H2S Attenuates Sleep Deprivation-Induced Cognitive Impairment by Reducing Excessive Autophagy via Hippocampal Sirt-1 in WISTAR RATS

S100A8 knockdown activates the PI3K/AKT signaling pathway to inhibit microglial autophagy and improve cognitive impairment mediated by chronic sleep deprivation

OBJECTIVE

Cognitive dysfunction is one of the major symptoms of chronic sleep deprivation (CSD). Abnormal autophagy and apoptosis are thought to be important mechanisms. S100 Calcium Binding Protein A8 (S100A8) plays a key role in autophagy and apoptosis of microglia. This study investigated whether S100A8 knockdown can effectively inhibit aberrant autophagy in microglia and improve cognitive function by activating the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway under CSD conditions.

METHODS

CSD mouse models and BV2 cell autophagy models were established in vivo and in vitro. Transcriptome sequencing was used to determine the key regulator related to autophagy. The Morris water maze test was used to evaluate the cognitive behavior of the mice. RT-qPCR and western blot were conducted to examine S100A8 expression and autophagy signalling. HE, TUNEL, transmission electron microscopy, immunofluorescence, and histochemistry were performed to detect pathological changes, neuronal autophagy, apoptosis, or positive cells in hippocampal tissues, respectively.

RESULTS

Transcriptome sequencing showed that S100A8 was significantly elevated in CSD mice, and fluorescence colocalization results further suggested that S100A8 mainly colocalizes with microglia. In vivo studies revealed that knockdown of S100A8 alleviated CSD-induced cognitive impairment in mice. Through further mechanistic investigations employing both in vivo and in vitro models, we demonstrated that silencing S100A8 can activate the PI3K/AKT pathway, thereby reducing CSD-induced abnormal autophagy and apoptosis in microglia. Aberrant autophagy and apoptosis in microglia were reversed with the PI3K/AKT pathway inhibitor LY294002.

CONCLUSION

The S100A8/PI3K/AKT axis plays a crucial role in chronic sleep deprivation-mediated autophagy and apoptosis in microglia.

Continuous Theta Burst Stimulation Inhibits Oxidative Stress-Induced Inflammation and Autophagy in Hippocampal Neurons by Activating Glutathione Synthesis Pathway, Improving Cognitive Impairment in Sleep-Deprived Mice

Sleep deprivation (SD) has been reported to have a negative impact on cognitive function. Continuous theta burst stimulation (cTBS) shows certain effects in improving sleep and neurological diseases, and its molecular or cellular role in SD-induced cognition impairment still need further exploration. In this study, C57BL/6 mice were subjected to 48 h of SD and cTBS treatment, and cTBS treatment significantly improved SD-triggered impairment of spatial learning and memory abilities in mice. Additionally, cTBS reduced malondialdehyde levels, increased superoxide dismutase activities, and inhibited the production of inflammatory cytokines, alleviating oxidative stress and inflammation levels in hippocampal tissues of SD model mice. cTBS decreased LC3II/LC3I ratio, Beclin1 protein levels, and LC3B puncta intensity, and elevated p62 protein levels to suppress excessive autophagy in hippocampal tissues of SD-stimulated mice. Then, we proved that inhibiting oxidative stress alleviated inflammation, autophagy, and death of hippocampal neuron cells through an in vitro cellular model for oxidative stress, and cTBS treatment promoted the production of glutathione (GSH), the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) and the mRNA expression of GSH synthesis-related genes to enhance antioxidant capacity in hippocampal tissues of SD mice. An Nrf2 inhibitor ML385 or a GSH synthesis inhibitor BSO reversed the alleviating effects of cTBS treatment on oxidative stress-associated damage of hippocampal tissues and cognitive impairment in SD model mice. Altogether, our study demonstrated that cTBS mitigates oxidative stress-associated inflammation and autophagy through activating the Nrf2-mediated GSH synthesis pathway, improving cognitive impairment in SD mice.

