Orexin/hypocretin activates mTOR complex 1 (mTORC1) via an Erk/Akt-independent and calcium-stimulated lysosome v-ATPase pathway

Suvorexant improves mitochondrial dynamics with the regulation of orexinergic and mTOR activation in rats exhibiting PTSD-like symptoms

BACKGROUND

Increasing evidence suggests that mitochondrial dysfunction plays a significant role in PTSD. However, the exact mechanism is still unclear. Mitochondrial dynamics could be one of the mechanisms, as it is crucial for mitochondrial homeostasis and is widely affected in traumatic situations. Mitochondrial dynamics regulate mitochondrial homeostasis via orexinergic receptors, and it is shown that antagonism of orexinergic receptors attenuates PTSD-like symptoms. Therefore, the present study aimed to determine how orexin antagonists affect mitochondrial dynamics in rats exhibiting PTSD-like symptoms.

METHODS

Using rats, a stress-re-stress (SRS) model with PTSD-like symptoms was established. On day 2 (D-2), the animals were exposed to variable stressors including 2 h of restraint followed by brief mild foot shock and exposure to 4%halothane. Foot shock was performed as a re-stress from D-8 to D-32 at six-day intervals.

RESULTS

SRS exposure caused PTSD-like phenotype, hypothalamic-pituitary-adrenal axis dysfunction, activation of mammalian target of rapamycin (mTOR), and mitochondrial-fission-process-1 (MTFP-1). SRS-subjected rats exhibited enhanced expression of fission-regulating proteins, including dynamin-related protein-1 and mitochondrial-fission-protein-1 and reduced expression of fusion-regulating proteins, including optic-atrophy-1 and mitofusin-2, in the amygdala. TEM analysis revealed that SRS exposure further damaged the mitochondria. Treatment with suvorexant with rapamycin significantly mitigated PTSD-like symptoms and improved mitochondrial dynamics in SRS-exposed rats. However, their combination showed a more pronounced effect. Further, suvorexant in combination with rapamycin significantly mitigated mTOR and MTFP-1 activation. Sertraline attenuated PTSD-like symptoms without affecting SRS-induced activation of mTOR and disparity in mitochondrial dynamics. Suvorexant pharmacological effects on mitochondrial biogenesis also involve the mTOR pathway.

LIMITATION

The role of orexinergic pathway in SRS-induced mitochondrial mitophagy was not explored.

CONCLUSIONS

Targeting both the orexinergic and mTOR pathways might exert a beneficial synergistic effect for treating PTSD.

Nutrition as the foundation for successful aging: a focus on dietary protein and omega-3 polyunsaturated fatty acids

Skeletal muscle plays a critical role throughout the aging process. People living with sarcopenia, a progressive and generalized loss of skeletal muscle mass and function, often experience diminished quality of life, which can be attributed to a long period of decline and disability. Therefore, it is important to identify modifiable factors that preserve skeletal muscle and promote successful aging (SA). In this review, SA was defined as (1) low cardiometabolic risk, (2) preservation of physical function, and (3) positive state of wellbeing, with nutrition as an integral component. Several studies identify nutrition, specifically high-quality protein (eg, containing all essential amino acids), and long-chain omega-3 polyunsaturated fatty acids (n-3 PUFAs), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), as positive regulators of SA. Recently, an additive anabolic effect of protein and n-3 PUFAs has been identified in skeletal muscle of older adults. Evidence further suggests that the additive effect of protein and n-3 PUFAs may project beyond skeletal muscle anabolism and promote SA. The key mechanism(s) behind the enhanced effects of intake of protein and n-3 PUFAs needs to be defined. The first objective of this review is to evaluate skeletal muscle as a driver of cardiometabolic health, physical function, and wellbeing to promote SA. The second objective is to examine observational and interventional evidence of protein and n-3 PUFAs on skeletal muscle to promote SA. The final objective is to propose mechanisms by which combined optimal intake of high-quality protein and n-3 PUFAs likely play a key role in SA. Current evidence suggests that increased intake of protein above the Recommended Dietary Allowance and n-3 PUFAs above the Dietary Guidelines for Americans recommendations for late middle-aged and older adults is required to maintain skeletal muscle mass and to promote SA, potentially through the mechanistical target of rapamycin complex 1 (mTORC1).

Orexin-A/OX1R is involved in regulation of autophagy to promote cortisol secretion in adrenocortical cell

BACKGROUND

Hypercortisolism has emerged as a prominent clinical condition worldwide caused by biochemical cortisol excess in patients, and optimization treatment is needed urgently in the clinic. Previously, we observed that orexin-A/orexin type 1 receptor (OX1R) promoted cell proliferation, inhibited apoptosis, and increased cortisol release in adrenocortical cells. However, the functions of orexin-A/OX1R on autophagy and its molecular mechanism are not known.

METHODS

Transmission electron microscopy and confocal microscope were performed to detect autophagosomes. Western blot were performed to detect autophagy proteins. The cortisol concentration was assessed with an ELISA.

FINDINGS

Our data demonstrated that orexin-A/OX1R activated the mammalian target of rapamycin/p70 ribosomal protein S6 kinase-1 pathway, thereby inhibiting autophagy in H295R cells and Y-1 cells. Furthermore, the orexin-A/OX1R-mediated suppression of autophagy played a crucial role in cortisol secretion. Mechanistically, the expression of 3β-hydroxysteroid dehydrogenase/isomerase, the rate-limiting enzyme in cortisol synthesis, was increased with autophagy inhibition mediated by orexin-A/OX1R.

INTERPRETATION

This study provided the evidence that orexin-A/OX1R participated in modulating mTOR/p70S6K1/autophagy signaling pathway to promote cortisol secretion in adrenocortical cell. The findings suggest the mechanistic basis for disorders of cortisol secretion, providing the potential therapeutic targets for hypercortisolism treatment. FUND: This work was supported by National Natural Science Foundation of China (32170603, 31871286), the Doctoral Start-up Foundation of Liaoning Province (20180540008, 2019-BS-298), the Natural Science Foundation of Liaoning Province (2019-ZD-0779), and Shenyang Science and Technology Plan Fund Projects (21-173-9-28).

