Neuroprotective effects of hydrogen sulfide in Parkinson's disease animal models: methods and protocols

The Role of Hydrogen Sulfide in Regulation of Cell Death following Neurotrauma and Related Neurodegenerative and Psychiatric Diseases

Injuries of the central (CNS) and peripheral nervous system (PNS) are a serious problem of the modern healthcare system. The situation is complicated by the lack of clinically effective neuroprotective drugs that can protect damaged neurons and glial cells from death. In addition, people who have undergone neurotrauma often develop mental disorders and neurodegenerative diseases that worsen the quality of life up to severe disability and death. Hydrogen sulfide (H₂S) is a gaseous signaling molecule that performs various cellular functions in normal and pathological conditions. However, the role of H₂S in neurotrauma and mental disorders remains unexplored and sometimes controversial. In this large-scale review study, we examined the various biological effects of H₂S associated with survival and cell death in trauma to the brain, spinal cord, and PNS, and the signaling mechanisms underlying the pathogenesis of mental illnesses, such as cognitive impairment, encephalopathy, depression and anxiety disorders, epilepsy and chronic pain. We also studied the role of H₂S in the pathogenesis of neurodegenerative diseases: Alzheimer's disease (AD) and Parkinson's disease (PD). In addition, we reviewed the current state of the art study of H₂S donors as neuroprotectors and the possibility of their therapeutic uses in medicine. Our study showed that H₂S has great neuroprotective potential. H₂S reduces oxidative stress, lipid peroxidation, and neuroinflammation; inhibits processes associated with apoptosis, autophagy, ferroptosis and pyroptosis; prevents the destruction of the blood-brain barrier; increases the expression of neurotrophic factors; and models the activity of Ca²⁺ channels in neurotrauma. In addition, H₂S activates neuroprotective signaling pathways in psychiatric and neurodegenerative diseases. However, high levels of H₂S can cause cytotoxic effects. Thus, the development of H₂S-associated neuroprotectors seems to be especially relevant. However, so far, all H₂S modulators are at the stage of preclinical trials. Nevertheless, many of them show a high neuroprotective effect in various animal models of neurotrauma and related disorders. Despite the fact that our review is very extensive and detailed, it is well structured right down to the conclusions, which will allow researchers to quickly find the proper information they are interested in.

Hydrogen sulfide signalling in neurodegenerative diseases

The gaseous neurotransmitter hydrogen sulfide (H2 S) exerts neuroprotective efficacy in the brain via post-translational modification of cysteine residues by sulfhydration, also known as persulfidation. This process is comparable in biological impact to phosphorylation and mediates a variety of signalling events. Unlike conventional neurotransmitters, H2 S cannot be stored in vesicles due to its gaseous nature. Instead, it is either locally synthesized or released from endogenous stores. Sulfhydration affords both specific and general neuroprotective effects and is critically diminished in several neurodegenerative disorders. Conversely, some forms of neurodegenerative disease are linked to excessive cellular H2 S. Here, we review the signalling roles of H2 S across the spectrum of neurodegenerative diseases, including Huntington's disease, Parkinson's disease, Alzheimer's disease, Down syndrome, traumatic brain injury, the ataxias, and amyotrophic lateral sclerosis, as well as neurodegeneration generally associated with ageing.

Theoretical investigation on FRET strategy of ratio metric fluorescent probe sensing hydrogen sulfide

The level of hydrogen sulfide (H₂S) in human body is related to many diseases, such as Alzheimer's disease, Down syndrome, etc. Therefore, the detection of H₂S level in biological systems is very important and has attracted great attention from scientific and clinical researchers. Understanding the design and working mechanism of fluorescent probes for H₂S level detection is important for building new highly efficient fluorescent probe. The mechanisms of a recently reported efficient small molecule fluorescent probe based on the Fluorescence Resonance Energy Transfer (FRET) were investigated thoroughly in this work. The theoretical results would provide the insights for designing new efficient and multi-functional fluorescent probe applicable in the biological systems.

