A narrative review of methane in treating neurological diseases.

Methane has shown protective effects on a variety of diseases. Among these, neurological diseases have attracted much attention. However, there are many different indicators and application methods of methane in the treatment of neurological diseases. In this review, we summarize the indicators related to the protective effects of methane and evaluate the preparation and administration of methane. Thus, we hope to offer available indicators and effective ways to produce and administer methane in future research.

Effects of hyperbaric oxygen on Notch signaling pathway after severe carbon monoxide poisoning in mice.

Demyelination of the cerebral white matter is the most common pathological change after carbon monoxide (CO) poisoning. Notch signaling, the mechanism underlying the differentiation of astrocytes and oligodendrocytes, is critical to remyelination of the white matter after brain lesion. The purpose of this work was to determine the effects of hyperbaric oxygen (HBO) on Notch signaling pathway after CO poisoning for the explanation of the protective effects of HBO on CO-poisoning-related cerebral white matter demyelination. The male C57 BL/6 mice with severe CO poisoning were treated by HBO. And HBO therapy shortened the escape latency and improved the body mass after CO poisoning. HBO therapy also significantly suppressed protein and mRNA levels of Notch1 and Hes5 after CO poisoning. Our findings suggested that HBO could suppress the activation of Notch signaling pathway after CO poisoning, which is the mechanism underlying the neuroprotection of HBO on demyelination after severe CO poisoning.

Hydrogen exerts neuroprotective effects by inhibiting oxidative stress in experimental diabetic peripheral neuropathy rats.

Diabetic peripheral neuropathy (DPN) is a complex disorder caused by long-standing diabetes. Oxidative stress was considered the critical creed in this DPN pathophysiology. Hydrogen has antioxidative effects on diabetes mellitus and related complications. However, there is still no concern on the beneficial effects of hydrogen in DPN. This paper aimed to evaluate the effects of exogenous hydrogen to reduce the severity of DPN in streptozotocin-induced diabetic rats. Compared with hydrogen-rich saline treatment, hydrogen inhalation significantly reduced blood glucose levels in diabetic rats in the 4th and 8th weeks. With regard to nerve function, hydrogen administration significantly attenuated the decrease in the velocity of motor nerve conduction in diabetic animals. In addition, hydrogen significantly attenuated oxidative stress by reducing the level of malondialdehyde, reactive oxygen species, and 8-hydroxy-2-deoxyguanosine and meaningfully enhanced the antioxidant capability by partially restoring the activities of superoxide dismutase. Further studies showed that hydrogen significantly upregulated the expression of nuclear factor erythroid-2-related factor 2 and downstream proteins such as catalase and hemeoxygenase-1 in the nerves of diabetic animals. Our paper showed that hydrogen exerts significant protective effects in DPN by downregulating oxidative stress via the pathway of nuclear factor erythroid-2-related factor 2, which suggests its potential value in clinical applications.

Combined Inhibition of Fyn and c-Src Protects Hippocampal Neurons and Improves Spatial Memory via ROCK after Traumatic Brain Injury.

Our previous studies demonstrated that traumatic brain injury (TBI) and ventricular administration of thrombin caused hippocampal neuron loss and cognitive dysfunction via activation of Src family kinases (SFKs). Based on SFK localization in brain, we hypothesized SFK subtypes Fyn and c-Src, as well as SFK downstream molecule Rho-associated protein kinase (ROCK), contribute to cell death and cognitive dysfunction after TBI. We administered nanoparticle wrapped small interfering RNA (siRNA)-Fyn and siRNA-c-Src, or ROCK inhibitor Y-27632 to adult rats subjected to moderate lateral fluid percussion (LFP)-induced TBI. Spatial memory function was assessed from 12 to 16 days, and NeuN stained hippocampal neurons were assessed 16 days after TBI. The combination of siRNA-Fyn and siRNA-c-Src, but neither alone, prevented hippocampal neuron loss and spatial memory deficits after TBI. The ROCK inhibitor Y-27632 also prevented hippocampal neuronal loss and spatial memory deficits after TBI. The data suggest that the combined actions of three kinases (Fyn, c-Src, ROCK) mediate hippocampal neuronal cell death and spatial memory deficits produced by LFP-TBI, and that inhibiting this pathway prevents the TBI-induced cell death and memory deficits.

