Oral administration of Japanese sake yeast (Saccharomyces cerevisiae sake) promotes non-rapid eye movement sleep in mice via adenosine A2A receptors

Functions and mechanisms of adenosine and its receptors in sleep regulation

Sleep is a natural and recurring state of life. Long-term insomnia can lead to physical and mental fatigue, inattention, memory loss, anxiety, depression and other symptoms, imposing immense public health and economic burden worldwide. The sleep and awakening regulation system is composed of many nerve nuclei and neurotransmitters in the brain, and it forms a neural network that interacts and restricts each other to regulate the occurrence and maintenance of sleep-wake. Adenosine (AD) is a neurotransmitter in the central nervous system and a driver of sleep. Meanwhile, the functions and mechanisms underlying sleep-promoting effects of adenosine and its receptors are still not entirely clear. However, in recent years, the increasing evidence indicated that adenosine can promote sleep through inhibiting arousal system and activating sleep-promoting system. At the same time, astrocyte-derived adenosine in modulating sleep homeostasis and sleep loss-induced related cognitive and memory deficits plays an important role. This review, therefore, summarizes the current research on the functions and possible mechanisms of adenosine and its receptors in the regulation of sleep and homeostatic control of sleep. Understanding these aspects will provide us better ideas on clinical problems such as insomnia, hypersomnia and other sleep disorders.

Neurobehavioral protective effects of Japanese sake yeast supplement against chronic stress-induced anxiety and depression-like symptoms in mice: Possible role of central adenosine receptors

RATIONALE

Using routine synthetic drugs in the treatment of psychiatric disorders may have some restrictions due to serious side effects and pharmacoresistance. Some natural agents may be promising alternatives in this case. The neuroprotective activity of the neuromodulator adenosine and its receptor, A1 receptor (A1R) in the central nervous system has been mentioned in different studies.

OBJECTIVE

We aimed to determine the anxiolytic, antidepressant and sedative effects of Japanese sake yeast as the first report.

METHOD

Mice were subjected to a one-week stress protocol and concomitantly treated orally with sake yeast at the dose levels of 100, 200 and 300 mg kg-1 once daily for a week. The anxiolytic, antidepressant, and sedative actions of sake yeast were evaluated with the related tests.

RESULTS

In all dose regiments, sake yeast significantly improved functions in the EPM and FST. 200 and 300 mg/kg of sake yeast significantly increased sleep duration and reduced sleep latency. Anxiolytic and antidepressant-like activities of sake yeast were maintained by the injection of ZM241385 (15 mg kg-1), a selective adenosine A2AR antagonist but completely counteracted by the injection of 8-cyclopentyltheophylline (10 mg kg-1), a selective adenosine A1R antagonist. 300 mg/kg of the yeast significantly increased the BDNF levels. Amygdala corticosterone levels did not show any significant changes at any dosage. Amygdala TNF-α, IL-6 and IL-1β levels also decreased significantly with all the sake regiments compared to the control group.

CONCLUSIONS

We conclude that oral sake yeast supplement exerts a neurobehavioral protective effect predominantly by activating central A1Rs.

Adenosine A2A receptors and sleep

Adenosine, a known endogenous somnogen, induces sleep via A1 and A2A receptors. In this chapter, we review the current knowledge regarding the role of the adenosine A2A receptor and its agonists, antagonists, and allosteric modulators in sleep-wake regulation. Although many adenosine A2A receptor agonists, antagonists, and allosteric modulators have been identified, only a few have been tested to see if they can promote sleep or wakefulness. In addition, the growing popularity of natural sleep aids has led to an investigation of natural compounds that may improve sleep by activating the adenosine A2A receptor. Finally, we discuss the potential therapeutic advantage of allosteric modulators of adenosine A2A receptors over classic agonists and antagonists for treating sleep and neurologic disorders.

