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

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.

Eurycoma longifolia (Tongkat Ali) enhances wakefulness during active periods but facilitates sleep during resting periods in C57BL/6 mice

The effects of the Eurycoma longifolia (also known as Tongkat Ali [TA]) on sleep and wakefulness was evaluated in C57BL/6 mice. While TA has been used as an aphrodisiac in males, it exhibits various pharmacological effects. The most notable effect observed with TA was wake-enhancement during the second half of the active period, accompanied by significant elevations in core body temperature (CBT). In contrast, sleep was enhanced during the resting period (i.e., increase in rapid eye movement [REM] sleep and delta electroencephalography [EEG] power in non-REM sleep) with significant declines in CBT. The transition of TA's effects between resting and active periods was rapid. The results of the experiments in constant darkness indicate that TA prolongs the circadian tau and that this transition is governed by circadian clock mechanisms rather than light exposure. TA did not demonstrate efficacy in aiding sleep in an acute stress-induced insomnia model; thus, TA may be more suitable as a wake-enhancing agent for daytime sleepiness, as sleep propensity tends to accumulate towards the end of active period. Since TA amplifies the rest-activity pattern, prolongs circadian tau and increases REM sleep, thereby reversing some common symptoms seen in elderly subjects, it may also hold promise as a rejuvenating medicine.

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.

Sleep Basic Research on Verifying the Effects of Natural Compounds on Wakefulness or Sleep

I studied at the Sleep and Circadian Neurobiology Laboratory, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, from April 2018 to March 2020. At Stanford University, I mainly researched the following themes: (1) sleep basic research using mice (administering compounds with sleep or wakefulness effects to mice and examining their effects), and (2) research on circadian rhythm disorders. There are only a few institutions in the world that can conduct sleep basic research using mice, and Stanford University is a wonderful environment to immerse yourself in research, as it is home to not only psychiatrists but also neurologists and many basic researchers. In this article, I would like to review the experiments I conducted during my study abroad, using mice to verify the effects of natural compounds on wakefulness or sleep. In one study, we evaluated the effects of ginkgolides (A, B, and C) and bilobalide on arousal, locomotion, and core body temperature. The results showed that only ginkgolide B dose-dependently increased the amount of arousal and decreased the amount of NREM sleep in the physiological sleep-wake cycle of mice. In another study, we tested the sleep-inducing effects of sake yeast in mice under an acute insomnia model. We showed that sake yeast dose-dependently increased REM and non-REM sleep, decreased arousal within 6 hours after oral administration of sake yeast, and decreased locomotion and core body temperature in a new cage.