The Lacto-Tetrapeptide Gly-Thr-Trp-Tyr, β-Lactolin, Improves Spatial Memory Functions via Dopamine Release and D1 Receptor Activation in the Hippocampus

NEAT1 Promotes Valproic Acid-Induced Autism Spectrum Disorder by Recruiting YY1 to Regulate UBE3A Transcription

Evidence suggests that long non-coding RNAs (lncRNAs) play a significant role in autism. Herein, we explored the functional role and possible molecular mechanisms of NEAT1 in valproic acid (VPA)-induced autism spectrum disorder (ASD). A VPA-induced ASD rat model was constructed, and a series of behavioral tests were performed to examine motor coordination and learning-memory abilities. qRT-PCR and western blot assays were used to evaluate target gene expression levels. Loss-and-gain-of-function assays were conducted to explore the functional role of NEAT1 in ASD development. Furthermore, a combination of mechanistic experiments and bioinformatic tools was used to assess the relationship and regulatory role of the NEAT1-YY1-UBE3A axis in ASD cellular processes. Results showed that VPA exposure induced autism-like developmental delays and behavioral abnormalities in the VPA-induced ASD rat model. We found that NEAT1 was elevated in rat hippocampal tissues after VPA exposure. NEAT1 promoted VPA-induced autism-like behaviors and mitigated apoptosis, oxidative stress, and inflammation in VPA-induced ASD rats. Notably, NEAT1 knockdown improved autism-related behaviors and ameliorated hippocampal neuronal damage. Mechanistically, it was observed that NEAT1 recruited the transcription factor YY1 to regulate UBE3A expression. Additionally, in vitro experiments further confirmed that NEAT1 knockdown mitigated hippocampal neuronal damage, oxidative stress, and inflammation through the YY1/UBE3A axis. In conclusion, our study demonstrates that NEAT1 is highly expressed in ASD, and its inhibition prominently suppresses hippocampal neuronal injury and oxidative stress through the YY1/UBE3A axis, thereby alleviating ASD development. This provides a new direction for ASD-targeted therapy.

Bioinformatics Analysis of the Molecular Networks Associated with the Amelioration of Aberrant Gene Expression by a Tyr-Trp Dipeptide in Brains Treated with the Amyloid-β Peptide

Short-chain peptides derived from various protein sources have been shown to exhibit diverse bio-modulatory and health-promoting effects in animal experiments and human trials. We recently reported that the oral administration of the Tyr-Trp (YW) dipeptide to mice markedly enhances noradrenaline metabolism in the brain and ameliorates the working-memory deficits induced by the β-amyloid 25-35 peptide (Aβ_25-35). In the current study, we performed multiple bioinformatics analyses of microarray data from Aβ_25-35/YW-treated brains to determine the mechanism underlying the action of YW in the brain and to infer the molecular mechanisms and networks involved in the protective effect of YW in the brain. We found that YW not only reversed inflammation-related responses but also activated various molecular networks involving a transcriptional regulatory system, which is mediated by the CREB binding protein (CBP), EGR-family proteins, ELK1, and PPAR, and the calcium-signaling pathway, oxidative stress tolerance, and an enzyme involved in de novo l-serine synthesis in brains treated with Aβ_25-35. This study revealed that YW has a neuroprotective effect against Aβ_25-35 neuropathy, suggesting that YW is a new functional-food-material peptide.

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 β-lactopeptides, including β-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 β-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 β-lactolin, may be beneficial for preventing dementia.

β-Lactolin improves mitochondrial function in Aβ-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). β-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 β-lactolin on neuronal cells and neuronal mitochondrial functions remains unknown. Here, we investigated the effects of β-lactolin on mitochondrial functions in amyloid β (Aβ)-treated mouse hippocampal neuronal HT22 cells and human induced-pluripotent cell (hiPSC)-derived AD model neurons. Adding β-lactolin to Aβ-treated HT22 cells increased both the oxygen consumption rate and cellular ATP concentrations, suggesting that β-lactolin improves mitochondrial respiration and energy production. Using high content image analysis, we found that β-lactolin improved mitochondrial fragmentation, membrane potential, and oxidative stress in Aβ-treated cells, eventually preventing neuronal cell death. From a mechanistic perspective, we found that β-lactolin increased gene expression of mitofusin-2, which contributes to mitochondrial fusion events. Finally, we showed that β-lactolin improves both mitochondrial morphologies and membrane potentials in hiPSC-derived AD model neurons. Taken together, β-lactolin improved mitochondrial functions AD-related neuronal cell models and prevented neuronal cell death. The dual function of β-lactolin on both neuron and microglia marks an advantage in maintaining neuronal health.

