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Cirino G, Szabo C, Papapetropoulos A. Physiological roles of hydrogen sulfide in mammalian cells, tissues and organs. Physiol Rev 2022; 103:31-276. [DOI: 10.1152/physrev.00028.2021] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
H2S belongs to the class of molecules known as gasotransmitters, which also includes nitric oxide (NO) and carbon monoxide (CO). Three enzymes are recognized as endogenous sources of H2S in various cells and tissues: cystathionine g-lyase (CSE), cystathionine β-synthase (CBS) and 3-mercaptopyruvate sulfurtransferase (3-MST). The current article reviews the regulation of these enzymes as well as the pathways of their enzymatic and non-enzymatic degradation and elimination. The multiple interactions of H2S with other labile endogenous molecules (e.g. NO) and reactive oxygen species are also outlined. The various biological targets and signaling pathways are discussed, with special reference to H2S and oxidative posttranscriptional modification of proteins, the effect of H2S on channels and intracellular second messenger pathways, the regulation of gene transcription and translation and the regulation of cellular bioenergetics and metabolism. The pharmacological and molecular tools currently available to study H2S physiology are also reviewed, including their utility and limitations. In subsequent sections, the role of H2S in the regulation of various physiological and cellular functions is reviewed. The physiological role of H2S in various cell types and organ systems are overviewed. Finally, the role of H2S in the regulation of various organ functions is discussed as well as the characteristic bell-shaped biphasic effects of H2S. In addition, key pathophysiological aspects, debated areas, and future research and translational areas are identified A wide array of significant roles of H2S in the physiological regulation of all organ functions emerges from this review.
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Affiliation(s)
- Giuseppe Cirino
- Department of Pharmacy, School of Medicine, University of Naples Federico II, Naples, Italy
| | - Csaba Szabo
- Chair of Pharmacology, Section of Medicine, University of Fribourg, Switzerland
| | - Andreas Papapetropoulos
- Laboratory of Pharmacology, Faculty of Pharmacy, National and Kapodistrian University of Athens, Athens, Greece & Clinical, Experimental Surgery and Translational Research Center, Biomedical Research Foundation of the Academy of Athens, Greece
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Shackelford RE, Li Y, Ghali GE, Kevil CG. Bad Smells and Broken DNA: A Tale of Sulfur-Nucleic Acid Cooperation. Antioxidants (Basel) 2021; 10:1820. [PMID: 34829691 PMCID: PMC8614844 DOI: 10.3390/antiox10111820] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 11/11/2021] [Accepted: 11/13/2021] [Indexed: 12/19/2022] Open
Abstract
Hydrogen sulfide (H2S) is a gasotransmitter that exerts numerous physiologic and pathophysiologic effects. Recently, a role for H2S in DNA repair has been identified, where H2S modulates cell cycle checkpoint responses, the DNA damage response (DDR), and mitochondrial and nuclear genomic stability. In addition, several DNA repair proteins modulate cellular H2S concentrations and cellular sulfur metabolism and, in turn, are regulated by cellular H2S concentrations. Many DDR proteins are now pharmacologically inhibited in targeted cancer therapies. As H2S and the enzymes that synthesize it are increased in many human malignancies, it is likely that H2S synthesis inhibition by these therapies is an underappreciated aspect of these cancer treatments. Moreover, both H2S and DDR protein activities in cancer and cardiovascular diseases are becoming increasingly apparent, implicating a DDR-H2S signaling axis in these pathophysiologic processes. Taken together, H2S and DNA repair likely play a central and presently poorly understood role in both normal cellular function and a wide array of human pathophysiologic processes. Here, we review the role of H2S in DNA repair.
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Affiliation(s)
- Rodney E. Shackelford
- Department of Pathology and Translational Pathobiology, Louisiana State University Health Sciences Center, Shreveport, LA 71130, USA; (Y.L.); (C.G.K.)
| | - Yan Li
- Department of Pathology and Translational Pathobiology, Louisiana State University Health Sciences Center, Shreveport, LA 71130, USA; (Y.L.); (C.G.K.)
| | - Ghali E. Ghali
- Head & Neck Oncologic/Microvascular Reconstructive Surgery Department of Oral & Maxillofacial/Head & Neck Surgery, Louisiana State University Health Sciences Center, Shreveport, LA 71130, USA;
| | - Christopher G. Kevil
- Department of Pathology and Translational Pathobiology, Louisiana State University Health Sciences Center, Shreveport, LA 71130, USA; (Y.L.); (C.G.K.)
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Molecular Functions of Hydrogen Sulfide in Cancer. PATHOPHYSIOLOGY 2021; 28:437-456. [PMID: 35366284 PMCID: PMC8830448 DOI: 10.3390/pathophysiology28030028] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 09/08/2021] [Accepted: 09/16/2021] [Indexed: 12/30/2022] Open
Abstract
Hydrogen sulfide (H2S) is a gasotransmitter that exerts a multitude of functions in both physiologic and pathophysiologic processes. H2S-synthesizing enzymes are increased in a variety of human malignancies, including colon, prostate, breast, renal, urothelial, ovarian, oral squamous cell, and thyroid cancers. In cancer, H2S promotes tumor growth, cellular and mitochondrial bioenergetics, migration, invasion, angiogenesis, tumor blood flow, metastasis, epithelia–mesenchymal transition, DNA repair, protein sulfhydration, and chemotherapy resistance Additionally, in some malignancies, increased H2S-synthesizing enzyme expression correlates with a worse prognosis and a higher tumor stage. Here we review the role of H2S in cancer, with an emphasis on the molecular mechanisms by which H2S promotes cancer development, progression, dedifferentiation, and metastasis.
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Sokolov AS, Nekrasov PV, Shaposhnikov MV, Moskalev AA. Hydrogen sulfide in longevity and pathologies: Inconsistency is malodorous. Ageing Res Rev 2021; 67:101262. [PMID: 33516916 DOI: 10.1016/j.arr.2021.101262] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 01/18/2021] [Accepted: 01/24/2021] [Indexed: 02/08/2023]
Abstract
Hydrogen sulfide (H2S) is one of the biologically active gases (gasotransmitters), which plays an important role in various physiological processes and aging. Its production in the course of methionine and cysteine catabolism and its degradation are finely balanced, and impairment of H2S homeostasis is associated with various pathologies. Despite the strong geroprotective action of exogenous H2S in C. elegans, there are controversial effects of hydrogen sulfide and its donors on longevity in other models, as well as on stress resistance, age-related pathologies and aging processes, including regulation of senescence-associated secretory phenotype (SASP) and senescent cell anti-apoptotic pathways (SCAPs). Here we discuss that the translation potential of H2S as a geroprotective compound is influenced by a multiplicity of its molecular targets, pleiotropic biological effects, and the overlapping ranges of toxic and beneficial doses. We also consider the challenges of the targeted delivery of H2S at the required dose. Along with this, the complexity of determining the natural levels of H2S in animal and human organs and their ambiguous correlations with longevity are reviewed.
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Goyak KO, Lewis RJ. Application of adverse outcome pathway networks to integrate mechanistic data informing the choice of a point of departure for hydrogen sulfide exposure limits. Crit Rev Toxicol 2021; 51:193-208. [PMID: 33905294 DOI: 10.1080/10408444.2021.1897085] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Acute exposure to hydrogen sulfide initiates a series of hallmark biological effects that occur progressively at increasing exposure levels: odor perception, conjunctivitis, olfactory paralysis, "knockdown," pulmonary edema, and apnea. Although effects of exposure to high concentrations of hydrogen sulfide are clear, effects associated with chronic, low-level exposure in humans is under debate, leading to uncertainty in the critical effect used in regulatory risk assessments addressing low dose exposures. This study integrates experimental animal, observational epidemiology, and occupational exposure evidence by applying a pathway-based approach. A hypothesized adverse outcome pathway (AOP) network was developed from 34 studies, composed of 4 AOPs sharing 1 molecular initiating events (MIE) and culminating in 4 adverse outcomes. A comparative assessment of effect levels and weight of evidence identified an AOP leading to a biologically-plausible, low-dose outcome relative to the other outcomes (nasal lesions, 30 ppm versus olfactory paralysis, >100 ppm; neurological effects, >80 ppm; pulmonary edema, >80 ppm). This AOP (i.e. AOP1) consists of the following key events: cytochrome oxidase inhibition (>10 ppm), neuronal cell loss (>30 ppm), and olfactory nasal lesions (defined as both neuronal cell loss and basal cell hyperplasia; >30 ppm) in rodents. The key event relationships in this pathway were supported by moderate empirical evidence and have high biological plausibility due to known mechanistic understanding and consistency in observations for diverse chemicals.
