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.

Improving Effects of Hop-Derived Bitter Acids in Beer on Cognitive Functions: A New Strategy for Vagus Nerve Stimulation.

Dementia and cognitive decline are global public health problems. Moderate consumption of alcoholic beverages reduces the risk of dementia and cognitive decline. For instance, resveratrol, a polyphenolic compound found in red wine, has been well studied and reported to prevent dementia and cognitive decline. However, the effects of specific beer constituents on cognitive function have not been investigated in as much detail. In the present review, we discuss the latest reports on the effects and underlying mechanisms of hop-derived bitter acids found in beer. Iso-α-acids (IAAs), the main bitter components of beer, enhance hippocampus-dependent memory and prefrontal cortex-associated cognitive function via dopamine neurotransmission activation. Matured hop bitter acids (MHBAs), oxidized components with ß-carbonyl moieties derived from aged hops, also enhance memory functions via norepinephrine neurotransmission-mediated mechanisms. Furthermore, the effects of both IAAs and MHBAs are attenuated by vagotomy, suggesting that these bitter acids enhance cognitive function via vagus nerve stimulation. Moreover, supplementation with IAAs attenuates neuroinflammation and cognitive impairments in various rodent models of neurodegeneration including Alzheimer's disease. Daily supplementation with hop-derived bitter acids (e.g., 35 mg/day of MHBAs) may be a safe and effective strategy to stimulate the vagus nerve and thus enhance cognitive function.

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.

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

SCOPE: Peptides containing tryptophan-tyrosine sequences, including the lacto-tetrapeptide glycine-threonine-tryptophan-tyrosine (GTWY) and ß-lactolin, from ß-lactoglobulin in whey enzymatic digestion, enhance hippocampus-dependent memory functions, which are blocked by the systemic administration of dopamine D1-like antagonist. In this study, we investigated the role of the hippocampal dopaminergic system in the memory-enhancing effect of ß-lactolin. METHODS AND RESULTS: The results of in vivo microdialysis revealed that oral administration of ß-lactolin increased the extracellular concentration of dopamine in the hippocampus and enhanced both spatial working memory, as measured in the Y-maze test, and spatial reference memory, as measured in the novel object location test. These memory-enhancing effects of ß-lactolin, but not the baseline memory functions, were impaired by the knockdown of the dopamine D1 receptor subtype in the hippocampus. ß-Lactolin also enhanced object memory, as measured by the novel object recognition test. However, D1 knockdown in the hippocampus spared this memory function either with or without the administration of ß-lactolin. CONCLUSIONS: The present results indicate that oral administration of ß-lactolin increases dopamine release and D1 receptor signaling in the hippocampus, thereby enhancing spatial memory, but it may improve object memory via a separate mechanism.

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.

Matured hop bitter acids improve spatial working and object recognition memory via nicotinic acetylcholine receptors.

RATIONALE: Cognitive decline and dementia are major concerns in today's aging society. As limited treatments are available, measures to prevent cognitive decline and dementia are needed. We previously demonstrated that matured hop bitter acids (MHBA), bitter components of beer, increase norepinephrine in the hippocampus and improve memory in amnesia model mice induced by scopolamine (SCP), an antagonist of muscarinic receptor. However, other neurotransmitters involved in the effects of MHBA on memory improvement remain unknown. OBJECTIVES: This study aimed to assess the role of acetylcholine receptors (AChR) in the effects of MHBA on memory. METHOD: The involvement of AChR on the effects of MHBA (10 mg/kg) on cognitive function was evaluated using AChR antagonists, SCP, mecamylamine hydrochloride (MEC), a non-competitive antagonist of nicotinic-AChR (nAChR), and methyllycaconitine citrate (MLA), an α7nAChR antagonist, for the Y-maze test and the novel object recognition test (NORT). A separate population of mice, which underwent vagotomy or sham operation, was subjected to NORT to elucidate further mechanism. In addition, the effect of MHBA on acetylcholinesterase (AChE) activity was measured in vitro. RESULTS: In accordance with previous reports, MHBA improved spontaneous alternations of the Y-maze test in SCP-induced amnesia mice and increased discrimination index evaluated by the NORT in normal mice. On the other hand, treatment with MEC or MLA attenuated the effects of MHBA on memory improvement in the Y-maze test and the NORT. Vagotomized mice also showed attenuated memory enhancement by MHBA in the NORT. In addition, MHBA did not alter AChE activity in vitro. CONCLUSIONS: The results support the involvement of nAChRs in memory improvement in mice by MHBA. MHBA is thus thought to activate the vagal nerve and enhance hippocampus-dependent memory via nAChRs.