Vacuolar ATPase Is a Possible Therapeutic Target in Acute Myeloid Leukemia: Focus on Patient Heterogeneity and Treatment Toxicity

Vacuolar ATPase (V-ATPase) is regarded as a possible target in cancer treatment. It is expressed in primary acute myeloid leukemia cells (AML), but the expression varies between patients and is highest for patients with a favorable prognosis after intensive chemotherapy. We therefore investigated the functional effects of two V-ATPase inhibitors (bafilomycin A1, concanamycin A) for primary AML cells derived from 80 consecutive patients. The V-ATPase inhibitors showed dose-dependent antiproliferative and proapoptotic effects that varied considerably between patients. A proteomic comparison of primary AML cells showing weak versus strong antiproliferative effects of V-ATPase inhibition showed a differential expression of proteins involved in intracellular transport/cytoskeleton functions, and an equivalent phosphoproteomic comparison showed a differential expression of proteins that regulate RNA processing/function together with increased activity of casein kinase 2. Patients with secondary AML, i.e., a heterogeneous subset with generally adverse prognosis and previous cytotoxic therapy, myeloproliferative neoplasia or myelodysplastic syndrome, were characterized by a strong antiproliferative effect of V-ATPase inhibition and also by a specific mRNA expression profile of V-ATPase interactome proteins. Furthermore, the V-ATPase inhibition altered the constitutive extracellular release of several soluble mediators (e.g., chemokines, interleukins, proteases, protease inhibitors), and increased mediator levels in the presence of AML-supporting bone marrow mesenchymal stem cells was then observed, especially for patients with secondary AML. Finally, animal studies suggested that the V-ATPase inhibitor bafilomycin had limited toxicity, even when combined with cytarabine. To conclude, V-ATPase inhibition has antileukemic effects in AML, but this effect varies between patients.

Regulatory effect of orexin system on various diseases through mTOR signaling pathway

Orexin (OX)A and OXB are a pair of neuropeptides secreted by orexin-producing neurons in the lateral hypothalamus. The orexin system can regulate many physiological processes through these two receptor pathways, such as feeding behavior, sleep/wake state, energy homeostasis, reward, and the coordination of emotion. Mammalian target of rapamycin (mTOR) can coordinate upstream signals with downstream effectors, thereby regulating fundamental cellular processes and also plays an essential role in the signaling network downstream of the orexin system. In turn, the orexin system can activate mTOR. Here, we review the association of the orexin system with the mTOR signaling pathway mainly by discussing that drugs in various diseases exert their effects on the orexin system, indirectly affecting the mTOR signaling pathway.

A molecular network map of orexin-orexin receptor signaling system

Orexins are excitatory neuropeptides, which are predominantly associated with feeding behavior, sleep-wake cycle and energy homeostasis. The orexinergic system comprises of HCRTR1 and HCRTR2, G-protein-coupled receptors of rhodopsin family and the endogenous ligands processed from HCRT pro-hormone, Orexin A and Orexin B. These neuropeptides are biosynthesized by the orexin neurons present in the lateral hypothalamus area, with dense projections to other brain regions. The orexin-receptor signaling is implicated in various metabolic as well as neurological disorders, making it a promising target for pharmacological interventions. However, there is limited information available on the collective representation of the signal transduction pathways pertaining to the orexin-orexin receptor signaling system. Here, we depict a compendium of the Orexin A/B stimulated reactions in the form of a basic signaling pathway map. This map catalogs the reactions into five categories: molecular association, activation/inhibition, catalysis, transport, and gene regulation. A total of 318 downstream molecules were annotated adhering to the guidelines of NetPath curation. This pathway map can be utilized for further assessment of signaling events associated with orexin-mediated physiological functions and is freely available on WikiPathways, an open-source pathway database ( https://www.wikipathways.org/index.php/Pathway:WP5094 ).

New Insights into the Regulation of mTOR Signaling via Ca2+-Binding Proteins

Environmental factors are important regulators of cell growth and proliferation. Mechanistic target of rapamycin (mTOR) is a central kinase that maintains cellular homeostasis in response to a variety of extracellular and intracellular inputs. Dysregulation of mTOR signaling is associated with many diseases, including diabetes and cancer. Calcium ion (Ca²⁺) is important as a second messenger in various biological processes, and its intracellular concentration is tightly regulated. Although the involvement of Ca²⁺ mobilization in mTOR signaling has been reported, the detailed molecular mechanisms by which mTOR signaling is regulated are not fully understood. The link between Ca²⁺ homeostasis and mTOR activation in pathological hypertrophy has heightened the importance in understanding Ca²⁺-regulated mTOR signaling as a key mechanism of mTOR regulation. In this review, we introduce recent findings on the molecular mechanisms of regulation of mTOR signaling by Ca²⁺-binding proteins, particularly calmodulin (CaM).

A novel sulfur dioxide probe inhibits high glucose-induced endothelial cell senescence

Sulfur dioxide (SO₂) is an important gas signal molecule produced in the cardiovascular system, so it has an important regulatory effect on human umbilical vascular endothelial cells (HUVECs). Studies have shown that high glucose (HG) has become the main cause of endothelial dysfunction and aging. However, the mechanism by which SO₂ regulates the senescence of vascular endothelial cells induced by HG has not yet been clarified, so it is necessary to find effective tools to elucidate the effect of SO₂ on senescence of HUVECs. In this paper, we identified a novel sulfur dioxide probe (2-(4-(dimethylamino)styryl)-1,1,3-trimethyl-1H-benzo [e]indol-3-ium, DLC) that inhibited the senescence of HUVECs. Our results suggested that DLC facilitated lipid droplets (LDs) translocation to lysosomes and triggered upregulation of LAMP1 protein levels by targeting LDs. Further study elucidated that DLC inhibited HG-induced HUVECs senescence by promoting the decomposition of LDs and protecting the proton channel of V-ATPase on lysosomes. In conclusion, our study revealed the regulatory effect of lipid droplet-targeted sulfur dioxide probes DLC on HG-induced HUVECs senescence. At the same time, it provided the new experimental evidence for elucidating the regulatory mechanism of intracellular gas signaling molecule sulfur dioxide on vascular endothelial fate.