Therapeutic effect of methane and its mechanism in disease treatment.

Methane is the simplest hydrocarbon, consisting of one carbon atom and four hydrogen atoms. It is abundant in marsh gas, livestock rumination, and combustible ice. Little is known about the use of methane in human disease treatment. Current research indicates that methane is useful for treating several diseases including ischemia and reperfusion injury, and inflammatory diseases. The mechanisms underlying the protective effects of methane appear primarily to involve anti-oxidation, anti-inflammation, and anti-apoptosis. In this review, we describe the beneficial effects of methane on different diseases, summarize possible mechanisms by which methane may act in these conditions, and discuss the purpose of methane production in hypoxic conditions. Then we propose several promising directions for the future research.

Effect of helium preconditioning on neurological decompression sickness in rats.

Decompression sickness (DCS) occurs because of an excessively rapid and extensive reduction of the ambient pressure. Bubble-induced spinal cord ischemia is generally considered as a part of neurological DCS pathogenesis. Because helium preconditioning (HPC) recently demonstrated beneficial properties against ischemic damage, we hypothesized that HPC may decrease the neurological deficits of DCS in rats. Seventy-five male Sprague-Dawley rats were divided into a non-HPC group ( n = 25) and a HPC group ( n = 25) and 25 naive animals that were euthanized for histological examination ( n = 5) or anesthetized for baseline somatosensory evoked potential (SSEP) recordings ( n = 20). To induce DCS, rats were compressed with air to a pressure of 709 kPa for 60 min and decompressed at a rate of 203 kPa/min. HPC was administered as three episodes of 79% helium-21% oxygen mixture inhalation for 5 min interspersed with 5 min of air breathing. We found that HPC resulted in significantly decreased DCS incidence and delay of DCS onset. HPC also improved animal performance on the grip test after decompression and significantly ameliorated decompression-induced decrease of platelet number. Furthermore, the incidence of abnormal SSEP waves and histological spinal lesions was significantly reduced by HPC. We conclude that HPC can decrease the occurrence of DCS and ameliorate decompression-induced neurological deficits. NEW & NOTEWORTHY Helium preconditioning ameliorates decompression-induced neurological deficits in rats. Helium breathing before air dives may prevent neurological deficit and attenuate symptoms after decompression.

Cleaved ß-Actin May Contribute to DNA Fragmentation Following Very Brief Focal Cerebral Ischemia.

Our previous study demonstrated caspase independent DNA fragmentation after very brief cerebral ischemia, the mechanism of which was unclear. In this study, we explore whether actin is cleaved following focal cerebral ischemia, and whether these structural changes of actin might modulate DNA fragmentation observed following focal ischemia. Results showed that a cleaved ß-actin fragment was identified in brains of rats 24 hours following 10-minute and 2-hour focal ischemia. Though granzyme B and caspase-3 cleaved ß-actin in vitro, the fragment size of ß-actin cleaved by granzyme B was the same as those found after 10-minute and 2-hour focal ischemia. This was consistent with increases of granzyme B activity after 10-minute and 2-hour ischemia compared with controls. Cerebral extracts from 10-minute and 2-hour ischemic brains degraded DNA in vitro. Adding intact ß-actin to these samples completely abolished DNA degradation from the 10-minute ischemia group but not from the 2-hour ischemia group. We concluded that ß-actin is likely cleaved by granzyme B by 24 hours following 10-minute and 2-hour focal cerebral ischemia. Intact ß-actin inhibits DNase, and cleavage of ß-actin activates DNase, which leads to DNA fragmentation observed in the brain following very brief focal ischemia.

