ß-Lactolin improves mitochondrial function in Aß-treated mouse hippocampal neuronal cell line and a human iPSC-derived neuronal cell model of Alzheimer's disease.

Mitochondrial dysfunctions are a key hallmark of Alzheimer's disease (AD). ß-Lactolin, a whey-derived glycine-threonine-tryptophan-tyrosine tetrapeptide, has been previously reported to prevent AD-like pathologies in an AD mouse model via regulation of microglial functions. However, the direct effect of ß-lactolin on neuronal cells and neuronal mitochondrial functions remains unknown. Here, we investigated the effects of ß-lactolin on mitochondrial functions in amyloid ß (Aß)-treated mouse hippocampal neuronal HT22 cells and human induced-pluripotent cell (hiPSC)-derived AD model neurons. Adding ß-lactolin to Aß-treated HT22 cells increased both the oxygen consumption rate and cellular ATP concentrations, suggesting that ß-lactolin improves mitochondrial respiration and energy production. Using high content image analysis, we found that ß-lactolin improved mitochondrial fragmentation, membrane potential, and oxidative stress in Aß-treated cells, eventually preventing neuronal cell death. From a mechanistic perspective, we found that ß-lactolin increased gene expression of mitofusin-2, which contributes to mitochondrial fusion events. Finally, we showed that ß-lactolin improves both mitochondrial morphologies and membrane potentials in hiPSC-derived AD model neurons. Taken together, ß-lactolin improved mitochondrial functions AD-related neuronal cell models and prevented neuronal cell death. The dual function of ß-lactolin on both neuron and microglia marks an advantage in maintaining neuronal health.

Tryptophan-tyrosine dipeptide improves tau-related symptoms in tauopathy mice.

Neurodegenerative diseases involving pathological tau protein aggregation are collectively known as tauopathies and include Alzheimer's disease and Pick's disease. Recent studies show that the intake of tryptophan-tyrosine (Trp-Tyr)-related ß-lactopeptides, including ß-lactolin, attenuates cognitive decline in the elderly and prevents the amyloid pathology in mouse models of Alzheimer's disease. However, the effects of Trp-Tyr-related ß-lactopeptides on tau-related pathology have not been investigated. In the present study, we examined the effects of Trp-Tyr dipeptide intake on tauopathy in PS19 transgenic mice, a well-established tauopathy model. Intake of Trp-Tyr dipeptide improved the behavioral deficits observed in the open field test, prevented tau phosphorylation, and increased the dopamine turnover and synaptophysin expression in the frontal cortex. Levels of short-chain fatty acids in the cecum were lower in PS19 mice than those in wild-type mice and were increased by treatment with Trp-Tyr dipeptide. In addition, intake of Trp-Tyr dipeptide extended the lifespan of PS19 mice. These findings suggest that the intake of Trp-Tyr-related peptides improves tauopathy symptoms, resulting in improvements in behavioral deficits and longevity. Hence, the intake of Trp-Tyr-related peptides, including ß-lactolin, may be beneficial for preventing dementia.

Effect of non-alcoholic beer containing matured hop bitter acids on mood states in healthy adults: A single-arm pilot study.

This study aimed to investigate the effect of non-alcoholic beer containing matured hop bitter acids on mood states among healthy adults older than 20 years. This study was an open-label longitudinal intervention design in which each participant served as their control. For 3 weeks, we evaluated the effect of non-alcoholic beer containing 35 mg of matured hop bitter acids on mood, sleep quality, and work performance. The data of 97 participants (age range: 23-72 years, median age: 42) were analyzed. After the intervention, we found that matured hop bitter acids significantly improved total mood state, including anxiety, depression, fatigue, and vigor, compared with the baseline. Furthermore, sleep quality and absolute presenteeism were significantly improved after the intervention compared with the baseline. The present exploratory study suggested that 3-week supplementation with matured hop bitter acids improved mood and peripheral symptoms in persons of a wide range of ages. Although further investigation is needed, the findings suggested that non-alcoholic beer in daily life might become a choice for maintaining mood states.

Effect of Microglial Inflammation in Prion Disease.

Prion diseases are a group of transmissible fatal neurodegenerative disorders. Neuropatho- logical features of prion diseases include neuroinflammation featuring the infiltration of activated microglia in affected brain areas as well as the accumulation of an abnormal isoform of the cellular prion protein and neuronal loss. Recent studies have elucidated that inflammation in the brain induced by microglia plays an important role in the pathogenesis of neurodegenerative disorders including prion disease. Thus, the regulation of neuroin- flammation is key in terms of therapeutic and preventative approaches. The functions of neuroinflammation and microglia in this disease are discussed in this article.

