A tryptic hydrolysate from bovine milk αs1-casein enhances pentobarbital-induced sleep in mice via the GABAA receptor

Extracts of Prunella vulgaris Enhanced Pentobarbital-Induced Sleeping Behavior in Mice Potentially via Adenosine A2A Receptor Activity

The increasing prevalence of sleep dysregulation cases has prompted the search for effective and safe sleep-enhancing agents. Numerous medications used in the treatment of sleep disorders function by enhancing γ-aminobutyric acid neurotransmitter activity. Unfortunately, these substances may induce significant adverse effects in chronic users, such as dependence and motor behavior impairments. Consequently, there is a growing interest in exploring therapeutic sleep-enhancing agents derived from natural sources, with the anticipation of causing less severe side effects. Prunella vulgaris (PV), a perennial plant indigenous to South Korea, exhibits various pharmacological effects, likely attributed to its chemical composition. Rosmarinic acid, one of its components, has previously demonstrated sleep-potentiating properties, suggesting the potential for PV to exhibit similar pharmacological effects. This study aims to investigate the potential effects of repeated administration of PV extract on the sleep behavior, brainwave activity, sleep-wake cycle, and physiological behavior of mice. Findings indicate that PV extracts exhibit sleep-enhancing effects in mice, characterized by prolonged sleep duration and a reduced onset time of pentobarbital-induced sleep. However, PV extracts only reduced alpha wave powers, with minor alterations in wakefulness and rapid-eye-movement sleep duration. In contrast to diazepam, PV extracts lack adverse effects on locomotor activity, motor coordination, or anxiety in mice. Receptor-binding assay and caffeine treatment support the potential involvement of adenosine A2A receptors in the effects of PV, suggesting distinct mechanisms of action compared to diazepam, despite both exhibiting sleep-altering effects. Overall, our results suggest that PV holds promise as a potential source of sleep-aiding agents.

Exploring structural features of sleep-enhancing peptides derived from casein hydrolysates by chemometrics and random forest methodology

Milk casein is regarded as source to release potential sleep-enhancing peptides. Although various casein hydrolysates exhibited sleep-enhancing activity, the underlying reason remains unclear. This study firstly revealed the structural features of potential sleep-enhancing peptides from casein hydrolysates analyzed through peptidomics and multivariate analysis. Additionally, a random forest model and a potential Tyr-based peptide library were established, and then those peptides were quantified to facilitate rapidly-screening. Our findings indicated that YP-, YI/L, and YQ-type peptides with 4-10 amino acids contributed more to higher sleep-enhancing activity of casein hydrolysates, due to their crucial structural features and abundant numbers. Furthermore, three novel strong sleep-enhancing peptides, YQKFPQY, YPFPGPIPN, and YIPIQY were screened, and their activities were validated in vivo. Molecular docking results elucidated the importance of the YP/I/L/Q- structure at the N-terminus of casein peptides in forming crucial hydrogen bond and π-alkyl interactions with His-102 and Asn-60, respectively in the GABAA receptor for activation.

Anxiolytic-like effects of milk proteins

Milk varieties and specific proteins exhibit anxiolytic-like actions in mice and rats exposed to several tests, the most prominent being the elevated plus-maze. Administrations of αs1-casein, its 91-100 (α-casozepine), 91-97, 91-93, and 91-92 fragments, the 60-69 fragment of β-casein, lactoferrin, β-lactotensin, wheylin-1, wheylin-2, and α-lactalbumin have been reported to increase open arm exploration relative to enclosed arm exploration. Anxiolytic-like actions have also been described for 91-93 and 91-92 fragments of αs1-casein, wheylin-1, α-lactalbumin, and lactoferrin in the open-field. Some effects appear to be mediated by the GABAA receptor complex, since antagonists mitigated the anxiolytic-like actions of αs1-casein, the 91-92 fragment of αs1-casein, and wheylin-1. Other neurotransmitters purported to affect such behaviors include 5HT, dopamine, and neurotensin. Further research is needed to identify their neuropharmacological actions.

