Improved spatial learning and memory by perilla diet is correlated with immunoreactivities to neurofilament and α-synuclein in hilus of dentate gyrus

Feeding the Brain: Effect of Nutrients on Cognition, Synaptic Function, and AMPA Receptors

In recent decades, traditional eating habits have been replaced by a more globalized diet, rich in saturated fatty acids and simple sugars. Extensive evidence shows that these dietary factors contribute to cognitive health impairment as well as increase the incidence of metabolic diseases such as obesity and diabetes. However, how these nutrients modulate synaptic function and neuroplasticity is poorly understood. We review the Western, ketogenic, and paleolithic diets for their effects on cognition and correlations with synaptic changes, focusing mainly (but not exclusively) on animal model studies aimed at tracing molecular alterations that may contribute to impaired human cognition. We observe that memory and learning deficits mediated by high-fat/high-sugar diets, even over short exposure times, are associated with reduced arborization, widened synaptic cleft, narrowed post-synaptic zone, and decreased activity-dependent synaptic plasticity in the hippocampus, and also observe that these alterations correlate with deregulation of the AMPA-type glutamate ionotropic receptors (AMPARs) that are crucial to neuroplasticity. Furthermore, we explored which diet-mediated mechanisms modulate synaptic AMPARs and whether certain supplements or nutritional interventions could reverse deleterious effects, contributing to improved learning and memory in older people and patients with Alzheimer’s disease.

Perilla seed oil in combination with the nobiletin-rich ponkan powder enhances cognitive function in healthy elderly Japanese individuals: Possible supplement for brain health in the elderly

Perilla (Perilla frutescens) seed oil (PO), rich in α-linolenic acid (ALA), can improve cognitive function in healthy elderly Japanese people. Here, supplements containing either PO alone or PO with nobiletin-rich...

Anti-inflammatory effect of Perilla frutescens seed oil rich in omega-3 fatty acid on dextran sodium sulfate-induced colitis in mice

Background and purpose

Ulcerative colitis is a chronic inflammatory bowel disease that involves diffused inflammation of the large intestine. Omega-3 fatty acid (FA) has been known to regulate the inflammatory response associated with ulcerative colitis pathogenesis. Perilla frutescens is a valuable source of omega-3 FA and α-linolenic acid (ALA) contained in its seed oil. Therefore, the aim of this study was to evaluate the anti-inflammatory effect of Perilla seed oil (PSO) on colitis induced by dextran sulfate sodium (DSS) in a mouse model.

Experimental approach

PSO was extracted using a cold-pressed extractor and FA composition of PSO was analyzed by GC-MS. Acute colitis in mice was induced with 3% DSS in drinking water for 7 days. Some mice were treated with PSO (20, 100, 200 mg/kg BW) for 3 weeks before the DSS administration. Sulfasalazine was used as a positive control. The clinical features, histopathologic, serum, and gene expression of proinflammatory cytokines in the colon were assessed.

Finding/Results

PSO contained the highest proportion of ALA (61.51%). Furthermore, PSO pretreatment evidently reduced body weight loss, diminished diarrhea, gross bleeding, and DSS-induced colon shortening. PSO pretreatment attenuated histopathological changes in response to DSS-induced colitis. PSO pretreatment also markedly decreased inflammatory response in serum and the colon tissue of DSS-induced mice.

Conclusion and implication

ALA in PSO is suggested to be mainly responsible for the reduction of DSS-induced colitis through suppressing inflammatory markers. PSO could be further developed as a functional health supplement, which would be beneficial for anti-inflammation in the colonic mucosa.