Mitochondrial Dysfunction in Parkinson’s Disease: From Mechanistic Insights to Therapy

Parkinson’s disease (PD) is one of the most common neurodegenerative movement disorders worldwide. There are currently no cures or preventative treatments for PD. Emerging evidence indicates that mitochondrial dysfunction is closely associated with pathogenesis of sporadic and familial PD. Because dopaminergic neurons have high energy demand, cells affected by PD exhibit mitochondrial dysfunction that promotes the disease-defining the loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc). The mitochondrion has a particularly important role as the cellular “powerhouse” of dopaminergic neurons. Therefore, mitochondria have become a promising therapeutic target for PD treatments. This review aims to describe mitochondrial dysfunction in the pathology of PD, outline the genes associated with familial PD and the factors related to sporadic PD, summarize current knowledge on mitochondrial quality control in PD, and give an overview of therapeutic strategies for targeting mitochondria in neuroprotective interventions in PD.

Sequential detection of H2S and HOBr with a novel lysosome-targetable fluorescent probe and its application in biological imaging

Understanding the complex relationship between active small molecules is of great significance in various physiological processes. Herein, we present the design and synthesis of a sequential responsive Lysosome-Naphthalene imide-Azido (lyso-NP-N₃) reporter for probing the H₂S and HOBr within organelle (lysosome) in living cells. Probe lyso-NP-N₃ exhibited high selectivity and sensitivity towards H₂S (LOD = 23.5 nM) and HOBr (LOD = 254 nM). Additionally, lyso-NP-N₃ possessed an excellent lysosome targeting ability and was utilized to visualize the exogenous/endogenous H₂S and HOBr in RAW 264.7, Hela and HepG2 cells. Facilitated by this sequentially activated mechanism, the probe was successfully applied to confirm that the reported scavenger of HOBr, N-acetyl-L-cysteine (NAC) mainly relied on its metabolite H₂S to eliminate excess HOBr, thereby playing the role of cell regulation and protection. These results establish the crosstalk between H₂S and HOBr in lysosome and provide a promising tool to study metabolite interactions.

Investigating Different Forms of Hydrogen Sulfide in Cerebrospinal Fluid of Various Neurological Disorders

Over the past 30 years a considerable amount of data has accumulated on the multifaceted role of hydrogen sulfide (H₂S) in the central nervous system. Depending on its concentrations, H₂S has opposite actions, ranging from neuromodulator to neurotoxic. Nowadays, accurate determination of H₂S is still an important challenge to understand its biochemistry and functions. In this perspective, this study aims to explore H₂S levels in cerebrospinal fluid (CSF), key biofluid for neurological studies, and to assess alleged correlations with neuroinflammatory and neurodegenerative mechanisms. A validated analytical determination combining selective electrochemical detection with ion chromatography was developed to measure free and bound sulfur forms of H₂S. A first cohort of CSF samples (n = 134) was analyzed from patients with inflammatory and demyelinating disorders (acute disseminated encephalomyelitis; multiple sclerosis), chronic neurodegenerative diseases (Alzheimer disease; Parkinson disease), and motor neuron disease (Amyotrophic lateral sclerosis). Given its analytical features, the chromatographic method resulted sensitive, reproducible and robust. We also explored low molecular weight-proteome linked to sulphydration by proteomics analysis on matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). This study is a first clinical report on CSF H₂S concentrations from neurological diseases and opens up new perspectives on the potential clinical relevance of H₂S and its potential therapeutic application.

Interaction among Hydrogen Sulfide and Other Gasotransmitters in Mammalian Physiology and Pathophysiology