Effect of Whey-Derived Lactopeptide β-Lactolin on Memory in Healthy Adults: An Integrated Analysis of Data from Randomized Controlled Trials

CONTEXT

Epidemiological studies have shown that consumption of dairy products reduces the risk of dementia and cognitive decline in older individuals. Tryptophan-tyrosine-related β-lactopeptides and their representative β-lactolin of glycine-threonine-tryptophan-tyrosine tetra-peptide have been identified as agents in dairy products, which improve cognitive function as well as memory function via the activation of the dopaminergic system in a mouse model of amnesia. Previous clinical trials have shown that supplementation with β-lactolin improves memory retrieval in healthy older adults. Specifically, β-lactolin improved the scores in some neuropsychological tests. However, the effects of β-lactolin on memory function have not been clarified.

OBJECTIVES

The aim of this study was to evaluate the effect of β-lactolin on memory function using statistical methods.

DATA SOURCES

We searched the Web of Science, Cochrane Library, and JDream III until November 2021 to identify relevant randomized controlled trials for integrated analysis.

DATA SYNTHESIS

Three randomized controlled trials evaluating the effect of β-lactolin on memory in healthy adults were selected for the integrated analysis. The results showed that the score of cued recall among the neuropsychological tests in the β-lactolin group was significantly higher than that in the placebo group (g=0.33; 95% CI: 0.10, 0.55). In addition, the total memory score was higher but this difference was not significant (g=0.17; 95% CI: -0.09, 0.43).

CONCLUSIONS

Taken together, these results suggest that supplementation with β-lactolin improves cued recall in healthy older adults.

Mung Bean Protein Suppresses Undernutrition-Induced Growth Deficits and Cognitive Dysfunction in Rats via Gut Microbiota-TLR4/NF-kB Pathway

Early undernutrition has been found to be closely associated with subsequent neurodevelopment. However, studies examining crude growth in terms of body weight/tail length cannot clarify how diets might mediate associations between the gut microbiota and cognitive dysfunction. In the present study, Sprague-Dawley (SD) rats were fed a 7% protein diet and mung bean protein diet (MBPD) for 6 weeks to assess central nervous system functions. Bifidobacterium longum subsp, Alloprevotella, and Lactobacillus were significantly altered after supplementary MBPD. Additionally, tryptophan, tyrosine, and glycine significantly restored in the brain, and the choline system also improved. Moreover, mung bean supplementation also upregulated expression of the brain-derived neurotrophic factor, postsynaptic density 95 protein (PSD95), synaptosome-associated protein 25 (SNAP25), downregulated toll-like receptor 4 (TLR4), and nuclear factor kB (NF-kB). Metabolites in the serum also underwent changes. Together, these results showed that malnutrition perturbed neurodevelopment, while MBPD reversed this trend.

β-Lactolin Reduces Age-Related Inflammation and Cognitive Decline

With the rapid increase in aging populations worldwide, there has been an increase in demand for preventive and therapeutic measures for age-related cognitive decline and dementia. Epidemiological studies show that consumption of dairy products reduces the risk for cognitive decline and dementia in the elderly. We have previously demonstrated in randomized trials that the consumption of β-lactolin, a whey-derived Gly-Thr-Trp-Tyr lactotetrapeptide, improves cognitive function in older adults. Orally administered β-lactolin is delivered to the brain and inhibits monoamine oxidase, resulting in alleviation of memory impairment. However, there is currently no evidence of the effects of long-term β-lactolin intake on aging. Here, we found that the discrimination index in the novel object recognition test for object recognition memory was reduced in mice aged 20 months compared with that in young mice, indicating that age-related cognitive decline was induced in the aged mice; in aged mice fed β-lactolin for 3 months, memory impairment was subsequently alleviated. In aged mice, impairment of light/dark activity cycles was found to be induced, which was subsequently alleviated by β-lactolin consumption. Additionally, the number of activated microglia in the hippocampus and cortex and the production of cytokines (tumor necrosis factor-α, macrophage inflammatory protein-1α, and macrophage chemoattractant protein-1) were increased in aged mice compared with those in young mice but were reduced in aged mice fed β-lactolin. The age-related hippocampal atrophy was improved in aged mice fed β-lactolin. Cytochrome c levels in the hippocampus and cortex were increased in aged mice compared with those in young mice but were also reduced by β-lactolin consumption. These results suggest that β-lactolin consumption prevents neural inflammation and alleviates aging-related cognitive decline.

β-Lactolin Enhances Neural Activity, Indicated by Event-Related P300 Amplitude, in Healthy Adults: A Randomized Controlled Trial

Background:

Epidemiological studies have shown that dairy product consumption is beneficial for cognitive function in elderly individuals. β-lactolin is a Gly–Thr–Trp–Tyr lacto-tetrapeptide rich in fermented dairy products that improves memory retrieval, attention, and executive function in older adults with subjective cognitive decline and prevents the pathology of Alzheimer’s disease in rodents. There has been no study on the effects of β-lactolin on neural activity in humans.

