Analgesic Effect of Methane Rich Saline in a Rat Model of Chronic Inflammatory Pain

Methane-rich saline ameliorates depressive-like behaviors during chronic unpredictable mild stress (CUMS)

Depression, considered the most prevalent neuropsychiatric disorder, is multifactorial and complex. Oxidative stress and inflammation significantly contribute to its etiology. Conversely, methane, a novel therapeutic gas, has demonstrated efficacy in enhancing tissue resilience against ischemic injuries and inflammation. In this study, we investigated the effect of methane-rich saline (MRS) on depression using the chronic unpredictable mild stress (CUMS) model. Depressed rats received MRS treatment, and depression-like behaviors and cognitive function were assessed through sucrose preference, open field, forced swimming, and Morris water maze tests. Additionally, we measured serum corticosterone levels, antioxidant enzyme activity, hippocampal malondialdehyde (MDA), and TNFα levels, and investigated histological changes in the hippocampus. Our findings revealed that MRS significantly ameliorated Depressive-like behaviors and cognitive impairment. Furthermore, MRS administration regulated serum corticosterone levels and also MRS reduced hippocampal lipid peroxidation, TNFα, and hippocampus tissue damage. MRS likely exerts its effects by reducing oxidative stress and inflammatory factors and modulating the function of the hypothalamus-pituitary-adrenal (HPA) axis. These results demonstrate the protective effects of MRS on the hippocampus in CUMS animals.

Paclitaxel Regulates TRPA1 Function and Expression Through PKA and PKC

Paclitaxel (PTX) is a frequently used anticancer drug that causes peripheral neuropathy. Transient receptor potential ankyrin 1 (TRPA1), a plasma membrane calcium channel, has been associated with PTX toxicity and with other chemotherapy agents such as oxaliplatin and vincristine. However, the effect of PTX on the functional expression and calcium currents of TRPA1 has not been determined. The present study shows the effect of PTX on TRPA1 activity in a neuronal cell line (SH-SY5Y). The effect of PTX on the expression of TRPA1 was assessed through quantitative PCR and Western blot analyses to determine the relative mRNA and protein expression levels. To assess the effect on calcium flux and currents, cells were exposed to PTX; simultaneously, a specific agonist and antagonist of TRPA1 were added to evaluate the differential response in exposed versus control cells. To assess the effect of PKA, PKC and PI3K on PTX-induced TRPA1 increased activity, selective inhibitors were added to these previous experiments. PTX increased the mRNA and protein expression of TRPA1 as well as the TRPA1-mediated Ca2+ currents and intracellular Ca2+ concentrations. This effect was dependent on AITC (a selective specific agonist) and was abolished with HC-030031 (a selective specific antagonist). The inhibition of PKA and PKC reduced the effect of PTX on the functional expression of TRPA1, whereas the inhibition of PI3K had no effects. PTX-induced neuropathy involves TRPA1 activity through an increase in functional expression and is regulated by PKA and PKC signaling. These findings support the role of the TRPA1 channel in the mechanisms altered by PTX, which can be involved in the process that lead to chemotherapy-induced neuropathy.

Emodin alleviates arthritis pain through reducing spinal inflammation and oxidative stress