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Affiliation(s)
- Katy O Goyak
- ExxonMobil Biomedical Sciences, Inc., Annandale, NJ, USA
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GASOMEDIATOR H2S IN THROMBOSIS AND HEMOSTASIS. BIOTECHNOLOGIA ACTA 2020. [DOI: 10.15407/biotech13.06.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
This review was aimed to briefly summarize current knowledge of the biological roles of gasomediator H2S in hemostasis and cardiovascular diseases. Since the discovery that mammalian cells are enzymatically producing H2S, this molecule underwent a dramatic metamorphosis from dangerous pollutant to a biologically relevant mediator. As a gasomediator, hydrogen sulfide plays a role of signaling molecule, which is involved in a number of processes in health and disease, including pathogenesis of cardiovascular abnormalities, mainly through modulating different patterns of vasculature functions and thrombotic events. Recently, several studies have provided unequivocal evidence that H2S reduces blood platelet reactivity by inhibiting different stages of platelet activation (platelet adhesion, secretion and aggregation) and thrombus formation. Moreover, H2S changes the structure and function of fibrinogen and proteins associated with fibrinolysis. Hydrogen sulfide regulates proliferation and apoptosis of vascular smooth muscle cells, thus modulating angiogenesis and vessel function. Undoubtedly, H2S is also involved in a multitude of other physiological functions. For example, it exhibits anti-inflammatory effects by inhibiting ROS production and increasing expression of antioxidant enzymes. Some studies have demonstrated the role of hydrogen sulfide as a therapeutic agent in various diseases, including cardiovascular pathologies. Further studies are required to evaluate its importance as a regulator of cell physiology and associated cardiovascular pathological conditions such as myocardial infarction and stroke.
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Pecze L, Randi EB, Szabo C. Meta-analysis of metabolites involved in bioenergetic pathways reveals a pseudohypoxic state in Down syndrome. Mol Med 2020; 26:102. [PMID: 33167881 PMCID: PMC7653803 DOI: 10.1186/s10020-020-00225-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 10/12/2020] [Indexed: 12/14/2022] Open
Abstract
Clinical observations and preclinical studies both suggest that Down syndrome (DS) may be associated with significant metabolic and bioenergetic alterations. However, the relevant scientific literature has not yet been systematically reviewed. The aim of the current study was to conduct a meta-analysis of metabolites involved in bioenergetics pathways in DS to conclusively determine the difference between DS and control subjects. We discuss these findings and their potential relevance in the context of pathogenesis and experimental therapy of DS. Articles published before July 1, 2020, were identified by using the search terms “Down syndrome” and “metabolite name” or “trisomy 21” and “metabolite name”. Moreover, DS-related metabolomics studies and bioenergetics literature were also reviewed. 41 published reports and associated databases were identified, from which the descriptive information and the relevant metabolomic parameters were extracted and analyzed. Mixed effect model revealed the following changes in DS: significantly decreased ATP, CoQ10, homocysteine, serine, arginine and tyrosine; slightly decreased ADP; significantly increased uric acid, succinate, lactate and cysteine; slightly increased phosphate, pyruvate and citrate. However, the concentrations of AMP, 2,3-diphosphoglycerate, glucose, and glutamine were comparable in the DS vs. control populations. We conclude that cells of subjects with DS are in a pseudo-hypoxic state: the cellular metabolic and bio-energetic mechanisms exhibit pathophysiological alterations that resemble the cellular responses associated with hypoxia, even though the supply of the cells with oxygen is not disrupted. This fundamental alteration may be, at least in part, responsible for a variety of functional deficits associated with DS, including reduced exercise difference, impaired neurocognitive status and neurodegeneration.
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Affiliation(s)
- Laszlo Pecze
- Chair of Pharmacology, Section of Medicine, University of Fribourg, Fribourg, Switzerland
| | - Elisa B Randi
- Chair of Pharmacology, Section of Medicine, University of Fribourg, Fribourg, Switzerland
| | - Csaba Szabo
- Chair of Pharmacology, Section of Medicine, University of Fribourg, Fribourg, Switzerland.
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Szabo C. The re-emerging pathophysiological role of the cystathionine-β-synthase - hydrogen sulfide system in Down syndrome. FEBS J 2020; 287:3150-3160. [PMID: 31955501 DOI: 10.1111/febs.15214] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 12/13/2019] [Accepted: 01/14/2020] [Indexed: 12/21/2022]
Abstract
Down syndrome (DS) is associated with significant perturbances in many morphological and biochemical features. Cystathionine-β-synthase (CBS) is one of the key mammalian enzymes that is responsible for the biological production of the gaseous transmitter hydrogen sulfide (H2 S). When H2 S is overproduced, it can exert detrimental cellular effects, in part due to inhibition of mitochondrial Complex IV activity. An increased expression of CBS and the consequent overproduction of H2 S are well documented in individuals with DS. Two decades ago, it has been proposed that a toxic overproduction of H2 S importantly contributes to the metabolic and neurological deficits associated with DS. However, until recently, this hypothesis has not yet been tested experimentally. Recent data generated in human dermal fibroblasts show that DS cells overproduce H2 S, which, in turn, suppresses mitochondrial Complex IV activity and impairs mitochondrial oxygen consumption and ATP generation. Therapeutic CBS inhibition lifts the tonic (and reversible) suppression of Complex IV: This results in the normalization of mitochondrial function in DS cells. H2 S may also contribute to the cellular dysfunction via several other molecular mechanisms through interactions with various mitochondrial and extramitochondrial molecular targets. The current article provides a historical background of the field, summarizes the recently published data and their potential implications, and outlines potential translational approaches (such as CBS inhibition and H2 S neutralization) and future experimental studies in this re-emerging field of pathobiochemistry.
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Affiliation(s)
- Csaba Szabo
- Chair of Pharmacology, Section of Medicine, University of Fribourg, Switzerland
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Cao X, Ding L, Xie ZZ, Yang Y, Whiteman M, Moore PK, Bian JS. A Review of Hydrogen Sulfide Synthesis, Metabolism, and Measurement: Is Modulation of Hydrogen Sulfide a Novel Therapeutic for Cancer? Antioxid Redox Signal 2019; 31:1-38. [PMID: 29790379 PMCID: PMC6551999 DOI: 10.1089/ars.2017.7058] [Citation(s) in RCA: 268] [Impact Index Per Article: 53.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 05/14/2018] [Accepted: 05/22/2018] [Indexed: 02/07/2023]
Abstract
Significance: Hydrogen sulfide (H2S) has been recognized as the third gaseous transmitter alongside nitric oxide and carbon monoxide. In the past decade, numerous studies have demonstrated an active role of H2S in the context of cancer biology. Recent Advances: The three H2S-producing enzymes, namely cystathionine γ-lyase (CSE), cystathionine β-synthase (CBS), and 3-mercaptopyruvate sulfurtransferase (3MST), have been found to be highly expressed in numerous types of cancer. Moreover, inhibition of CBS has shown anti-tumor activity, particularly in colon cancer, ovarian cancer, and breast cancer, whereas the consequence of CSE or 3MST inhibition remains largely unexplored in cancer cells. Intriguingly, H2S donation at high amounts or a long time duration has also been observed to induce cancer cell apoptosis in vitro and in vivo while sparing noncancerous fibroblast cells. Therefore, a bell-shaped model has been proposed to explain the role of H2S in cancer development. Specifically, endogenous H2S or a relatively low level of exogenous H2S may exhibit a pro-cancer effect, whereas exposure to H2S at a higher amount or for a long period may lead to cancer cell death. This indicates that inhibition of H2S biosynthesis and H2S supplementation serve as two distinct ways for cancer treatment. This paradoxical role of H2S has stimulated the enthusiasm for the development of novel CBS inhibitors, H2S donors, and H2S-releasing hybrids. Critical Issues: A clear relationship between H2S level and cancer progression remains lacking. The possibility that the altered levels of these byproducts have influenced the cell viability of cancer cells has not been excluded in previous studies when modulating H2S producing enzymes. Future Directions: The consequence of CSE or 3MST inhibition in cancer cells need to be examined in the future. Better portrayal of the crosstalk among these gaseous transmitters may not only lead to an in-depth understanding of cancer progression but also shed light on novel strategies for cancer therapy.