Heukharang (Lactuca sativa L.) extracts enhanced the sleep behavior of mice: potential involvement of adenosine A1 and A2A receptors

A significant proportion of the world's population suffers from insomnia, a disorder characterized by complications in initiating and maintaining sleep. Many medications used to treat insomnia target the γ-aminobutyric acid (GABA) neurotransmitter system. However, these substances, such as benzodiazepines, induce significant adverse consequences, including dependence and memory impairment, after prolonged use. Thus, current studies are aimed at developing therapeutic hypnotics derived from natural sources that may cause less severe side effects. Heukharang is a variety of lettuce from Korea that was discovered to contain sleep-promoting compounds. Therefore, we investigated the potential effects of sub-chronic administration of Heukharang extract (FSD-LS) on sleep behavior (pentobarbital-induced sleeping test), brain wave activity and sleep architecture (electroencephalography), and physiological behavior (open-field test and rota-rod) in mice, along with radioligand binding assays (GABAA, adenosine A1 and A2A receptors). We found that FSD-LS prolonged the total sleep duration and reduced the onset time of sleep, and enhanced delta wave power and non-rapid eye movement (NREM) sleep duration, all indicating persistent sleep-enhancing effects. FSD-LS lacked adverse effects on the spontaneous locomotor activity and motor coordination of mice, unlike diazepam. Pharmacological blocking using caffeine and bicuculline supported the possible involvement of adenosine receptors in the sleep-promoting effects of FSD-LS, with partial contribution from GABA receptor activity. Overall, our study recommends FSD-LS as a potential source for the development of sleep-aiding therapeutics.

Comparison of the Protective Effects of Casein Hydrolysate Containing Tyr-Pro-Val-Glu-Pro-Phe and Casein on the Behaviors and Peripheral and Brain Functions in Mice with Chronic-Stress-Induced Anxiety and Insomnia

Chronic stress is a major inducer of anxiety and insomnia. Milk casein has been studied for its stress-relieving effects. We previously prepared a casein hydrolysate (CP) rich in the sleep-enhancing peptide YPVEPF, and this study aims to systemically investigate the different protective effects of CP and casein on dysfunction and anxiety/insomnia behavior and its underlying mechanisms in chronically stressed mice. Behavioral results showed that CP ameliorated stress-induced insomnia and anxiety more effectively than milk casein, and this difference in amelioration was highly correlated with an increase in GABA, 5-HT, GABAA, 5-HT1A receptors, and BDNF and a decrease in IL-6 and NMDA receptors in stressed mice. Furthermore, CP restored these dysfunctions in the brain and colon by activating the HPA response, modulating the ERK/CREB-BDNF-TrκB signaling pathway, and alleviating inflammation. The abundant YPVEPF (1.20 ± 0.04%) and Tyr-based/Trp-containing peptides of CP may be the key reasons for its different effects compared to casein. Thus, this work revealed the main active structures of CP and provided a novel dietary intervention strategy for the prevention and treatment of chronic-stress-induced dysfunction and anxiety/insomnia behaviors.

Milk: A Natural Guardian for the Gut Barrier

The gut barrier plays an important role in health maintenance by preventing the invasion of dietary pathogens and toxins. Disruption of the gut barrier can cause severe intestinal inflammation. As a natural source, milk is enriched with many active constituents that contribute to numerous beneficial functions, including immune regulation. These components collectively serve as a shield for the gut barrier, protecting against various threats such as biological, chemical, mechanical, and immunological threats. This comprehensive review delves into the active ingredients in milk, encompassing casein, α-lactalbumin, β-lactoglobulin, lactoferrin, the milk fat globular membrane, lactose, transforming growth factor, and glycopeptides. The primary focus is to elucidate their impact on the integrity and function of the gut barrier. Furthermore, the implications of different processing methods of dairy products on the gut barrier protection are discussed. In conclusion, this study aimed to underscore the vital role of milk and dairy products in sustaining gut barrier health, potentially contributing to broader perspectives in nutritional sciences and public health.

Combination of Walnut Peptide and Casein Peptide alleviates anxiety and improves memory in anxiety mices

Introduction

Anxiety disorders continue to prevail as the most prevalent cluster of mental disorders following the COVID-19 pandemic, exhibiting substantial detrimental effects on individuals' overall well-being and functioning. Even after a search spanning over a decade for novel anxiolytic compounds, none have been approved, resulting in the current anxiolytic medications being effective only for a specific subset of patients. Consequently, researchers are investigating everyday nutrients as potential alternatives to conventional medicines. Our prior study analyzed the antianxiety and memory-enhancing properties of the combination of Walnut Peptide (WP) and Casein Peptide (CP) in zebrafish.