Hop-Derived Iso-α-Acids in Beer Improve Visual Discrimination and Reversal Learning in Mice as Assessed by a Touch Panel Operant System.

Dementia and cognitive decline have become worldwide health problems due to rapid growth of the aged population in many countries. We previously demonstrated that single or short-term administration of iso-α-acids, hop-derived bitter acids in beer, improves the spatial memory of scopolamine-induced amnesia model mice in the Y-maze and enhances novel object recognition in normal mice via activation of the vagus nerve and hippocampal dopaminergic system. However, these behavioral tests do not replicate the stimulus conditions or response requirements of human memory tests, and so may have poor translational validity. In this report, we investigated the effects of iso-α-acids on visual discrimination (VD) and reversal discrimination (RD) using a touch panel-based operant system similar to that used for human working memory tests. In the VD task, scopolamine treatment reduced correct response rate and prolonged response latency in mice, deficits reversed by prior oral administration of iso-α-acids. In the RD task, administration of iso-α-acids significantly increased correct response rate compared to vehicle administration. Previous studies have reported that dopamine signaling is involved in both VD and RD learning, suggesting that enhancement of dopamine release contributes to improved memory performance in mice treated with iso-α-acids. Taken together, iso-α-acids improve VD and RD learning, which are considered high-order cognitive functions. Given the translational advantages of the touch panel-based operant system, the present study suggests that iso-α-acids could be effective for improvement of working memory in human dementia patients.

Tryptophan-Tyrosine Dipeptide, the Core Sequence of ß-Lactolin, Improves Memory by Modulating the Dopamine System.

Tryptophan-tyrosine (WY)-related peptides including the ß-lactopeptide of the glycine-threonine-tryptophan-tyrosine peptide, ß-lactolin, improve spatial memory. However, whether and how the WY dipeptide as the core sequence in WY-related peptides improves memory functions has not been investigated. This study assessed the pharmacological effects of the WY dipeptide on memory impairment to elucidate the mechanisms. Here, we showed that oral administration of dipeptides of WY, tryptophan-methionine (WM), tryptophan-valine, tryptophan-leucine, and tryptophan-phenylalanine improved spontaneous alternation of the Y-maze test in scopolamine-induced amnesic mice. In contrast, tyrosine-tryptophan, methionine-tryptophan, tryptophan, tyrosine, and methionine had no effect. These results indicated that the conformation of dipeptides with N-terminal tryptophan is required for their memory improving effects. WY dipeptide inhibited the monoamine oxidase B activity in vitro and increased dopamine levels in the hippocampus and frontal cortex, whereas tryptophan did not cause these effects. In addition, the treatment with SCH-23390, a dopamine D1-like receptor antagonist, and the knockdown of the hippocampal dopamine D1 receptor partially attenuated the memory improvement induced by the WY dipeptide. Importantly, WY dipeptide improved the spontaneous alternations of the Y-maze test in aged mice. These results suggest that the WY dipeptide restores memory impairments by augmenting dopaminergic activity. The development of supplements rich in these peptides might help to prevent age-related cognitive decline.

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.

Matured Hop-Derived Bitter Components in Beer Improve Hippocampus-Dependent Memory Through Activation of the Vagus Nerve.