High-concentration hydrogen protects mouse heart against ischemia/reperfusion injury through activation of thePI3K/Akt1 pathway.

The study investigated the role of Akt1 through the cardioprotection of high-concentration hydrogen (HCH). C57BL/6 mice were randomly divided into the following groups: sham, I/R, I/R + HCH, I/R + HCH + LY294002 (PI3K inhibitor), I/R + HCH + wortmannin (PI3K inhibitor), I/R + LY294002, and I/R + wortmannin. After 45 min of ischemia, HCH (67% H2 and 33% O2) was administered to mice during a 90-min reperfusion. To investigate the role of Akt1 in the protective effects of HCH, mice were divided into the following groups: I/R + A-674563 (Akt1 selective inhibitor), I/R + HCH + A-674563, I/R + CCT128930 (Akt2 selective inhibitor), and I/R + HCH + CCT128930. After a 4-h reperfusion, serum biochemistry, histological, western blotting, and immunohistochemical analyses were performed to evaluate the role of the PI3K-Akt1 pathway in the protection of HCH. In vitro, 75% hydrogen was administered to cardiomyocytes during 4 h of reoxygenation after 3-h hypoxia. Several analyses were performed to evaluate the role of the Akt1 in the protective effects of hydrogen. HCH resulted in the phosphorylation of Akt1 but not Akt2, and Akt1 inhibition markedly abolished HCH-induced cardioprotection. Our findings reveal that HCH may exert cardioprotective effects through a PI3K-Akt1-dependent mechanism.

Protective Effects of Methane-Rich Saline on Rats with Lipopolysaccharide-Induced Acute Lung Injury.

Objective. The aim of this research is to evaluate the protective effects of methane-rich saline (MS) on lipopolysaccharide- (LPS-) induced acute lung injury (ALI) and investigate its potential antioxidative, anti-inflammatory, and antiapoptotic activities. Methods. LPS-induced (20 mg/kg) ALI rats were injected with MS (2 ml/kg and 20 ml/kg) before the initiation of LPS induction. Survival rate was determined until 96 h after LPS was induced. Lung injury was assayed by oxygenation index, lung permeability index (LPI), wet-to-dry weight (W/D), and histology. The cells in the bronchoalveolar lavage fluid (BALF) were counted. Oxidative stress was examined by the level of malondialdehyde (MDA) and superoxide dismutase (SOD). Inflammatory factors including tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), and interleukin-6 (IL-6) in BALF were determined by ELISA. Lung tissue apoptosis was detected by TUNEL staining and western blotting of caspase-3. Results. It was found that methane significantly prolonged the rat survival, decreased the lung W/D ratio and the content of the inflammatory factors, and reduced the amount of caspase-3 and apoptotic index. In addition, MS increased the level of SOD and decreased the level of MDA significantly. Conclusions. MS protects the LPS-challenged ALI via antioxidative, anti-inflammatory, and antiapoptotic effect, which may prove to be a novel therapy for the clinical management of ALI.

Inhalation of high concentrations of hydrogen ameliorates liver ischemia/reperfusion injury through A2A receptor mediated PI3K-Akt pathway.