Bitter taste receptor activation by hop-derived bitter components induces gastrointestinal hormone production in enteroendocrine cells.

Matured hop bitter acids (MHBA) are bitter acid oxides derived from hops, widely consumed as food ingredients to add bitterness and flavor in beers. Previous studies have suggested a potential gut-brain mechanism in which MHBA simulates enteroendocrine cells to produce cholecystokinin (CCK), a gastrointestinal hormone which activates autonomic nerves, resulting in body fat reduction and cognitive improvement; however, the MHBA recognition site on enteroendocrine cells has not been fully elucidated. In this study, we report that MHBA is recognized by specific human and mouse bitter taste receptors (human TAS2R1, 8, 10 and mouse Tas2r119, 130, 105) using a heterologous receptor expression system in human embryonic kidney 293T cells. In addition, knockdown of each of these receptors using siRNA transfection partially but significantly suppressed an MHBA-induced calcium response and CCK production in enteroendocrine cells. Furthermore, blocking one of the essential taste signaling components, transient receptor potential cation channel subfamily M member 5, remarkably inhibited the MHBA-induced calcium response and CCK production in enteroendocrine cells. Our results demonstrate that specific bitter taste receptor activation by MHBA drives downstream calcium response and CCK production in enteroendocrine cells. These findings reveal a mechanism by which food ingredients derived from hops in beer activate the gut-brain axis for the first time.

Iso-α-acids, the bitter components of beer, improve hippocampus-dependent memory through vagus nerve activation.

Iso-α-acids (IAAs) are hop-derived bitter acids of beer. Epidemiologic studies suggest that moderate alcohol consumption is beneficial for cognitive function, but they do not show the ingredients in alcoholic beverages. Previously, we reported that long-term consumption of IAAs prevents inflammation and Alzheimer pathologies in mice, but their effects on cognitive function have not been evaluated. In the present study, we demonstrated that the consumption of IAAs improves spatial and object recognition memory functions not only in normal Crl:CD1(ICR) male mice but also in mice with pharmacologically induced amnesia. IAA consumption increased the total and extracellular levels of dopamine in the hippocampus of mice and Sprague-Dawley male rats, respectively. Dopamine D1 receptor antagonist treatment and knockdown of dopamine D1 receptor expression in the hippocampus attenuated IAA-induced spatial memory improvement. Furthermore, vagotomy attenuated the effects of IAAs in improving spatial and object recognition memory functions and increasing the total level of dopamine in the hippocampus. These results suggest that the consumption of IAAs activates dopamine D1 receptor-signaling in the hippocampus in a vagus nerve-dependent manner and, consequently, improves spatial and object recognition memory functions. Vagal activation with food components including IAAs may be an easy and safe approach to improve cognitive functions.-Ano, Y., Hoshi, A., Ayabe, T., Ohya, R., Uchida, S., Yamada, K., Kondo, K., Kitaoka, S., Furuyashiki, T. Iso-α-acids, the bitter components of beer, improve hippocampus-dependent memory through vagus nerve activation.

ß-lactolin, a whey-derived glycine-threonine-tryptophan-tyrosine lactotetrapeptide, improves prefrontal cortex-associated reversal learning in mice.

Dementia and cognitive decline have become worldwide public health problems. We have previously reported that a whey-derived glycine-threonine-tryptophan-tyrosine peptide, ß-lactolin, improves hippocampus-dependent memory functions in mice. The supplementation with a whey digest rich in ß-lactolin improves memory retrieval and executive function in a clinical trial, but the effect of ß-lactolin on prefrontal cortex (PFC)-associated cognitive function was unclear. Here we examined the effect of ß-lactolin and the whey digest on PFC-associated visual discrimination (VD) and reversal discrimination (RD) learning, using a rodent touch panel-based operant system. ß-Lactolin and the whey digest significantly improved the RD learning, and the whey digest enhanced the response latency during the VD task, indicating that ß-lactolin and the whey digest improve PFC-associated cognitive functions. Given the translational advantages of the touch panel operant system, consumption of ß-lactolin in daily life could be beneficial for improving human PFC-associated cognitive function, helping to prevent dementia.

Hop Bitter Acids Increase Hippocampal Dopaminergic Activity in a Mouse Model of Social Defeat Stress.