Methods and Results

Based on this work, our current research further validates their effects in mice models exhibiting elevated anxiety levels through a combination of gavage oral administration. Our results demonstrated that at 170 + 300 mg human dose, the WP + CP combination significantly improved performances in relevant behavioral assessments related to anxiety and memory. Furthermore, our analysis revealed that the combination restores neurotransmitter dysfunction observed while monitoring Serotonin, gamma-aminobutyric acid (GABA), dopamine (DA), and acetylcholine (ACh) levels. This supplementation also elevated the expression of brain-derived neurotrophic factor mRNA, indicating protective effects against the neurological stresses of anxiety. Additionally, there were strong correlations among behavioral indicators, BDNF (brain-derived neurotrophic factor), and numerous neurotransmitters.

Conclusion

Hence, our findings propose that the WP + CP combination holds promise as a treatment for anxiety disorder. Besides, supplementary applications are feasible when produced as powdered dietary supplements or added to common foods like powder, yogurt, or milk.

Associations between Milk Intake and Sleep Disorders in Chinese Adults: A Cross-Sectional Study

We aimed to examine the association of milk intake with sleep disorders and their specific indicators. The current study included 768 adults aged 28-95 from Wenling, China. Milk intake was assessed using a food frequency questionnaire with ten food items, while sleep disorders were measured using the Pittsburgh Sleep Quality Index (PSQI), with higher scores indicating poorer sleep. The participants were divided into two groups according to the average intake of milk per week: rare intake (≤62.5 mL/week) and regular intake (>62.5 mL/week). Primary measurements were multivariate-adjusted odds ratios (ORs) with 95% confidence intervals (CIs) for the prevalence of sleep disorders concerning regular milk intake compared with rare intake. In secondary analyses, linear regression analyses were performed to assess the effects of milk intake on sleep disorders and their specific dimensions. Regular intake of milk did not have a significant association with sleep disorders compared with rare intake (adjusted OR: 0.72, 95%; CI: 0.51, 1.03), but this association was found to be pronounced with sleep disturbances (OR: 0.49, 95%; CI: 0.28, 0.87). Increased intake of milk was significantly associated with the lower scores of PSQI for sleep quality (β: -0.045, 95%; CI: -0.083, -0.007) and sleep disturbances (β: -0.059, 95%; CI: -0.090, -0.029), respectively. When stratified by age and gender, the benefits of milk intake for sleep disorders and sleep disturbances were more significant in older adults (≥65) and men than in younger persons and women. In summary, regular milk intake benefits sleep quality, which may contribute to nutritional psychiatric support for prevention against sleep disorders.

Pharmacological Analysis of GABAA Receptor and Sigma1R Chaperone Interaction: Research Report I-Investigation of the Anxiolytic, Anticonvulsant and Hypnotic Effects of Allosteric GABAA Receptors' Ligands

Two groups of facts have been established in previous drug development studies of the non-benzodiazepine anxiolytic fabomotizole. First, fabomotizole prevents stress-induced decrease in binding ability of the GABA_A receptor's benzodiazepine site. Second, fabomotizole is a Sigma1R chaperone agonist, and exposure to Sigma1R antagonists blocks its anxiolytic effect. To prove our main hypothesis of Sigma1R involvement in GABA_A receptor-dependent pharmacological effects, we performed a series of experiments on BALB/c and ICR mice using Sigma1R ligands to study anxiolytic effects of benzodiazepine tranquilizers diazepam (1 mg/kg i.p.) and phenazepam (0.1 mg/kg i.p.) in the elevated plus maze test, the anticonvulsant effects of diazepam (1 mg/kg i.p.) in the pentylenetetrazole-induced seizure model, and the hypnotic effects of pentobarbital (50 mg/kg i.p.). Sigma1R antagonists BD-1047 (1, 10, and 20 mg/kg i.p.), NE-100 (1 and 3 mg/kg i.p.), and Sigma1R agonist PRE-084 (1, 5, and 20 mg/kg i.p.) were used in the experiments. Sigma1R antagonists have been found to attenuate while Sigma1R agonists can enhance GABA_ARs-dependent pharmacological effects.