BACKGROUND AND AIMS: This study explored the hepatoprotection of high concentrations of hydrogen (HCH) inhalation in a mouse hepatic ischemia/reperfusion (I/R) injury model and the potential mechanism. METHODS: To explore the role of the PI3K-Akt pathway in the hepatoprotection of HCH, C57BL/6 mice were randomly divided into five groups: Sham, I/R, I/R+HCH, LY294002 (PI3K inhibitor)+I/R+HCH, and LY+I/R groups. Mice received inhalation of 66.7% hydrogen and 33.3% oxygen for 1h immediately after surgery. LY294002 was intravenously injected at 10mol/kg. To explore whether PI3K-Akt pathway activation was mediated by the A2A receptor, additional four groups were included: ZM241385 (A2A receptor antagonist)+I/R+HCH, ZM241385+I/R, bpv(HOpic) (PTEN inhibitor)+I/R, and ZM241385+bpv+I/R+HCH. Six hours after I/R, serum biochemistry, histological examination, Western blotting, and immunohistochemistry were performed to evaluate the hepatoprotection of HCH and the role of the PI3K-Akt pathway and A2A receptor in this protection. RESULTS: Liver dysfunction, hepatic pathological injury, infiltration of inflammatory cytokines, and hepatocyte apoptosis were observed after hepatic I/R, accompanied by inhibition of the PI3K-Akt pathway. HCH significantly improved liver function, reduced serum inflammatory cytokines, and inhibited hepatocyte apoptosis, and also induced the PI3K-Akt pathway activation. In the presence of LY294002 or ZM241385, the protective effects of HCH were markedly attenuated, but the effects of ZM241385 were reversed by bpv(HOpic). CONCLUSION: Our findings indicate that HCH may protect the liver against I/R injury through the A2A dependent PI3K-Akt pathway.

Characteristics of exogenous carbon monoxide deliveries.

Carbon monoxide (CO) has long been considered an environmental pollutant and a poison. Exogenous exposure to amounts of CO beyond the physiologic level of the body can result in a protective or adaptive response. However, as a gasotransmitter, endogenous CO is important for multiple physiologic functions. To date, at least seven distinct methods of delivering CO have been utilized in animal and clinical studies. In this mini-review, we summarize the exogenous CO delivery methods and compare their advantages and disadvantages.

Hypoxia therapy--a new hope for the treatment of mitochondrial dysfunctions.

Mitochondrial dysfunctions are characteristic features of numerous diseases and play a critical role in disease pathogenesis. Despite intensive research in this area, there are no approved therapies that directly target mitochondria. Recently a study by Jain et al. from Massachusetts General Hospital, USA reported the effectiveness of hypoxia for treatment of mitochondrial disease in mice. In this commentary, we summarized the potential mechanisms underlying the therapeutic effects of hypoxia on mitochondrial dysfunction, and clinical limitations of hypoxia as a therapy for human patients. We hope that our concerns will be helpful for further clinical studies addressing moderate hypoxia in mitochondrial dysfunction.

Methane attenuates myocardial ischemia injury in rats through anti-oxidative, anti-apoptotic and anti-inflammatory actions.

Myocardial infarction (MI) remains the most frequent cardiovascular disease with high mortality. Recently, methane has been shown protective effects on small intestinal ischemia-reperfusion injury. We hypothesized that methane-rich saline (MS) could protect the myocardium again MI via its anti-oxidative, anti-apoptotic and anti-inflammatory effects. In experiment 1, tetrazolium chloride staining and detection of myocardial enzymes and oxidative and inflammatory parameters were performed at 12h after MI to determine the optimal dose at which intraperitoneal MS exerted the best protective effects on MI. In experiment 2, rats were treated with 10 ml/kg MS. Myocyte apoptosis was detected 72 h after MI, and cardiac function and myocardial remodeling were evaluated 4 weeks after MI. Results showed different dose of MS reduced infarct area, decreased myocardial enzymes, inhibited inflammation and oxidative stress following MI. The optimal dose of MS was 10 mg/kg. Moreover, treatment with 10mg/kg MS for 3 days significantly reduced myocyte apoptosis, improved cardiac function and inhibited myocardial remodeling (reduced anterior wall thickness, attenuated myocyte hypertrophy, and decreased myocardial collagen). MS protects the myocardium of MI rats via its anti-oxidative, anti-inflammatory, anti-apoptotic and anti-remodeling activities. Thus, MS provides a novel and promising strategy for the treatment of ischemic heart diseases.

Neuroprotective effects of exogenous methane in a rat model of acute carbon monoxide poisoning.

