Methyl Jasmonate Ameliorates Unpredictable Chronic Mild Stress-Induced Behavioral and Biochemical Alterations in Mouse Brain

Morin hydrate attenuates chronic stress-induced memory impairment and degeneration of hippocampal subfields in mice: The role of oxidative, nitrergic and neuroinflammatory pathways

Morin hydrate (MH) is the major flavonoid constituent of Morus alba acclaimed to have antioxidant, anti-inflammatory, anti-stress and neuroprotective properties. However, report on the effect of MH on memory performance and the underlying mechanism following chronic stress exposure is lacking. The current study aimed at investigating the neuroprotective effect of MH on chronic unpredictable stress (CUS)-induced memory impairment in mice using the Y maze test. Mice were subjected to unpredicted stress for 14 days, during which MH (5, 10 and 20 mg/kg i.p) or 25 mg/kg Ginseng was administered to them. On the 14th day, 1 h after treatment, learning and memory deficit was evaluated using the Y maze test and thereafter brains were harvested for the estimation of glutathione (GSH), lipid peroxidation product; malondialdehyde (MDA) and nitrite. Levels of inflammatory mediators tumor necrosis factor-alpha (TNF-α) and interleukin1-beta (IL-1β), inducible nitric oxide synthase (iNOS) and nuclear factor-kappa B (NF-кB) expressions were also determined. The hippocampus was stained with hematoxylin-eosin (H&E) to examine any morphological changes in the neurons. Mice exposed to CUS showed evidence of impaired memory and increase levels of MDA, nitrite, TNF-α and IL-1β. Furthermore, CUS reduced GSH level, increased the expressions of iNOS and NFкB immune-positive cells and produced loss of neuronal cells in the hippocampus. The MH treatment however improved memory, reduced MDA and nitrite levels, and enhanced brain GSH levels in CUS-mice. Besides, MH reduced brain levels of TNF-α and IL-1β levels, down regulated the expressions of iNOS and NF-кB and rescue neurons in the hippocampal CA3 region of mice exposed to CUS. The results of the study indicate that MH improved CUS-induced memory impairment, which may be related to its ability to boost antioxidant defense system and suppress neuroinflammatory pathways.

Chronic stress and endothelial dysfunction: mechanisms, experimental challenges, and the way ahead

Although chronic stress is an important risk factor for cardiovascular diseases (CVD) onset, the underlying mechanisms driving such pathophysiological complications remain relatively unknown. Here, dysregulation of innate stress response systems and the effects of downstream mediators are strongly implicated, with the vascular endothelium emerging as a primary target of excessive glucocorticoid and catecholamine action. Therefore, this review article explores the development of stress-related endothelial dysfunction by focusing on the following: 1) assessing the phenomenon of stress and complexities surrounding this notion, 2) discussing mechanistic links between chronic stress and endothelial dysfunction, and 3) evaluating the utility of various preclinical models currently employed to study mechanisms underlying the onset of stress-mediated complications such as endothelial dysfunction. The data reveal that preclinical models play an important role in our efforts to gain an increased understanding of mechanisms underlying stress-mediated endothelial dysfunction. It is our understanding that this provides a good foundation going forward, and we propose that further efforts should be made to 1) more clearly define the concept of stress and 2) standardize protocols of animal models with specific guidelines to better indicate the mental complications that are simulated.

The antidepressant effects of hesperidin on chronic unpredictable mild stress-induced mice

Hesperidin, a kind of citrus bioflavonoid distributed in foods including grapefruits, oranges and lemons, has many pharmacological activities. This study was aimed to evaluate the anti-depressant-like effect of hesperidin on chronic unpredictable mild stress (CUMS)-induced mice. Depressive-like behavior was detected by the sucrose preference test (SPT), tail suspension test (TST) and forced swimming test (FST). A 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay was performed to assess the cell viability of corticosterone-induced PC12 cells. The serum, hippocampal and cell supernatant concentrations of interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α were determined using enzyme-linked immunosorbent assay (ELISA) commercial kits. Furthermore, the protein expression levels of high-mobility group box 1 protein (HMGB1), receptor for advanced glycation end-products (RAGE)/NF-κB and brain-derived neurotrophic factor (BDNF)/tropomyosin-related kinase B (TrkB) pathway in the hippocampus and corticosterone-induced PC12 cells were detected by Western blot. Our results showed that hesperidin (100, 200 mg/kg) significantly relieved depressive-like behaviors, including decreased sucrose consumption in sucrose preference test (SPT), immobility in the forced swimming test (FST), tail suspension test, and locomotor activity in the open field test (OFT). Hesperidin reduced inflammatory cytokine levels by attenuating the HMGB1/RAGE/NF-κB signaling pathway and BDNF/TrkB pathway both in vivo and in vitro. In conclusion, hesperidin possessed efficient neuroprotective effects on depression, which was associated with neuroinflammation mediated by the HMGB1/RAGE/NF-κB and BDNF/TrkB pathways.

Notes on the Recent History of Neuroscience in Africa

Neuroscience began with neuroanatomy and neurosurgery in Egypt more than 5000 years ago. Knowledge grew over time and specialized neurosurgery centers were established in north Africa in the eleventh century. However, it was not until the twentieth century that neuroscience research became established in sub-Saharan Africa. In most African countries, clinical research focused on understanding the rationale and improving treatment of epilepsy, infections, nutritional neuropathies, stroke and tumors. Significant advances were made. In the twenty-first century, African knowledge expanded to include all branches of neuroscience, contributing to genetic, biochemical and inflammatory determinants of brain disorders. A major focus of basic neuroscience research has been, and is, investigation of plant extracts, drugs and stress in animal models, providing insight and identifying potential novel therapies. A significant event in the history of African neuroscience was the founding of the Society of Neuroscientists of Africa (SONA) in 1993. The International Brain Research Organization (IBRO) supported SONA conferences, as well as workshops and neuroscience training schools in Africa. Thanks to their investment, as well as that of funding agencies, such as the National Institutes of Health (NIH), International Society for Neurochemistry (ISN), World Federation of Neurosurgical Societies (WFNS), World Federation of Neurology (WFN) and the International League Against Epilepsy (ILAE), neuroscience research is well-established in Africa today. However, in order to continue to develop, African neuroscience needs continued international support and African neuroscientists need to engage in policy and decision-making to persuade governments to fund studies that address the unique regional needs in Africa.