DL-/PO-phosphatidylcholine restores restraint stress-induced depression-related behaviors and spatial memory impairment

Dietary Milk Phospholipids Attenuate Chronic Stress-Induced Changes in Behavior and Endocrine Responses across the Lifespan

SCOPE

Increasing scientific evidence is validating the use of dietary strategies to support and improve brain health throughout the lifespan, with tailored nutritional interventions catering for specific life stages. Dietary phospholipid supplementations in early life and adulthood are shown to alleviate some of the behavioral consequences associated with chronic stress. This study aims to explore the protective effects of a tailored phospholipid-enriched buttermilk on behavioral and endocrine responses induced by chronic psychosocial stress in adulthood, and to compare these effects according to the life stage at which the supplementation is started.

METHODS AND RESULTS

A novel developed phospholipid-enriched dairy product is assessed for its effects on social, anxiety- and depressive-like behaviors, as well as the stress response and cognitive performance following chronic psychosocial stress in C57BL/6J mice, with supplementation beginning in adulthood or early life. Milk phospholipid supplementation from birth protects adult mice against chronic stress-induced changes in endocrine response to a subsequent acute stressor and reduces innate anxiety-like behavior in non-stressed animals. When starting in adulthood, the dietary intervention reverses the anxiety-like phenotype caused by chronic stress exposure.

CONCLUSION

Dairy-derived phospholipids exert differential protective effects against chronic psychosocial stress depending on the targeted life stage and duration of the dietary supplementation.

Dietary EPA-Enriched Phospholipids Alleviate Chronic Stress and LPS-Induced Depression- and Anxiety-Like Behavior by Regulating Immunity and Neuroinflammation

SCOPE

A growing number of studies have reported the effects of eicosapentaenoic acid (EPA) and terrestrial phospholipids on ameliorating mood disorders. Marine-derived EPA-enriched phospholipids (EPA-PL) exhibit the structural characteristics of EPA and phospholipids. However, the effect of dietary EPA-PL, and the differences between amphiphilic EPA-PL and lyophobic EPA on mood disorders had not been studied.

METHODS AND RESULTS

A comparative investigation to determine the effects of dietary EPA-enriched ethyl ester (EPA-EE) and EPA-PL on improving depression- and anxiety-like behavior in a mouse model is performed, induced by 4 week chronic unpredictable mild stress (CUMS) coupled with lipopolysaccharide (LPS) challenge. It is found that dietary 4 week 0.6% (w/w) EPA-PL rescued depression- and anxiety-like behavior to a greater extent than did EPA-EE. Moreover, dietary EPA-PL significantly reduced the immobility time by 56.6%, close to the normal level, in forced swimming test, which revealed a reversal of depression-like behavior. Further studies revealed that dietary EPA-PL regulated immunity, monoamine systems, and the hypothalamic-pituitary-adrenal (HPA) axis by multi-target interactions, including inhibition of neuroinflammation and apoptosis.

CONCLUSION

EPA-PL exerted superior effects to EPA-EE in alleviating depression- and anxiety-like behavior. The data suggest potential novel candidate or targeted dietary patterns to prevent and treat mood disorder.

Effects of Dietary Food Components on Cognitive Functions in Older Adults

Population aging has recently been an important issue as the number of elderly people is growing worldwide every year, and the extension of social security costs is financially costly. The increase in the number of elderly people with cognitive decline is a serious problem related to the aging of populations. Therefore, it is necessary to consider not only physical care but also cognitive patterns in the future care of older adults. Since food contains a variety of bioactive substances, dietary patterns may help improve age-related cognitive decline. However, the relationship between cognitive function and individual food components remains ambiguous as no clear efficacy or mechanism has been confirmed. Against this background, this review summarizes previous reports on the biological process of cognitive decline in the elderly and the relationship between individual compounds in foods and cognitive function, as well as the role of individual components of food in cognitive function, in the following order: lipids, carotenoids, vitamins, phenolic compounds, amino acids, peptides, and proteins. Based on the research presented in this review, a proper diet that preserves cognitive function has the potential to improve age-related cognitive decline, Alzheimer's disease, and Parkinson's disease. Hopefully, this review will help to trigger the development of new foods and technologies that improve aging and cognitive functions and extend the healthy life span.