Perilla Seed Oil Enhances Cognitive Function and Mental Health in Healthy Elderly Japanese Individuals by Enhancing the Biological Antioxidant Potential

Oxidative stress plays an important role in age-associated cognitive decline. We recently reported that dietary intake of perilla seed oil (PO), a rich source of α-linolenic acid (LNA, C18:3, ω-3), helps in maintaining good mental health in adults. This study aimed to investigate the impacts of dietary PO intake on cognitive functions and mental health in healthy, elderly Japanese individuals. Seventy-five healthy volunteers aged 64–84 years were randomly divided into two groups: a control group and a PO-administered group. At baseline and at 12 months of intervention, cognitive function, mental health condition, fatty acid profile of the red blood cell plasma membranes (RBC-PM), and serum biochemical parameters were evaluated. Results showed that serum biological antioxidant potential and LNA levels in the RBC-PM at 12 months after the trial were significantly higher in the PO group compared to the control group. Further, both the cognitive function measures, as evaluated by the Frontal Assessment Battery test and the apathy scores, tended to be improved after 12 months in the PO group. Our results demonstrate that dietary PO intake enhances the antioxidant potential and prevents the age-related cognitive and mental decline in healthy elderly individuals by enhancing the blood LNA levels.

Special bioactive compounds and functional foods may exhibit neuroprotective effects in patients with dementia (Review)

Dementia is a failure of cognitive ability characterized by severe neurodegeneration in select neural systems, and Alzheimer's disease (AD) is the most common type of neurodegenerative disease. Although numerous studies have provided insights into the pathogenesis of AD, the underlying signaling and molecular pathways mediating the progressive decline of cognitive function remain poorly understood. Recent progress in molecular biology has provided an improved understanding of the importance of molecular pathogenesis of AD, and has proposed an association between DNA repair mechanisms and AD. In particular, the fundamental roles of phosphatase and tensin homologue deleted on chromosome 10 (PTEN) and breast cancer gene 1 (BRCA1) tumor suppressors have been shown to regulate the pathogenesis of neurodegeneration. Consequently, onset of neurodegenerative diseases may be deferred with the use of dietary neuroprotective agents which alter the signaling mediated by the aforementioned tumor suppressors. In a healthy neuron, homeostasis of key intracellular molecules is of great importance, and preventing neuronal apoptosis is one of the primary goals of treatments designed for dementia-associated diseases. In the present review, progress into the understanding of dietary regulation for preventing or limiting development of dementia is discussed with a focus on the modulatory roles of PTEN and BRCA1 signaling.

Outcomes of Perilla Seed Oil as an Additional Neuroprotective Therapy in Patients with Mild to Moderate Dementia: A Randomized Control Trial

BACKGROUND

Dementia is a common medical disorder in the elderly. Oxidative stress plays a major role in the process of cognitive decline in dementia. Perilla seed oil demonstrates its neuroprotective effects via anti-oxidative mechanisms against dementia. We investigate neuroprotective effects of perilla seed oil as an additional treatment in patients with mild to moderate dementia.

METHOD

A double-blind, randomized-control trial (perilla seed oil versus placebo) in patients with mild to moderate dementia was conducted. Perilla seed oil or placebo was added on with standard treatment for six months. Cognitive function was compared at nine months after enrollment.

RESULT

182 patients, with 94 in the experimental group and 88 in the placebo group, were able to complete the study. Cognitive function is not significantly different compared between groups. However, the total cholesterol and LDL cholesterol were significantly lower in the experimental group. Perilla seed oil had no adverse effect to kidney, liver, blood components or glucose metabolism.

CONCLUSION

Perilla seed oil as additional neuroprotective therapy in patients with mild to moderate dementia does not improve cognitive function. Perilla seed oil significantly reduced total cholesterol and LDL cholesterol. A clinical trial is needed to prove the benefit of cholesterol-lowering effects with perilla seed oil in human.

Ethnomedicinal, Phytochemical and Pharmacological Investigations of Perilla frutescens (L.) Britt