OBJECTIVE: Delayed neuropsychological sequelae (DNS) are the most common and serious effects of severe carbon monoxide (CO) poisoning, occurring in approximately half of all CO poisoning cases. Growing evidence suggests that oxidative stress and secondary reactions in delayed brain injury are crucial to CO toxicity, similar to ischaemia-reperfusion injury. Exogenous methane plays a protective role in ischaemia-reperfusion injury by affecting key events through anti-oxidant, anti-inflammatory, and anti-apoptosis actions. Our study aimed to explore the potential of exogenous methane to relieve the severity of DNS. METHODS: Thirty-six male Sprague-Dawley (SD) rats were divided into three groups of normal-, CO- and CO plus methane-treated rats. The rats in the latter two groups were exposed to 1000 ppm CO for 40 min and then to 3000 ppm CO for another 20 min. Following CO exposure, saline or methane saline (10 ml/kg) was intraperitoneally administered to rats in the CO group or the CO plus methane group, respectively. On the ninth day after CO exposure, Morris water maze testing, histological analysis, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL) and immunohistochemical labelling were performed on 6 rats in each group. The remaining 6 rats in each group were used to detect oxidative damage markers, inflammatory cytokines and apoptosis proteins. RESULTS: Methane significantly improved CO-impaired pathological characteristics as well as learning and memory performance. In addition, methane significantly increased the superoxide dismutase (SOD) activity, lowered the CO-increased level of malondialdehyde (MDA) 3-nitrotyrosine (3-NT) and 8-hydroxy-2-deoxyguanosine (8-OHdG), inhibited levels of tumour necrosis factor-α (TNF-α), interleukin 1-ß (IL1-ß) and caspase-3 in the rat cerebral cortex and hippocampus but had no effect on IL-6 levels. CONCLUSION: The hippocampus was the main target of CO-induced alterations in the rat brain compared to the cerebral cortex. Methane treatment protected the rat brain from the harmful effects induced by CO exposure and improved the outcome of DNS through anti-oxidant, anti-inflammatory and anti-apoptosis activities.

Protective effects of methane-rich saline on diabetic retinopathy via anti-inflammation in a streptozotocin-induced diabetic rat model.

As the commonest complication of diabetes mellitus (DM), diabetic retinopathy (DR) is a neuro-vascular disease with chronic inflammatory. Methane could exert potential therapeutic interest in inflammatory pathologies in previous studies. Our study aims to evaluate the protective effects of methane-rich saline on DR and investigate the potential role of related MicroRNA (miRNA) in diabetic rats. Streptozotocin-induced diabetic Sprague-Dawley rats were injected intraperitoneally with methane-rich or normal saline (5 ml/kg) daily for eight weeks. Morphology changes and blood-retinal barrier (BRB) permeability were assessed by hematoxylin eosin staining and Evans blue leakage. Retinal inflammatory cytokines levels of tumor necrosis factor-α (TNF-α) and interleukin-1ß (IL1-ß) were evaluated by immunohistochemistry. Retinal protein expressions of glial fibrillary acidic protein (GFAP) and vascular endothelial growth factor (VEGF) were determined by western blotting. Retinal miRNA expressions were examined by miRNA-specific microarray, verified by quantitative RT-PCR and predicted by GO enrichment and KEGG pathway analysis. There was no significant changes in blood glucose level and body weight of diabetic rats with methane-rich or normal saline treatment, but the decreased retinal thickness, retinal ganglial cell loss and BRB breakdown were all significantly suppressed by methane treatment. DM-induced retinal overexpressions of TNF-α, IL-1ß, GFAP and VEGF were also significantly ameliorated. Moreover, the methane treatment significantly up-regulated retinal levels of miR-192-5p (related to apoptosis and tyrosine kinase signaling pathway) and miR-335 (related to proliferation, oxidative stress and leukocyte). Methane exerts protective effect on DR via anti-inflammation, which may be related to the regulatory mechanism of miRNAs.

Inhalation of hydrogen gas ameliorates glyoxylate-induced calcium oxalate deposition and renal oxidative stress in mice.

