Stress and Western diets increase vulnerability to neuropsychiatric disorders: A common mechanism

Association of Dietary Polyunsaturated Fatty Acid Intake with Allergic Rhinitis in Adults: A Cross-Sectional Study of NHANES 2005-2006

INTRODUCTION

The incidence of allergic rhinitis (AR) is increasing year by year, and the pathogenesis is complex, in which diet may play an important role. The role of polyunsaturated fatty acids (PUFAs) in AR is still controversial. Previous studies have looked at the effects of PUFA during pregnancy, childhood, and adolescence. In this study, we aimed to determine the association between dietary intake of PUFA and AR in adults.

METHODS

We used the NHANES database from 2005 to 2006 to include a total of 4,211 adult subjects. We collected dietary PUFA intake data and information on AR. Logistic regression and restricted cubic spline models were constructed to examine the association between PUFA intake and AR in adults. The t test was used to compare daily PUFA intakes in patients with and without AR.

RESULTS

In the fully adjusted model (OR: 1.016; 95% CI: 1.003; 1.028), PUFA intake was positively correlated with allergic symptoms, hay fever, and AR in adults (p < 0.05). In addition, daily PUFA intake was significantly higher in people with allergic symptoms, hay fever, and AR than in people without the disease (p < 0.01).

CONCLUSIONS

Our results suggest a positive association between dietary PUFA intake and AR in adults to a certain extent. Future studies on dietary PUFA dose will provide new strategies for the prevention and treatment of allergic diseases such as AR related to non-pharmaceutical interventions.

A high ratio of linoleic acid (n-6 PUFA) to alpha-linolenic acid (n-3 PUFA) adversely affects early stage of human neuronal differentiation and electrophysiological activity of glutamatergic neurons in vitro

Introduction: There is a growing interest in the possibility of dietary supplementation with polyunsaturated fatty acids (PUFAs) for treatment and prevention of neurodevelopmental and neuropsychiatric disorders. Studies have suggested that of the two important classes of polyunsaturated fatty acids, omega-6 (n-6) and omega-3 (n-3), n-3 polyunsaturated fatty acids support brain development and function, and when used as a dietary supplement may have beneficial effects for maintenance of a healthy brain. However, to date epidemiological studies and clinical trials on children and adults have been inconclusive regarding treatment length, dosage and use of specific n-3 polyunsaturated fatty acids. The aim of this study is to generate a simplified in vitro cell-based model system to test how different n-6 to n-3 polyunsaturated fatty acids ratios affect human-derived neurons activity as a cellular correlate for brain function and to probe the mechanism of their action. Methods: All experiments were performed by use of human induced pluripotent stem cells (iPSCs). In this study, we examined the effect of different ratios of linoleic acid (n-6) to alpha-linolenic acid in cell growth medium on induced pluripotent stem cell proliferation, generation of neuronal precursors and electrophysiology of cortical glutamatergic neurons by multielectrode array (MEA) analysis. Results: This study shows that at a n-6:n-3 ratio of 5:1 polyunsaturated fatty acids induce stem cell proliferation, generating a large increase in number of cells after 72 h treatment; suppress generation of neuronal progenitor cells, as measured by decreased expression of FOXG1 and Nestin in neuronal precursor cells (NPC) after 20 days of development; and disrupt neuronal activity in vitro, increasing spontaneous neuronal firing, reducing synchronized bursting receptor subunits. We observed no significant differences for neuronal precursor cells treated with ratios 1:3 and 3:1, in comparison to 1:1 control ratio, but higher ratios of n-6 to n-3 polyunsaturated fatty acids adversely affect early stages of neuronal differentiation. Moreover, a 5:1 ratio in cortical glutamatergic neurons induce expression of GABA receptors which may explain the observed abnormal electrophysiological activity.