Effects of Vestibular Damage on the Sleep and Expression Level of Orexin in the Hypothalamus of Rats and Its Correlation with Autophagy and Akt Tumor Signal Pathway

The aim of this study was to investigate the effect of vestibular disruption on autophagy-related proteins and the tumour-associated pathway P13K/Akt in rat sleep and its hypothalamus tissue and to examine whether catechins trigger tumour autophagy. Healthy adult male rats were randomly selected and divided into the vestibular damage group, the sham operation group, and the control group, with 8 rats in each group. A vestibular damage model was established through penetrating the tympanic membrane of the external auditory canal by injecting sodium p-aminophenylarsonate. The electroencephalogram (EGG) activity was used to record the sleep-wakefulness cycle of rats, and the expression levels of hypothalamic orexin (orexin) mRNA and autophagy proteins were detected. Primary hippocampal neurons were intervened with orexin at different concentrations and at different times to detect cell viability and the expression of autophagy protein and P13K/Akt signal pathway protein. The results showed that compared with the control group and the sham operation group, NREM duration in the vestibular damage group decreased significantly (P < 0.05), while its  W  time increased significantly (P < 0.05). The expression level of orexin mRNA in the hypothalamus of the vestibular damage group was significantly higher than that of the other two groups (P < 0.05), the expression of autophagy microtubule-related proteins LC3B and Beclin-1 increased significantly (P < 0.05), and the protein expression level of p62 decreased significantly (P < 0.05). After orexin intervention, compared with the control group, the expression of Beclin-1 protein that positively correlated with autophagy decreased significantly (P < 0.05) and the expression of mTOR, PDK1, and Akt protein increased significantly (P < 0.05). Compared with the orexin intervention group, the expression of Beclin-1 and LC3B proteins in cells of the orexin receptor inhibitor (Almorexant) group, the autophagy activator (Rapamycin) group, the orexin + Almorexant group, and the orexin + Rapamycin group increased significantly (P < 0.05), and the expression of mTOR, PDK1, and Akt proteins decreased significantly (P < 0.05). Catechins trigger autophagy in part by regulating the p-Akt/p-mTOR and P13K pathways and by stimulating the MAPK pathway. Catechins initiate apoptosis in common tumour types of hepatocellular carcinoma cells by activating autophagy-related pathways. The conclusion is that vestibular damage can affect the sleep-wakefulness cycle of rats; the level of autophagy in hypothalamic tissue is upregulated and may affect cell proliferation and activity through mTOR-P13K/Akt, which has a certain reference value for tumor formation and provides a basis for the research of insomnia or sleep disorders caused by tumors. Autophagy activation is a key process by which catechins promote apoptosis in tumour cells, providing an avenue for more research on the use of catechins-rich diets for cardiovascular protection in the treatment of tumours.

Orexin Signaling: A Complex, Multifaceted Process

The orexin system comprises two G protein-coupled receptors, OX₁ and OX₂ receptors (OX₁R and OX₂R, respectively), along with two endogenous agonists cleaved from a common precursor (prepro-orexin), orexin-A (OX-A) and orexin-B (OX-B). For the receptors, a complex array of signaling behaviors has been reported. In particular, it becomes obvious that orexin receptor coupling is very diverse and can be tissue-, cell- and context-dependent. Here, the early signal transduction interactions of the orexin receptors will be discussed in depth, with particular emphasis on the direct G protein interactions of each receptor. In doing so, it is evident that ligands, additional receptor-protein interactions and cellular environment all play important roles in the G protein coupling profiles of the orexin receptors. This has potential implications for our understanding of the orexin system’s function in vivo in both central and peripheral environments, as well as the development of novel agonists, antagonists and possibly allosteric modulators targeting the orexin system.

G-Protein Coupled Receptor Signaling and Mammalian Target of Rapamycin Complex 1 Regulation

The mammalian target of rapamycin (mTOR) senses upstream stimuli to regulate numerous cellular functions such as metabolism, growth, and autophagy. Increased activation of mTOR complex 1 (mTORC1) is typically observed in human disease and continues to be an important therapeutic target. Understanding the upstream regulators of mTORC1 will provide a crucial link in targeting hyperactivated mTORC1 in human disease. In this mini-review, we will discuss the regulation of mTORC1 by upstream stimuli, with a specific focus on G-protein coupled receptor signaling to mTORC1. SIGNIFICANCE STATEMENT: mTORC1 is a master regulator of many cellular processes and is often hyperactivated in human disease. Therefore, understanding the molecular underpinnings of G-protein coupled receptor signaling to mTORC1 will undoubtedly be beneficial for human disease.

New Aspects of Corpus Luteum Regulation in Physiological and Pathological Conditions: Involvement of Adipokines and Neuropeptides

The corpus luteum is a small gland of great importance because its proper functioning determines not only the appropriate course of the estrous/menstrual cycle and embryo implantation, but also the subsequent maintenance of pregnancy. Among the well-known regulators of luteal tissue functions, increasing attention is focused on the role of neuropeptides and adipose tissue hormones—adipokines. Growing evidence points to the expression of these factors in the corpus luteum of women and different animal species, and their involvement in corpus luteum formation, endocrine function, angiogenesis, cells proliferation, apoptosis, and finally, regression. In the present review, we summarize the current knowledge about the expression and role of adipokines, such as adiponectin, leptin, apelin, vaspin, visfatin, chemerin, and neuropeptides like ghrelin, orexins, kisspeptin, and phoenixin in the physiological regulation of the corpus luteum function, as well as their potential involvement in pathologies affecting the luteal cells that disrupt the estrous cycle.

Calcium Ions Aggravate Alzheimer's Disease Through the Aberrant Activation of Neuronal Networks, Leading to Synaptic and Cognitive Deficits

Alzheimer’s disease (AD) is a neurodegenerative disease that is characterized by the production and deposition of β-amyloid protein (Aβ) and hyperphosphorylated tau, leading to the formation of β-amyloid plaques (APs) and neurofibrillary tangles (NFTs). Although calcium ions (Ca²⁺) promote the formation of APs and NFTs, no systematic review of the mechanisms by which Ca²⁺ affects the development and progression of AD has been published. Therefore, the current review aimed to fill the gaps between elevated Ca²⁺ levels and the pathogenesis of AD. Specifically, we mainly focus on the molecular mechanisms by which Ca²⁺ affects the neuronal networks of neuroinflammation, neuronal injury, neurogenesis, neurotoxicity, neuroprotection, and autophagy. Furthermore, the roles of Ca²⁺ transporters located in the cell membrane, endoplasmic reticulum (ER), mitochondria and lysosome in mediating the effects of Ca²⁺ on activating neuronal networks that ultimately contribute to the development and progression of AD are discussed. Finally, the drug candidates derived from herbs used as food or seasoning in Chinese daily life are summarized to provide a theoretical basis for improving the clinical treatment of AD.