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Affiliation(s)
- Xu Cao
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Lei Ding
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Zhi-zhong Xie
- Institute of Pharmacy and Pharmacology, University of South China, Hengyang, China
| | - Yong Yang
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- State Key Laboratory of Natural Medicines, Jiangsu Key Laboratory of Drug Discovery for Metabolic Disease, Center for New Drug Safety Evaluation and Research, China Pharmaceutical University, Nanjing, China
| | | | - Philip K. Moore
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Jin-Song Bian
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
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Andreeva NV, Zotov KV, Yusupov VI, Belyavsky AV. Hydrogen Sulfide Donor NaHS Protects Mesenchymal Stem and Melanoma Cells from the Negative Effects of Infrared Laser Irradiation. Mol Biol 2019. [DOI: 10.1134/s002689331902002x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Szabo C. A timeline of hydrogen sulfide (H 2S) research: From environmental toxin to biological mediator. Biochem Pharmacol 2018; 149:5-19. [PMID: 28947277 PMCID: PMC5862769 DOI: 10.1016/j.bcp.2017.09.010] [Citation(s) in RCA: 155] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 09/20/2017] [Indexed: 02/07/2023]
Abstract
The history of H2S - as an environmental toxin - dates back to 1700, to the observations of the Italian physician Bernardino Ramazzini, whose book "De Morbis Artificum Diatriba" described the painful eye irritation and inflammation of "sewer gas" in sewer workers. The gas has subsequently been identified as hydrogen sulfide (H2S), and opened three centuries of research into the biological roles of H2S. The current article highlights the key discoveries in the field of H2S research, including (a) the toxicological studies, which characterized H2S as an environmental toxin, and identified some of its modes of action, including the inhibition of mitochondrial respiration; (b) work in the field of bacteriology, which, starting in the early 1900s, identified H2S as a bacterial product - with subsequently defined roles in the regulation of periodontal disease (oral bacterial flora), intestinal epithelial cell function (enteral bacterial flora) as well as in the regulation of bacterial resistance to antibiotics; and (c), work in diverse fields of mammalian biology, which, starting in the 1940s, identified H2S as an endogenous mammalian enzymatic product, the functions of which - among others, in the cardiovascular and nervous system - have become subjects of intensive investigation for the last decade. The current review not only enumerates the key discoveries related to H2S made over the last three centuries, but also compiles the most frequently cited papers in the field which have been published over the last decade and highlights some of the current 'hot topics' in the field of H2S biology.
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Affiliation(s)
- Csaba Szabo
- Department of Anesthesiology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA.
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Yalçın Yeler D, Aydin M, Gül M, Hocaoğlu T, Özdemir H, Koraltan M. Systemic effects of H 2S inhalation at human equivalent dose of pathologic halitosis on rats. Acta Odontol Scand 2017; 75:517-523. [PMID: 28693361 DOI: 10.1080/00016357.2017.1350992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
OBJECTIVES Halitosis is composed by hundreds of toxic gases. It is still not clear whether halitosis gases self-inhaled by halitosis patients cause side effects. The aim of the study was to investigate the effect of H2S inhalation at a low concentration (human equivalent dose of pathologic halitosis) on rats. MATERIALS AND METHODS The threshold level of pathologic halitosis perceived by humans at 250 ppb of H2S was converted to rat equivalent concentration (4.15 ppm). In the experimental group, 8 rats were exposed to H2S via continuous inhalation but not the control rats. After 50 days, blood parameters were measured and tissue samples were obtained from the brain, kidney and liver and examined histopathologically to determine any systemic effect. RESULTS While aspartate transaminase, creatine kinase-MB and lactate dehydrogenase levels were found to be significantly elevated, carbondioxide and alkaline phosphatase were decreased in experimental rats. Other blood parameters were not changed significantly. Experimental rats lost weight and became anxious. Histopathological examination showed mononuclear inflammatory cell invasion in the portal areas, nuclear glycogen vacuoles in the parenchymal area, single-cell necrosis in a few foci, clear expansion in the central hepatic vein and sinusoids, hyperplasia in Kupffer cells and potential fibrous tissue expansion in the portal areas in the experimental rats. However, no considerable histologic damage was observed in the brain and kidney specimens. CONCLUSIONS It can be concluded that H2S inhalation equivalent to pathologic halitosis producing level in humans may lead to systemic effects, particularly heart or liver damage in rats.
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Affiliation(s)
- Defne Yalçın Yeler
- Department of Oral and Maxillofacial Radiology, Faculty of Dentistry, Cumhuriyet University, Sivas,Türkiye
| | | | - Mehmet Gül
- Department of Histology and Embryology, Faculty of Medicine, Inönü University, Malatya, Türkiye
| | - Turgay Hocaoğlu
- Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Cumhuriyet University, Sivas,Türkiye
| | - Hakan Özdemir
- Department of Periodontology, Faculty of Dentistry, Osmangazi University, Eskisehir, Türkiye
| | - Melike Koraltan
- Department of Oral and Maxillofacial Radiology, Faculty of Dentistry, Cumhuriyet University, Sivas,Türkiye
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Cao X, Cao L, Ding L, Bian JS. A New Hope for a Devastating Disease: Hydrogen Sulfide in Parkinson's Disease. Mol Neurobiol 2017; 55:3789-3799. [PMID: 28536975 DOI: 10.1007/s12035-017-0617-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 05/11/2017] [Indexed: 01/08/2023]
Abstract
Hydrogen sulfide (H2S) has been regarded as the third gaseous transmitter alongside nitric oxide (NO) and carbon monoxide (CO). In mammalian brain, H2S is produced redundantly by four enzymatic pathways, implying its abundance in the organ. In physiological conditions, H2S has been found to induce the formation of long-term potential in neuronal cells by augmenting the activity of N-methyl-D-aspartate (NMDA) receptor. Likewise, it also actively takes part in the regulation of intracellular Ca2+ and pH homeostasis in both neuronal cells and glia cells. Intriguingly, emerging evidence indicates a connection of H2S with Parkinson's disease. Specifically, the endogenous H2S level in the substantia nigra (SN) is significantly reduced along with 6-hydroxydopamine (6-OHDA) treatment in rats, while supplementation of H2S not only reverses 6-OHDA-induced neuronal loss but also attenuates the following disorders of movement, suggesting a protective effect of H2S in Parkinson's disease (PD). Remarkably, the protective effect has been extensively demonstrated with various in vitro and in vivo PD models. These suggest that H2S may be a new hope for the treatment of PD. Further studies have shown that the protective effects can be ascribed to H2S-mediated anti-oxidation, anti-inflammation, anti-apoptosis, and pro-survival activity, which are also summarized in the review. Moreover, the progresses on the development of H2S donors are also conveyed with an emphasis on the treatment of PD. Nevertheless, one should bear in mind that the precise role of H2S in the pathogenesis of PD remains largely elusive. Therefore, more studies are warranted before turning the hope into a real therapy for PD.
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Affiliation(s)
- Xu Cao
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Lei Cao
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Lei Ding
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Jin-Song Bian
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore. .,Life Science Institute, National University of Singapore, Singapore, Singapore.
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Cao X, Bian JS. The Role of Hydrogen Sulfide in Renal System. Front Pharmacol 2016; 7:385. [PMID: 27803669 PMCID: PMC5067532 DOI: 10.3389/fphar.2016.00385] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 10/03/2016] [Indexed: 12/21/2022] Open
Abstract
Hydrogen sulfide has gained recognition as the third gaseous signaling molecule after nitric oxide and carbon monoxide. This review surveys the emerging role of H2S in mammalian renal system, with emphasis on both renal physiology and diseases. H2S is produced redundantly by four pathways in kidney, indicating the abundance of this gaseous molecule in the organ. In physiological conditions, H2S was found to regulate the excretory function of the kidney possibly by the inhibitory effect on sodium transporters on renal tubular cells. Likewise, it also influences the release of renin from juxtaglomerular cells and thereby modulates blood pressure. A possible role of H2S as an oxygen sensor has also been discussed, especially at renal medulla. Alternation of H2S level has been implicated in various pathological conditions such as renal ischemia/reperfusion, obstructive nephropathy, diabetic nephropathy, and hypertensive nephropathy. Moreover, H2S donors exhibit broad beneficial effects in renal diseases although a few conflicts need to be resolved. Further research reveals that multiple mechanisms are underlying the protective effects of H2S, including anti-inflammation, anti-oxidation, and anti-apoptosis. In the review, several research directions are also proposed including the role of mitochondrial H2S in renal diseases, H2S delivery to kidney by targeting D-amino acid oxidase/3-mercaptopyruvate sulfurtransferase (DAO/3-MST) pathway, effect of drug-like H2S donors in kidney diseases and understanding the molecular mechanism of H2S. The completion of the studies in these directions will not only improves our understanding of renal H2S functions but may also be critical to translate H2S to be a new therapy for renal diseases.