As daily lifestyle is closely associated with mental illnesses, diet-based preventive approaches are receiving attention. Supplementation with hop bitter acids such as iso-α-acids (IAA) and mature hop bitter acids (MHBA) improves mood states in healthy older adults. However, the underlying mechanism remains unknown. Since acute oral consumption with IAA increases dopamine levels in hippocampus and improves memory impairment via vagal nerve activation, here we investigated the effects of chronic administration of hop bitter acids on the dopaminergic activity associated with emotional disturbance in a mouse model of repeated social defeat stress (R-SDS). Chronic administration of IAA and MHBA significantly increased dopaminergic activity based on the dopamine metabolite to dopamine ratio in the hippocampus and medial prefrontal cortex following R-SDS. Hippocampal dopaminergic activity was inversely correlated with the level of R-SDS-induced social avoidance with or without IAA administration. Therefore, chronic treatment with hop bitter acids enhances stress resilience-related hippocampal dopaminergic activity.

Iso-α-acids and matured hop bitter acids in beer improve obesity-induced cognitive impairment.

Dementia and cognitive decline have become public health issues worldwide and life-style-related diseases and obesity have recently been reported as key risk factors. We have recently demonstrated that short-term administration of iso-α-acids (IAAs), hop-derived bitter components of beer, improves spatial and object recognition memory. However, the short-term effects of IAAs on obesity-induced cognitive impairment remain to be investigated. Furthermore, although matured hop bitter acids (MHBAs) are also derived from hops, their effect on obesity-induced cognitive decline remains unknown. In the present study, the short-term administration of IAAs improved memory deficits in high-fat diet (HFD)-fed mice, as assessed in the novel object recognition test (NORT). Dietary MHBAs supplementation administered to HFD-fed mice prevented obesity and improved memory deficits in the NORT. Moreover, the short-term administration of MHBAs improved episodic and spatial reference memory in obese mice. These hop-derived bitter acids may contribute toward improving obesity-induced cognitive impairments. Abbreviations: IAAs: iso-α-acids; MHBAs: matured hop bitter acids; HFD: high fat diet; NORT: novel object recognition test; NOLT: novel object location test.

Anxiolytic effects of theaflavins via dopaminergic activation in the frontal cortex.

Epidemiological investigations have reported that the habit of drinking tea reduces the risk of developing a mental disorder, including anxiety disorder and depression. Theaflavins, black tea polyphenols, show antibacterial and anti-oxidative effects, but their effects on brain function, especially mental condition, have not been elucidated. The present study demonstrated that theaflavins increased dopamine (DA) turnover in the frontal cortex and showed an anxiolytic effect in mice. Theaflavin consumption increased the time spent by mice in the open arms of an elevated plus maze test. Theaflavin administration increased the levels of 3,4-dihydroxyphenylacetic acid (DOPAC) and the ratios of DOPAC/DA and (DOPAC+homovanillic acids)/DA indicating DA turnover, in the frontal cortex. These results suggest that the consumption of theaflavins induced anxiolytic effects via activation of the dopaminergic system in the frontal cortex, which support the findings of previous epidemiological studies. Theaflavins in black tea may be helpful to reduce anxiety in daily life. (150/150 words).

Preventive Effects of Tryptophan-Methionine Dipeptide on Neural Inflammation and Alzheimer's Pathology.

Preventive approaches for age-related memory decline and dementia have become a high priority in the aging society because of the lack of therapeutic approaches. Recent epidemiological studies have reported that fermented dairy products can help prevent dementia. Previously, we identified tryptophan-tyrosine (WY) and tryptophan-methionine (WM) peptides as the suppressants of activation of the primary microglia and showed that WY peptide consumption suppresses inflammation in the brains of Alzheimer's disease model mice. However, the effects of the WM peptide on inflammation in the brain and Alzheimer's pathology have not been investigated. Here, we evaluated the effect of WM peptide consumption on Alzheimer's disease model (5×FAD) mice. In 5×FAD mice, intake of WM peptide suppressed the production of inflammatory cytokines, activation of microglia, and infiltration of activated microglia around ß amyloid (Aß) depositions. WM peptide intake reduced Aß deposition in the cortex and hippocampus and then improved the object recognition memory. Taken together with previous reports, the current findings indicate that ingestion of tryptophan-related peptides or food material rich in tryptophan-related peptides, thereby regulating microglial activity, represents a potential preventive approach for cognitive decline and dementia related to inflammation.

Theaflavins Improve Memory Impairment and Depression-Like Behavior by Regulating Microglial Activation.