Ion Channels and Pumps in Autophagy: A Reciprocal Relationship

Autophagy, the process of cellular self-degradation, is intrinsically tied to the degradative function of the lysosome. Several diseases have been linked to lysosomal degradative defects, including rare lysosomal storage disorders and neurodegenerative diseases. Ion channels and pumps play a major regulatory role in autophagy. Importantly, calcium signaling produced by TRPML1 (transient receptor potential cation channel, mucolipin subfamily) has been shown to regulate autophagic progression through biogenesis of autophagic-lysosomal organelles, activation of mTORC1 (mechanistic target of rapamycin complex 1) and degradation of autophagic cargo. ER calcium channels such as IP₃Rs supply calcium for the lysosome, and lysosomal function is severely disrupted in the absence of lysosomal calcium replenishment by the ER. TRPML1 function is also regulated by LC3 (microtubule-associated protein light chain 3) and mTORC1, two critical components of the autophagic network. Here we provide an overview of the current knowledge about ion channels and pumps-including lysosomal V-ATPase (vacuolar proton-ATPase), which is required for acidification and hence proper enzymatic activity of lysosomal hydrolases-in the regulation of autophagy, and discuss how functional impairment of some of these leads to diseases.

In vivo Ca2+ dynamics during cooling after eccentric contractions in rat skeletal muscle

The effect of cooling on in vivo intracellular calcium ion concentration [Ca²⁺]_i after eccentric contractions (ECs) remains to be determined. We tested the hypothesis that cryotherapy following ECs promotes an increased [Ca²⁺]_i and induces greater muscle damage in two muscles with substantial IIb and IIx fiber populations. The thin spinotrapezius (SPINO) muscles of Wistar rats were used for in vivo [Ca²⁺]_i imaging, and tibialis anterior (TA) muscles provided greater fidelity and repeatability of contractile function measurements. SPINO [Ca²⁺]_i was estimated using fura 2-AM and the magnitude, location, and temporal profile of [Ca²⁺]_i determined as the temperature near the muscle surface post-ECs was decreased from 30°C (control) to 20°C or 10°C. Subsequently, in the TA, the effect of post-ECs cooling to 10°C on muscle contractile performance was determined at 1 and 2 days after ECs. TA muscle samples were examined by hematoxylin and eosin staining to assess damage. In SPINO, reducing the muscle temperature from 30°C to 10°C post-ECs resulted in a 3.7-fold increase in the spread of high [Ca²⁺]_i sites generated by ECs (P < 0.05). These high [Ca²⁺]_i sites demonstrated partial reversibility when rewarmed to 30°C. Dantrolene, a ryanodine receptor Ca²⁺ release inhibitor, reduced the presence of high [Ca²⁺] sites at 10°C. In the TA, cooling exacerbated ECs-induced muscle strength deficits via enhanced muscle fiber damage (P < 0.05). By demonstrating that cooling post-ECs potentiates [Ca²⁺]_i derangements, this in vivo approach supports a putative mechanistic basis for how postexercise cryotherapy might augment muscle fiber damage and decrease subsequent exercise performance.

Orexin system is expressed in avian liver and regulates hepatic lipogenesis via ERK1/2 activation

Orexins are originally characterized as orexigenic hypothalamic neuropeptides in mammals. Subsequent studies found orexin to be expressed and perform pleiotropic functions in multiple tissues in mammals. In avian (non-mammalian) species, however, orexin seemed to not affect feeding behavior and its physiological roles are poorly understood. Here, we provide evidence that orexin and its related receptors are expressed in chicken hepatocytes. Double immunofluorescence staining showed that orexin is localized in the ER, Golgi, and in the lysosomes in LMH cells. Brefeldin A treatment reduced orexin levels in the culture media, but increased it in the cell lysates. Administration of recombinant orexins upregulated the expression of orexin system in the liver of 9-day old chicks, but did not affect feed intake. Recombinant orexins increased fatty acid synthase (FASN) protein levels in chicken liver, activated acetyl-CoA carboxylase (ACCα), and increased FASN, ATP citrate lyase(ACLY), and malic enzyme (ME) protein expression in LMH cells. Blockade ERK1/2 activation by PD98059 attenuated these stimulating effects of orexin on lipogenic factors. Overexpression of ERK1/2 increased the expression of lipogenic genes, and orexin treatment induced the phosphorylated levels of ERK1/2^{Thr202/Tyr204}, but not that of p38 ^{Thr180/Tyr182} or JNK1/2 ^{Thr183/Tyr185} in chicken liver and LMH cells. Taken together, this is the first report evidencing that orexin is expressed and secreted from chicken hepatocytes, and that orexin induced hepatic lipogenesis via activation of ERK1/2 signaling pathway.

Regulation of mTORC1 by Upstream Stimuli

The mammalian target of rapamycin (mTOR) is an evolutionary conserved Ser/Thr protein kinase that senses multiple upstream stimuli to control cell growth, metabolism, and autophagy. mTOR is the catalytic subunit of mTOR complex 1 (mTORC1). A significant amount of research has uncovered the signaling pathways regulated by mTORC1, and the involvement of these signaling cascades in human diseases like cancer, diabetes, and ageing. Here, we review advances in mTORC1 regulation by upstream stimuli. We specifically focus on how growth factors, amino acids, G-protein coupled receptors (GPCRs), phosphorylation, and small GTPases regulate mTORC1 activity and signaling.

Ultrasound Stimulation Increases Neurite Regeneration in Injured Dorsal Root Ganglion Neurons through Mammalian Target of Rapamycin Activation

Ultrasound stimulation (US) is reported to be a safe and useful technology for improving injured nerve regeneration. However, the intracellular mechanisms underlying its stimulatory effects are only partially understood. Mammalian target of rapamycin (mTOR) signaling is involved in neuronal survival and axonal outgrowth. In this study, we investigated the effect of US on regeneration of injured dorsal root ganglion (DRG) neurons and activation of the mTOR pathway. We showed that US significantly increased neurite regeneration and enhanced mTOR activation. Moreover, the expression of growth-associated protein-43 (GAP-43), a crucial factor for axonal outgrowth and regeneration in neurons, was significantly increased by US. These data suggest that US-induced neurite regeneration is mediated by upregulation of mTOR activity, which promotes the regeneration of injured DRG neurons.