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Affiliation(s)
| | - Jin-Song Bian
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of SingaporeSingapore, Singapore
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Slow sulfide donor GYY4137 differentiates NG108-15 neuronal cells through different intracellular transporters than dbcAMP. Neuroscience 2016; 325:100-10. [PMID: 27038748 DOI: 10.1016/j.neuroscience.2016.03.057] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2015] [Revised: 03/07/2016] [Accepted: 03/24/2016] [Indexed: 11/20/2022]
Abstract
Cellular differentiation is the process, by which a cell changes from one cell type to another, preferentially to the more specialized one. Calcium fluxes play an important role in this action. Differentiated NG108-15 or PC12 cells serve as models for studying neuronal pathways. NG108-15 cell line is a reliable model of cholinergic neuronal cells. These cells differentiate to a neuronal phenotype due to the dibutyryl cAMP (dbcAMP) treatment. We have shown that a slow sulfide donor - GYY4137 - can also act as a differentiating factor in NG108-15 cell line. Calcium is an unavoidable ion required in NG108-15 cell differentiation by both, dbcAMP and GYY4137, since cultivation in EGTA completely prevented differentiation of these cells. In this work we focused primarily on the role of reticular calcium in the process of NG108-15 cell differentiation. We have found that dbcAMP and also GYY4137 decreased reticular calcium concentration by different mechanisms. GYY4137 caused a rapid decrease in type 2 sarco/endoplasmic calcium ATPase (SERCA2) mRNA and protein, which results in lower calcium levels in the endoplasmic reticulum compared to the control, untreated group. The dbcAMP revealed rapid increase in expression of the type 3 IP3 receptor, which participates in a calcium clearance from the endoplasmic reticulum. These results point to the important role of reticular calcium in a NG108-15 cell differentiation.
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Cronican AA, Frawley KL, Ahmed H, Pearce LL, Peterson J. Antagonism of Acute Sulfide Poisoning in Mice by Nitrite Anion without Methemoglobinemia. Chem Res Toxicol 2015; 28:1398-408. [PMID: 25951111 DOI: 10.1021/acs.chemrestox.5b00015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
There are currently no FDA-approved antidotes for H2S/sulfide intoxication. Sodium nitrite, if given prophylactically to Swiss Webster mice, was shown to be highly protective against the acute toxic effects of sodium hydrosulfide (∼LD40 dose) with both agents administered by intraperitoneal injections. However, sodium nitrite administered after the toxicant dose did not detectably ameliorate sulfide toxicity in this fast-delivery, single-shot experimental paradigm. Nitrite anion was shown to rapidly produce NO in the bloodstream, as judged by the appearance of EPR signals attributable to nitrosylhemoglobin and methemoglobin, together amounting to less than 5% of the total hemoglobin present. Sulfide-intoxicated mice were neither helped by the supplemental administration of 100% oxygen nor were there any detrimental effects. Compared to cyanide-intoxicated mice, animals surviving sulfide intoxication exhibited very short knockdown times (if any) and full recovery was extremely fast (∼15 min) irrespective of whether sodium nitrite was administered. Behavioral experiments testing the ability of mice to maintain balance on a rotating cylinder showed no motor impairment up to 24 h post sulfide exposure. It is argued that antagonism of sulfide inhibition of cytochrome c oxidase by NO is the crucial antidotal activity of nitrite rather than formation of methemoglobin.
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Affiliation(s)
- Andrea A Cronican
- Department of Environmental and Occupational Health, Graduate School of Public Health, The University of Pittsburgh, 100 Technology Drive, Pittsburgh, Pennsylvania 15219, United States
| | - Kristin L Frawley
- Department of Environmental and Occupational Health, Graduate School of Public Health, The University of Pittsburgh, 100 Technology Drive, Pittsburgh, Pennsylvania 15219, United States
| | - Humza Ahmed
- Department of Environmental and Occupational Health, Graduate School of Public Health, The University of Pittsburgh, 100 Technology Drive, Pittsburgh, Pennsylvania 15219, United States
| | - Linda L Pearce
- Department of Environmental and Occupational Health, Graduate School of Public Health, The University of Pittsburgh, 100 Technology Drive, Pittsburgh, Pennsylvania 15219, United States
| | - Jim Peterson
- Department of Environmental and Occupational Health, Graduate School of Public Health, The University of Pittsburgh, 100 Technology Drive, Pittsburgh, Pennsylvania 15219, United States
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Szabo C, Ransy C, Módis K, Andriamihaja M, Murghes B, Coletta C, Olah G, Yanagi K, Bouillaud F. Regulation of mitochondrial bioenergetic function by hydrogen sulfide. Part I. Biochemical and physiological mechanisms. Br J Pharmacol 2014; 171:2099-122. [PMID: 23991830 DOI: 10.1111/bph.12369] [Citation(s) in RCA: 304] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2013] [Revised: 08/08/2013] [Accepted: 08/12/2013] [Indexed: 12/11/2022] Open
Abstract
Until recently, hydrogen sulfide (H2 S) was exclusively viewed a toxic gas and an environmental hazard, with its toxicity primarily attributed to the inhibition of mitochondrial Complex IV, resulting in a shutdown of mitochondrial electron transport and cellular ATP generation. Work over the last decade established multiple biological regulatory roles of H2 S, as an endogenous gaseous transmitter. H2 S is produced by cystathionine γ-lyase (CSE), cystathionine β-synthase (CBS) and 3-mercaptopyruvate sulfurtransferase (3-MST). In striking contrast to its inhibitory effect on Complex IV, recent studies showed that at lower concentrations, H2 S serves as a stimulator of electron transport in mammalian cells, by acting as a mitochondrial electron donor. Endogenous H2 S, produced by mitochondrially localized 3-MST, supports basal, physiological cellular bioenergetic functions; the activity of this metabolic support declines with physiological aging. In specialized conditions (calcium overload in vascular smooth muscle, colon cancer cells), CSE and CBS can also associate with the mitochondria; H2 S produced by these enzymes, serves as an endogenous stimulator of cellular bioenergetics. The current article overviews the biochemical mechanisms underlying the stimulatory and inhibitory effects of H2 S on mitochondrial function and cellular bioenergetics and discusses the implication of these processes for normal cellular physiology. The relevance of H2 S biology is also discussed in the context of colonic epithelial cell physiology: colonocytes are exposed to high levels of sulfide produced by enteric bacteria, and serve as a metabolic barrier to limit their entry into the mammalian host, while, at the same time, utilizing it as a metabolic 'fuel'.
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Affiliation(s)
- Csaba Szabo
- Department of Anesthesiology, University of Texas Medical Branch, Galveston, TX, USA
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Jurkowska H, Roman HB, Hirschberger LL, Sasakura K, Nagano T, Hanaoka K, Krijt J, Stipanuk MH. Primary hepatocytes from mice lacking cysteine dioxygenase show increased cysteine concentrations and higher rates of metabolism of cysteine to hydrogen sulfide and thiosulfate. Amino Acids 2014; 46:1353-65. [PMID: 24609271 DOI: 10.1007/s00726-014-1700-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 02/14/2014] [Indexed: 01/12/2023]
Abstract
The oxidation of cysteine in mammalian cells occurs by two routes: a highly regulated direct oxidation pathway in which the first step is catalyzed by cysteine dioxygenase (CDO) and by desulfhydration-oxidation pathways in which the sulfur is released in a reduced oxidation state. To assess the effect of a lack of CDO on production of hydrogen sulfide (H2S) and thiosulfate (an intermediate in the oxidation of H2S to sulfate) and to explore the roles of both cystathionine γ-lyase (CTH) and cystathionine β-synthase (CBS) in cysteine desulfhydration by liver, we investigated the metabolism of cysteine in hepatocytes isolated from Cdo1-null and wild-type mice. Hepatocytes from Cdo1-null mice produced more H2S and thiosulfate than did hepatocytes from wild-type mice. The greater flux of cysteine through the cysteine desulfhydration reactions catalyzed by CTH and CBS in hepatocytes from Cdo1-null mice appeared to be the consequence of their higher cysteine levels, which were due to the lack of CDO and hence lack of catabolism of cysteine by the cysteinesulfinate-dependent pathways. Both CBS and CTH appeared to contribute substantially to cysteine desulfhydration, with estimates of 56 % by CBS and 44 % by CTH in hepatocytes from wild-type mice, and 63 % by CBS and 37 % by CTH in hepatocytes from Cdo1-null mice.