Hydrogen sulfide (H₂S), nitric oxide (NO), carbon monoxide (CO), and sulfur dioxide (SO₂) were previously considered as toxic gases, but now they are found to be members of mammalian gasotransmitters family. Both H₂S and SO₂ are endogenously produced in sulfur-containing amino acid metabolic pathway in vivo. The enzymes catalyzing the formation of H₂S are mainly CBS, CSE, and 3-MST, and the key enzymes for SO₂ production are AAT1 and AAT2. Endogenous NO is produced from L-arginine under catalysis of three isoforms of NOS (eNOS, iNOS, and nNOS). HO-mediated heme catabolism is the main source of endogenous CO. These four gasotransmitters play important physiological and pathophysiological roles in mammalian cardiovascular, nervous, gastrointestinal, respiratory, and immune systems. The similarity among these four gasotransmitters can be seen from the same and/or shared signals. With many studies on the biological effects of gasotransmitters on multiple systems, the interaction among H₂S and other gasotransmitters has been gradually explored. H₂S not only interacts with NO to form nitroxyl (HNO), but also regulates the HO/CO and AAT/SO₂ pathways. Here, we review the biosynthesis and metabolism of the gasotransmitters in mammals, as well as the known complicated interactions among H₂S and other gasotransmitters (NO, CO, and SO₂) and their effects on various aspects of cardiovascular physiology and pathophysiology, such as vascular tension, angiogenesis, heart contractility, and cardiac protection.

Effect of Wenshen-Yanggan Decoction on Movement Disorder and Substantia Nigra Dopaminergic Neurons in Mice with Chronic Parkinson's Disease

This study aimed to explore the protective effects of Wenshen-Yanggan decoction on dopaminergic (DA) neuron injury in a rotenone-induced mouse model with chronic Parkinson's disease (PD) and explore its mechanism of action. Ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used to measure the content of six main components in the Wenshen-Yanggan decoction. The chronic PD mouse model was established by treating 10-month-old healthy wild C57BL/6 male mice with rotenone 30 mg/kg/day for 28 days in succession. The pole test and rotarod test were applied to detect the rescue effect of Wenshen-Yanggan decoction in high, medium, and low dosages, respectively, on PD-like behaviors in mice with chronic PD. The protective effect of Wenshen-Yanggan decoction on the mesencephalic nigrostriatal DA neuron injury was determined employing tyrosine hydroxylase (TH) immunofluorescence staining. Enzyme-linked immunosorbent assay (ELISA) was adopted to measure the inflammatory cytokines in serum, including TNF-α (tumor necrosis factor-alpha), IFN-γ (interferon gamma), NF-κB (nuclear factor kappa-B), and IL-1β (interleukin-1 beta). Western blotting was performed to quantify the expression of phosphorylated c-Jun N-terminal kinase (p-JNK), cleaved caspase-3, B-cell lymphoma-2 (Bcl-2), and NF-κB in the brain. Our results showed that the Wenshen-Yanggan decoction in high, medium, and low dosages reduced the turning time of mice (P < 0.01, P < 0.01,  and P < 0.05). The high and medium dosages shortened the total climbing time of PD mice in the pole test (P < 0.01 and P < 0.05). Meanwhile, the high, medium, and low dosages increased the rod-standing time of PD mice in the rotarod test (P < 0.01, P < 0.05,  and P < 0.05). Besides, the decoction reversed the decrease in TH-positive neurons induced by rotenone, upregulated TH protein expression, and downregulated the α-syn expression in the PD model. Moreover, the decoction in high dosage significantly inhibited the expression of p-JNK, cleaved caspase-3, and NF-κB in the midbrain of PD mice (P < 0.05, P < 0.05,  and P < 0.01), upregulated the expression of Bcl-2 (P < 0.05), and decreased the content of TNF-α, IFN-γ, NF-κB, and IL-1β in the serum (P < 0.001, P < 0.001, P < 0.001,  and P < 0.001). Taken together, the Wenshen-Yanggan decoction could protect mice from rotenone-induced chronic PD, which might be related to the reduction of the DA neuron apoptosis via suppressing the inflammatory reaction and the neuronal apoptosis pathway.

Hydrogen Sulfide and Endoplasmic Reticulum Stress: A Potential Therapeutic Target for Central Nervous System Degeneration Diseases