The loss of NDRG2 expression improves depressive behavior through increased phosphorylation of GSK3β

N-myc downstream-regulated gene 2 (NDRG2) is one of the important stress-inducible genes and plays a critical role in negatively regulating PI3K/AKT signaling during hypoxia and inflammation. Through recruitment of PP2A phosphatase, NDRG2 maintains the dephosphorylated status of PTEN to suppress excessive PI3K/AKT signaling, and loss of NDRG2 expression is frequently seen in various types of cancer with enhanced activation of PI3K/AKT signaling. Because NDRG2 is highly expressed in the nervous system, we investigated whether NDRG2 plays a functional role in the nervous system using Ndrg2-deficient mice. Ndrg2-deficient mice do not display any gross abnormalities in the nervous system, but they have a diminished behavioral response associated with anxiety. Ndrg2-deficient mice exhibited decreased immobility and increased head-dipping and rearing behavior in two behavioral models, indicating an improvement of emotional anxiety-like behavior. Moreover, treatment of wild-type mice with the antidepressant drug imipramine reduced the expression of Ndrg2 in the frontal cortex, which was due to the degradation of HIF-1α through reduced expression of HSP90 protein. Furthermore, we found that the down-regulation of Ndrg2 in Ndrg2-deficient mice and imipramine treatment improved mood behavior with enhanced phosphorylation of GSK3β through activation of PI3K/AKT signaling, suggesting that the expression level of NDRG2 has a causal influence on mood-related phenotypes. Collectively, these results suggest that NDRG2 may be a potential target for mood disorders such as depression and anxiety.

Flupirtine attenuates chronic restraint stress-induced cognitive deficits and hippocampal apoptosis in male mice

Chronic restraint stress (CRS) causes hippocampal neurodegeneration and hippocampus-dependent cognitive deficits. Flupirtine represents neuroprotective effects and we have previously shown that flupirtine can protect against memory impairment induced by acute stress. The present study aimed to investigate whether flupirtine could alleviate spatial learning and memory impairment and hippocampal apoptosis induced by CRS. CRS mice were restrained in well-ventilated Plexiglass tubes for 6h daily beginning from 10:00 to 16:00 for 21 consecutive days. Mice were injected with flupirtine (10mg/kg and 25mg/kg) or vehicle (10% DMSO) 30min before restraint stress for 21 days. After stressor cessation, the spatial learning and memory, dendritic spine density, injured neurons and the levels of Bcl-2, Bax, p-Akt, p-GSK-3β, p-Erk1/2 and synaptophysin of hippocampal tissues were examined. Our results showed that flupirtine significantly prevented spatial learning and memory impairment induced by CRS in the Morris water maze. In addition, flupirtine (10mg/kg and 25mg/kg) treatment alleviated neuronal apoptosis and the reduction of dendritic spine density and synaptophysin expression in the hippocampal CA1 region of CRS mice. Furthermore, flupirtine (10mg/kg and 25mg/kg) treatment significantly decreased the expression of Bax and increased the p-Akt and p-GSK-3β, and flupirtine (25mg/kg) treatment up-regulated the p-Erk1/2 in the hippocampus of CRS mice. These results suggested that flupirtine exerted protective effects on the CRS-induced cognitive impairment and hippocampal neuronal apoptosis, which is possibly associated with the activation of Akt/GSK-3β and Erk1/2 signaling pathways.

Acute restraint stress impairs induction of long-term potentiation by activating GSK-3β

The present study investigated the effect of acute restraint stress on long-term potentiation (LTP) and the underlying mechanism. Induction of Schaffer collateral-CA1 LTP was suppressed in hippocampal slices from mice with 1-h restraint stress. Cell surface localization of the N-methyl-D-aspartate (NMDA) receptor subunits NR1 and NR2B and the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor subunits GluA1 and GluA2 was not affected in the hippocampus from mice with 1-h restraint stress. Phosphorylation of Akt at Ser473, but not at Thr308, and phosphorylation of GSK-3β at Ser9, but not at Tyr216, were significantly inhibited in the hippocampus with 1-h restraint stress. Taken together, the results of the present study show that acute restraint stress impairs induction of LTP by enhancing GSK-3β activity following suppressed Akt activity, without affecting cell surface localization of the NMDA and AMPA receptor subunits.