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Affiliation(s)
- Halina Jurkowska
- Division of Nutritional Sciences, Cornell University, 227 Savage Hall, Ithaca, NY, 14853, USA
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Álvarez C, García I, Romero LC, Gotor C. Mitochondrial sulfide detoxification requires a functional isoform O-acetylserine(thiol)lyase C in Arabidopsis thaliana. MOLECULAR PLANT 2012; 5:1217-26. [PMID: 22511607 DOI: 10.1093/mp/sss043] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
In non-cyanogenic species, the main source of cyanide derives from ethylene and camalexin biosyntheses. In mitochondria, cyanide is a potent inhibitor of the cytochrome c oxidase and is metabolized by the β-cyanoalanine synthase CYS-C1, catalyzing the conversion of cysteine and cyanide to hydrogen sulfide and β-cyanoalanine. The hydrogen sulfide released also inhibits the cytochrome c oxidase and needs to be detoxified by the O-acetylserine(thiol)lyase mitochondrial isoform, OAS-C, which catalyzes the incorporation of sulfide to O-acetylserine to produce cysteine, thus generating a cyclic pathway in the mitochondria. The loss of functional OAS-C isoforms causes phenotypic characteristics very similar to the loss of the CYS-C1 enzyme, showing defects in root hair formation. Genetic complementation with the OAS-C gene rescues the impairment of root hair elongation, restoring the wild-type phenotype. The mitochondria compromise their capacity to properly detoxify cyanide and the resulting sulfide because the latter cannot re-assimilate into cysteine in the oas-c null mutant. Consequently, we observe an accumulation of sulfide and cyanide and of the alternative oxidase, which is unable to prevent the production of reactive oxygen species probably due to the accumulation of both toxic molecules. Our results allow us to suggest that the significance of OAS-C is related to its role in the proper sulfide and cyanide detoxification in mitochondria.
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Affiliation(s)
- Consolación Álvarez
- Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas y Universidad de Sevilla, Avda. Américo Vespucio, 49, 41092 Sevilla, Spain
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Wei X, Duan L, Bai L, Tian M, Li W, Zhang B. Effects of exogenous hydrogen sulfide on brain metabolism and early neurological function in rabbits after cardiac arrest. Intensive Care Med 2012; 38:1877-85. [PMID: 23011534 DOI: 10.1007/s00134-012-2714-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Accepted: 09/09/2012] [Indexed: 10/27/2022]
Abstract
PURPOSE Some of the neuroprotective effects of hydrogen sulfide (H(2)S) have been attributed to systemic hypometabolism and hypothermia. However, systemic metabolism may vary more dramatically than brain metabolism after cardiac arrest (CA). The authors investigated the effects of inhaled exogenous hydrogen sulfide on brain metabolism and neurological function in rabbits after CA and resuscitation. METHODS Anesthetized rabbits were randomized into a sham group, a sham/H(2)S group, a CA group, and a CA/H(2)S group. Exogenous 80 ppm H(2)S was administered to the sham/H(2)S group and the CA/H(2)S group which suffered 3 min of untreated CA by asphyxia and resuscitation. Effects on brain metabolism (cerebral extraction of oxygen (CEO(2)), arterio-jugular venous difference of glucose [AJVD(glu)] and lactate clearance), S100B, viable neuron counts, neurological dysfunction score, and survival rate were evaluated. RESULTS CEO(2), AJVD(glu), and lactate increased significantly after CA. Inhalation of 80 ppm H(2)S significantly increased CEO(2) (25.04 ± 7.11 vs. 16.72 ± 6.12 %) and decreased AJVD(glu) (0.77 ± 0.29 vs. 1.18 ± 0.38 mmol/L) and lactate (5.11 ± 0.43 vs. 6.01 ± 0.64 mmol/L) at 30 min after resuscitation when compared with the CA group (all P < 0.05). In addition, neurologic deficit scores, viable neuron counts, and survival rate were significantly better whereas S100B was decreased after H(2)S inhalation. CONCLUSIONS The present study reveals that inhalation of 80 ppm H(2)S reduced neurohistopathological damage and improves early neurological function after CA and resuscitation in rabbits. The increased CEO(2) and decreased AJVD(glu) and enhanced lactate clearance may be involved in the protective effects.
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Affiliation(s)
- Xia Wei
- Department of Anesthesiology, Second Affiliated Hospital of Harbin Medical University, 150086, Harbin, China
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Wang R. Physiological implications of hydrogen sulfide: a whiff exploration that blossomed. Physiol Rev 2012; 92:791-896. [PMID: 22535897 DOI: 10.1152/physrev.00017.2011] [Citation(s) in RCA: 1372] [Impact Index Per Article: 114.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The important life-supporting role of hydrogen sulfide (H(2)S) has evolved from bacteria to plants, invertebrates, vertebrates, and finally to mammals. Over the centuries, however, H(2)S had only been known for its toxicity and environmental hazard. Physiological importance of H(2)S has been appreciated for about a decade. It started by the discovery of endogenous H(2)S production in mammalian cells and gained momentum by typifying this gasotransmitter with a variety of physiological functions. The H(2)S-catalyzing enzymes are differentially expressed in cardiovascular, neuronal, immune, renal, respiratory, gastrointestinal, reproductive, liver, and endocrine systems and affect the functions of these systems through the production of H(2)S. The physiological functions of H(2)S are mediated by different molecular targets, such as different ion channels and signaling proteins. Alternations of H(2)S metabolism lead to an array of pathological disturbances in the form of hypertension, atherosclerosis, heart failure, diabetes, cirrhosis, inflammation, sepsis, neurodegenerative disease, erectile dysfunction, and asthma, to name a few. Many new technologies have been developed to detect endogenous H(2)S production, and novel H(2)S-delivery compounds have been invented to aid therapeutic intervention of diseases related to abnormal H(2)S metabolism. While acknowledging the challenges ahead, research on H(2)S physiology and medicine is entering an exponential exploration era.
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Affiliation(s)
- Rui Wang
- Department of Biology, Lakehead University, Thunder Bay, Ontario, Canada.
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Liu YH, Lu M, Hu LF, Wong PTH, Webb GD, Bian JS. Hydrogen sulfide in the mammalian cardiovascular system. Antioxid Redox Signal 2012; 17:141-85. [PMID: 22304473 DOI: 10.1089/ars.2011.4005] [Citation(s) in RCA: 198] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
For more than a century, hydrogen sulfide (H(2)S) has been regarded as a toxic gas. This review surveys the growing recognition of the role of H(2)S as an endogenous signaling molecule in mammals, with emphasis on its physiological and pathological pathways in the cardiovascular system. In biological fluids, H(2)S gas is a weak acid that exists as about 15% H(2)S, 85% HS(-), and a trace of S(2-). Here, we use "H(2)S" to refer to this mixture. H(2)S has been found to influence heart contractile functions and may serve as a cardioprotectant for treating ischemic heart diseases and heart failure. Alterations of the endogenous H(2)S level have been found in animal models with various pathological conditions such as myocardial ischemia, spontaneous hypertension, and hypoxic pulmonary hypertension. In the vascular system, H(2)S exerts biphasic regulation of a vascular tone with varying effects based on its concentration and in the presence of nitric oxide. Over the past decade, several H(2)S-releasing compounds (NaHS, Na(2)S, GYY4137, etc.) have been utilized to test the effect of exogenous H(2)S under different physiological and pathological situations in vivo and in vitro. H(2)S has been found to promote angiogenesis and to protect against atherosclerosis and hypertension, while excess H(2)S may promote inflammation in septic or hemorrhagic shock. H(2)S-releasing compounds and inhibitors of H(2)S synthesis hold promise in alleviating specific disease conditions. This comprehensive review covers in detail the effects of H(2)S on the cardiovascular system, especially in disease situations, and also the various underlying mechanisms.
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Affiliation(s)
- Yi-Hong Liu
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
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Hydrogen sulfide (H2S) metabolism in mitochondria and its regulatory role in energy production. Proc Natl Acad Sci U S A 2012; 109:2943-8. [PMID: 22323590 DOI: 10.1073/pnas.1115634109] [Citation(s) in RCA: 334] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Although many types of ancient bacteria and archea rely on hydrogen sulfide (H(2)S) for their energy production, eukaryotes generate ATP in an oxygen-dependent fashion. We hypothesize that endogenous H(2)S remains a regulator of energy production in mammalian cells under stress conditions, which enables the body to cope with energy demand when oxygen supply is insufficient. Cystathionine γ-lyase (CSE) is a major H(2)S-producing enzyme in the cardiovascular system that uses cysteine as the main substrate. Here we show that CSE is localized only in the cytosol, not in mitochondria, of vascular smooth-muscle cells (SMCs) under resting conditions, revealed by Western blot analysis and confocal microscopy of SMCs transfected with GFP-tagged CSE plasmid. After SMCs were exposed to A23187, thapsigargin, or tunicamycin, intracellular calcium level was increased, and CSE translocated from the cytosol to mitochondria. CSE was coimmunoprecipitated with translocase of the outer membrane 20 (Tom20) in mitochondrial membrane. Tom20 siRNA significantly inhibited mitochondrial translocation of CSE and mitochondrial H(2)S production. The cysteine level inside mitochondria is approximately three times that in the cytosol. Translocation of CSE to mitochondria metabolized cysteine, produced H(2)S inside mitochondria, and increased ATP production. Inhibition of CSE activity reversed A23187-stimulated mitochondrial ATP production. H(2)S improved mitochondrial ATP production in SMCs with hypoxia, which alone decreased ATP production. These results suggest that translocation of CSE to mitochondria on specific stress stimulations is a unique mechanism to promote H(2)S production inside mitochondria, which subsequently sustains mitochondrial ATP production under hypoxic conditions.