Comprehensive effects of various nutrients on sleep

Sleep problems have become common among people today. Sleep disorders are closely associated with physiological and psychological diseases. Among the ways of improving objective or subjective sleep quality, controlling elements associated with food intake can be more efficient than other methods in terms of time and cost. Therefore, the purpose of this study was to understand the effects of nutrients and natural products on sleep. An extensive literature search was conducted, and related articles were identified through online databases, such as Elsevier, Google Scholar, PubMed, Springer, and Web of Science. Expert opinion, conference abstracts, unpublished studies, and studies published in languages other than English were excluded from this review. The effects of macronutrients and diet adjustment on sleep differed. Although not all nutrients independently affect sleep, they comprehensively affect it through tryptophan metabolism. Furthermore, natural foods related to GABA have an effect on sleep similar to that of sleeping pills. Taken together, our results suggest that humans can control both their objective and subjective sleep quality based on their lifestyle and food consumption. However, until now, direct studies on the relationship between human sleep and nutrition, such as clinical trials, have been insufficient. As both objective and subjective sleep quality are the factors determining the quality of life of individuals, further studies on those are needed to improve it.

A Lupin (Lupinusangustifolius) Protein Hydrolysate Exerts Anxiolytic-Like Effects in Western Diet-Fed ApoE−/− Mice

Anxiety is the most prevalent psychiatric disorder worldwide, causing a substantial economic burden due to the associated healthcare costs. Given that commercial anxiolytic treatments may cause important side effects and have medical restrictions for prescription and high costs, the search for new natural and safer treatments is gaining attention. Since lupin protein hydrolysate (LPH) has been shown to be safe and exert anti-inflammatory and antioxidant effects, key risk factors for the anxiety process and memory impairment, we evaluated in this study the potential effects of LPH on anxiety and spatial memory in a Western diet (WD)-induced anxiety model in ApoE^−/− mice. We showed that 20.86% of the 278 identified LPH peptides have biological activity related to anxiolytic/analgesic effects; the principal motifs found were the following: VPL, PGP, YL, and GQ. Moreover, 14 weeks of intragastrical LPH treatment (100 mg/kg) restored the WD-induced anxiety effects, reestablishing the anxiety levels observed in the standard diet (SD)-fed mice since they spent less time in the anxiety zones of the elevated plus maze (EPM). Furthermore, a significant increase in the number of head dips was recorded in LPH-treated mice, which indicates a greater exploration capacity and less fear due to lower levels of anxiety. Interestingly, the LPH group showed similar thigmotaxis, a well-established indicator of animal anxiety and fear, to the SD group, counteracting the WD effect. This is the first study to show that LPH treatment has anxiolytic effects, pointing to LPH as a potential component of future nutritional therapies in patients with anxiety.

The Anxiolytic-like Properties of a Tryptic Hydrolysate of Bovine αs1 Casein Containing α-Casozepine Rely on GABAA Receptor Benzodiazepine Binding Sites but Not the Vagus Nerve

(1) Background: A tryptic hydrolysate of bovine α_s1-casein (CH) exerts anxiolytic-like properties in many species, including humans. This is mainly related to the presence of α-casozepine (α-CZP), which yields these properties in rodents. This study evaluates, in a rat model, the roles of the vagus nerve and the benzodiazepine binding site of GABA_A receptors in the mode of action of CH. (2) Methods: The conditioned defensive burying test was used to evaluate anxiety. (3) Results: Participation of the vagus nerve in the mode of action of CH was excluded, as the global anxiety score in vagotomised rats was not significantly different from that of non-vagotomised animals. The blocking of the binding sites of benzodiazepines with flumazenil antagonised CH anxiolytic-like properties. (4) Conclusions: The vagus nerve does not play a role in the anxiolytic-like properties of CH. On the other hand, this anxiolytic-like activity relies on the benzodiazepine binding site of the GABA_A receptors. This result is consistent with previous in vitro studies and, more specifically with the discovery of α-CZP, the peptide responsible for the anxiolytic-like properties of CH.