Phytogenic feed- and water-additives improve feed efficiency in broilers via modulation of (an)orexigenic hypothalamic neuropeptide expression

Fueled by consumer preference for natural and antibiotic-free products, phytogenics have become the fastest growing segment of the animal feed additives. Yet, their modes of action are not fully understood. This study was undertaken to determine the effect of 5 phytogenics (3 feed- and 2 water-supplements) on the growth performance of commercial broilers, and their potential underlying molecular mechanisms. Day-old male Cobb 500 chicks (n = 576) were randomly assigned into 48 pens consisting of 6 treatments (Control; AVHGP; SCP; BHGP; AVSSL; SG) in a complete randomized design (12 birds/pen, 8 pens/treatment, 96 birds/treatment). Chicks had ad libitum access to feed and water. Individual body weight (BW) was recorded weekly and feed intake was measured daily. Core body temperatures were continuously recorded using thermo-loggers. At d 35, hypothalamic tissues were excised from the thermo-logger-equipped chickens (n = 8 birds/treatment) to determine the expression of feeding-related neuropeptides. Both feed (AVHGP, SCP, BHGP) and water-supplemented (AVSSL, SG) phytogenics significantly improved feed efficiency (FE) compared to the control birds. This higher FE was achieved via a reduction in core body temperature and improvement of market BW, without changes in feed intake in broilers supplemented with phytogenic water additives as compared to the control group. Broilers fed dietary phytogenics, however, attained higher feed efficiency via a reduction in feed intake while maintaining similar BW as the control group. At the molecular levels, the effects of the phytogenic water additives seemed to be mediated by the activation of the hypothalamic AgRP-ORX-mTOR-S6k1 and inhibition of CRH pathways. The effect of the phytogenic feed additives appeared to be exerted through the activation of AdipoQ, STAT3, AMPK, and MC1R pathways. This is the first report describing the likely central mechanisms through which phytogenic additives improve the growth performance and feed efficiency in broilers.

The Important Role of Adiponectin and Orexin-A, Two Key Proteins Improving Healthy Status: Focus on Physical Activity

Exercise represents the most important integrative therapy in metabolic, immunologic and chronic diseases; it represents a valid strategy in the non-pharmacological intervention of lifestyle linked diseases. A large body of evidence indicates physical exercise as an effective measure against chronic non-communicable diseases. The worldwide general evidence for health benefits are both for all ages and skill levels. In a dysregulated lifestyle such as in the obesity, there is an imbalance in the production of different cytokines. In particular, we focused on Adiponectin, an adipokine producted by adipose tissue, and on Orexin-A, a neuropeptide synthesized in the lateral hypothalamus. The production of both Adiponectin and Orexin-A increases following regular and structured physical activity and both these hormones have similar actions. Indeed, they improve energy and glucose metabolism, and also modulate energy expenditure and thermogenesis. In addition, a relevant biological role of Adiponectin and Orexin A has been recently highlighted in the immune system, where they function as immune-suppressor factors. The strong connection between these two cytokines and healthy status is mediated by physical activity and candidates these hormones as potential biomarkers of the beneficial effects induced by physical activity. For these reasons, this review aims to underly the interconnections among Adiponectin, Orexin-A, physical activity and healthy status. Furthermore, it is analyzed the involvement of Adiponectin and Orexin-A in physical activity as physiological factors improving healthy status through physical exercise.

Wakefulness/sleep architecture and electroencephalographic activity in mice lacking the translational repressor 4E-BP1 or 4E-BP2

Sleep and sleep loss are affecting protein synthesis in the brain, but the contribution of translational control to wakefulness and sleep regulation remains poorly understood. Here, we studied the role of two suppressors of protein synthesis, the eukaryotic translation initiation factor 4E-binding proteins 1 and 2 (4E-BP1 and 4E-BP2), in sleep architecture and electroencephalographic (EEG) activity as well as in the EEG and molecular responses to acute sleep loss. The EEG of mice mutant for the genes encoding 4E-BP1 or 4E-BP2 (Eif4ebp1 and Eif4ebp2 knockout [KO] mice) was recorded under undisturbed conditions and following a 6-hour sleep deprivation (SD). The effect of SD on the expression of genes known to respond to SD was also measured in the prefrontal cortex of Eif4ebp1 and Eif4ebp2 KO mice. Eif4ebp1 KO mice differed from wild-type mice in parameters of wakefulness and sleep quantity and quality, and more subtly in the gene expression response to SD. For instance, Eif4ebp1 KO mice spent more time in slow-wave sleep (SWS) and showed altered baseline 24-h time courses of SWS delta (1-4 Hz) activity and sigma (10-13 Hz) activity. Eif4ebp2 KO mice differed from wild-type mice only for wakefulness and sleep quality, expressing changes in EEG spectral activity generally revealed during and after SD. These findings suggest different roles of effectors of translational control in the regulation of wakefulness and sleep and of synchronized cortical activity.

Differential Roles of Each Orexin Receptor Signaling in Obesity

Orexins are hypothalamic neuropeptides that regulate feeding, energy expenditure, and sleep. Although orexin-deficient mice are susceptible to obesity, little is known about the roles of the orexin receptors in long-term energy metabolism. Here, we performed the metabolic characterization of orexin receptor-deficient mice. Ox1r-deficient mice were resistant to diet-induced obesity, and their food intake was similar between chow and high-fat food. Ox2r-deficient mice exhibited less energy expenditure than wild-type mice when fed a high-fat diet. Neither Ox1r-deficient nor Ox2r-deficient mice showed body weight gain similar to orexin-deficient mice. Although the presence of a running wheel suppressed diet-induced obesity in wild-type mice, the effect was weaker in orexin neuron-ablated mice. Finally, we did not detect abnormalities in brown adipose tissues of orexin-deficient mice. Thus, each orexin receptor signaling has a unique role in energy metabolism, and orexin neurons are involved in the interactive effect of diet and exercise on body weight gain.

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Food intakes of Ox1r-deficient mice are similar between chow and high-fat food

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Ox2r-deficient mice exhibit less energy expenditure when fed a high-fat diet

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Orexin neurons are involved in the interactive effect of diet and exercise

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Orexin-deficient mice have normal brown adipose tissue

[Multimodality of clinical effects of orexin]

The article describes the main biological properties of orexin as a wakefulness hormone and its possible points of application in practical medicine. An example of a drug, which blocks orexin receptors and can be used as a hypnotic drug to treat sleep disorders, is presented.