Chronic exposure to aflatoxin B1 increases hippocampal microglial pyroptosis and vulnerability to stress in mice

BACKGROUND

Chronic aflatoxin B1 (AFB1) exposure may increase the risk of multiple neuropsychiatric disorders. Stress is considered one of the main contributors to major depressive disorder. Whether and how chronic AFB1 exposure affects vulnerability to stress is unclear.

METHODS

Mice were exposed for three weeks to AFB1 (100 µg/kg/d) and/or chronic mild stress (CMS). The vulnerability behaviors in response to stress were assessed in the forced swimming test (FST), sucrose preference test (SPT), and tail suspension test (TST). Microglial pyroptosis was investigated using immunofluorescence, enzyme-linked immunosorbent assays, and western blot assay in the hippocampus of mice. Hippocampal neurogenesis and the effects of AFB1-treated microglia on proliferation and differentiation of neural stem/precursor cells (NSPCs) were assessed via immunofluorescence in the hippocampus of mice.

RESULTS

Mice exposed to CMS in the presence of AFB1 exhibited markedly greater vulnerability to stress than mice treated with CMS or AFB1 alone, as indicated by reduced sucrose preference and longer immobility time in the forced swimming test. Chronic aflatoxin B1 exposure resulted in changes in the microglial morphology and increase in TUNEL⁺ microglia and GSDMD⁺ microglia in the hippocampal dentate gyrus. When mice were exposed to both CMS and AFB1, pyroptosis-related molecules (such as NLRP3, caspase-1, GSDMD-N, and interleukin-1β) were significantly upregulated in the hippocampus. These molecules were also significantly enhanced by AFB1 in primary microglial cultures. AFB1-treated mice showed decrease in the numbers of BrdU⁺, BrdU-DCX⁺, and BrdU-NeuN⁺ cells in the hippocampal dentate gyrus, as well as the percentages of BrdU⁺ cells that were NeuN⁺ in the presence or absence of CMS when compared with vehicle-treated mice. The combination of AFB1 and CMS exacerbated these effects to an even greater extent. The number of DCX⁺ cells correlated negatively with the percentage of ameboid microglia, TUNEL⁺ microglia and GSDMD⁺ microglia in the hippocampal dentate gyrus. AFB1-treated microglia suppressed the proliferation and neuronal differentiation of NSPCs in vitro.

CONCLUSION

Chronic AFB1 exposure induces microglial pyroptosis, promoting an adverse neurogenic microenvironment that impairs hippocampal neurogenesis, which may render mice more vulnerable to stress.

Tarooneh extract relieves anxiety-like behaviors and cognitive deficits by inhibiting synaptic loss in the hippocampus and frontal cortex in rats subjected to chronic restraint stress

In traditional medicine, Tarooneh (a hardcover of the date palm; Phoenix dactylifera) has known as a sedative and relaxant medicine. In this study, we evaluated the protective effects of Tarooneh in the anxiety-like behavior, cognitive deficit, and neuronal damages in the CA1, CA3, and dentate gyrus (DG) regions of the hippocampus and frontal cortex neurons employing a rat model of chronic restraint stress. The animal received Tarooneh extract for 14 consecutive days in water, and chronic restraint stress was performed daily during this period. The results of the Barnes maze test showed that treatment with Tarooneh significantly improves spatial memory parameters such as latency time to find the target hole, number of errors, and distance traveling compared to the stress group. The EPM results showed that Tarooneh significantly increased the time spent in open arms and the percentage of entries into open arms and significantly decreased the frequency of head dipping behavior compared to animals in the stress group. Golgi-Cox staining indicates that loss of neural spine density in DG, CA1, CA3, and frontal cortex due to chronic restraint stress, was prevented with daily administration of Tarooneh. The results of cresyl-violet staining indicate that Tarooneh significantly increased the number of CV-positive neurons in the frontal cortex and CA1 region of the hippocampus compared to the stress group. Our results suggest that Tarooneh potentially prevented and improved effects in anxiety-like behavior, memory impairment, and synaptic plasticity loss in frontal and hippocampal neurons induced by chronic restraint stress. In conclusion, our results suggest that Tarooneh prevented and improved anxiety-like behavior, cognitive deficit, and neuronal damages in the CA1, CA3, and DG regions of the hippocampus and frontal cortex neurons induced by chronic restraint stress.