Objective:

We investigated the effects of β-lactolin on neural activity and cognitive function in healthy adults.

Methods:

In this randomized, double-blind, placebo-controlled study, 30 participants (45–64 years old) consumed β-lactolin or placebo for 6 weeks. Neural activity during auditory and language tasks was measured through 64-channel electroencephalography. Moreover, verbal fluency tests were performed at baseline and after 6 weeks.

Results:

The β-lactolin group had a significantly higher P300 amplitude at the Cp2 site (a part of the parietal lobe near the center of brain, p = 0.011), and C4 site (the area between the frontal and parietal lobe, p = 0.02) during the auditory tasks after 6 weeks than the placebo group. Thus, β-lactolin supplementation promoted neural activity in the parietal area, which increases concentration and attention during auditory cognitive tasks. Compared with the placebo group, the β-lactolin group also showed significant changes in the scores of verbal fluency test after 6 weeks (p = 0.033).

Conclusion:

Our findings provide insight into the mechanisms underlying the effects of β-lactolin on attention in healthy adults.

Early IGF-1 Gene Therapy Prevented Oxidative Stress and Cognitive Deficits Induced by Traumatic Brain Injury

Traumatic Brain Injury (TBI) remains a leading cause of morbidity and mortality in adults under 40 years old. Once primary injury occurs after TBI, neuroinflammation and oxidative stress (OS) are triggered, contributing to the development of many TBI-induced neurological deficits, and reducing the probability of critical trauma patients´ survival. Regardless the research investment on the development of anti-inflammatory and neuroprotective treatments, most pre-clinical studies have failed to report significant effects, probably because of the limited blood brain barrier permeability of no-steroidal or steroidal anti-inflammatory drugs. Lately, neurotrophic factors, such as the insulin-like growth factor 1 (IGF-1), are considered attractive therapeutic alternatives for diverse neurological pathologies, as they are neuromodulators linked to neuroprotection and anti-inflammatory effects. Considering this background, the aim of the present investigation is to test early IGF-1 gene therapy in both OS markers and cognitive deficits induced by TBI. Male Wistar rats were injected via Cisterna Magna with recombinant adenoviral vectors containing the IGF-1 gene cDNA 15 min post-TBI. Animals were sacrificed after 60 min, 24 h or 7 days to study the advanced oxidation protein products (AOPP) and malondialdehyde (MDA) levels, to recognize the protein oxidation damage and lipid peroxidation respectively, in the TBI neighboring brain areas. Cognitive deficits were assessed by evaluating working memory 7 days after TBI. The results reported significant increases of AOPP and MDA levels at 60 min, 24 h, and 7 days after TBI in the prefrontal cortex, motor cortex and hippocampus. In addition, at day 7, TBI also reduced working memory performance. Interestingly, AOPP, and MDA levels in the studied brain areas were significantly reduced after IGF-1 gene therapy that in turn prevented cognitive deficits, restoring TBI-animals working memory performance to similar values regarding control. In conclusion, early IGF-1 gene therapy could be considered a novel therapeutic approach to targeting neuroinflammation as well as to preventing some behavioral deficits related to TBI.

Effects of β-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 β-lactolin is beneficial for cognitive decline among elderly individuals. Although previous studies have shown that β-lactolin supplementation improves memory function and attention in healthy adults, the mechanism through which β-lactolin affects human brain function has yet to be elucidated. This placebo-controlled randomized double-blind study therefore examined the effects of β-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 β-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 β-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 β-lactolin supplementation increases rCBF and DLPFC activity during working memory tasks.

β-lactolin increases cerebral blood flow in dorsolateral prefrontal cortex in healthy adults: a randomized controlled trial

The number of elderly individuals with age-related cognitive decline or dementia is rapidly increasing. Dairy product consumption, including β-lactolin, is beneficial for their cognitive function. The underlying mechanism of β-lactolin's effects on human brain activity is yet to be investigated. We examined the β-lactolin effects on human cerebral blood flow (CBF) using near-infrared spectroscopy (NIRS) in a placebo-controlled randomized double-blind study, which reported according to the CONSORT guidelines. Fifty healthy participants (aged 45-60 years) were randomly allocated into the β-lactolin or the placebo group (n = 25 each) and supplemented for 6 weeks. During the 6^th week, oxy-hemoglobin during the working memory tasks was measured using 34-channels (CHs) NIRS. The changes of oxy-hemoglobin, which represents the CBF, in CH 23 located at the left dorsolateral prefrontal cortex (DLPFC) during the spatial working memory task showed higher statistical significance (false discovery rate (q) = 0.045) in the β-lactolin than in the placebo group. The oxy-Hb changes in CH23 have a co-relationship with the working memory task reaction time. This clinical trial showed an increase in the CBF in the left DLPFC area during the 6-week β-lactolin supplementation. This study contributes to elucidating the underlying mechanisms of β-lactolin on cognitive performance.

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