Orexin-A Stimulates Insulin Secretion Through the Activation of the OX1 Receptor and Mammalian Target of Rapamycin in Rat Insulinoma Cells

OBJECTIVES

The study aimed to investigate the involvement of the mammalian target of rapamycin (mTOR) signaling pathway in orexin-A/OX1 receptor-induced insulin secretion in rat insulinoma INS-1 cells.

METHODS

Rat insulinoma INS-1 cells were grown and treated with various concentrations of orexin-A, with or without OX1 receptor-selective antagonist SB674042 or the phosphatidylinositol 3-kinase/mTOR antagonist PF-04691502. Insulin release experiments, Western blot analysis, and statistical analysis were conducted using INS-1 cells.

RESULTS

Our results showed that treating cells with orexin-A increased the expression of the OX1 receptor and the phosphorylation of mTOR in a concentration-dependent manner. An increase in insulin secretion was also observed for cells treated with orexin-A. We further demonstrated that the increase in insulin secretion was dependent on the activation of the OX1 receptor and mTOR signaling pathway by using the OX1 receptor-selective antagonist SB674042 or the phosphatidylinositol 3-kinase/mTOR antagonist PF-04691502, which abolished the effects of orexin-A treatment.

CONCLUSIONS

Our results concluded that orexin-A/OX1 receptor stimulates insulin secretion by activating AKT and its downstream target, mTOR. Therefore, orexins may regulate the energy balance for cell survival with the involvement of mTOR in this process.

A pH probe inhibits senescence in mesenchymal stem cells

BACKGROUND

Bone marrow-derived mesenchymal stem cells (BMSCs) are gradually getting attention because of its multi-directional differentiation potential, hematopoietic support, and promotion of stem cell implantation. However, cultured BMSCs in vitro possess a very limited proliferation potential, and the presence of stem cell aging has substantially restricted the effect together with the efficiency in clinical treatment. Recently, increasing attention has been paid to the connection between cellular aging and lysosomal acidification as new reports indicated that vacuolar H⁺-ATPase (v-ATPase) activity was altered and lysosomal pH was dysregulated in the process of cellular aging. Therefore, promoting lysosomal acidification might contribute to inhibition of cell senescence. Our previous studies showed that a novel small molecule, 3-butyl-1-chloro imidazo [1, 5-a] pyridine-7-carboxylic acid (SGJ), could selectively and sensitively respond to acidic pH with fast response (within 3 min), but whether SGJ can promote lysosomal acidification and inhibit senescence in BMSCs is unknown.

METHODS

Rat BMSCs were cultured based on our system that had been already documented. BMSCs were treated with SGJ and/or Bafilomycin-A1 (Baf-A1). The co-localization between SGJ and lysosomes was assessed by a confocal microscope. Acridine orange (AO) staining and the Lysosensor™ Green DND-189 reagents were used for indicating changes in lysosomal concentration of H⁺. Changes of senescence were detected by immunoblotting of p21 and senescence-associated beta-galactosidase (SA-β-gal) staining as well as immunofluorescence assay of senescence-associated heterochromatin foci (SAHF). Changes of autophagy were detected by immunoblotting of MAP1LC3 (LC3B) and SQSTM1 (p62). Cell proliferation was determined by flow cytometry. Cell viability was calculated by sulforhodamine B assay (SRB). The V0 proton channel of v-ATPase was knocked down by transfecting with its small interfering RNA (si-ATP6V0C).

RESULTS

Our work showed that SGJ can promote lysosomal acidification and inhibit senescence in BMSCs. Firstly, SGJ and lysosomes were well co-located in senescent BMSCs with the co-localization coefficient of 0.94. Secondly, SGJ increased the concentration of H⁺ and the protein expression of lysosome-associated membrane protein 1 (LAMP1) and lysosome-associated membrane protein 2 (LAMP2). Thirdly, SGJ suppressed the expression of p21 in the senescent BMSCs and reduced SA-β-gal positive cells. Fourthly, SGJ promoted senescent BMSCs' proliferation and protein level of LC3B but reduced the p62/SQSTM1 protein level. Furthermore, experimental group pretreated with 20 μM SGJ showed a stronger red fluorescent intensity, thinner cell morphology, less SA-β-gal positive cell, and less p21 protein level as well as higher cell viability in the presence of Baf-A1. Notably, ATP6V0C knockdown decreased the activity of v-ATPase and SGJ increased the concentration of H⁺.

CONCLUSION

Our work showed that SGJ could inhibit senescence in BMSCs and protect lysosomes by promoting expression of LAMP1 and LAMP2. Meanwhile, SGJ could promote autophagy. Furthermore, our study also suggested that SGJ was a new Baf-A1 antagonist because SGJ could target and occupy the V0 proton channel of v-ATPase.

Macrophage Raptor Deficiency-Induced Lysosome Dysfunction Exacerbates Nonalcoholic Steatohepatitis

BACKGROUND & AIMS

Nonalcoholic steatohepatitis (NASH) is an increasingly prevalent nonalcoholic fatty liver disease, characterized by inflammatory cell infiltration and hepatocellular damage. Mammalian target of rapamycin complex 1 (mTORC1) has been investigated extensively in the context of cancer, including hepatocellular carcinoma. However, the role of mTORC1 in NASH remains largely unknown.

METHODS

mTORC1 activity in macrophages in human mild and severe NASH liver was compared. Mice with macrophage-specific deletion of the regulatory-associated protein of mTOR (Raptor) subunit and littermate controls were fed a high-fructose, palmitate, and cholesterol diet for 24 weeks or a methionine- and choline-deficient diet for 4 weeks to develop NASH.

RESULTS

We report that in human beings bearing NASH, macrophage mTORC1 activity was lower in livers experiencing severe vs mild NASH liver. Moreover, macrophage mTORC1 disruption exacerbated the inflammatory response in 2 diet-induced NASH mouse models. Mechanistically, in response to apoptotic hepatocytes (AHs), macrophage polarization toward a M2 anti-inflammatory phenotype was inhibited in Raptor-deficient macrophages. During the digestion of AHs, macrophage mTORC1 was activated and coupled with dynamin-related protein 1 to facilitate the latter's phosphorylation, leading to mitochondrial fission-mediated calcium release. Ionomycin or A23187, calcium ionophores, prevented Raptor deficiency-mediated failure of lysosome acidification and subsequent lipolysis. Blocking dynamin-related protein 1-dependent mitochondria fission impaired lysosome function, resulting in reduced production of anti-inflammatory factors such as interleukins 10 and 13.

