Hyperlipidemia Downregulate Brain Antioxidant Defense Enzymes and Neurotrophins in Rats: Assessment of the Modulatory Potential of EPA+DHA and Zerumbone

Resistant starches from dietary pulses improve neurocognitive health via gut-microbiome-brain axis in aged mice

Introduction

Cognitive decline is a common consequence of aging. Dietary patterns that lack fibers and are high in saturated fats worsen cognitive impairment by triggering pro-inflammatory pathways and metabolic dysfunctions. Emerging evidence highlights the neurocognitive benefits of fiber-rich diets and the crucial role of gut-microbiome-brain signaling. However, the mechanisms of this diet-microbiome-brain regulation remain largely unclear.

Methods

Accordingly, we herein investigated the unexplored neuroprotective mechanisms of dietary pulses-derived resistant starch (RS) in improving aging-associated neurocognitive function in an aged (60-weeks old) murine model carrying a human microbiome.

Results and discussion

Following 20-weeks dietary regimen which included a western-style diet without (control; CTL) or with 5% w/w fortification with RS from pinto beans (PTB), black-eyed-peas (BEP), lentils (LEN), chickpeas (CKP), or inulin fiber (INU), we find that RS, particularly from LEN, ameliorate the cognitive impairments induced by western diet. Mechanistically, RS-mediated improvements in neurocognitive assessments are attributed to positive remodeling of the gut microbiome-metabolome arrays, which include increased short-chain fatty acids and reduced branched-chain amino acids levels. This microbiome-metabolite-brain signaling cascade represses neuroinflammation, cellular senescence, and serum leptin/insulin levels, while enhancing lipid metabolism through improved hepatic function. Altogether, the data demonstrate the prebiotic effects of RS in improving neurocognitive function via modulating the gut-brain axis.

Role of Zerumbone, a Phytochemical Sesquiterpenoid from Zingiber zerumbet Smith, in Maintaining Macrophage Polarization and Redox Homeostasis

Macrophages and microglia are highly versatile cells that can be polarized into M1 and M2 phenotypes in response to diverse environmental stimuli, thus exhibiting different biological functions. In the central nervous system, activated resident macrophages and microglial cells trigger the production of proinflammatory mediators that contribute to neurodegenerative diseases and psychiatric disorders. Therefore, modulating the activation of macrophages and microglia by optimizing the inflammatory environment is beneficial for disease management. Several naturally occurring compounds have been reported to have anti-inflammatory and neuroprotective properties. Zerumbone is a phytochemical sesquiterpenoid and also a cyclic ketone isolated from Zingiber zerumbet Smith. In this study, we found that zerumbone effectively reduced the expression of lipocalin-2 in macrophages and microglial cell lines. Lipocalin-2, also known as neutrophil gelatinase-associated lipocalin (NGAL), has been characterized as an adipokine/cytokine implicated in inflammation. Moreover, supplement with zerumbone inhibited reactive oxygen species production. Phagocytic activity was decreased following the zerumbone supplement. In addition, the zerumbone supplement remarkably reduced the production of M1-polarization-associated chemokines CXC10 and CCL-2, as well as M1-polarization-associated cytokines interleukin (IL)-6, IL-1β, and tumor necrosis factor-α. Furthermore, the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 and the production of NO were attenuated in macrophages and microglial cells supplemented with zerumbone. Notably, we discovered that zerumbone effectively promoted the production of the endogenous antioxidants heme oxygenase-1, glutamate-cysteine ligase modifier subunit, glutamate-cysteine ligase catalytic subunit, and NAD(P)H quinone oxidoreductase-1 and remarkably enhanced IL-10, a marker of M2 macrophage polarization. Endogenous antioxidant production and M2 macrophage polarization were increased through activation of the AMPK/Akt and Akt/GSK3 signaling pathways. In summary, this study demonstrated the protective role of zerumbone in maintaining M1 and M2 polarization homeostasis by decreasing inflammatory responses and enhancing the production of endogenous antioxidants in both macrophages and microglia cells. This study suggests that zerumbone can be used as a potential therapeutic drug for the supplement of neuroinflammatory diseases.

Differential proteomic analysis of mouse cerebrums with high-fat diet (HFD)-induced hyperlipidemia

Hyperlipidemia is a chronic disease characterized by elevated blood cholesterol and triglycerides and there is accumulated evidence that the disease might affect brain functions. Here we report on a proteomic analysis of the brain proteins in hyperlipidemic mice. Hyperlipidemia was successfully induced in mice by a 20 week high-fat diet (HFD) feeding (model group). A control group with a normal diet and a treatment group with HFD-fed mice treated with a lipid-lowering drug simvastatin (SIM) were established accordingly. The proteins were extracted from the left and right cerebrum hemispheres of the mice in the three groups and subjected to shotgun proteomic analysis. A total of 4,422 proteins were detected in at least half of the samples, among which 324 proteins showed significant difference (fold change >1.5 or <0.67, p < 0.05) in at least one of the four types of comparisons (left cerebrum hemispheres of the model group versus the control group, right cerebrums of model versus control, left cerebrums of SIM versus model, right cerebrums of SIM versus model). Biological process analysis revealed many of these proteins were enriched in the processes correlated with lipid metabolism, neurological disorders, synaptic events and nervous system development. For the first time, it has been reported that some of the proteins have been altered in the brain under the conditions of HFD feeding, obesity or hyperlipidemia. Further, 22 brain processes-related proteins showed different expression in the two cerebrum hemispheres, suggesting changes of the brain proteins caused by hyperlipidemia might also be asymmetric. We hope this work will provide useful information to understand the effects of HFD and hyperlipidemia on brain proteins.