There are three members of the endogenous gas transmitter family. The first two are nitric oxide and carbon monoxide, and the third newly added member is hydrogen sulfide (H₂S). They all have similar functions: relaxing blood vessels, smoothing muscles, and getting involved in the regulation of neuronal excitation, learning, and memory. The cystathionine β-synthase (CBS), 3-mercaptopyruvate sulfur transferase acts together with cysteine aminotransferase (3-MST/CAT), cystathionine γ-lyase (CSE), and 3-mercaptopyruvate sulfur transferase with D-amino acid oxidase (3-MST/DAO) pathways are involved in the enzymatic production of H₂S. More and more researches focus on the role of H₂S in the central nervous system (CNS), and H₂S plays a significant function in neuroprotection processes, regulating the function of the nervous system as a signaling molecule in the CNS. Endoplasmic reticulum stress (ERS) and protein misfolding in its mechanism are related to neurodegenerative diseases. H₂S exhibits a wide variety of cytoprotective and physiological functions in the CNS degenerative diseases by regulating ERS. This review summarized on the neuroprotective effect of H₂S for ERS played in several CNS diseases including Alzheimer’s disease, Parkinson’s disease, and depression disorder, and discussed the corresponding possible signaling pathways or mechanisms as well.

Hydrogen Sulfide in Pharmacotherapy, Beyond the Hydrogen Sulfide-Donors

Hydrogen sulfide (H₂S) is one of the important biological mediators involved in physiological and pathological processes in mammals. Recently developed H₂S donors show promising effects against several pathological processes in preclinical and early clinical studies. For example, H₂S donors have been found to be effective in the prevention of gastrointestinal ulcers during anti-inflammatory treatment. Notably, there are well-established medicines used for the treatment of a variety of diseases, whose chemical structure contains sulfur moieties and may release H₂S. Hence, the therapeutic effect of these drugs may be partly the result of the release of H₂S occurring during drug metabolism and/or the effect of these drugs on the production of endogenous hydrogen sulfide. In this work, we review data regarding sulfur drugs commonly used in clinical practice that can support the hypothesis about H₂S-dependent pharmacotherapeutic effects of these drugs.

Leptin mediates protection of hydrogen sulfide against 6-hydroxydopamine-induced Parkinson's disease: Involving enhancement in Warburg effect

BACKGROUND

Hydrogen sulfide (H₂S) has therapeutic effects on Parkinson's disease (PD). Warburg effect, namely aerobic glycolysis, is benefit to PD. Leptin, a hormone secreted in adipose, plays an important role in the treatment of PD.

OBJECTIVE

To determine whether the mechanism underlying protection of H₂S against PD is involved in promoting Warburg effect via upregulation of leptin.

METHODS

We set a PD model via unilateral intrastriatal injection of 6-hydroxydopamine (6-OHDA) in Sprague Dawley rat. PD-like behavior was analyzed by apomorphine-induced rotations, open field activity test, stepping test and cylinder test. Dopaminergic neurons were detected by immunohistochemistry. The expressions of Hexokinase-2, pyruvate kinase M-2, lactate dehydrogenase, pyruvate dehydrogenase kinase, pyruvate dehydrogenase, and leptin were measured by Western blot. Lactate dehydrogenase (LDHA) activity was monitored by ELISA. The lactate content was measured by lactate assay kit.

RESULTS

We showed that NaHS (a donor of H₂S) prevented 6-OHDA-induced PD-like behaviors as well as the loss of dopaminergic neurons. We also found that NaHS enhanced the Warburg effect and upregulated leptin expression in the substantia nigra of 6-OHDA-exposed rats. While, inhibited leptin signaling by OBR13-A reversed the protections of H₂S against 6-OHDA-exerted PD-like behaviors and the loss of dopaminergic neurons in the substantia nigra, and abolished H₂S-enhanced in the Warburg effect in the substantia nigra.

CONCLUSION

These data indicated that leptin mediates the protection of H₂S against PD, which involves enhancing the Warburg effect of the substantia nigra.

Involvement of adenosine triphosphate-sensitive potassium channels in the neuroprotective activity of hydrogen sulfide in the 6-hydroxydopamine-induced animal model of Parkinson's disease