Perilla frutescens (L.) Britt. (PF) is an annual herbal medicinal, aromatic, functional food, and ornamental plant that belongs to the mint family, Lamiaceae. The origin of perilla traces back to East Asian countries (China, Japan, Korea, Taiwan, Vietnam, and India), where it has been used as a valuable source of culinary and traditional medicinal uses. The leaves, seeds, and stems of P. frutescens are used for various therapeutic applications in folk medicine. In the absence of a comprehensive review regarding all aspects of perilla, this review aims to present an overview pertaining to the botanical drug, ethnobotany, phytochemistry, and biological activity. It was found that the taxonomic classification of perilla species is quite confused, and the number of species is vague. Perilla has traditionally been prescribed to treat depression-related disease, anxiety, asthma, chest stuffiness, vomiting, coughs, colds, flus, phlegm, tumors, allergies, intoxication, fever, headache, stuffy nose, constipation, abdominal pain, and indigestion, and acts as an analgesic, anti-abortive agent, and a sedative. Until now, 271 natural molecules have been identified in perilla organs including phenolic acids, flavonoids, essential oils, triterpenes, carotenoids, phytosterols, fatty acids, tocopherols, and policosanols. In addition to solvent extracts, these individual compounds (rosmarinic acid, perillaldehyde, luteolin, apigenin, tormentic acid, and isoegomaketone) have attracted researchers' interest for its pharmacological properties. Perilla showed various biological activities such as antioxidant, antimicrobial, anti-allergic, antidepressant, anti-inflammatory, anticancer, and neuroprotection effects. Although the results are promising in preclinical studies (in vitro and in vivo), clinical studies are insufficient; therefore, further study needs to be done to validate its therapeutic effects and to ensure its safety and efficacy.

Identification of a Novel Anticancer Oligopeptide from Perilla frutescens (L.) Britt. and Its Enhanced Anticancer Effect by Targeted Nanoparticles In Vitro

Objective. Perilla frutescens (L.) Brittis is a dietary herbal medicine and has anticancer effect. However, little is known about its anticancer peptides. This study is aimed at identifying cytotoxic oligopeptides which are loaded by a drug delivery system, to explore its anticancer application. Methods. The oligopeptides were isolated from enzymatic hydrolysates of Perilla seed crude protein by using ultrafiltration, gel filtration chromatography, and reversed-phase high-performance liquid chromatography (RP-HPLC). The structure of the oligopeptide was determined using a peptide sequencer, and its anticancer effect was examined by the MTT assay. PSO (Perilla seed oligopeptide), the most potent anticancer oligopeptide, was loaded by chitosan nanoparticles (NPs) modified by hyaluronic acid (HA). Then, the particle size, zeta potential, encapsulation efficiency (EE), drug loading efficiency (LE), the cumulative release rates of NPs, and its cytotoxic effect on cancer cells were investigated. Results. Three fractions were isolated by the chromatography assay. The third fraction has a broad-spectrum and the strongest anticancer effect. This fraction was further purified and identified as SGPVGLW with a molecular weight of 715 Da and named as PSO. Then, PSO was loaded by HA-conjugated chitosan to prepare HA/PSO/C NPs, which had a uniform size of 216.7 nm, a zeta potential of 35.4 mV, an EE of 38.7%, and an LE of 24.3%. HA/PSO/C NPs had a slow release rate in vitro, with cumulative release reaching to 81.1%. Compared with free PSO, HA/PSO/C NPs showed notably enhanced cytotoxicity and had the strongest potency to human glioma cell line U251. Conclusion. This study demonstrated that PSO, a novel oligopeptide from Perilla seeds, has a broad-spectrum anticancer effect and could be encapsulated by NPs, which enhanced tumor targeting cytotoxicity with obvious controlled release. Our study indicates that Perilla seeds are valuable for anticancer peptide development.

Feasibility and Safety of Perilla Seed Oil as an Additional Antioxidative Therapy in Patients with Mild to Moderate Dementia

Dementia is a broad-spectrum terminology for a degenerate in cognitive function severe enough to intervene in activities of daily living. Oxidative stress plays a major role in the neurodegenerative cascade, leading to the irreversible mechanism in dementia. Perilla seed oil is extracted from its seeds and contains a high source of antioxidative substances such as omega-3 fatty acid. With its prominent antioxidative property, perilla seed oil demonstrates neuroprotective effects against dementia in preclinical studies. We aim to prove the feasibility and safety of perilla seed oil as an additional antioxidative therapy in patients with dementia. This single-centered, double-blinded, placebo-controlled trial randomized 239 patients with clinical diagnosis of mild to moderate dementia according to the Thai Mini-Mental State Examination (TMSE) score of 10 to 23 or the Thai Montreal Cognitive Assessment score of 12 to 25. Either two capsules containing 500 milligrams of perilla seed oil or similarly appearing two capsules containing 500 milligrams of olive oil (placebo) four times daily was added to conventional standard treatment of dementia for six months. Clinical side effects and routine laboratory results at baseline and after treatment were compared between both groups. Nausea and vomiting were the most common clinical side effects (3%) found equally in both groups. Three patients in the placebo group prematurely discontinued the medication, while only one patient in the treatment group quit the medication early. However, about 5% of patients in both groups could not comply with the regimen of the treatment. The routine laboratory results, including complete blood counts, kidney function tests, and liver function panels, at baseline and after treatment, were not significantly different in both groups. In conclusion, perilla seed oil was feasible and safe to add on with standard treatment in patients with mild to moderate dementia. Further study is needed to confirm its benefit to use as additional antioxidative therapy in patients with dementia.