The aim of this study is to evaluate the protective effect and underlying mechanism of hydrogen gas (H2) to glyoxylate induced renal calcium oxalate (CaOx) crystal deposition in mice. In present work, rodent renal CaOx crystal deposition model was introduced by intra-abdominal injection of glyoxylate (100 mg/kg/d) for 5 days. Two days before administration of glyoxylate, inhalation of H2 for 30 min per day was initiated and continued for 7 days. By the end of the study, the samples of 24 hours urine, serum and renal tissue were collected for biochemical and pathological assay. According to levels of urine calcium excretion, renal calcium deposition, a serum excretion of kidney injury molecule-1 (KIM-1) assay and a TUNEL assay, inhalation of H2 could successfully decrease the CaOx crystallizations and protect against renal injury. Crystal deposition in the kidneys is associated with oxidative stress, which was indicated by increased levels of renal malondialdehyde (MDA) and 8-hydroxydeoxyguanosine (8-OHdG) and decreased activities of superoxide dismutase (SOD), glutathione (GSH) and catalase (CAT). These effects were reversed by a high-dose H2 pretreatment. The renal expressions of osteopontin (OPN), CD44, monocyte chemoattractant protein-1 (MCP-1) and interleukin-10 (IL-10) were markedly increased in glyoxylate-treated mice, and H2 significantly attenuated the increase of OPN, CD44 and MCP-1 but upregulated the expression of IL-10. Our findings demonstrate that inhalation of H2 reduces renal crystallization, renal oxidative injury and inflammation and it may be a candidate agent with few adverse effects for prevention of nephrolithiasis.

Methane Attenuates Hepatic Ischemia/Reperfusion Injury in Rats Through Antiapoptotic, Anti-Inflammatory, and Antioxidative Actions.

Hepatic ischemia/reperfusion (I/R) injury, which occurs in various diseases, introduces severe tissue damage and liver dysfunction. However, no promising therapies for such a significant condition currently exist. Methane has been suggested to exert a protective effect against intestinal I/R injury. In this study, we introduced methane to treat hepatic I/R injury to show its promising protective effect. Also, intraperitoneal injection with methane-rich saline, which could have potential clinical applications, was applied as a new method. Partial liver warm ischemia was applied in Sprague-Dawley rats for 60 min followed by succedent reperfusion. In the test for effective dosage, methane-rich saline was administrated intraperitoneally to the rats at doses of 1, 5, 20, or 40 mL/kg at onset of reperfusion. In the test for protective effect, rats received methane-rich saline intraperitoneally at a dose of 10 mL/kg before the initiation of reperfusion. We found that methane-rich saline significantly decreased serum alanine aminotransferase, aspartate aminotransferase activity, and the occurrence of necrosis. Moreover, methane-rich saline reduced the amount of caspase-3 and the number of apoptotic cells. In addition, methane-rich saline increased the level of superoxide dismutase and decreased the level of malondialdehyde and 8-hydroxyguanosine. Furthermore, research indicated that methane-rich saline markedly decreased gene expression and content of tumor necrosis factor-α and interleukin-6. Also, reduced CD68-positive cells showed decreased inflammatory cells in the liver. Our results suggest that methane protects the liver against I/R injury through antiapoptotic, antioxidative, and anti-inflammatory actions.

Progress in the study of biological effects of hydrogen on higher plants and its promising application in agriculture.

While the medical effects of hydrogen have been broadly analyzed, research into the effects of hydrogen on higher plants has often been of lesser concern. Recent studies on the botanical effects of hydrogen have shown that it is involved in signal transduction pathways of plant hormones and can improve the resistance of plants to stressors, such as drought, salinity, cold and heavy metals. In addition, hydrogen could delay postharvest ripening and senescence of fruits. Observational evidence has also shown that hydrogen can regulate the flowering time of plants. These results indicate that hydrogen may have great potential applications within agricultural production, indicating that there may be a new 'hydrogen agricultural era' to come.