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Hydrogen sulfide replacement therapy protects the vascular endothelium in hyperglycemia by preserving mitochondrial function. Proc Natl Acad Sci U S A 2011; 108:13829-34. [PMID: 21808008 DOI: 10.1073/pnas.1105121108] [Citation(s) in RCA: 225] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The goal of the present studies was to investigate the role of changes in hydrogen sulfide (H(2)S) homeostasis in the pathogenesis of hyperglycemic endothelial dysfunction. Exposure of bEnd3 microvascular endothelial cells to elevated extracellular glucose (in vitro "hyperglycemia") induced the mitochondrial formation of reactive oxygen species (ROS), which resulted in an increased consumption of endogenous and exogenous H(2)S. Replacement of H(2)S or overexpression of the H(2)S-producing enzyme cystathionine-γ-lyase (CSE) attenuated the hyperglycemia-induced enhancement of ROS formation, attenuated nuclear DNA injury, reduced the activation of the nuclear enzyme poly(ADP-ribose) polymerase, and improved cellular viability. In vitro hyperglycemia resulted in a switch from oxidative phosphorylation to glycolysis, an effect that was partially corrected by H(2)S supplementation. Exposure of isolated vascular rings to high glucose in vitro induced an impairment of endothelium-dependent relaxations, which was prevented by CSE overexpression or H(2)S supplementation. siRNA silencing of CSE exacerbated ROS production in hyperglycemic endothelial cells. Vascular rings from CSE(-/-) mice exhibited an accelerated impairment of endothelium-dependent relaxations in response to in vitro hyperglycemia, compared with wild-type controls. Streptozotocin-induced diabetes in rats resulted in a decrease in the circulating level of H(2)S; replacement of H(2)S protected from the development of endothelial dysfunction ex vivo. In conclusion, endogenously produced H(2)S protects against the development of hyperglycemia-induced endothelial dysfunction. We hypothesize that, in hyperglycemic endothelial cells, mitochondrial ROS production and increased H(2)S catabolism form a positive feed-forward cycle. H(2)S replacement protects against these alterations, resulting in reduced ROS formation, improved endothelial metabolic state, and maintenance of normal endothelial function.
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Levitt MD, Abdel-Rehim MS, Furne J. Free and acid-labile hydrogen sulfide concentrations in mouse tissues: anomalously high free hydrogen sulfide in aortic tissue. Antioxid Redox Signal 2011; 15:373-8. [PMID: 20812866 DOI: 10.1089/ars.2010.3525] [Citation(s) in RCA: 134] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Endogenously produced hydrogen sulfide is thought to function as an intracellular messenger. There is, however, little information on tissue concentrations of free hydrogen sulfide, the putative messenger form of this molecule, versus that of the bound (acid-labile) form. The present report describes the application of a novel technique to measure free and acid-labile hydrogen sulfide in mouse tissues. Very low free hydrogen sulfide concentrations (<0.050 μmol/kg) were observed in brain, liver, blood, heart, kidney, striated muscle, and esophagus. Aortic concentrations of free hydrogen sulfide were 20 to 100 times greater than that of the other tissues. Acid-labile hydrogen sulfide concentrations were multiple orders of magnitude greater than that of the free form in every tissue other than aorta. Previous reports of tissue hydrogen sulfide concentrations of 30 to >100 μmol/kg measured bound rather than free hydrogen sulfide, the observation that aorta contains anomalously high free hydrogen sulfide concentrations lends support for a vasodilator function for this molecule, and the very low free hydrogen sulfide concentrations in most tissues seemingly requires intermediation of a yet to be described receptor-like mechanism if this molecule is to serve as a gasotransmitter.
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Affiliation(s)
- Michael D Levitt
- Research Service, Veterans Affairs Medical Center, Minneapolis, Minnesota 55417, USA
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Wu N, Du X, Wang D, Hao F. Myocardial and lung injuries induced by hydrogen sulfide and the effectiveness of oxygen therapy in rats. Clin Toxicol (Phila) 2011; 49:161-6. [PMID: 21495884 DOI: 10.3109/15563650.2011.565419] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE To study myocardial and lung injuries initiated by hydrogen sulfide, and evaluate the role and effectiveness of normobaric and hyperbaric oxygen (HBO) treatment in rats. METHODS One hundred healthy male Wistar rats were randomly divided into five groups: A: Normal control group (no H2S); B: H2S-exposed group; C: H2S+33% oxygen treatment group; D: H2S+50% oxygen treatment group; E: H2S+HBO group. The rats in groups C, D and E were exposed to H2S in an exposure chamber (1 m3) and were made to inhale 300 ppm hydrogen sulfide for 60 min, and then they were subjected to normobaric or HBO therapy. Normobaric oxygen was at concentrations of 33% or 50%, HBO was for 100 min including compression and decompression; the rats in group A inhaled air under the same conditions. Blood was sampled immediately after the experiment for analysis of arterial blood gases, myocardial enzymes and cardiac troponin I. Lung was rapidly removed to be made into tissue homogenates and then cytochrome c oxidase activity was measured; myocardial and lung ultrastructural changes were observed by electron microscopy. RESULTS Arterial blood gases: partial pressure of O2 (mmHg) (Group A, 97.6 ± 8.38; B, 76.5 ± 6.95*; C, 83.2 ± 2.66*; D, 86.20 ± 10.75*; E, 93.50 ± 4.97: *p < 0.01 compared to group A) was significantly lower than that in group in all but HBO rats. For myocardial enzymes and cardiac troponin I every parameter in groups B and C was significantly higher than that in group A (p<0.01),with no difference in D and E. Cytochrome c oxidase activity (u/mg) of lung tissue was reduced compared to group A after all treatments (A, 1.76 ± 0.02; B, 0.36 ± 0.04; C, 0.50 ± 0.12; D, 0.56 ± 0.07; E, 0.68 ± 0.05 (A vs. B p < 0.01; B vs. C,D,E p < 0.05 or p < 0.01), with a graded effect of oxygen dose in C, D and E. Pathological changes: (1) Myocardium - Mitochondrial swelling and autolysis with blurred or broken cristae was observed in the myocardium of H2S-exposed group; in group E, mitochondrial structure was basically normal, and clear cristae were found. (2) Lung tissue - In H2S-exposed group, alveolar epithelial cells disappeared, vacuolization of the organelle occurred, nuclear membrane was irregular and marginal condensation of heterochromatin was present; nucleus showed relatively normal morphology in group E, although some vacuoles still persisted within them. CONCLUSIONS HBO therapy can effectively improve arterial oxygen partial pressure, and significantly reduce myocardial damage, as well as potentially relieve lung injury in this model. Further work in humans appears warranted.
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Affiliation(s)
- Na Wu
- Department of Occupational Diseases and Clinical Toxicology, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China
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Hu LF, Lu M, Tiong CX, Dawe GS, Hu G, Bian JS. Neuroprotective effects of hydrogen sulfide on Parkinson's disease rat models. Aging Cell 2010; 9:135-46. [PMID: 20041858 DOI: 10.1111/j.1474-9726.2009.00543.x] [Citation(s) in RCA: 262] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Parkinson's disease (PD) is a neurodegenerative disorder characterized by a progressive loss of dopaminergic neurons in the substantia nigra (SN). The present study was designed to examine the therapeutic effect of hydrogen sulfide (H(2)S, a novel biological gas) on PD. The endogenous H(2)S level was markedly reduced in the SN in a 6-hydroxydopamine (6-OHDA)-induced PD rat model. Systemic administration of NaHS (an H(2)S donor) dramatically reversed the progression of movement dysfunction, loss of tyrosine-hydroxylase positive neurons in the SN and the elevated malondialdehyde level in injured striatum in the 6-OHDA-induced PD model. H(2)S specifically inhibited 6-OHDA evoked NADPH oxidase activation and oxygen consumption. Similarly, administration of NaHS also prevented the development of PD induced by rotenone. NaHS treatment inhibited microglial activation in the SN and accumulation of pro-inflammatory factors (e.g. TNF-alpha and nitric oxide) in the striatum via NF-kappaB pathway. Moreover, significantly less neurotoxicity was found in neurons treated with the conditioned medium from microglia incubated with both NaHS and rotenone compared to that with rotenone only, suggesting that the therapeutic effect of NaHS was, at least partially, secondary to its suppression of microglial activation. In summary, we demonstrate for the first time that H(2)S may serve as a neuroprotectant to treat and prevent neurotoxin-induced neurodegeneration via multiple mechanisms including anti-oxidative stress, anti-inflammation and metabolic inhibition and therefore has potential therapeutic value for treatment of PD.