An Interdisciplinary Approach for Compulsive Behavior in Dogs: A Case Report

Compulsive disorder is a debilitating condition affecting both humans and animals, characterized by intrusive thoughts and recurring out-of-place behaviors. Among them, tail chasing might represent one of the most common traits in compulsive dogs. Herein, we reported the case of a 7-year-old intact male German Shepherd mixed-breed dog, presenting with tail chasing behavior. He underwent a first behavioral evaluation 1 year before (at the age of 6), when he injured himself with severe wounds at level of the tail and left thigh. To avoid any specific suffering and increase his physical health, of course, the study was carried out through an interdisciplinary approach, employing a veterinary behaviorist and a rehabilitating dog instructor. Three months after pharmacological treatment with fluoxetine and α-s1 casozepine, associated with a behavioral recovery program, the owner reported an improvement of compulsive events in his dog, in terms of intensity and frequency. Interestingly, over the following 3 months, the dog did not experience any new tail chasing episodes.

Involvement of the adenosine A1 receptor in the hypnotic effect of rosmarinic acid

Insomnia, the most common sleep disorder, is characterized by a longer sleep latency, greater sleep fragmentation, and consequent excessive daytime fatigue. Due to the various side effects of prescribed hypnotics, demand for new drugs is still high. Recent studies have suggested the adenosine receptor (AR) as a potential therapeutic target for insomnia, however, clinically useful hypnotics targeting AR are not yet available. In the present study, we evaluated the hypnotic effect of rosmarinic acid, a phenolic compound widely found in medicinal plants, through pentobarbital-induced sleep test, electroencephalography/electromyography (EEG/EMG), and immunohistochemistry in mice. The underlying mechanisms were assessed by pharmacological approach using 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) and SCH5826, antagonists for A1R and A2AR, respectively. Receptor-binding assay and functional agonism were also performed. Our study provides a new evidence that rosmarinic acid has a direct binding activity (Ki = 14.21 ± 0.3 μM) and agonistic activity for A1R. We also found that rosmarinic acid significantly decreased sleep fragmentation and onset latency to NREM sleep, and these effects were abolished by DPCPX. The results from c-Fos immunostaining showed that rosmarinic acid decreased the neuronal activity in wake-promoting brain regions, such as the basal forebrain and the lateral hypothalamus, while increasing the neuronal activity in the ventrolateral preoptic nucleus, a sleep-promoting region; all these effects were significantly inhibited by DPCPX. Taken together, this study suggests that rosmarinic acid possesses novel activity as an A1R agonist and thereby exerts a hypnotic effect, and thus it may serve as a potential therapeutic agent for insomnia through targeting A1R.

Identification and Screening of Potential Bioactive Peptides with Sleep-Enhancing Effects in Bovine Milk Casein Hydrolysate

Casein tryptic hydrolysate (CTH) has been proven to possess stress-relieving and sleep-enhancing effects, but only one decapeptide YLGYLEQLLR (α-CZP) in CTH was reported to exhibit affinity for the benzodiazepine site of a GABA_A receptor (GABA_AR). This study aimed to compare the sleep-enhancing effects between CTH and α-CZP and to explore novel sleep-enhancing peptides. Our results showed that CTH significantly prolonged sleep duration in mice, which was almost 2-fold longer than that of α-CZP. The α-CZP in CTH was degraded more slowly than the synthetic α-CZP; meanwhile, CTH could release other potential sleep-enhancing peptides during gastrointestinal digestion. Additionally, two peptides YPVEPF and YFYPEL with strong sleep-enhancing activity were explored by virtual screening. Especially, YPVEPF could significantly prolong the sleep duration from 559.00 ± 272.24 to 2501.63 ± 1021.21 s and increase the sleep rate from 58.33 to 83.33% in mice. Moreover, YPVEPF and YFYPEL could bind with the Ser-205 and Phe-77 residues of GABA_AR via hydrogen bonds and lipid contacts. They were largely released after digestion with 11.19 ± 0.15 and 1.78 ± 0.01 g/kg, respectively.