CONCLUSIONS

Persistent mTORC1 deficiency in macrophages contributes to the progression of NASH by causing lysosome dysfunction and subsequently attenuating anti-inflammatory M2-like response in macrophages during clearance of AHs.

The Orexin/Receptor System: Molecular Mechanism and Therapeutic Potential for Neurological Diseases

Orexins, also known as hypocretins, are two neuropeptides secreted from orexin-containing neurons, mainly in the lateral hypothalamus (LH). Orexins orchestrate their effects by binding and activating two G-protein–coupled receptors (GPCRs), orexin receptor type 1 (OX1R) and type 2 (OX2R). Orexin/receptor pathways play vital regulatory roles in many physiological processes, especially feeding behavior, sleep–wake rhythm, reward and addiction and energy balance. Furthermore several reports showed that orexin/receptor pathways are involved in pathological processes of neurological diseases such as narcolepsy, depression, ischemic stroke, drug addiction and Alzheimer’s disease (AD). This review article summarizes the expression patterns, physiological functions and potential molecular mechanisms of the orexin/receptor system in neurological diseases, providing an overall framework for considering these pathways from the standpoints of basic research and clinical treatment of neurological diseases.

RNA-seq expression profiling of rat MCAO model following reperfusion Orexin-A

Orexin-A is a neuropeptide with potent neuroprotective activity towards cerebral ischemia-reperfusion (I/R) injury, but few studies have attempted to elucidate the mechanism. Herein, we performed global gene expression profiling of the hippocampus following reperfusion with Orexin-A using RNA sequencing (RNA-seq). RNA-seq identified 649 differentially expressed genes (DEGs) in the Orexin-A group compared with saline controls (I/R group), of which 149 were up-regulated and 500 were down-regulated. DEGs were confirmed using qRT-PCR, their molecular functions, biological processes and molecular components were explored using Gene Ontology (GO) analysis and 206 KEGG pathways were associated with Orexin-A treatment. MAPK, chemokine and calcium signalling pathways were mainly responsible for the neuroprotective effects of Orexin-A. Hspb1, Igf2 and Ptk2b were selected for functional interaction analysis by GeneMANIA. The results suggest that Orexin-A modifies gene expression in the hippocampus, leading to neuroprotection from I/R injury. The study provides a basis for future elucidation of the molecular mechanisms underlying Orexin-A.

Orexin/Hypocretin Signaling

Orexin/hypocretin peptide (orexin-A and orexin-B) signaling is believed to take place via the two G-protein-coupled receptors (GPCRs), named OX1 and OX2 orexin receptors, as described in the previous chapters. Signaling of orexin peptides has been investigated in diverse endogenously orexin receptor-expressing cells - mainly neurons but also other types of cells - and in recombinant cells expressing the receptors in a heterologous manner. Findings in the different systems are partially convergent but also indicate cellular background-specific signaling. The general picture suggests an inherently high degree of diversity in orexin receptor signaling.In the current chapter, I present orexin signaling on the cellular and molecular levels. Discussion of the connection to (potential) physiological orexin responses is only brief since these are in focus of other chapters in this book. The same goes for the post-synaptic signaling mechanisms, which are dealt with in Burdakov: Postsynaptic actions of orexin. The current chapter is organized according to the tissue type, starting from the central nervous system. Finally, receptor signaling pathways are discussed across tissues, cell types, and even species.

The Function of V-ATPases in Cancer

The vacuolar ATPases (V-ATPases) are a family of proton pumps that couple ATP hydrolysis to proton transport into intracellular compartments and across the plasma membrane. They function in a wide array of normal cellular processes, including membrane traffic, protein processing and degradation, and the coupled transport of small molecules, as well as such physiological processes as urinary acidification and bone resorption. The V-ATPases have also been implicated in a number of disease processes, including viral infection, renal disease, and bone resorption defects. This review is focused on the growing evidence for the important role of V-ATPases in cancer. This includes functions in cellular signaling (particularly Wnt, Notch, and mTOR signaling), cancer cell survival in the highly acidic environment of tumors, aiding the development of drug resistance, as well as crucial roles in tumor cell invasion, migration, and metastasis. Of greatest excitement is evidence that at least some tumors express isoforms of V-ATPase subunits whose disruption is not lethal, leading to the possibility of developing anti-cancer therapeutics that selectively target V-ATPases that function in cancer cells.

Potential of GPCRs to modulate MAPK and mTOR pathways in Alzheimer's disease

Despite efforts to understand the mechanism of neuronal cell death, finding effective therapies for neurodegenerative diseases is still a challenge. Cognitive deficits are often associated with neurodegenerative diseases. Remarkably, in the absence of consensus biomarkers, diagnosis of diseases such as Alzheimer's still relies on cognitive tests. Unfortunately, all efforts to translate findings in animal models to the patients have been unsuccessful. Alzheimer's disease may be addressed from two different points of view, neuroprotection or cognitive enhancement. Based on recent data, the mammalian target of rapamycin (mTOR) pathway arises as a versatile player whose modulation may impact on mechanisms of both neuroprotection and cognition. Whereas direct targeting of mTOR does not seem to constitute a convenient approach in drug discovery, its indirect modulation by other signaling pathways seems promising. In fact, G-protein-coupled receptors (GPCRs) remain the most common 'druggable' targets and as such pharmacological manipulation of GPCRs with selective ligands may modulate phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K), mitogen-activated protein (MAP) kinase and mTOR signaling pathways. Thus, GPCRs become important targets for potential drug treatments in different neurodegenerative disorders including, but not limited to, Alzheimer's disease. GPCR-mediated modulation of mTOR may take advantage of different GPCRs coupled to different G-dependent and G-independent signal transduction routes, of functional selectivity and/or of biased agonism. Signals mediated by GPCRs may act as coincidence detectors to achieve different benefits in different stages of the neurodegenerative disease.