Chronic pain is the predominant problem for rheumatoid arthritis patients, and negatively affects quality of life. Arthritis pain management remains largely inadequate, and developing new treatment strategies are urgently needed. Spinal inflammation and oxidative stress contribute to arthritis pain and represent ideal targets for the treatment of arthritis pain. In the present study, collagen-induced arthritis (CIA) mouse model was established by intradermally injection of type II collagen (CII) in complete Freund's adjuvant (CFA) solution, and exhibited as paw and ankle swelling, pain hypersensitivity and motor disability. In spinal cord, CIA inducement triggered spinal inflammatory reaction presenting with inflammatory cells infiltration, increased Interleukin-1β (IL-1β) expression, and up-regulated NOD-like receptor thermal protein domain associated protein 3 (NLRP3) and cleaved caspase-1 levels, elevated spinal oxidative level presenting as decreased nuclear factor E2-related factor 2 (Nrf2) expression and Superoxide dismutase (SOD) activity. To explore potential therapeutic options for arthritis pain, emodin was intraperitoneally injected for 3 days on CIA mice. Emodin treatment statistically elevated mechanical pain sensitivity, suppressed spontaneous pain, recovered motor coordination, decreased spinal inflammation score and IL-1β expression, increased spinal Nrf2 expression and SOD activity. Further, AutoDock data showed that emodin bind to Adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) through two electrovalent bonds. And emodin treatment increased the phosphorylated AMPK at threonine 172. In summary, emodin treatment activates AMPK, suppresses NLRP3 inflammasome response, elevates antioxidant response, inhibits spinal inflammatory reaction and alleviates arthritis pain.

Recent Advances in the Role of Nuclear Factor Erythroid-2-Related Factor 2 in Spinal Cord Injury: Regulatory Mechanisms and Therapeutic Options

Nuclear factor erythroid-2-related factor 2 (Nrf2) is a pleiotropic transcription factor, and it has been documented that it can induce defense mechanisms both oxidative stress and inflammatory injury. At present, more and more evidences show that the Nrf2 signaling pathway is a key pharmacological target for the treatment of spinal cord injury (SCI), and activating the Nrf2 signaling pathway can effectively treat the inflammatory injury and oxidative stress after SCI. This article firstly introduces the biological studies of the Nrf2 pathway. Meanwhile, it is more powerful to explain that activating the Nrf2 signaling pathway can effectively treat SCI by deeply exploring the relationship between Nrf2 and oxidative stress, inflammatory injury, and SCI. In addition, several potential drugs for the treatment of SCI by promoting Nrf2 activation and Nrf2-dependent gene expression are reviewed. And some other treatment strategies of SCI by modulating the Nrf2 pathway are also summarized. It will provide new ideas and directions for the treatment of SCI.

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.

Methane alleviates sepsis-induced injury by inhibiting pyroptosis and apoptosis: in vivo and in vitro experiments

Sepsis is defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection. Methane has been reported to have anti-oxidative, anti-apoptotic and anti-inflammatory properties. We investigated the potential protective effects of methane on sepsis-induced injury and determined the related mechanisms. C57BL/6 mice received laparotomy with cecal ligation and puncture (CLP) to create a septic model, followed by methane-rich saline (MRS) treatment after CLP. MRS treatment improved the 5-day survival rate and organ functions and alleviated pathological damage of the mice, as well as reduced excessive inflammatory mediators, such as tumor necrosis factor-α and interleukin-6. MRS treatment also decreased the levels of oxidative stress index proteins, decreased the apoptosis of cells and inhibited nod-liker receptor protein (NLRP)3-mediated pyroptosis in the lung and intestine. In in vitro experiments, RAW264.7 and primary peritoneal macrophages were treated with lipopolysaccharide (LPS) plus adenosine-triphosphate (ATP) to induce inflammation and pyroptosis. Consistent with the in vivo results, methane-rich medium (MRM) treatment also reduced the levels of excessive inflammatory mediators, and decreased the levels of ROS, inhibited apoptosis and pyroptosis. Our results indicate that methane offers a protective effect for septic mice via its anti-inflammation, anti-oxidation, anti-pyroptosis and anti-apoptosis properties.

Xenon produces rapid antidepressant- and anxiolytic-like effects in lipopolysaccharide-induced depression mice model