Inflammation in the brain is associated with various disorders including Alzheimer's disease and depression. Thus, inflammation has received increasing attention regarding preventive approaches to such disorders. Epidemiological investigations have reported that drinking tea reduces the risk of dementia and depression. Theaflavins, a polyphenol found in black tea, are known to have anti-oxidative and anti-inflammation effects, but the effects of theaflavins on cognitive decline and depression induced by inflammation have not been investigated. To address this research gap, the present study assessed whether theaflavins could protect synapses and dendrites damaged by inflammation and prevent concomitant memory impairment and depression-like behavior in mice. Intracerebroventricular injection with lipopolysaccharide (LPS) induces neural inflammation associated with reduced spontaneous alternations in the Y-maze test and increased immobility in the tail suspension test, indicating impaired spatial memory and depression-like behavior, respectively. Oral administration with theaflavins prevented these behavioral changes induced by LPS. Theaflavins also suppressed productions of inflammatory cytokines and prevented dendritic atrophy and spine loss in the brain. Notably, theaflavins have a stronger anti-inflammatory effect than other polyphenols such as catechin, chlorogenic acid, and caffeic acid. These results suggest that theaflavins can suppress neural inflammation and prevent the symptoms of inflammation-related brain disorders.

Iso-α-acids, Bitter Components of Beer, Prevent Inflammation and Cognitive Decline Induced in a Mouse Model of Alzheimer's Disease.

Alongside the rapid growth in aging populations worldwide, prevention and therapy for age-related memory decline and dementia are in great demand to maintain a long, healthy life. Here we found that iso-α-acids, hop-derived bitter compounds in beer, enhance microglial phagocytosis and suppress inflammation via activation of the peroxisome proliferator-activated receptor γ. In normal mice, oral administration of iso-α-acids led to a significant increase both in CD11b and CD206 double-positive anti-inflammatory type microglia (p < 0.05) and in microglial phagocytosis in the brain. In Alzheimer's model 5xFAD mice, oral administration of iso-α-acids resulted in a 21% reduction in amyloid ß in the cerebral cortex as observed by immunohistochemical analysis, a significant reduction in inflammatory cytokines such as IL-1ß and chemokines including macrophage inflammatory protein-1α in the cerebral cortex (p < 0.05) and a significant improvement in a novel object recognition test (p < 0.05), as compared with control-fed 5xFAD mice. The differences in iso-α-acid-fed mice were due to the induction of microglia to an anti-inflammatory phenotype. The present study is the first to report that amyloid ß deposition and inflammation are suppressed in a mouse model of Alzheimer's disease by a single component, iso-α-acids, via the regulation of microglial activation. The suppression of neuroinflammation and improvement in cognitive function suggests that iso-α-acids contained in beer may be useful for the prevention of dementia.

Short-term administration of iso-α-acids increases transthyretin transcription in the hippocampus.

Cognitive decline and dementia are currently recognized as major problems in the aging population; however, there is still no promising treatment for these conditions. Previously, our group reported that iso-α-acids (IAAs), which are hop-derived bitter components present in beer, prevent inflammation and cognitive impairment in an Alzheimer's disease model mice (5xFAD mice) and yield significant reduction in amyloid ß (Αß) in the brain. However, data on the molecular mechanisms underlying these physiological effects of IAAs remain limited. Here, we used transcriptome analysis and found that oral administration of IAAs to 5xFAD mice for 7 days induces a 58.9-fold increase in the expression of transthyretin (TTR; Ttr) in the hippocampus compared with controls. In addition, real-time quantitative PCR showed that oral administration of IAAs significantly increased Ttr transcription in the hippocampi of wild type C57BL/6J mice but not in the cerebral cortex. TTR is an Αß protein scavenger; thus, an increase in its expression could prevent amyloid aggregate formation. These results indicate that IAAs reduce Αß in the brain by elevating TTR levels.

Preventive Effects of Dairy Products on Dementia and the Underlying Mechanisms.

Alongside the rapid population aging occurring worldwide, the prevention of age-related memory decline and dementia has become a high priority. Dairy products have many physiological effects owing to their contents of lactic acid bacteria and the fatty acids and peptides generated during their fermentation. In particular, several recent studies have elucidated the effects of fermented dairy products on cognitive function. Epidemiological and clinical evidence has indicated that fermented dairy products have preventive effects against dementia, including Alzheimer's disease. Recent preclinical studies have identified individual molecules generated during fermentation that are responsible for those preventive effects. Oleamide and dehydroergosterol have been identified as the agents responsible for reducing microglial inflammatory responses and neurotoxicity. In this review, the protective effects of fermented dairy products and their components on cognitive function, the mechanisms underlying those effects, and the prospects for their future clinical development will be discussed.

Iso-α-Acids, the Bitter Components of Beer, Suppress Microglial Inflammation in rTg4510 Tauopathy.