Soluble Epoxide Hydrolase as a Therapeutic Target for Neuropsychiatric Disorders

It has been found that soluble epoxide hydrolase (sEH; encoded by the EPHX2 gene) in the metabolism of polyunsaturated fatty acids (PUFAs) plays a key role in inflammation, which, in turn, plays a part in the pathogenesis of neuropsychiatric disorders. Meanwhile, epoxy fatty acids such as epoxyeicosatrienoic acids (EETs), epoxyeicosatetraenoic acids (EEQs), and epoxyeicosapentaenoic acids (EDPs) have been found to exert neuroprotective effects in animal models of neuropsychiatric disorders through potent anti-inflammatory actions. Soluble expoxide hydrolase, an enzyme present in all living organisms, metabolizes epoxy fatty acids into the corresponding dihydroxy fatty acids, which are less active than the precursors. In this regard, preclinical findings using sEH inhibitors or Ephx2 knock-out (KO) mice have indicated that the inhibition or deficiency of sEH can have beneficial effects in several models of neuropsychiatric disorders. Thus, this review discusses the current findings of the role of sEH in neuropsychiatric disorders, including depression, autism spectrum disorder (ASD), schizophrenia, Parkinson’s disease (PD), and stroke, as well as the potential mechanisms underlying the therapeutic effects of sEH inhibitors.

Depression and Cognitive Impairment-Extrahepatic Manifestations of NAFLD and NASH

Non-alcoholic fatty liver disease (NAFLD) and its complication non-alcoholic steatohepatitis (NASH) are important causes of liver disease worldwide. Recently, a significant association between these hepatic diseases and different central nervous system (CNS) disorders has been observed in an increasing number of patients. NAFLD-related CNS dysfunctions include cognitive impairment, hippocampal-dependent memory impairment, and mood imbalances (in particular, depression and anxiety). This review aims at summarizing the main correlations observed between NAFLD development and these CNS dysfunctions, focusing on the studies investigating the mechanism(s) involved in this association. Growing evidences point at cerebrovascular alteration, neuroinflammation, and brain insulin resistance as NAFLD/NASH-related CNS manifestations. Since the pharmacological options available for the management of these conditions are still limited, further studies are needed to unravel the mechanism(s) of NAFLD/NASH and their central manifestations and identify effective pharmacological targets.

Changes in Plasma Fatty Acids, Free Amino Acids, Antioxidant Defense, and Physiological Stress by Oleuropein Supplementation in Pigs Prior to Slaughter

Olive tree leaves are characterized for having not only a potent antioxidant power but also effects on glucose and lipid metabolism. The impact of the individual oleuropein (OLE), vitamin E + Se (VE), or a combined supplementation of oleuropein, vitamin E, and selenium (VEOLE) was evaluated on pig plasma metabolites under fasting prior to slaughter. VEOLE and OLE had lesser n-3 plasma polyunsaturated fatty acids and greater monounsaturated free fatty acids compared to control. The n-3-fatty acid mobilization was directly correlated with greater cystine and inversely with oxidized glutathione/reduced glutathione (GSSH/GSH) levels. This faster use of n-3 fatty acids might act as an indicator of glutathione synthesis mediated by an increase of cystine in plasma. Different correlations and linear adjustments were observed between plasma antioxidant power and free cystine, free glycine, free glutamine, monounsaturated free fatty acids, and total n-3. The best response to stress was found in VEOLE. Cortisol reached the greatest positive correlation with plasma total n-3 fatty acids, which suggests a faster uptake of n-3 for biological functions such as stress control or energy supply in the brain. From a practical point of view, an enhanced oxidative status as well as control of physiological stress prior to slaughter by the combined antioxidants supplementation might have positive effects on pork quality.