Possible influence of neurosteroids in the anxiolytic effects of alpha-casozepine

Alpha-casozepine (α CZP), a tryptic hydrolysate of milk casein is a decapeptide shown to promote sleep and produce anxiolytic or anticonvulsant activity. Intriguingly, studies indicate structural similarities to benzodiazepine (BZD)-like molecules (e.g., diazepam), resulting in positive modulation of γ-aminobutyric acid A type (GABA_A) receptors. However, some unexplained anomalous behaviour of α-CZP includes 1) 1000 times less affinity for BZD site on GABA_A receptor in vitro conditions, whereas in vivo it showed 10-fold increased affinity when compared to diazepam; 2) anxiolytic effects were observed only in stressed conditions and 3) unlike diazepam, it failed to exhibit dependence or habituation. Interestingly, neurosteroids like allopregnanolone or its analogues that are synthesized de novo have both genomic and non-genomic actions. The rapid nongenomic neuronal inhibition of these compounds is mediated by GABA_A receptors through autocrine and paracrine actions. Studies have shown that changes in the levels of neurosteroids during acute (rise) and chronic stress (decreased), consequently, altering the senetivity of GABA_A receptor subunits. Neurosteroids even at low concentration (nanomolar range) potentiate the response of GABA indirectly, while at higher concentrations they directly activate the receptor-channel complex. Interestingly, coadministration of neurosteroids and BZPs has shown not only to prevent the development of tolerance of BZP and augmented recovery from BZP withdrawal anxiety and hyperactivity in mice. The combination also produced synergetic anxiolytic effects. Taken together, the evidence suggests possible implications of neurosteroids in the actions of CZP via BZD receptors. The present hypothesis brings out the possible role of neurosteroids and the various factors that might participate in CZP-induce anxiolytic effects.

Fast Anxiolytic-Like Effect Observed in the Rat Conditioned Defensive Burying Test, after a Single Oral Dose of Natural Protein Extract Products

Anxiety appears among the most frequent psychiatric disorders. During recent years, a growing incidence of anxiety disorders can be attributed, at least in part, to the modification of our eating habits. To treat anxiety disorders, clinicians use benzodiazepines, which unfortunately display many side effects. Herein, the anxiolytic-like properties of two natural products (αS1–casein hydrolysate and Gabolysat^®) were investigated in rats and compared to the efficacy of benzodiazepine (diazepam). Thus, the conditioned defensive burying test was performed after a unique oral dose of 15 mg/kg, at two time-points (60 min and then 30 min post oral gavage) to show potential fast-onset of anxiolytic effect. Both natural products proved to be as efficient as diazepam to reduce the time rats spent burying the probe (anxiety level). Additionally, when investigated as early as 30 min post oral gavage, Gabolysat^® also revealed a fast-anxiolytic activity. To date, identification of bioactive peptide, as well as how they interact with the gut–brain axis to sustain such anxiolytic effect, still remains poorly understood. Regardless, this observational investigation argues for the consideration of natural compounds in care pathway.

The Effect of A Whey-Protein and Galacto-Oligosaccharides Based Product on Parameters of Sleep Quality, Stress, and Gut Microbiota in Apparently Healthy Adults with Moderate Sleep Disturbances: A Randomized Controlled Cross-Over Study

People experiencing sleep problems may benefit from nutrients supporting serotonin metabolism and stress reduction. We studied the effect of a dairy-based product (DP) containing protein, galacto-oligosaccharides, vitamins and minerals, on sleep quality, stress, and gut-microbiota. In a cross-over RCT (three weeks intervention; three weeks washout), adults (n = 70; 30–50 y) with sleep disturbances (Pittsburgh Sleep Quality Index (PSQI) ≥ 9) consumed products 1 h before bed-time. Sleep quality (PSQI) was measured weekly, stress at base- and end-line (Depression Anxiety Stress Scale and saliva cortisol). Fecal samples were collected in the 1st intervention period only. Compared to placebo (skimmed milk), PSQI was only lower at day 14 in the 2nd intervention period in intention-to-treat (ITT) (p = 0.017; n = 69) and per-protocol (PP) (p = 0.038; n = 64) analyses. Post-hoc analysis (modified-PP: n=47, with baseline PSQI ≥ 9, and endline day 14), however, showed a decrease in PSQI (−1.60 ± 2.53; p = 0.034). Early morning saliva cortisol decreased versus placebo (p = 0.045). Relative abundance of Bifidobacterium increased (p = 0.02). Redundancy analysis showed an inverse relationship between baseline microbiota composition and baseline PSQI (p = 0.046). Thus, although DP did not improve sleep quality in ITT and PP populations, it did in the modPP. DP reduced salivary cortisol and stimulated Bifidobacterium, which possibly is important for sleep improvement.