GDF11 mediates H2S to prevent chronic stress-induced cognitive impairment by reducing hippocampal NLRP3/caspase-1-dependent pyroptosis

BACKGROUND

We previously revealed that hydrogen sulfide (H2S) attenuates chronic stress-induced cognitive impairment, but the underlying mechanism needs to be further clarified. Growth differentiation factor 11 (GDF11) plays an important regulatory role in cognitive function and that hippocampal NLRP3/caspase-1-mediated pyroptosis contributes to the pathogenesis of cognitive impairment. Hence, this research aimed to explore whether promoting GDF11 levels and suppressing hippocampal NLRP3/caspase-1-mediated pyroptosis mediate H2S to alleviate chronic stress-induced cognitive impairment.

METHODS

Sprague-Dawley rats were subjected to unpredictable chronic mild stress lasting four weeks to establish an animal model of chronic stress-induced cognitive impairment. Behavioral performance was assessed by the Y-maze test and the novel object recognition test. The expression levels of proteins were analyzed by Western blot analysis. The levels of IL-1β and IL-18 in the hippocampus were measured by ELISA.

RESULTS

NaHS upregulated the expression of GDF11 in the hippocampus of chronic unpredictable mild stress (CUMS)-exposed rats. Silencing GDF11 blocked NaHS-improved cognitive impairment in CUMS-exposed rats, according to the Y-maze test and the novel object recognition test. Furthermore, NaHS mitigated NLRP3/caspase-1-mediated pyroptosis in the hippocampus of CUMS-exposed rats and this effect was reversed by silencing GDF11. Moreover, overexpression of GDF11 alleviated CUMS-induced cognitive impairment and NLRP3/caspase-1-mediated hippocampal pyroptosis.

CONCLUSIONS

GDF11 mediates H2S to attenuate chronic stress-induced cognitive impairment via inhibiting hippocampal NLRP3/caspase-1-mediated pyroptosis.

Protective Effects of NaHS/miR-133a-3p on Lipopolysaccharide-Induced Cardiomyocytes Injury

Objective

The aim of this study was to investigate the effects of sodium hydrosulfide (NaHS) on Lipopolysaccharide (LPS)-induced cardiomyocyte injury in H9c2 cells.

Methods

H9c2 cardiomyocytes cultivated with medium containing 10 μg/mL LPS were used to recapitulate the phenotypes of those in sepsis. Two sequential experiments were performed. The first contained a control group, a LPS group, and a LPS + NaHS group, with the aim to assure the protective effects of NaHS on LPS-treated cardiomyocytes. The second experiment added a fourth group, the LPS + NaHS + miR-133a-3p inhibition group, with the aim to preliminarily explore whether miR-133-3p exerts a protective function downstream of NaHS. The adenosine triphosphate (ATP) kit was used to detect ATP content; real-time quantitative polynucleotide chain reaction (qPCR) was used to measure the levels of mammalian targets of rapamycin (mTOR), AMP-dependent protein kinase (AMPK), and miR-133a-3p, and Western blot (WB) was used to detect protein levels of mTOR, AMPK, myosin-like Bcl2 interacting protein (Beclin-1), microtubule-associated protein 1 light chain 3 (LC3I/II), and P62 (sequestosome-1, sqstm-1/P62).

Results

Compared with the control group, the expressions of miR-133a-3p (P < 0.001), P62 (P < 0.001), and the content of ATP (P < 0.001) decreased, while the expressions of Beclin-1 (P = 0.023) and LC3I/II (P = 0.048) increased in the LPS group. Compared with the LPS group, the expressions of miR-133a-3p (P < 0.001), P62 (P < 0.001), and the content of ATP (P < 0.001) in the NaHS + LPS group increased, while the expressions of Beclin-1 (P = 0.023) and LC3I/II (P = 0.022) decreased. Compared with the NaHS + LPS group, the expression levels of miR-133a-3p (P < 0.001), P62 (P = 0.001), and the content of ATP (P < 0.001) in the LPS + NaHS + miR-133a-3p inhibition group were downregulated, and the expression levels of Beclin-1 (P = 0.012) and LC3I/II (P = 0.010) were upregulated. The difference was statistically significant. There was no significant difference in the expression of AMPK and mTOR between groups.