Improving and maintaining memory function is effective in preventing cognitive decline and dementia. Previously, we demonstrated that iso-α-acids, the hop-derived bitter components in beer, prevent cognitive impairment in an Alzheimer's disease mouse model. In this report, we investigated the effects of matured hop bitter acids (MHBA) containing components of oxides derived from α- and ß-acids, and structurally similar to iso-α-acids, on cognitive function using behavioral pharmacological procedures. MHBA and the representative components of MHBA, 4'-hydroxyallohumulinone (HAH) and 4'-hydroxy-cis-alloisohumulone (HAIH) improved spatial working memory in scopolamine-induced amnesia mice. MHBA also enhanced episodic memory in the novel object recognition test (NORT). The administration of MHBA increased the amount of norepinephrine (NE) and NE release into cerebrospinal fluid (CSF) in hippocampus. The MHBA activity in improving memory function was attenuated by treatment with a ß-adrenergic receptor inhibitor. In addition, vagotomized mice did not display the memory improvement induced by MHBA. Together, our results suggest that MHBA improves memory function via stimulation of the vagus nerve and enhancement of NE release in the hippocampus. Vagus nerve activation by the intake of food materials including MHBA may be a safe and effective approach for improving cognitive function.

Novel lactopeptides in fermented dairy products improve memory function and cognitive decline.

Alongside the rapid growth in aging populations, prevention of age-related memory decline and dementia has become a high priority. Several epidemiological and clinical studies have concluded that fermented dairy products can help to prevent cognitive decline; furthermore, intake of Camembert cheese prevents Alzheimer's pathology in model mice. To elucidate molecular mechanisms underlying the preventive effects of fermented dairy products, here we screened peptides from digested fermented dairy products for ability to improve memory function in a scopolamine-induced amnesia mouse model. We found that Trp-Tyr (WY)-containing peptides from whey protein improved memory function in the mice, and the effects were confirmed in aged mice. The WY-containing peptides directly inhibited monoamine oxidase-B activity and increased dopamine levels in brain tissue. Pretreatment with dopamine receptor antagonist abolished the improvement in memory function due to WY-containing peptides. These results suggest that WY-containing peptides in fermented dairy products increase monoamine levels by inhibiting monoamine oxidase-B activity, helping to prevent age-related cognitive decline.

Iso-α-acids, bitter components of beer, prevent obesity-induced cognitive decline.

Dementia and cognitive decline have become worldwide public health problems, and it was recently reported that life-style related diseases and obesity are key risk factors in dementia. Iso-α-acids, hop-derived bitter components of beer, have been reported to have various physiological functions via activation of peroxisome proliferator-activated receptor γ. In this report, we demonstrated that daily intake of iso-α-acids suppresses inflammations in the hippocampus and improves cognitive decline induced by high fat diet (HFD). Body weight, epididymal fat weight, and plasma triglyceride levels were increased in HFD-fed mice, and significantly decreased in iso-α-acids supplemented HFD-fed mice. HFD feeding enhances the production of inflammatory cytokines and chemokines, such as TNF-α, which was significantly suppressed by iso-α-acids administration. HFD-induced neuroinflammation caused lipid peroxidation, neuronal loss, and atrophy in hippocampus, and those were not observed in iso-α-acids-treated mice. Furthermore, iso-α-acids intake significantly improved cognitive decline induced by HFD-feeding. Iso-α-acids are food derived components that suppressing both lipid accumulation and brain inflammation, thus iso-α-acids might be beneficial for the risk of dementia increased by obesity and lifestyle-related diseases.

A novel Alaska pollack-derived peptide, which increases glucose uptake in skeletal muscle cells, lowers the blood glucose level in diabetic mice.

We found that the tryptic digest of Alaska pollack protein exhibits a glucose-lowering effect in KK-Ay mice, a type II diabetic model. We then searched for glucose-lowering peptides in the digest. Ala-Asn-Gly-Glu-Val-Ala-Gln-Trp-Arg (ANGEVAQWR) was identified from a peak of the HPLC fraction selected based on the glucose-lowering activity in an insulin resistance test using ddY mice. ANGEVAQWR (3 mg kg(-1)) decreased the blood glucose level after intraperitoneal administration. Among its fragment peptides, the C-terminal tripeptide, Gln-Trp-Arg (QWR, 1 mg kg(-1)), lowered the blood glucose level, suggesting that the C-terminal is critical for glucose-lowering activity. QWR also enhanced glucose uptake into C2C12, a mouse skeletal muscle cell line. QWR did not induce the phosphorylation of serine/threonine protein kinase B (Akt) and adenosine monophosphate-activated protein kinase (AMPK). We also demonstrated that QWR lowered the blood glucose level in NSY and KK-Ay, type II diabetic models.