a causal link between HHCys and cognition-related- especially dementia-like disorders, and points out the further urge for large-scale, well-designed clinical studies in order to elucidate the normalization of HCys levels as a potential preventative or therapeutic approach in human pathologies.

Every-other day fasting prevents memory impairment induced by high fat-diet: Role of oxidative stress

Imbalance of diet consumption results in memory and learning deterioration. High-fat diet (HFD) causes neuronal damage and eventually cognitive impairment, which can be related to increasing oxidative stress in the brain. Using the every other day fasting (EODF) paradigm, as a method of dietary restriction is thought to provide protection of learning and memory in several experimental studies. In the current work, the preventive effect of EODF paradigm on memory impairment-induced by HFD was investigated. Adult male Wistar rats were fed with HFD using the EODF paradigm for six weeks. At the end of these six weeks, and while the previous treatment were continued, rats were examined for learning and memory (both the short-term and the long-term memory) using the radial arm water maze (RAWM). Oxidative stress in the brain, namely in the hippocampus was also assessed. Chronic administration of HFD induced impairment in both, short- and long- term memory that was prevented using EODF paradigm. Furthermore, EODF prevented HFD-induced decrease in the activities of the antioxidant enzymes, SOD and catalase along with reduction of glutathione (GSH) level and the ratio of reduced glutathione/oxidized glutathione (GSH/GSSG ratio). The EODF also inhibited rise in oxidized glutathione (GSSG) and thiobarbituric acid reactive substances (TBARS) seen with HFD. In conclusion, EODF ameliorated oxidative stress and memory impairment induced by chronic HFD. This probably, can be explained by the ability of EODF to normalize mechanisms involved in oxidative stress in the hippocampus.