Food protein-derived anxiolytic peptides: their potential role in anxiety management

Could bioactive peptides from food proteins be used as prophylactic in the management of anxiety disorders?

Transport of a Peptide from Bovine αs1-Casein across Models of the Intestinal and Blood-Brain Barriers

The effect of food components on brain growth and development has attracted increasing attention. Milk has been shown to contain peptides that deliver important signals to the brains of neonates and infants. In order to reach the brain, milk peptides have to resist proteolytic degradation in the gastrointestinal tract, cross the gastrointestinal barrier and later cross the highly selective blood–brain barrier (BBB). To investigate this, we purified and characterized endogenous peptides from bovine milk and investigated their apical to basal transport by using human intestinal Caco-2 cells and primary porcine brain endothelial cell monolayer models. Among 192 characterized milk peptides, only the α_S1-casein peptide ¹⁸⁵PIGSENSEKTTMPLW¹⁹⁹, and especially fragments of this peptide processed during the transport, could cross both the intestinal barrier and the BBB cell monolayer models. This peptide was also shown to resist simulated gastrointestinal digestion. This study demonstrates that a milk derived peptide can cross the major biological barriers in vitro and potentially reach the brain, where it may deliver physiological signals.

Efficacy of low-fat milk and yogurt fortified with encapsulated vitamin D3 on improvement in symptoms of insomnia and quality of life: Evidence from the SUVINA trial

INTRODUCTION

Sleep disorders are a common condition globally. Vitamin D receptors are present on cells in several regions of the brain. It is possible that vitamin D status may affect brain function, including sleep patterns. We aimed to evaluate the 1,500 IU of Nano-encapsulated vitamin D fortified in dairy products on the symptoms of insomnia and associated improvement of quality of life.

METHODS

A case series was undertaken as part of the Survey of ultraviolent intake by nutritional approach project. Subjects enrolled among adults with abdominal obesity. Twenty-nine subjects with insomnia were selected according to the results of Insomnia Severity Index questionnaire and quality of life using a Short Form Health Survey (SF-36) questionnaire. Subjects were allocated to four groups: low-fat milk fortified by 1,500 IU vitamin D3 (n = 8), simple milk (n = 8), low-fat yogurt fortified by 1,500 IU vitamin D3 (n = 7), and simple yogurt (n = 6) and were treated for 10 weeks.

RESULTS

The insomnia score improved after the intervention in the group receiving vitamin D fortified milk compared to group receiving unfortified milk (p < .001). There were no significant differences between the two groups taking yogurt (fortified vs. unfortified). Comparison of quality of life scores between baseline and after intervention indicated significant improvements in both fortified and simple milk groups (p = .002 and p = .03, respectively); but no differences were found in the groups taking yogurt.

CONCLUSION

Fortified low-fat milk containing 1,500 IU vitamin D3 can improve insomnia symptoms and subsequently quality of life.Trial registration number: IRCT20101130005280N27, www.IRCT.ir.

Anxiolytic Activity and Brain Modulation Pattern of the α-Casozepine-Derived Pentapeptide YLGYL in Mice

α-Casozepine (α-CZP) is an anxiolytic-like bioactive decapeptide derived from bovine α_s1-casein. The N-terminal peptide YLGYL was previously identified after proteolysis of the original peptide in an in vitro digestion model. Its putative anxiolytic-like properties were evaluated in a Swiss mice model using a light/dark box (LDB) after an intraperitoneal injection (0.5 mg/kg). The effect of YLGYL on c-Fos expression in brain regions linked to anxiety regulation was afterwards evaluated via immunofluorescence and compared to those of α-CZP and diazepam, a reference anxiolytic benzodiazepine. YLGYL elicited some anxiolytic-like properties in the LDB, similar to α-CZP and diazepam. The two peptides displayed some strong differences compared with diazepam in terms of c-Fos expression modulation in the prefontal cortex, the amygdala, the nucleus of the tractus solitarius, the periaqueductal grey, and the raphe magnus nucleus, implying a potentially different mode of action. Additionally, YLGYL modulated c-Fos expression in the amygdala and in one of the raphe nuclei, displaying a somewhat similar pattern of activation as α-CZP. Nevertheless, some differences were also spotted between the two peptides, making it possible to formulate the hypothesis that these peptides could act differently on anxiety regulation. Taken together, these results showed that YLGYL could contribute to the in vivo overall action of α-CZP.