Conclusion

Our research demonstrated that NaHS relieved LPS-induced myocardial injury in H9c2 by promoting the expression of miR-133a-3p, inhibiting autophagy in cardiomyocytes, and restoring cellular ATP levels.

Lifestyle effects on aging and CVD: A spotlight on the nutrient-sensing network

Aging is widespread worldwide and a significant risk factor for cardiovascular disease (CVD). Mechanisms underlying aging have attracted considerable attention in recent years. Remarkably, aging and CVD overlap in numerous ways, with deregulated nutrient sensing as a common mechanism and lifestyle as a communal modifier. Interestingly, lifestyle triggers or suppresses multiple nutrient-related signaling pathways. In this review, we first present the composition of the nutrient-sensing network (NSN) and its metabolic impact on aging and CVD. Secondly, we review how risk factors closely associated with CVD, including adverse life states such as sedentary behavior, sleep disorders, high-fat diet, and psychosocial stress, contribute to aging and CVD, with a focus on the bridging role of the NSN. Finally, we focus on the positive effects of beneficial dietary interventions, specifically dietary restriction and the Mediterranean diet, on the regulation of nutrient metabolism and the delayed effects of aging and CVD that depend on the balance of the NSN. In summary, we expound on the interaction between lifestyle, NSN, aging, and CVD.

Acetyl-11-keto-beta boswellic acid(AKBA) modulates CSTC-pathway by activating SIRT-1/Nrf2-HO-1 signalling in experimental rat model of obsessive-compulsive disorder: Evidenced by CSF, blood plasma and histopathological alterations

Obsessive-Compulsive disorder (OCD) is a long-term and persistent mental illness characterised by obsessive thoughts and compulsive behaviours. Numerous factors can contribute to the development or progression of OCD. These factors may result from the dysregulation of multiple intrinsic cellular pathways, including SIRT-1, Nrf2, and HO-1. Inhibitors of selective serotonin reuptake (SSRIs) are effective first-line treatments for OCD. In our ongoing research, we have investigated the role of SIRT-1, Nrf2, and HO-1, as well as the neuroprotective potential of Acetyl-11-keto-beta boswellic acid (AKBA) against behavioural and neurochemical changes in rodents treated with 8-OH-DPAT. In addition, the effects of AKBA were compared to those of fluvoxamine (FLX), a standard OCD medication. Injections of 8-OH-DPAT into the intra-dorso raphe nuclei (IDRN) of rats for seven days induced repetitive and compulsive behaviour accompanied by elevated oxidative stress, inflammatory processes, apoptosis, and neurotransmitter imbalances in CSF, blood plasma, and brain samples. Chronic administration of AKBA at 50 mg/kg and 100 mg/kg p.o. restored histopathological alterations in the cortico-striatal-thalamo-cortical (CSTC) pathway, including the cerebral cortex, striatum, and hippocampal regions. Our investigation revealed that when AKBA and fluvoxamine were administered together, the alterations were restored to a greater degree than when administered separately. These findings demonstrate that the neuroprotective effect of AKBA can serve as an effective basis for developing a novel OCD treatment.

YT521-B homology domain containing 1 ameliorates mitochondrial damage and ferroptosis in sleep deprivation by activating the sirtuin 1/nuclear factor erythroid-derived 2-like 2/heme oxygenase 1 pathway