Onset delay of current antidepressants is always the most significant limitation for the treatment of depression. More attention has been given to the glutamate acid system for developing fast-onset antidepressants. Xenon, acting as a well-known N-methyl-D-aspartate receptors antagonist, has been widely used clinically as anesthetics and was reported to exert antidepressant-like effects in rats under normal condition. The robust and rapid-acting antidepressant- and anxiolytic-like activities of xenon through the use of depression rodent model are still elusive. By using lipopolysaccharide-induced depression mice models, the present study aimed to evaluate the fast-acting antidepressant-like effects of xenon pretreatment. Behavioral tests, mainly including open-field test, novelty-suppressed feeding test, sucrose preference test, tail suspension test, and forced swimming test, were conducted respectively. Our results showed that both xenon gas and xenon-rich saline pretreatment intraperitoneally produced significant antidepressant- and anxiolytic-like activities in mice under normal condition. Further, xenon gas pretreatment (intraperitoneally) rapidly blocked lipopolysaccharide-induced depression- and anxiety-like behaviors of mice. These findings provide direct evidence that xenon could produce fast-onset antidepressant- and anxiolytic-like activities, which highlights the possibility to develop xenon as a promising fast-acting drug for treatment of depression, anxiety, and even other stress-related diseases.

The role of methane in plant physiology: a review

Methane (CH₄), one of the most important greenhouse gases, has conventionally been considered as a physiologic inert gas. However, this perspective has been challenged by the observation that CH₄ has diverse biological functions in animals, such as anti-inflammatory, antioxidant, and anti-apoptosis. Meanwhile, it has now been identified as a possible candidate of gaseous signaling molecule in plants, although its biosynthetic and metabolic pathways as well as the mechanism(s) of CH₄ signaling have not fully understood yet. This paper aims to review the available evidence for the biological roles of CH₄ in regulating plant physiology. Although currently available reports do not fully support the notion of CH₄ as a gasotransmitter, they do show that CH₄ might be produced by an aerobic, non-microbial pathway from plants, and plays important roles in enhancing plant tolerance against abiotic stresses, such as salinity, drought, heavy metal exposure, and promoting root development, as well as delaying senescence and browning. Further results showed that CH₄ could interact with reactive oxygen species (ROS), other gaseous signaling molecules [e.g., nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H₂S)], and glutathione (GSH). These reports thus support the idea that plant-produced CH₄ might be a component of a survival strategy of plants. Finally, the possibility of CH₄ application in agriculture is preliminarily discussed.

Methane and Inflammation - A Review (Fight Fire with Fire)

Mammalian methanogenesis is regarded as an indicator of carbohydrate fermentation by anaerobic gastrointestinal flora. Once generated by microbes or released by a non-bacterial process, methane is generally considered to be biologically inactive. However, recent studies have provided evidence for methane bioactivity in various in vivo settings. The administration of methane either in gas form or solutions has been shown to have anti-inflammatory and neuroprotective effects in an array of experimental conditions, such as ischemia/reperfusion, endotoxemia and sepsis. It has also been demonstrated that exogenous methane influences the key regulatory mechanisms and cellular signalling pathways involved in oxidative and nitrosative stress responses. This review offers an insight into the latest findings on the multi-faceted organ protective activity of exogenous methane treatments with special emphasis on its versatile effects demonstrated in sepsis models.

Methane-Rich Saline: A Potential Resuscitation Fluid for Hemorrhagic Shock

Hemorrhagic shock is caused by massive blood loss. If the patient is not fully resuscitated in time, this may eventually lead to multiple organ failure and even death. Previous studies on methane-rich saline in animal models showed that it confers resistance against many diseases. In this study, we explored the protective effect of methane-rich saline, used as a resuscitation fluid, in hemorrhagic shock. Hemorrhagic shock was induced in SD rats by bloodletting via intubation of the right femoral artery. The rats were divided into three groups: a sham control group (sham control), a shock group resuscitated by an infusion of autologous blood and an equivalent volume of normal saline (Shock+NS), and a shock group resuscitated by an infusion of autologous blood and an equivalent volume of methane-rich saline (Shock+MRS). Assessment of blood pressure and levels of plasma lactate showed that resuscitation using methane-rich saline (MRS) restored systemic blood pressure and reduced the levels of lactate in the plasma. Meanwhile, lower levels of serum IL-6 and TNF-α were also observed in the group resuscitated with MRS. In the heart, liver, and kidney, MRS reduced inflammation and oxidative stress levels. Analysis of organ function via levels of biochemical indicators revealed that the group resuscitated with MRS had reduced serum levels of AST and CK, indicating a potential cardioprotective effect. The expression levels of apoptosis-related proteins, including those of Bcl-2/Bax, and the results of TUNEL-labeling assay indicated that MRS significantly reduced apoptosis in the heart. Methane also had a positive effect on the expression of the PGC-1α/SIRT3/SOD2 signaling pathway. Our results showed that MRS can potentially serve as a novel resuscitation fluid because of its anti-inflammatory, antioxidative, and antiapoptotic properties.