Studies have shown that hydrogen sulfide (H2S) exerts a neuroprotective effect and may have a therapeutic value for treating neurodegenerative diseases including Parkinson's disease. However, little is known about the mechanisms underlying the neuroprotective activity of H2S in vivo. Here, we evaluated the effect of glibenclamide, an ATP-sensitive potassium channel blocker, on the neuroprotective activity of H2S in the 6-hydroxydopamine (6-OHDA) animal model of Parkinson's disease. 6-OHDA was administered by stereotaxic surgery into the medial forebrain bundle. Sodium hydrosulfate (NaHS, 3 and 5.6 mg/kg), as a donor of H2S, alone or in combination with glibenclamide (5 mg/kg), was daily injected for 7 days starting 1-2 h before the stereotaxic surgery. After an apomorphine-induced rotational test, the number of tyrosine hydroxylase-positive neurons in the substantia nigra pars compacta was determined by immunofluorescence. The striatal dopamine level and oxidative stress markers were also measured in brain homogenates. Pretreatment with NaHS significantly attenuated 6-OHDA-induced motor asymmetry in the rotational test. Histological and biochemical evaluations demonstrated that NaHS, especially at high dose, increased the survival of tyrosine hydroxylase-positive neurons in the substantia nigra pars compacta and reduced the decreasing effect of 6-OHDA on striatal dopamine levels. However, co-administration of glibenclamide reversed the antiparkinsonian and neuroprotective effects of NaHS. However, glibenclamide did not change the reducing effect of NaHS on 6-OHDA-induced overproduction of malondialdehyde. Our data show that ATP-sensitive potassium channels are involved in the antiparkinsonian and neuroprotective effects of H2S in the 6-OHDA animal model of Parkinson's disease.

The H₂S Donor GYY4137 Stimulates Reactive Oxygen Species Generation in BV2 Cells While Suppressing the Secretion of TNF and Nitric Oxide

GYY4137 is a hydrogen sulfide (H₂S) donor that has been shown to act in an anti-inflammatory manner in vitro and in vivo. Microglial cells are among the major players in immunoinflammatory, degenerative, and neoplastic disorders of the central nervous system, including multiple sclerosis, Parkinson’s disease, Alzheimer’s disease, and glioblastoma multiforme. So far, the effects of GYY4137 on microglial cells have not been thoroughly investigated. In this study, BV2 microglial cells were stimulated with interferon-gamma and lipopolysaccharide and treated with GYY4137. The agent did not influence the viability of BV2 cells in concentrations up to 200 μM. It inhibited tumor necrosis factor but not interleukin-6 production. Expression of CD40 and CD86 were reduced under the influence of the donor. The phagocytic ability of BV2 cells and nitric oxide production were also affected by the agent. Surprisingly, GYY4137 upregulated generation of reactive oxygen species (ROS) by BV2 cells. The effect was mimicked by another H₂S donor, Na₂S, and it was not reproduced in macrophages. Our results demonstrate that GYY4137 downregulates inflammatory properties of BV2 cells but increases their ability to generate ROS. Further investigation of this unexpected phenomenon is warranted.

Hydrogen sulfide attenuates homocysteine-induced neurotoxicity by preventing mitochondrial dysfunctions and oxidative damage: In vitro and in vivo studies

Elevated homocysteine (Hcy) levels have been implicated in neurodevelopmental and neurodegenerative disorders. Induction of oxidative stress and apoptosis has been reported as major mechanism in Hcy-induced neurotoxicity. Hydrogen sulfide (H₂S), as an antioxidant molecule has been reported to exhibit novel protective effect against Hcy-induced cell damage. However, the mechanisms involved in protective effect of H₂S against Hcy-induced toxicity in neurons have not been fully elucidated. Herein, effect of sodium hydrogen sulfide (NaHS, a source of H₂S) on Hcy-induced neurotoxicity was studied on Neuro-2a (N2a) cells in vitro and in animals subjected to hyperhomocysteinemia. DCFH-DA staining revealed that NaHS effectively attenuated Hcy-induced oxidative damage by reducing intracellular reactive oxygen species (ROS) generation. JC-1 staining and western blot results showed that NaHS pre-treatment prevented Hcy-induced mitochondrial dysfunctions and mitochondria-mediated apoptosis. MTT assay, cell cycle analysis, ethidium bromide/acridine orange (EB/AO) and Hoechst staining results demonstrated that NaHS significantly alleviated Hcy-induced cytotoxicity in N2a cells by preventing oxidative damage. Importantly, the results from agarose gel electrophoresis, comet and TUNEL assay indicated that NaHS also prevented neurodegeneration by reducing DNA damage and apoptotic cell death in animals with hyperhomocysteinemia. Taken together, the results demonstrate that the protective potential of H₂S against Hcy-induced neurotoxicity is mediated by preventing oxidative DNA damage and mitochondrial dysfunctions. The findings validate that H₂S is a promising therapeutic molecule in neurodegenerative conditions associated with hyperhomocysteinemia.