Research advances in the influence of lipid metabolism on cognitive impairment

Cognitive impairment (CI) is a mental disorder related to cognition and understanding, which is mainly categorized into mild CI and senile dementia. This disease is associated with multiple factors, such as chronic brain injury, aging, chronic systemic disease, mental state, and psychological factors. However, the pathological mechanism of CI remains unclear; it is usually associated with such underlying diseases as diabetes and hyperlipidemia. It has been demonstrated that abundant lipid metabolism indexes in the human body are closely related to CI, including total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, apolipoprotein, and so forth. As a crucial risk factor for CI, hyperlipidemia is of great significance in the occurrence and development of CI. However, the specific correlation between dyslipidemia and CI is still not fully elucidated. Besides, the efficacy of lipid-lowering drugs in the prophylaxis and treatment of CI has not been clarified. In this study, relevant advances in the influence of lipid metabolism disorders in CI will be reviewed, in an attempt to explore the effect of mediating blood lipid levels on the prophylaxis and treatment of CI, thus providing a reference for its clinical management.

Zerumbone Exhibit Protective Effect against Zearalenone Induced Toxicity via Ameliorating Inflammation and Oxidative Stress Induced Apoptosis

Zearalenone are widely occurring food contaminants that cause hepatotoxicity. This research work aimed to investigate how zerumbone, a plant-derived dietary compound, can fight ZEA-induced hepatotoxicity. ZER is found to increase the cells’ toxin resistance. This study was performed on mice challenged with ZEA. The administration of ZER decreased the level of alkaline phosphatase and alanine aminotransferase (ALT). Simultaneously, ZER attenuated the inflammatory response via significantly reducing the levels of pro-inflammatory factors, including interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α) in serum. Pretreatment with ZER reduced the hepatic malondialdehyde (MDA) concentration, as well as the depletion of hepatic superoxide dismutase (SOD), hepatic glutathione (GSH), and hepatic catalase (CAT). Moreover, it significantly ameliorated ZEA-induced liver damage and histological hepatocyte changes. ZER also relieved ZEA-induced apoptosis by regulating the PI3K/AKT pathway and Nrf2 and HO-1 expression. Furthermore, ZER increasingly activated Bcl2 and suppressed apoptosis marker proteins. Our findings suggest that ZER exhibits the ability to prevent ZEA-induced liver injury and present the underlying molecular basis for potential applications of ZER to cure liver injuries.

Cognitive impairment in obese rat model: role of glial cells

BACKGROUND

Obesity is a worldwide problem. Some studies revealed that it leads to deterioration of the cognitive function, regardless of age.

AIM OF THE STUDY

explore the effect of obesity on cognitive function in a rat model of obesity highlighting the role of glial cells.

MATERIALS AND METHODS

twenty adult male albino rats were assigned to two groups: group I: consumed normal diet, group II: consumed high-fat diet. Body Mass Index (BMI), serum glucose, insulin, HOMA IR and lipid profile were measured. Also, hippocampal expression of Brain derived neurotrophic factor (Bdnf), synapsin, Ionized calcium binding adaptor molecule 1 (Iba), nuclear factor erythroid -related factor 2 (Nrf2), Myelin basic protein (Mbp) were measured by real-time polymerase chain reaction. The Morris Water Maze is a test used to assess spatial learning and memory capacities of rats.

RESULTS

There was a high significant increase in lipid profile, serum glucose, insulin serum levels and HOMA-IR in obese groups with impaired Morris water maze performance compared to control group. There was a significant downregulation in hippocampal Bdnf and synapsin mRNA expression. In addition to decrease in Mbp mRNA expression (P < 0.001). This could be explained by oxidative stress through significant downregulation of Nrf2 mRNA, and inflammation observed in significant upregulation Iba mRNA gene expression in the obese group.

CONCLUSION

Many factors contribute to obesity associated cognitive impairment. In our study, we figured out the crucial roles of glial cells including microglial activation and oligodendrocytes affection with other underlying mechanisms including oxidative stress and hippocampal inflammation.

Ginger and turmeric lipid-solubles attenuate heated oil-induced oxidative stress in the brain via the upregulation of NRF2 and improve cognitive function in rats

In this study, we elucidated the modulatory potentials of lipid-solubles from ginger and turmeric that may migrate to oils during heating on the brain antioxidant defense and cognitive response in rats. Male Wistar rats were fed with control diet [including native canola oil (N-CNO), and native sunflower oil (N-SFO)], or experimental diets [including heated canola oil (H-CNO), heated sunflower oil (H-SFO), heated canola oil with ginger (H-CNO + GI), heated canola oil with turmeric (H-CNO + TU), heated sunflower oil with ginger (H-SFO + GI), heated sunflower oil with turmeric (H-SFO + TU)] for 90 days. Memory parameters [Morris water maze, elevated plus maze, novel object recognition test, T-maze (spontaneous alteration)], locomotor skills (open field test and rotarod test), antioxidant defense enzymes, reactive oxygen species, NOS2, ICAM-1, and NRF-2 level in the brain were assessed. Compared to their respective controls, heated oil-fed rats, but not those fed oils heated with ginger or turmeric, showed significant (p < 0.05) reduction in the memory, motor coordination skills, antioxidant defense enzymes, and NRF-2 activation in the brain. Compared to their respective controls, the brain NOS-2 and ICAM-1 were significantly (p < 0.05) increased in heated oil-fed rats, but not those fed oils heated with ginger or turmeric. Chronic intake of repeatedly heated oil causes brain dysfunction by inducing oxidative stress through NRF-2 downregulation. Lipid-solubles from ginger and turmeric that may migrate to oil during heating prevent the oxidative stress and cognitive dysfunction triggered by heated oils in rats.