Reversal of chronic restraint stress-induced memory impairment by Japanese sake yeast supplement in mice: Role of adenosine A1 and A2A receptors

Controversial studies indicate the adenosine compound (a neuromodulator with neuroprotective activity) intervention on cognitive performance. On the other hand, Japanese sake yeast has been enriched with oral adenosine analogs as a novel natural agent. As the first report, we aimed to evaluate the effects of Japanese sake yeast supplement in a mouse model of chronic restraint stress-induced cognitive dysfunction. Mice were subjected to a one-week stress protocol and concomitantly treated orally with sake yeast at the dose level of 100, 200 and 300 mg/kg once daily for a week. The spatial and conditioned fear memory functions were evaluated with the Morris Water Maze (MWM) and the Passive Avoidance Learning (PAL) test, respectively. In all dosing regimens, improvements in spatial cognition were observed significantly in the MWM. 200 and 300 mg/kg of sake yeast significantly improved short- and long-term fear memory functions in the PAL test. Memory-enhancing effect of sake yeast was potentiated by the injection of ZM241385 (15 mg/kg), a selective adenosine A_2A receptor (A_2AR) antagonist, but completely disappeared by the injection of 8-cyclopentyltheophylline (CPT-8, 10 mg/kg), a selective adenosine A₁ receptor (A₁R) antagonist. The findings of the present study demonstrate the efficacy of sake yeast in acting as a cognitive performance-enhancing agent. Eventually, sake yeast and its ingredient S-adenosyl methionine (SAM) may be useful in improving memory in patients suffering from many dementia forms including Alzheimer's disease (AD).

Sake yeast induces the sleep-promoting effects under the stress-induced acute insomnia in mice

Sleep deprivation induces adverse effects on the health, productivity, and performance. The individuals who could not get enough sleep temporarily experience the symptoms of an induced acute insomnia. This study investigated the efficacy of sake yeast in treatment of acute insomnia in mice. The results of this study showed that sake yeast induced a significant dose-dependent wake reduction, a rapid eye movement (REM) and a non-REM (NREM) sleep enhancement during the first 6 h after the oral administration of sake yeast with locomotor activity and core body temperature decreases under the stressful environment in a new cage. In fact, the wake amounts at 3 h and 6 h were significantly reduced after the oral administration of sake yeast compared with the vehicle. The NREM sleep amounts at 3 h and 6 h significantly increased after the administration of sake yeast compared with the vehicle. The REM amount at 6 h significantly increased after the administration of sake yeast compared with the vehicle, but not at 3 h. The previous study suggested that the sleep-promoting effects of sake yeast could be referred from the activating effect of adenosine A_2A receptor (A_2AR). In summary, the sake yeast is an A_2AR agonist and may induce sleep due to its stress-reducing and anti-anxiety properties. Further verification of the involvement of adenosine in the pathophysiology of insomnia is needed.

Hypnotic Effects of Lactobacillus fermentum PS150TM on Pentobarbital-Induced Sleep in Mice

The bidirectional communication between the gastrointestinal tract and the central nervous system appears to be functionally linked to the intestinal microbiome, namely the microbiome-gut-brain axis (MGBA). Probiotics with health benefits on psychiatric or neurological illnesses are generally called psychobiotics, and some of them may also be able to improve sleep by targeting the MGBA. This study aimed to investigate the effects of a psychobiotic strain, Lactobacillus fermentum PS150TM (PS150TM), on sleep improvement by using a pentobarbital-induced sleep mouse model. Compared with the vehicle control group, the oral administration of PS150TM, but not the other L. fermentum strains, significantly decreased the sleep latency and increased the sleep duration of mice, suggesting strain-specific sleep-improving effects of PS150TM. Moreover, the ingestion of diphenhydramine, an antihistamine used to treat insomnia, as a drug control group, only increased the sleep duration of mice. We also found that the sleep-improving effects of PS150TM are time- and dose-dependent. Furthermore, the oral administration of PS150TM could attenuate a caffeine-induced sleep disturbance in mice, and PS150TM appeared to increase the expression of the gene encoding the adenosine 1 receptor in the hypothalamus of mice, as assessed by quantitative real-time polymerase chain reaction. Taken together, our results present a potential application of PS150TM as a dietary supplement for sleep improvement.

Dietary Zinc Acts as a Sleep Modulator

While zinc is known to be important for many biological processes in animals at a molecular and physiological level, new evidence indicates that it may also be involved in the regulation of sleep. Recent research has concluded that zinc serum concentration varies with the amount of sleep, while orally administered zinc increases the amount and the quality of sleep in mice and humans. In this review, we provide an exhaustive study of the literature connecting zinc and sleep, and try to evaluate which molecular mechanism is likely to be involved in this phenomenon. A better understanding should provide critical information not only about the way zinc is related to sleep but also about how sleep itself works and what its real function is.