Activation of autophagic flux and the Nrf2/ARE signaling pathway by hydrogen sulfide protects against acrylonitrile-induced neurotoxicity in primary rat astrocytes

Hydrogen sulfide (H₂S), the third gasotransmitter, has been shown to act as a neuroprotective factor in numerous pathological processes; however, its underlying mechanism(s) of action remain unclear. It is widely accepted that activation of moderate autophagy and the Nrf2/ARE signaling pathway play important roles in the biological self-defense systems. In the present study, we investigated whether exogenous H₂S protects against the cytotoxicity of acrylonitrile (AN), a neurotoxin, in primary rat astrocytes. We found that pretreatment for 1 h with sodium hydrosulfide (NaHS), a donor of H₂S (200-800 µM), significantly attenuated the AN-induced decrease in cell viability, increase in lactate dehydrogenase release and morphological changes. Furthermore, NaHS significantly attenuated AN-induced oxidative stress by reducing reactive oxygen species (ROS) levels and increasing glutathione (GSH) concentration. Moreover, NaHS activated the autophagic flux, detectable as a change in autophagy-related proteins (Beclin-1, Atg5 and p62), the formation of acidic vesicular organelles and LC3B aggregation, confirmed by adenoviral expression of mRFP-GFP-LC3. Additionally, NaHS stimulated translocation of Nrf2 into the nucleus and increased expression of heme oxygenase-1 and γ-glutamylcysteine synthetase, downstream targets of Nrf2. Notably, the autophagy inhibitor 3-methyladenine and Beclin-1, or Nrf2-targeted siRNA, significantly attenuated the neuroprotective effects of NaHS against AN-induced neurotoxicity. In conclusion, we identified a crucial role of  autophagy and the Nrf2/ARE signaling pathway in H₂S-mediated neuroprotection against AN-induced toxicity in primary rat astrocytes. Our findings provide novel insights into the mechanisms of H₂S-mediated neuroprotection, and suggest that H₂S-based donors may serve as potential new candidate drugs to treat AN-induced neurotoxicity.

Hydrogen sulfide therapy in brain diseases: from bench to bedside

Hydrogen sulfide (H₂S) has been recognized and studied for nearly 300 years, but past researches mainly focus on its toxicity effect. During the past two decades, the majority of researches have reported that H₂S is a novel endogenous gaseous signal molecule in organisms, and play an important role in various systems and diseases. H₂S is mainly produced by three enzymes, including cystathionine β-synthase, cystathionine γ-lyase and 3-mercaptopyruvate sulfurtransferase along with cysteine aminotransferase. H₂S had been firstly reported as a neuromodulator in the brain, because of its essential role in the facilitating hippocampal long-term potentiation at physiological concentration. It is subsequently reported that H₂S may have relevance to neurologic disorders through antioxidative, anti-inflammatory, anti-apoptotic and additional effects. Recent basic medical studies and preclinical studies on neurologic diseases have demonstrated that the administration of H₂S at physiological or pharmacological levels attenuates brain injury. However, the neuroprotective effect of H₂S is concentration-dependent, only a comparatively low dose of H₂S can provide beneficial effect. Herein, we review the neuroprotevtive role of H₂S therapy in brain diseases from its mechanism to clinical application in animal and human subjects, and therefore provide the potential strategies for further clinical treatment.