In sleep deprivation (SD) models, ferroptosis is increased. SIRT1 alleviates cognitive impairment in SD, and SIRT1/NRF2/HO1 pathway depresses ferroptosis in different diseases. Moreover, YTHDC1 can regulate SIRT1 mRNA stability. Therefore, our study explored effects of the YTHDC1/SIRT1/NRF2/HO1 axis on neuronal damage and ferroptosis in SD. The SD mouse model was established through a modified multi-platform water environment method and a cell model of ferroptosis was constructed with Erastin, followed by gain- and loss-of-function assays. In mice, the cognitive impairment and CLOCK and BMAL1 levels in hippocampal tissues were assessed. In cells, viability was measured. In mice and cells, mitochondrial ultrastructure, the content of reactive oxygen species (ROS), malondialdehyde (MDA), glutathione (GSH), and iron, and the expression of GPX4 and ACSL4 were detected. The potential relationships among YTHDC1, SIRT1, and NRF2 were analyzed. SD mice had downregulated YTHDC1, SIRT1, NRF2, and HO1 protein expression in hippocampal tissues and increased ferroptosis. Mechanically, SIRT1 activated the NRF2/HO1 pathway through deacetylation, and YTHDC1 increased SIRT1 mRNA stability. YTHDC1 overexpression diminished mitochondrial damage, the content of ROS, iron, and MDA, and the expression of ACSL4 while enhancing GSH contents and GPX4 expression in hippocampal tissues of SD mice and Erastin-induced HT22 cells. Additionally, YTHDC1 overexpression elevated viability in Erastin-induced HT22 cells. SIRT1 or NRF2 overexpression ameliorated Erastin-induced mitochondrial damage and ferroptosis in HT22 cells. Silencing SIRT1 abolished the impact of YTHDC1 overexpression on SD mice and Erastin-induced HT22 cells. Collectively, YTHDC1 ameliorates mitochondrial damage and ferroptosis after SD by activating the SIRT1/NRF2/HO1 pathway.

Brassica rapa L. (Tibetan turnip) prevents sleep-deprivation induced cognitive deficits via the inhibition of neuroinflammation and mitochondrial depolarization

Brassica rapa L., an edible, feeding and medicinal plant cultivated on the Tibetan plateau with altitudes above 3800 m, has several pharmacological effects. However, its therapeutic effects against memory impairment and central fatigue have yet to be conclusively established. In this study, the Y-maze and Morris water maze tasks revealed that Brassica rapa L. aqueous extract (BE) significantly ameliorated cognitive deficits of sleep deprivation (SD)-treated mice. Moreover, BE treatment partially alleviated SD-induced reductions in the levels of peripheral energy metabolism, and significantly decreased inflammatory factor levels in serum and hippocampus. In addition, BE treatment significantly relieved central fatigue and stabilized the excitability as well as activities of neurons by regulating the levels of hypothalamus tryptophan metabolites and striatum neurotransmitters. The neuroprotective effects of BE were also confirmed using glutamate-treated HT22 cells, whereby BE pretreatment significantly attenuated intracellular ROS production and mitochondrial depolarization via adenosine 5'-monophosphate activated protein kinase/peroxisome proliferators-activated receptors (AMPK/PPAR-γ) signaling pathways. Thus, BE might probably prevent SD-induced learning and memory deficits by inhibiting neuroinflammation and restoring mitochondrial energy metabolism in the hippocampus. These findings imply that BE is a potential complementary therapy for those suffering from deficient sleep or neurometabolic disorders, although this needs verification by prospective clinical studies.

The Role of Hydrogen Sulfide Targeting Autophagy in the Pathological Processes of the Nervous System

Autophagy is an important cellular process, involving the transportation of cytoplasmic contents in the double membrane vesicles to lysosomes for degradation. Autophagy disorder contributes to many diseases, such as immune dysfunction, cancers and nervous system diseases. Hydrogen sulfide (H₂S) is a volatile and toxic gas with a rotten egg odor. For a long time, it was considered as an environmental pollution gas. In recent years, H₂S is regarded as the third most important gas signal molecule after NO and CO. H₂S has a variety of biological functions and can play an important role in a variety of physiological and pathological processes. Increasingly more evidences show that H₂S can regulate autophagy to play a protective role in the nervous system, but the mechanism is not fully understood. In this review, we summarize the recent literatures on the role of H₂S in the pathological process of the nervous system by regulating autophagy, and analyze the mechanism in detail, hoping to provide the reference for future related research.