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Affiliation(s)
- Li-Fang Hu
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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Downs CA, Fauth JE, Downs VD, Ostrander GK. In vitro cell-toxicity screening as an alternative animal model for coral toxicology: effects of heat stress, sulfide, rotenone, cyanide, and cuprous oxide on cell viability and mitochondrial function. ECOTOXICOLOGY (LONDON, ENGLAND) 2010; 19:171-184. [PMID: 19757033 DOI: 10.1007/s10646-009-0403-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 08/12/2009] [Indexed: 05/28/2023]
Abstract
The logistics involved in obtaining and maintaining large numbers of corals hampers research on the toxicological effects of environmental contaminants for this ecologically and economically important taxon. A method for creating and culturing single-cell suspensions of viable coral cells was developed. Cell segregation/separation was based on specific cell densities and resulting cell cultures were viable for at least 2 mos. Low-density cells lacking symbiotic zooxanthallae and rich in mitochondria were isolated and cultured for toxicity studies. Cells were exposed to differing degrees or concentrations of heat stress, rotenone, cyanide, sulfide, and cuprous oxide. Cells were assayed for mitochondrial membrane potential using the fluorescent probe, JC-9, and for overall viability using the MTT/formazan spectrophotometric viability assay. Significant differences were observed between controls and treatments and the efficacy of this method was validated; only 2 cm(2) of tissue was required for a seven-point concentration-exposure series.
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Affiliation(s)
- Craig A Downs
- Haereticus Environmental Laboratory, P.O. Box 92, Clifford, VA 24533, USA.
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Gases in the mitochondria. Mitochondrion 2009; 10:83-93. [PMID: 20005988 DOI: 10.1016/j.mito.2009.12.142] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2009] [Revised: 11/03/2009] [Accepted: 12/07/2009] [Indexed: 12/20/2022]
Abstract
Gasomodulators - nitric oxide, carbon monoxide and hydrogen sulphide - are important physiological mediators that have been implicated in disorders such as neurodegeneration and sepsis. Some of their biological functions involve the mitochondria. In particular, their inhibition of cytochrome c oxidase has received much attention as this can cause energy depletion and cytotoxicity. However, reports that cellular energy production and cell survival are maintained even in the presence of gasomodulators are not uncommon. In both cases, modulation of mitochondrial targets by the gasomodulators appears to be an important event. We provide an overview of the effects of the gasomodulators on the mitochondria.
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Blachier F, Davila AM, Mimoun S, Benetti PH, Atanasiu C, Andriamihaja M, Benamouzig R, Bouillaud F, Tomé D. Luminal sulfide and large intestine mucosa: friend or foe? Amino Acids 2009; 39:335-47. [PMID: 20020161 DOI: 10.1007/s00726-009-0445-2] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2009] [Accepted: 12/02/2009] [Indexed: 02/06/2023]
Abstract
Hydrogen sulfide (H(2)S) is present in the lumen of the human large intestine at millimolar concentrations. However, the concentration of free (unbound) sulfide is in the micromolar range due to a large capacity of fecal components to bind the sulfide. H(2)S can be produced by the intestinal microbiota from alimentary and endogenous sulfur-containing compounds including amino acids. At excessive concentration, H(2)S is known to severely inhibit cytochrome c oxidase, the terminal oxidase of the mitochondrial electron transport chain, and thus mitochondrial oxygen (O(2)) consumption. However, the concept that sulfide is simply a metabolic troublemaker toward colonic epithelial cells has been challenged by the discovery that micromolar concentration of H(2)S is able to increase the cell respiration and to energize mitochondria allowing these cells to detoxify and to recover energy from luminal sulfide. The main product of H(2)S metabolism by the colonic mucosa is thiosulfate. The enzymatic activities involved in sulfide oxidation by the colonic epithelial cells appear to be sulfide quinone oxidoreductase considered as the first and rate-limiting step followed presumably by the action of sulfur dioxygenase and rhodanese. From clinical studies with human volunteers and experimental works with rodents, it appears that H(2)S can exert mostly pro- but also anti-inflammatory effects on the colonic mucosa. From the available data, it is tempting to propose that imbalance between the luminal concentration of free sulfide and the capacity of colonic epithelial cells to metabolize this compound will result in an impairment of the colonic epithelial cell O(2) consumption with consequences on the process of mucosal inflammation. In addition, endogenously produced sulfide is emerging as a prosecretory neuromodulator and as a relaxant agent toward the intestinal contractibility. Lastly, sulfide has been recently described as an agent involved in nociception in the large intestine although, depending on the experimental design, both pro- and anti-nociceptive effects have been reported.
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Affiliation(s)
- François Blachier
- INRA, AgroParisTech, CRNH IdF, UMR 914 Nutrition Physiology and Ingestive Behavior, Paris, France.
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Pong WW, Eldred WD. Interactions of the gaseous neuromodulators nitric oxide, carbon monoxide, and hydrogen sulfide in the salamander retina. J Neurosci Res 2009; 87:2356-64. [PMID: 19267415 DOI: 10.1002/jnr.22042] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The three gaseous neuromodulators nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S) are endogenously produced in vertebrate retinas. The NO/cyclic guanosine monophosphate (cGMP) and CO/cGMP pathways have been previously shown to interact synergistically in the turtle retina to increase cGMP levels. In this study, we examined H2S as a modulator of cGMP-like immunoreactivity (-LI) and its interactions with the NO/CO/cGMP signaling pathways in the tiger salamander retina. Stimulation with NO donor or CO significantly increased cGMP-LI from basal levels in bipolar and amacrine cells and in stratified arborizations in the inner plexiform layer. Stimulation with a combination of NO donor and CO significantly increased cGMP-LI above that seen with either stimulation alone. Nitric oxide synthase inhibitors reduced CO-induced cGMP-LI, suggesting that CO-induced cGMP-LI is not produced from direct activation of soluble guanylate cyclase. Exogenous H2S alone, from the donor NaHS, did not significantly modify cGMP-LI in dosages ranging from 2 to 1,200 microM NaHS, but there was a significant decrease in NO-induced cGMP-LI in the presence of 200 muM NaHS. This reduction of NO-induced cGMP-LI was not significantly affected by the addition of CuCl2, suggesting that the decrease was not a result of H2S and NO sequestering to form a novel nitrosothiol. NaHS did not have any significant effect on CO-induced cGMP-LI levels. Our results concur with previous studies showing synergistic interactions between NO and CO/cGMP retinal signaling pathways. We now show that H2S inhibits NO-induced cGMP-LI but not CO-induced cGMP-LI. In conclusion, all three gaseous neuromodulators have interactive roles in modulating retinal cGMP signaling.
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Affiliation(s)
- Winnie W Pong
- Laboratory of Visual Neurobiology, Department of Biology, Boston University, Boston, MA 02215, USA
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Krueger S, Niehl A, Lopez Martin MC, Steinhauser D, Donath A, Hildebrandt T, Romero LC, Hoefgen R, Gotor C, Hesse H. Analysis of cytosolic and plastidic serine acetyltransferase mutants and subcellular metabolite distributions suggests interplay of the cellular compartments for cysteine biosynthesis in Arabidopsis. PLANT, CELL & ENVIRONMENT 2009; 32:349-367. [PMID: 19143986 DOI: 10.1111/j.1365-3040.2009.01928.x] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In plants, the enzymes for cysteine synthesis serine acetyltransferase (SAT) and O-acetylserine-(thiol)-lyase (OASTL) are present in the cytosol, plastids and mitochondria. However, it is still not clearly resolved to what extent the different compartments are involved in cysteine biosynthesis and how compartmentation influences the regulation of this biosynthetic pathway. To address these questions, we analysed Arabidopsis thaliana T-DNA insertion mutants for cytosolic and plastidic SAT isoforms. In addition, the subcellular distribution of enzyme activities and metabolite concentrations implicated in cysteine and glutathione biosynthesis were revealed by non-aqueous fractionation (NAF). We demonstrate that cytosolic SERAT1.1 and plastidic SERAT2.1 do not contribute to cysteine biosynthesis to a major extent, but may function to overcome transport limitations of O-acetylserine (OAS) from mitochondria. Substantiated by predominantly cytosolic cysteine pools, considerable amounts of sulphide and presence of OAS in the cytosol, our results suggest that the cytosol is the principal site for cysteine biosynthesis. Subcellular metabolite analysis further indicated efficient transport of cysteine, gamma-glutamylcysteine and glutathione between the compartments. With respect to regulation of cysteine biosynthesis, estimation of subcellular OAS and sulphide concentrations established that OAS is limiting for cysteine biosynthesis and that SAT is mainly present bound in the cysteine-synthase complex.