Physiological Importance of Hydrogen Sulfide: Emerging Potent Neuroprotector and Neuromodulator

Hydrogen sulfide (H2S) is an emerging neuromodulator that is considered to be a gasotransmitter similar to nitrogen oxide (NO) and carbon monoxide (CO). H2S exerts universal cytoprotective effects and acts as a defense mechanism in organisms ranging from bacteria to mammals. It is produced by the enzymes cystathionine β-synthase (CBS), cystathionine ϒ-lyase (CSE), 3-mercaptopyruvate sulfurtransferase (MST), and D-amino acid oxidase (DAO), which are also involved in tissue-specific biochemical pathways for H2S production in the human body. H2S exerts a wide range of pathological and physiological functions in the human body, from endocrine system and cellular longevity to hepatic protection and kidney function. Previous studies have shown that H2S plays important roles in peripheral nerve regeneration and degeneration and has significant value during Schwann cell dedifferentiation and proliferation but it is also associated with axonal degradation and the remyelination of Schwann cells. To date, physiological and toxic levels of H2S in the human body remain unclear and most of the mechanisms of action underlying the effects of H2S have yet to be fully elucidated. The primary purpose of this review was to provide an overview of the role of H2S in the human body and to describe its beneficial effects.

Medical Functions of Hydrogen Sulfide

Hydrogen sulfide (H(2)S) is a gasomediator synthesized from L- and D-cysteine in various tissues. It is involved in a number of physiological and pathological processes. H(2)S exhibits antiatherosclerotic, vasodilator, and proangiogenic properties, and protects the kidney and heart from damage following ischemia/reperfusion injury. H(2)S donors may be natural or synthetic, and may be used for the safe treatment of a wide range of diseases. This review article summarizes the current state of knowledge of the therapeutic function of H(2)S.

Visualization of exhaled hydrogen sulphide on test paper with an ultrasensitive and time-gated luminescent probe

Luminescent chemosensors for hydrogen sulfide (H₂S) are of great interest because of the close association of H₂S with our health.

H2S protects PC12 cells against toxicity of corticosterone by modulation of BDNF-TrkB pathway

Corticosterone, one of the glucocorticoids, is toxic to neurons and plays an important role in depressive-like behavior and depression. We previously showed that hydrogen sulfide (H2S), a novel physiological mediator, plays an inhibitory role in depression. However, the mechanism underlying H2S-triggered antidepressant-like role is not clearly known. Brain-derived neurotrophic factor (BDNF), a neurotrophic factor, plays a neuroprotective role that is mediated by its high-affinity tropomysin-related kinase B (TrkB) receptor. In this study, to investigate the underlying mechanism of H2S-induced antidepressant-like role, we explored whether H2S could protect neurons against corticosterone-mediated cyctotoxicity and whether this protective role of H2S was involved in the regulation of BDNF-TrkB pathway. Our data demonstrated that sodium hydrosulfide (NaHS), the donor of H2S, could prevent corticosterone-induced cytotoxicity, apoptosis, accumulation of intracellular reactive oxygen species (ROS) and loss of mitochondrial membrane potential (MMP) in PC12 cells. NaHS not only induced the up-regulation of BDNF but also prevented the down-regulation of BDNF by corticosterone. It was also found that blocking BDNF-TrkB pathway by K252a, an inhibitor of TrkB, abolished the protection of H2S against corticosterone-induced cytotoxicity, apoptosis, accumulation of ROS, and loss of MMP. These results suggest that H2S protects against the neurotoxicity of corticosterone by modulation of the BDNF-TrkB pathway.

Hydrogen sulfide intervention in focal cerebral ischemia/reperfusion injury in rats

The present study aimed to explore the mechanism underlying the protective effects of hydrogen sulfide against neuronal damage caused by cerebral ischemia/reperfusion. We established the middle cerebral artery occlusion model in rats via the suture method. Ten minutes after middle cerebral artery occlusion, the animals were intraperitoneally injected with hydrogen sulfide donor compound sodium hydrosulfide. Immunofluorescence revealed that the immunoreactivity of P2X₇ in the cerebral cortex and hippocampal CA1 region in rats with cerebral ischemia/reperfusion injury decreased with hydrogen sulfide treatment. Furthermore, treatment of these rats with hydrogen sulfide significantly lowered mortality, the Longa neurological deficit scores, and infarct volume. These results indicate that hydrogen sulfide may be protective in rats with local cerebral ischemia/reperfusion injury by down-regulating the expression of P2X₇ receptors.