Molecular neurobiology of mTOR

Mammalian/mechanistic target of rapamycin (mTOR) is a serine-threonine kinase that controls several important aspects of mammalian cell function. mTOR activity is modulated by various intra- and extracellular factors; in turn, mTOR changes rates of translation, transcription, protein degradation, cell signaling, metabolism, and cytoskeleton dynamics. mTOR has been repeatedly shown to participate in neuronal development and the proper functioning of mature neurons. Changes in mTOR activity are often observed in nervous system diseases, including genetic diseases (e.g., tuberous sclerosis complex, Pten-related syndromes, neurofibromatosis, and Fragile X syndrome), epilepsy, brain tumors, and neurodegenerative disorders (Alzheimer's disease, Parkinson's disease, and Huntington's disease). Neuroscientists only recently began deciphering the molecular processes that are downstream of mTOR that participate in proper function of the nervous system. As a result, we are gaining knowledge about the ways in which aberrant changes in mTOR activity lead to various nervous system diseases. In this review, we provide a comprehensive view of mTOR in the nervous system, with a special focus on the neuronal functions of mTOR (e.g., control of translation, transcription, and autophagy) that likely underlie the contribution of mTOR to nervous system diseases.

Recent Insights into the Structure, Regulation, and Function of the V-ATPases

The vacuolar (H(+))-ATPases (V-ATPases) are ATP-dependent proton pumps that acidify intracellular compartments and are also present at the plasma membrane. They function in such processes as membrane traffic, protein degradation, virus and toxin entry, bone resorption, pH homeostasis, and tumor cell invasion. V-ATPases are large multisubunit complexes, composed of an ATP-hydrolytic domain (V1) and a proton translocation domain (V0), and operate by a rotary mechanism. This review focuses on recent insights into their structure and mechanism, the mechanisms that regulate V-ATPase activity (particularly regulated assembly and trafficking), and the role of V-ATPases in processes such as cell signaling and cancer. These developments have highlighted the potential of V-ATPases as a therapeutic target in a variety of human diseases.

Promoting axon regeneration in the adult CNS by modulation of the melanopsin/GPCR signaling

Cell-type-specific G protein-coupled receptor (GPCR) signaling regulates distinct neuronal responses to various stimuli and is essential for axon guidance and targeting during development. However, its function in axonal regeneration in the mature CNS remains elusive. We found that subtypes of intrinsically photosensitive retinal ganglion cells (ipRGCs) in mice maintained high mammalian target of rapamycin (mTOR) levels after axotomy and that the light-sensitive GPCR melanopsin mediated this sustained expression. Melanopsin overexpression in the RGCs stimulated axonal regeneration after optic nerve crush by up-regulating mTOR complex 1 (mTORC1). The extent of the regeneration was comparable to that observed after phosphatase and tensin homolog (Pten) knockdown. Both the axon regeneration and mTOR activity that were enhanced by melanopsin required light stimulation and Gq/11 signaling. Specifically, activating Gq in RGCs elevated mTOR activation and promoted axonal regeneration. Melanopsin overexpression in RGCs enhanced the amplitude and duration of their light response, and silencing them with Kir2.1 significantly suppressed the increased mTOR signaling and axon regeneration that were induced by melanopsin. Thus, our results provide a strategy to promote axon regeneration after CNS injury by modulating neuronal activity through GPCR signaling.

DNA Repair--A Double-Edged Sword in the Genomic Stability of Cancer Cells--The Case of Chronic Myeloid Leukemia

Genomic instability is a common feature of cancer cells, which can result from aberrant DNA damage reaction (DDR). We and others showed that the well-known BCR-ABL1 fusion oncogene, the cause of chronic myeloid leukemia, induced an increased production of reactive oxygen species (ROS) and conferred therapeutic drug resistance by suppression of apoptotic signaling, prolonged G2/M arrest and stimulation of several pathways of DNA repair. However, to protect from apoptosis, cancer cells may tolerate some DNA lesions, which may increase genomic instability. Moreover, BCR/ABL1-stimulated DNA repair might be faulty, especially non-homologous end joining in its alternative forms. Normal DNA repair can remove DNA damage and prevent mutations, reducing genome instability, but on the other hand, due to its imprecise nature, it may increase genomic instability by increasing the ratio of mutagenic DNA lesions. The example of BCR-ABL1-expressing cells shows that DNA repair can both increase and decrease genomic instability of cancer cells and understanding the mechanism of the regulation of these opposite effects would be helpful in anticancer strategies.

Involvement of Heme Oxygenase-1 in Orexin-A-induced Angiogenesis in Vascular Endothelial Cells

The cytoprotective enzyme heme oxygenase-1 (HO-1) influences endothelial cell survival, proliferation, inflammatory response, and angiogenesis in response to various angiogenic stimuli. In this study, we investigate the involvement of HO-1 in the angiogenic activity of orexin-A. We showed that orexin-A stimulates expression and activity of HO-1 in human umbilical vein endothelial cells (HUVECs). Furthermore, we showed that inhibition of HO-1 by tin (Sn) protoporphryin-IX (SnPP) reduced orexin-A-induced angiogenesis in vivo and ex vivo. Orexin-A-stimulated endothelial tube formation and chemotactic activity were also blocked in SnPP-treated vascular endothelial cells. Orexin-A treatment increased the expression of nuclear factor erythroid-derived 2 related factor 2 (Nrf2), and antioxidant response element (ARE) luciferase activity, leading to induction of HO-1. Collectively, these findings indicate that HO-1 plays a role as an important mediator of orexin-A-induced angiogenesis, and provide new possibilities for therapeutic approaches in pathophysiological conditions associated with angiogenesis.

Strategies of Functional Foods Promote Sleep in Human Being

Sleep is a vital segment of life, however, the mechanisms of diet promoting sleep are unclear and are the focus of research. Insomnia is a general sleep disorder and functional foods are known to play a key role in the prevention of insomnia. A number of studies have demonstrated that major insomnia risk factors in human being are less functional foods in dietary. There are higher functional components in functional foods promoting sleep, including tryptophan, GABA, calcium, potassium, melatonin, pyridoxine, L-ornithine and hexadecanoic acid; but wake-promoting neurochemical factors include serotonin, noradrenalin, acetylcholine, histamine, orexin and so on. The factors promoting sleep in human being are the functional foods include barley grass powder, whole grains, maca, panax, Lingzhi, asparagus powder, lettuce, cherry, kiwifruits, walnut, schisandra wine, and milk; Barley grass powder with higher GABA and calcium, as well as potassium is the most ideal functional food promoting sleep, however, the sleep duration for modern humans is associated with food structure of ancient humans. In this review, we put forward possible mechanisms of functional components in foods promoting sleep. Although there is clear relevance between sleep and diet, their molecular mechanisms need to be studied further.