Sleep Promoting Effect of Luteolin in Mice via Adenosine A1 and A2A Receptors

Luteolin, a widespread flavonoid, has been known to have neuroprotective activity against various neurologic diseases such as epilepsy, and Alzheimer’s disease. However, little information is available regarding the hypnotic effect of luteolin. In this study, we evaluated the hypnotic effect of luteolin and its underlying mechanism. In pentobarbital-induced sleeping mice model, luteolin (1, and 3 mg/kg, p.o.) decreased sleep latency and increased the total sleep time. Through electroencephalogram (EEG) and electromyogram (EMG) recording, we demonstrated that luteolin increased non-rapid eye movement (NREM) sleep time and decreased wake time. To evaluate the underlying mechanism, we examined the effects of various pharmacological antagonists on the hypnotic effect of luteolin. The hypnotic effect of 3 mg/kg of luteolin was not affected by flumazenil, a GABAA receptor-benzodiazepine (GABAAR-BDZ) binding site antagonist, and bicuculine, a GABAAR-GABA binding site antagonist. On the other hand, the hypnotic effect of 3 mg/kg of luteolin was almost completely blocked by caffeine, an antagonist for both adenosine A1 and A2A receptor (A1R and A2AR), 8-Cyclopentyl-1,3-dipropylxanthine (DPCPX), an A1R antagonist, and SCH-58261, an A2AR antagonist. From the binding affinity assay, we have found that luteolin significantly binds to not only A1R but also A2AR with IC₅₀ of 1.19, 0.84 μg/kg, respectively. However, luteolin did not bind to either BDZ-receptor or GABAAR. From these results, it has been suggested that luteolin has hypnotic efficacy through A1R and A2AR binding.

A Double-Blind, Randomized, Placebo-Controlled Crossover Clinical Study of the Effects of Alpha-s1 Casein Hydrolysate on Sleep Disturbance

This study evaluated the effects of alpha-s1 casein hydrolysate (ACH; Lactium^®) on the subjective and objective sleep profiles of a community-based sample of Koreans with poor sleep quality. We performed a double-blind, randomized crossover trial with 48 participants (49.0 ± 1.7 years old, 65% female) who exhibited a mild to moderate degree of sleep disturbance. Either ACH or placebo was administered for the initial four weeks, and the counterpart was administered in precisely the same manner after a four-week washout period. Sleep disturbance scales, daytime functioning, and psychiatric aspects showed a similar tendency to improve during both ACH and placebo phases without significant group differences. Overall perceived sleep profiles in sleep diaries were significantly improved during the ACH phase, represented by increased total sleep time and sleep efficiency (SE), as well as decreased sleep latency and wake after sleep onset (WASO). Interestingly, actigraphy demonstrated significantly increased SE after continuous use of ACH for four weeks, clearly more improved when compared to two weeks of use. The polysomnography measures showed a similar tendency without statistically significant group differences. Our findings suggest that refined ACH was well tolerated and could improve sleep quality, with possible cumulative beneficial effects with long-term administration.

Administration of Alphas1-Casein Hydrolysate Increases Sleep and Modulates GABAA Receptor Subunit Expression

Sleep is the most basic and essential physiological requirement for mental health, and sleep disorders pose potential risks of metabolic and neurodegenerative diseases. Tryptic hydrolysate of α_S1-casein (α_S1-CH) has been shown to possess stress relieving and sleep promoting effects. However, the differential effects of α_S1-CH on electroencephalographic wave patterns and its effects on the protein levels of γ-aminobutyric acid A (GABA_A) receptor subtypes in hypothalamic neurons are not well understood. We found α_S1-CH (120, 240 mg/kg) increased sleep duration in mice and reduced sleep-wake cycle numbers in rats. While α_S1-CH (300 mg/kg) increased total sleeping time in rats, it significantly decreased wakefulness. In addition, electroencephalographic theta (θ) power densities were increased whereas alpha (α) power densities were decreased by α_S1-CH (300 mg/kg) during sleep-wake cycles. Furthermore, protein expressions of GABA_A receptor β₁ subtypes were elevated in rat hypothalamus by α_S1-CH. These results suggest α_S1-CH, through GABA_A receptor modulation, might be useful for treating sleep disorders.