Alpha-Linolenic Acid from Perilla frutescens var. japonica Oil Protects Aβ-Induced Cognitive Impairment through Regulation of APP Processing and Aβ Degradation

Alzheimer's disease (AD) is characterized by progressive cognitive and memory impairment. The major pathological hallmark of AD is the accumulation of amyloid beta (Aβ), which is produced from the amyloid precursor protein (APP) through cleavage of β- and γ-secretase. Recently, dietary plant oil containing ω-3 polyunsaturated fatty acid has become an attractive alternative source to fish oil containing eicosapentaenoic acid or docosahexaenoic acid (DHA). We investigated whether ALA isolated from perilla oil has direct effects on improvement of cognitive ability and molecular mechanisms in APP processing in comparison with DHA. In the present study, ICR mice were treated orally with ALA or DHA (100 mg/kg/day) for 14 days after i.c.v. injection of Aβ_25-35. Administration of ALA resulted in a prevention of learning and memory deficit in Aβ_25-35-injected mice compared with the control group, as observed in T-maze, novel object recognition, and Morris water maze tests. ALA supplementation also markedly ameliorated the Aβ_25-35-induced oxidative stress by inhibition of lipid peroxidation and nitric oxide overproduction in the mouse brain, liver, and kidney, almost down to the levels in DHA-administered group. These effects of ALA on protective mechanisms were related to the regulation of APP processing via promoting nonamyloidogenic pathway such as up-regulation of soluble APP alpha, C-terminal fragment alpha/beta ratio, and A disintegrin and metalloprotease10 protein expressions. Furthermore, ALA inhibited the amyloidogenic pathway through the down-regulation of β-site APP-cleaving enzyme and presenilin2. ALA also enhanced Aβ degradation enzyme, insulin-degrading enzyme. In conclusion, the present study indicated a beneficial effect of ALA in improving the cognitive ability against Aβ_25-35, and these effects were comparable to those exerted by DHA. Its neuroprotective effects are mediated, in part, by regulation of APP processing and Aβ degradation, and thus, ALA might be a potential candidate for prevention or treatment of neurodegenerative diseases such as AD.

Phytochemical and phytopharmacological review of Perilla frutescens L. (Labiatae), a traditional edible-medicinal herb in China

Perilla frutescens (L.) Britt., a worldwide distributed plant, is an important economic crop and with a long cultivation history in China as well as some other countries in Asia. Except for the edible applications, the plant of P. frutescens is also traditionally used as a medicinal herb in China for thousands years. The leaves, seeds and stems of P. frutescens are recommended by the Chinese Pharmacopeia as three medicinal materials for various therapeutic applications. In the past decades, amount investigations have been done about different aspects for P. frutescens. However, no literature review about these works has been compiled. This review aims to present the findings of research conducted up-to-date (2015) on the traditional use, phytochemicals, pharmacological activities and toxicities of P. frutescens to provide scientific evidence for well-understanding and future research of P. frutescens. It was found that more than 100 compounds have been reported for P. frutescens and most of them are contributed to its medical benefits such as anti-allergic, anti-inflammatory, anti-oxidant, anticancer, anti-microbial, anti-depressive and anti-cough effects. Toxicology studies have been conducted to evaluate the safety of P. frutescens to provide information on their dosages and usages.