Sirtuins and cognition: implications for learning and memory in neurological disorders

Sirtuins are an evolutionarily conserved family of regulatory proteins that function in an NAD+ -dependent manner. The mammalian family of sirtuins is composed of seven histone deacetylase and ADP-ribosyltransferase proteins (SIRT1-SIRT7) that are found throughout the different cellular compartments of the cell. Sirtuins in the brain have received considerable attention in cognition due to their role in a plethora of metabolic and age-related diseases and their ability to induce neuroprotection. More recently, sirtuins have been shown to play a role in normal physiological cognitive function, and aberrant sirtuin function is seen in pathological cellular states. Sirtuins are believed to play a role in cognition through enhancing synaptic plasticity, influencing epigenetic regulation, and playing key roles in molecular pathways involved with oxidative stress affecting mitochondrial function. This review aims to discuss recent advances in the understanding of the role of mammalian sirtuins in cognitive function and the therapeutic potential of targeting sirtuins to ameliorate cognitive deficits in neurological disorders.

Genes Responsible for H2S Production and Metabolism Are Involved in Learning and Memory in Drosophila melanogaster

The gasotransmitter hydrogen sulfide (H₂S) produced by the transsulfuration pathway (TSP) is an important biological mediator, involved in many physiological and pathological processes in multiple higher organisms, including humans. Cystathionine-β-synthase (CBS) and cystathionine-γ-lyase (CSE) enzymes play a central role in H₂S production and metabolism. Here, we investigated the role of H₂S in learning and memory processes by exploring several Drosophila melanogaster strains with single and double deletions of CBS and CSE developed by the CRISPR/Cas9 technique. We monitored the learning and memory parameters of these strains using the mating rejection courtship paradigm and demonstrated that the deletion of the CBS gene, which is expressed predominantly in the central nervous system, and double deletions completely block short- and long-term memory formation in fruit flies. On the other hand, the flies with CSE deletion preserve short- and long-term memory but fail to exhibit long-term memory retention. Transcriptome profiling of the heads of the males from the strains with deletions in Gene Ontology terms revealed a strong down-regulation of many genes involved in learning and memory, reproductive behavior, cognition, and the oxidation–reduction process in all strains with CBS deletion, indicating an important role of the hydrogen sulfide production in these vital processes.

Protective Effects of Novel Substituted Triazinoindole Inhibitors of Aldose Reductase and Epalrestat in Neuron-like PC12 Cells and BV2 Rodent Microglial Cells Exposed to Toxic Models of Oxidative Stress: Comparison with the Pyridoindole Antioxidant Stobadine

Aldose reductase (AR) catalyzes the conversion of glucose to sorbitol in a NADPH-dependent reaction, thereby increasing the production of reactive oxygen species (ROS). Since AR activation is linked to redox dysregulation and cell damage in neurodegenerative diseases, AR inhibitors (ARIs) constitute promising therapeutic tools for the treatment of these disorders. Among these compounds, the novel substituted triazinoindole derivatives cemtirestat (CMTI) and COTI, as well as the clinically employed epalrestat (EPA) and the pyridoindole-antioxidant stobadine (STB), were tested in both PC12 cells and BV2 microglia exposed to four different neurotoxic models. These include (1) oxidative stress with hydrogen peroxide (H₂O₂), (2) mitochondrial complex IV inhibition with NaN₃, (3) endoplasmic reticulum-stress and lipotoxicity induced by palmitic acid/bovine serum albumin (PAM/BSA), and (4) advanced carbonyl compound lipotoxicity by 4-hydroxynonenal (4-HNE). All toxic compounds decreased cell viability and increased ROS formation in both PC12 and BV2 cells in a concentration-dependent manner (1-1000 μM; NaN₃ < H₂O₂≈PAM/BSA < 4-HNE). In PC12 cells, EPA increased cell viability in all toxic models only at 1 μM, whereas CMTI restored baseline viability in all toxic models. COTI afforded protection against lipotoxicity, while STB only prevented H₂O₂-induced toxicity. Except for the 4-HNE model, EPA prevented ROS generation in all other toxic models, whereas CMTI, COTI, and STB prevented ROS production in all toxic models. In BV2 cells, EPA and CMTI restored baseline cell viability in all toxic models tested, while COTI and STB did not prevent the loss of viability in the NaN₃ model. All ARIs and STB efficiently prevented ROS formation in all toxic models in a concentration-independent manner. The differential protective effects evoked by the novel ARIs and STB on the toxic models tested herein provide novel and relevant comparative evidence for the design of specific therapeutic strategies against neurodegenerative events associated with neurological disorders.