Methane Production and Bioactivity-A Link to Oxido-Reductive Stress

Biological methane formation is associated with anoxic environments and the activity of anaerobic prokaryotes (Archaea). However, recent studies have confirmed methane release from eukaryotes, including plants, fungi, and animals, even in the absence of microbes and in the presence of oxygen. Furthermore, it was found that aerobic methane emission in plants is stimulated by a variety of environmental stress factors, leading to reactive oxygen species (ROS) generation. Further research presented evidence that molecules with sulfur and nitrogen bonded methyl groups such as methionine or choline are carbon precursors of aerobic methane formation. Once generated, methane is widely considered to be physiologically inert in eukaryotes, but several studies have found association between mammalian methanogenesis and gastrointestinal (GI) motility changes. In addition, a number of recent reports demonstrated anti-inflammatory potential for exogenous methane-based approaches in model anoxia-reoxygenation experiments. It has also been convincingly demonstrated that methane can influence the downstream effectors of transiently increased ROS levels, including mitochondria-related pro-apoptotic pathways during ischemia-reperfusion (IR) conditions. Besides, exogenous methane can modify the outcome of gasotransmitter-mediated events in plants, and it appears that similar mechanism might be active in mammals as well. This review summarizes the relevant literature on methane-producing processes in eukaryotes, and the available results that underscore its bioactivity. The current evidences suggest that methane liberation and biological effectiveness are both linked to cellular redox regulation. The data collectively imply that exogenous methane influences the regulatory mechanisms and signaling pathways involved in oxidative and nitrosative stress responses, which suggests a modulator role for methane in hypoxia-linked pathologies.

Protective Effect of Methane-Rich Saline on Acetic Acid-Induced Ulcerative Colitis via Blocking the TLR4/NF-κB/MAPK Pathway and Promoting IL-10/JAK1/STAT3-Mediated Anti-inflammatory Response

Ulcerative colitis (UC) is an inflammation-related disease involved in uncontrolled inflammation and oxidative stress and is characterized by high recurrence and relapse risk. As a rising star in gas medicine, methane owns the properties of anti-inflammation, antioxidation, and antiapoptosis. Based on the possible mechanism, we aimed to investigate the effect of methane on UC. Methane-rich saline (MRS) was introduced here, and UC was induced by acetic acid. All the C57BL/6 mice were allocated into groups as follows: control group, colitis model group, colitis treated with salazosulfapyridine (SASP) group, and colitis treated with MRS (1 or 10 ml/kg) groups. Tissue damage, the degree of inflammation, oxidative stress, and apoptosis were evaluated in the study, as well as the TLR4/NF-κB/MAPK and IL-10/JAK1/STAT3 signaling pathways for further exploration of the potential mechanism. The results showed that MRS (1) alleviated tissue damage caused by acetic acid, (2) controlled acetic acid-induced inflammation, (3) inhibited acetic acid-caused oxidative stress, (4) reduced colonic cell apoptosis due to acetic acid, (5) suppressed the TLR-4/NF-κB/MAPK signaling pathway, and (6) activated IL-10/JAK1/STAT3 anti-inflammatory response to improve the injury induced by acetic acid. We conclude that MRS has a protective effect on acetic acid-induced ulcerative colitis in mice via blocking the TLR4/NF-κB/MAPK signaling pathway and promoting the IL-10/JAK1/STAT3-mediated anti-inflammatory response.