Due to the growth in aging populations, prevention for cognitive decline and dementia are in great demand. We previously demonstrated that the consumption of iso-α-acids (IAA), the hop-derived bitter compounds in beer, prevents inflammation and Alzheimer's disease pathology in model mice. However, the effects of iso-α-acids on inflammation induced by other agents aside from amyloid ß have not been investigated. In this study, we demonstrated that the consumption of iso-α-acids suppressed microglial inflammation in the frontal cortex of rTg4510 tauopathy mice. In addition, the levels of inflammatory cytokines and chemokines, including IL-1ß and MIP-1ß, in the frontal cortex of rTg4510 mice were greater than those of wild-type mice, and were reduced in rTg4510 mice fed with iso-α-acids. Flow cytometry analysis demonstrated that the expression of cells producing CD86, CD68, TSPO, MIP-1α, TNF-α, and IL-1ß in microglia was increased in rTg4510 mice compared with wild-type mice. Furthermore, the expression of CD86- and MIP-1α-producing cells was reduced in rTg4510 mice administered with iso-α-acids. Moreover, the consumption of iso-α-acids reduced the levels of phosphorylated tau in the frontal cortex. Collectively, these results suggest that the consumption of iso-α-acids prevents the inflammation induced in tauopathy mice. Thus, iso-α-acids may help in preventing inflammation-related brain disorders.

Role of microglia in oxidative toxicity associated with encephalomycarditis virus infection in the central nervous system.

The single-stranded RNA encephalomyocarditis virus (EMCV) can replicate in the central nervous system (CNS) and lead to prominent brain lesions in the stratum pyramidale hippocampus and the stratum granulosum cerebelli. Activated microglia cells infected by EMCV produce a massive burst of reactive oxygen species (ROS) via NADPH oxidase 2 (NOX2) activation, leading to neuronal death. Balancing this effect is mechanisms by which ROS are eliminated from the CNS. Cellular prion protein (PrP(C)) plays an important antioxidant role and contributes to cellular defense against EMCV infection. This review introduces recent knowledge on brain injury induced by EMCV infection via ROS generation as well as the involvement of various mediators and regulators in the pathogenesis.

[Hop Bitter Acids Activate the Brain-Gut Axis: Vagal Stimulus via Food Ingredients].

Maintenance and improvement of cognitive function and mood is important in an aging society. Preventive approaches, including diets used in daily life have received increasing attention in recent times. Clinical trials and preclinical studies have shown that hop bitter acids, which represent the bitter ingredients in beer, activate the bitter taste receptors and the brain-gut axis, which was shown to improve cognitive function and mood. Vagal stimulus via food ingredients may be a novel approach to maintain brain functions.

Uptake dynamics of scrapie agent in the intestinal villous epithelium of suckling and weanling Syrian hamsters.

In mice, the number of intestinal villous columnar epithelium cells that incorporate abnormal prion protein (PrP(Sc) ) decreases significantly after weaning. In this study, the dynamics of PrP(Sc) uptake during the growth of hamsters were investigated by inoculating scrapie 263K agent orally into suckling and weanling Syrian hamsters and estimating the number of PrP(Sc) -positive villous epithelium cells immunohistochemically. The number of PrP(Sc) -positive cells declined significantly as the hamsters aged. The present results suggest that a tendency toward decline of PrP(Sc) -positive cells with increasing age might be a common phenomenon among the superfamily Muridae.

Effects of ß-Lactolin on Regional Cerebral Blood Flow within the Dorsolateral Prefrontal Cortex during Working Memory Task in Healthy Adults: A Randomized Controlled Trial.

Epidemiological studies have reported that consumption of dairy products rich in ß-lactolin is beneficial for cognitive decline among elderly individuals. Although previous studies have shown that ß-lactolin supplementation improves memory function and attention in healthy adults, the mechanism through which ß-lactolin affects human brain function has yet to be elucidated. This placebo-controlled randomized double-blind study therefore examined the effects of ß-lactolin on human regional cerebral blood flow (rCBF) using near-infrared spectroscopy (NIRS) according to the Consolidated Standards of Reporting Trials guidelines. A total of 114 healthy participants aged between 50 and 75 years with relatively low cognition were randomly allocated into the ß-lactolin or placebo groups (n = 57 for both groups) and received supplementation for 6 weeks. After the 6 weeks of supplementation, total hemoglobin during cognitive tasks (Kraepelin and 2-back tasks) was measured using two-channel NIRS to determine rCBF. Accordingly, the ß-lactolin group had significantly higher changes in total hemoglobin at the left dorsolateral prefrontal cortex (DLPFC) area measured using the left-side channel during the 2-back tasks (p = 0.027) compared to the placebo group. The present study suggests that ß-lactolin supplementation increases rCBF and DLPFC activity during working memory tasks.