Sex-Specific Effects of Diets High in Unsaturated Fatty Acids on Spatial Learning and Memory in Guinea Pigs

Unsaturated fatty acids (UFAs), including omega-3, omega-6 polyunsaturated and omega-9 monounsaturated fatty acids, are essential components and modulators of neuromembranes and may affect various aspects of physiology and cognition. UFAs are suggested to positively affect spatial learning and memory and also to diminish the negative consequences of physiological stress on cognitive abilities. Due to pronounced sex differences in neurophysiological functions, we hypothesize that these UFA-related effects might differ between male and female individuals. We therefore determined the effects of dietary UFAs on cognitive performances in a radial-Y-maze in male and female guinea pigs in relation to saliva cortisol concentrations, a marker for physiological stress. Animals were assigned to four treatment groups and maintained on diets enriched in either chia seeds (omega-3), walnuts (omega-6), or peanuts (omega-9), or a control diet. Female learning abilities throughout a three-day learning phase were positively affected by omega-3 and omega-9, as determined by a decreasing latency to pass the test and the number of conducted errors, while males generally showed distinct learning abilities, irrespective of the diet. A sex difference in learning performances was found in the control group, with males outperforming females, which was not detected in the UFA-supplemented groups. This was paralleled by significantly increased saliva cortisol concentrations in males throughout the cognition test compared to females. Three days after this learning phase, UFA-supplemented males and all females showed unchanged performances, while control males showed an increased latency and therefore an impaired performance. These results were corroborated by pronounced differences in the plasma UFA-status, corresponding to the different dietary treatments. Our findings indicate sex-specific effects of dietary UFAs, apparently enhancing spatial learning abilities only in females and protecting males from long-term memory impairment, while male learning abilities seem to be more strongly affected by an acute physiological stress response to the maze task.

Differential effects of dopamine signalling on long-term memory formation and consolidation in rodent brain

Background

Using auditory discrimination learning in gerbils, we have previously shown that activation of auditory-cortical D1/D5 dopamine receptors facilitates mTOR-mediated, protein synthesis-dependent mechanisms of memory consolidation and anterograde memory formation. To understand molecular mechanisms of this facilitatory effect, we tested the impact of local pharmacological activation of different D1/D5 dopamine receptor signalling modes in the auditory cortex. To this end, protein patterns in soluble and synaptic protein-enriched fractions from cortical, hippocampal and striatal brain regions of ligand- and vehicle-treated gerbils were analysed by 2D gel electrophoresis and mass spectrometry 24 h after intervention.

Results

After auditory-cortical injection of SKF38393 – a D1/D5 dopamine receptor-selective agonist reported to activate the downstream effectors adenylyl cyclase and phospholipase C – prominent proteomic alterations compared to vehicle-treated controls appeared in the auditory cortex, striatum, and hippocampus, whereas only minor changes were detectable in the frontal cortex. In contrast, auditory-cortical injection of SKF83959 – a D1/D5 agonist reported to preferentially stimulate phospholipase C – induced pronounced changes in the frontal cortex. At the molecular level, we detected altered regulation of cytoskeletal and scaffolding proteins, changes in proteins with functions in energy metabolism, local protein synthesis, and synaptic signalling. Interestingly, abundance and/or subcellular localisation of the predominantly presynaptic protein α-synuclein displayed dopaminergic regulation. To assess the role of α-synuclein for dopaminergic mechanisms of memory modulation, we tested the impact of post-conditioning systemic pharmacological activation of different D1/D5 dopamine receptor signalling modes on auditory discrimination learning in α-synuclein-mutant mice. In C57BL/6JOlaHsd mice, bearing a spontaneous deletion of the α-synuclein-encoding gene, but not in the related substrains C57BL/6JCrl and C57BL/6JRccHsd, adenylyl cyclase-mediated signalling affected acquisition rates over future learning episodes, whereas phospholipase C-mediated signalling affected final memory performance.

Conclusions

Dopamine signalling modes via D1/D5 receptors in the auditory cortex differentially impact protein profiles related to rearrangement of cytomatrices, energy metabolism, and synaptic neurotransmission in cortical, hippocampal, and basal brain structures. Altered dopamine neurotransmission in α-synuclein-deficient mice revealed that distinct D1/D5 receptor signalling modes may control different aspects of memory consolidation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12953-015-0069-2) contains supplementary material, which is available to authorized users.

Perinatal α-linolenic acid availability alters the expression of genes related to memory and to epigenetic machinery, and the Mecp2 DNA methylation in the whole brain of mouse offspring

Many animal and human studies indicated that dietary ω-3 fatty acids could have beneficial roles on brain development, memory, and learning. However, the exact mechanisms involved are far from being clearly understood, especially for α-linolenic acid (ALA), which is the precursor for the ω-3 elongation and desaturation pathways. This study investigated the alterations induced by different intakes of flaxseed oil (containing 50% ALA), during gestation and lactation, upon the expression of genes involved in neurogenesis, memory-related molecular processes, and DNA methylation, in the brains of mouse offspring at the end of lactation (postnatal day 19, P19). In addition, DNA methylation status for the same genes was investigated. Maternal flaxseed oil supplementation during lactation increased the expression of Mecp2, Ppp1cc, and Reelin, while decreasing the expression of Ppp1cb and Dnmt3a. Dnmt1 expression was decreased by postnatal flaxseed oil supplementation but this effect was offset by ALA deficiency during gestation. Mecp2 DNA methylation was decreased by maternal ALA deficiency during gestation, with a more robust effect in the lactation-deficient group. In addition, linear regression analysis revealed positive correlations between Mecp2, Reelin, and Ppp1cc, between Gadd45b, Bdnf, and Creb1, and between Egr1 and Dnmt1, respectively. However, there were no correlations, in any gene, between DNA methylation and gene expression. In summary, the interplay between ALA availability during gestation and lactation differentially altered the expression of genes involved in neurogenesis and memory, in the whole brain of the offspring at the end of lactation. The Mecp2 epigenetic status was correlated with ALA availability during gestation. However, the epigenetic status of the genes investigated was not associated with transcript levels, suggesting that either the regulation of these genes is not necessarily under epigenetic control, or that the whole brain model is not adequate for the exploration of epigenetic regulation in the context of this study.

The differential hippocampal phosphoproteome of Apodemus sylvaticus paralleling spatial memory retrieval in the Barnes maze

Protein phosphorylation is a well-known and well-documented mechanism in memory processes. Although a large series of protein kinases involved in memory processes have been reported, information on phosphoproteins is limited. It was therefore the aim of the study to determine a partial and differential phosphoproteome along with the corresponding network in hippocampus of a wild caught mouse strain with excellent performance in several paradigms of spatial memory. Apodemus sylvaticus mice were trained in the Barnes maze, a non-invasive test system for spatial memory and untrained mice served as controls. Animals were sacrificed 6h following memory retrieval, hippocampi were taken, proteins extracted and in-solution digestion was carried out with subsequent iTRAQ double labelling. Phosphopeptides were enriched by a TiO2-based method and semi-quantified using two fragmentation principles on the LTQ-orbitrap Velos. In hippocampi of trained animals phosphopeptide levels representing signalling, neuronal, synaptosomal, cytoskeletal and metabolism proteins were at least twofold reduced or increased. Furthermore, a network revealing a link to pathways of ubiquitination, the androgen receptor, small GTPase Rab5 and MAPK signaling as well as synucleins was constructed. This work is relevant for interpretation of previous work and the design of future studies on protein phosphorylation in spatial memory.

Traditional Korean East Asian medicines and herbal formulations for cognitive impairment

Hanbang, the Traditional Korean Medicine (TKM), is an inseparable component of Korean culture both within the country, and further afield. Korean traditional herbs have been used medicinally to treat sickness and injury for thousands of years. Oriental medicine reflects our ancestor’s wisdom and experience, and as the elderly population in Korea is rapidly increasing, so is the importance of their health problems. The proportion of the population who are over 65 years of age is expected to increase to 24.3% by 2031. Cognitive impairment is common with increasing age, and efforts are made to retain and restore the cognition ability of the elderly. Herbal materials have been considered for this purpose because of their low adverse effects and their cognitive-enhancing or anti-dementia activities. Herbal materials are reported to contain several active compounds that have effects on cognitive function. Here, we enumerate evidence linking TKMs which have shown benefits in memory improvements. Moreover, we have also listed Korean herbal formulations which have been the subject of scientific reports relating to memory improvement.