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Affiliation(s)
- Stephan Krueger
- Max Planck Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, 14476 Potsdam-Golm, France
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Cardioprotection by metabolic shut-down and gradual wake-up. J Mol Cell Cardiol 2009; 46:804-10. [PMID: 19285082 DOI: 10.1016/j.yjmcc.2009.02.026] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Revised: 02/26/2009] [Accepted: 02/27/2009] [Indexed: 10/21/2022]
Abstract
Mitochondria play a critical role in cardiac function, and are also increasingly recognized as end effectors for various cardioprotective signaling pathways. Mitochondria use oxygen as a substrate, so by default their respiration is inhibited during hypoxia/ischemia. However, at reperfusion a surge of oxygen and metabolic substrates into the cell is thought to lead to rapid reestablishment of respiration, a burst of reactive oxygen species (ROS) generation and mitochondrial Ca(2+) overload. Subsequently these events precipitate opening of the mitochondrial permeability transition (PT) pore, which leads to myocardial cell death and dysfunction. Given that mitochondrial respiration is already inhibited during hypoxia/ischemia, it is somewhat surprising that many respiratory inhibitors can improve recovery from ischemia-reperfusion (IR) injury. In addition ischemic preconditioning (IPC), in which short non-lethal cycles of IR can protect against subsequent prolonged IR injury, is known to lead to endogenous inhibition of several respiratory complexes and glycolysis. This has led to a hypothesis that the wash-out of inhibitors or reversal of endogenous inhibition at reperfusion may afford protection by facilitating a more gradual wake-up of mitochondrial function, thereby avoiding a burst of ROS and Ca(2+) overload. This paper will review the evidence in support of this hypothesis, with a focus on inhibition of each of the mitochondrial respiratory complexes.
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Truong DH, Eghbal MA, Hindmarsh W, Roth SH, O'Brien PJ. Molecular Mechanisms of Hydrogen Sulfide Toxicity. Drug Metab Rev 2008; 38:733-44. [PMID: 17145698 DOI: 10.1080/03602530600959607] [Citation(s) in RCA: 181] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
RATIONALE The toxicity of H2S has been attributed to its ability to inhibit cytochrome c oxidase in a similar manner to HCN. However, the successful use of methemoglobin for the treatment of HCN poisoning was not successful for H2S poisonings even though the ferric heme group of methemoglobin scavenges H2S. Thus, we speculated that other mechanisms contribute to H2S induced cytotoxicity. Experimental procedure. Hepatocyte isolation and viability and enzyme activities were measured as described by Moldeus et al. (1978), and Steen et al. (2001). RESULTS Incubation of isolated hepatocytes with NaHS solutions (a H2S source) resulted in glutathione (GSH) depletion. Moreover, GSH depletion was also observed in TRIS-HCl buffer (pH 6.0) treated with NaHS. Several ferric chelators (desferoxamime and DETAPAC) and antioxidant enzymes (superoxide dismutase [SOD] and catalase) prevented cell-free and hepatocyte GSH depletion. GSH-depleted hepatocytes were very susceptible to NaHS cytotoxicity, indicating that GSH detoxified NaHS or H2S in cells. Cytotoxicity was also partly prevented by desferoxamine and DETAPC, but it was increased by ferric EDTA or EDTA. Cell-free oxygen consumption experiments in TRIS-HCl buffer showed that NaHS autoxidation formed hydrogen peroxide and was prevented by DETAPC but increased by EDTA. We hypothesize that H2S can reduce intracellular bound ferric iron to form unbound ferrous iron, which activates iron. Additionally, H2S can increase the hepatocyte formation of reactive oxygen species (ROS) (known to occur with electron transport chain). H2S cytotoxicity therefore also involves a reactive sulfur species, which depletes GSH and activates oxygen to form ROS.
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Affiliation(s)
- Don H Truong
- Department of Pharmaceutical Sciences, University of Toronto, Toronto, Ontario, Canada
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Furne J, Saeed A, Levitt MD. Whole tissue hydrogen sulfide concentrations are orders of magnitude lower than presently accepted values. Am J Physiol Regul Integr Comp Physiol 2008; 295:R1479-85. [PMID: 18799635 DOI: 10.1152/ajpregu.90566.2008] [Citation(s) in RCA: 446] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hydrogen sulfide is gaining acceptance as an endogenously produced modulator of tissue function. The present paradigm of H(2)S (diprotonated, gaseous form of hydrogen sulfide) as a tissue messenger consists of H(2)S being released from the desulfhydration of l-cysteine at a rate sufficient to maintain whole tissue hydrogen sulfide concentrations of 30 microM to >100 microM, and these tissue concentrations serve a messenger function. Utilizing physiological concentrations of l-cysteine and aerobic conditions, we found that catabolism of hydrogen sulfide by mouse liver and brain homogenates exceeded the rate of enzymatic release of this compound such that measureable hydrogen sulfide release was less with tissue-containing vs. tissue-free buffers. Analyses of the gas space over rapidly homogenized mouse brain and liver indicated that in situ tissue hydrogen sulfide concentrations were only about 15 nM. Human alveolar air measurements indicated negligible free H(2)S concentrations in blood. We conclude rapid tissue catabolism of hydrogen sulfide maintains whole tissue brain and liver concentrations of free hydrogen sulfide that are three orders of magnitude less than conventionally accepted values and only 1/5,000 of the hydrogen sulfide concentration (100 microM) required to alter cellular function in vitro. For hydrogen sulfide to serve as an endogenously produced messenger, tissue production and catabolism must result in intracellular microenvironments with a sufficiently high hydrogen sulfide concentration to activate a local signaling mechanism, while whole tissue concentrations remain very low.
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Affiliation(s)
- Julie Furne
- Research Service, 151 VAMC, 1 Veterans Dr., Minneapolis, MN 55417, USA
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Hydrogen sulfide decreases adenosine triphosphate levels in aortic rings and leads to vasorelaxation via metabolic inhibition. Life Sci 2008; 83:589-94. [PMID: 18790700 DOI: 10.1016/j.lfs.2008.08.006] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2008] [Revised: 07/04/2008] [Accepted: 08/15/2008] [Indexed: 12/16/2022]
Abstract
AIMS Hydrogen sulfide (H(2)S) at low concentrations serves as a physiological endogenous vasodilator molecule, while at higher concentrations it can trigger cytotoxic effects. The aim of our study was to elucidate the potential mechanisms responsible for the effects of H(2)S on vascular tone. MAIN METHODS We measured the vascular tone in vitro in precontracted rat thoracic aortic rings and we have tested the effect of different oxygen levels and a variety of inhibitors affecting known vasodilatory pathways. We have also compared the vascular effect of high concentrations of H(2)S to those of pharmacological inhibitors of oxidative phosphorylation. Furthermore, we measured adenosine triphosphate (ATP)-levels in the same vascular tissues. KEY FINDINGS We have found that in rat aortic rings: (1) H(2)S decreases ATP levels; (2) relaxations to H(2)S depend on the ambient oxygen concentration; (3) prostaglandins do not take part in the H(2)S induced relaxations; (4) the 3':5'-cyclic guanosine monophosphate (cGMP)-nitric oxide (NO) pathway does not have a role in the relaxations (5) the role of K(ATP) channels is limited, while Cl(-)/HCO(3)(-) channels have a role in the relaxations. (6): We have observed that high concentrations of H(2)S relax the aortic rings in a fashion similar to sodium cyanide, and both agents reduce cellular ATP levels to a comparable degree. SIGNIFICANCE H(2)S, a new gasotransmitter of emerging importance, leads to relaxation via Cl(-)/HCO(3)(-) channels and metabolic inhibition and the interactions of these two factors depend on the oxygen levels of the tissue.
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Volpato GP, Searles R, Yu B, Scherrer-Crosbie M, Bloch KD, Ichinose F, Zapol WM. Inhaled hydrogen sulfide: a rapidly reversible inhibitor of cardiac and metabolic function in the mouse. Anesthesiology 2008; 108:659-68. [PMID: 18362598 DOI: 10.1097/aln.0b013e318167af0d] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
BACKGROUND Breathing hydrogen sulfide (H2S) has been reported to induce a suspended animation-like state with hypothermia and a concomitant metabolic reduction in rodents. However, the impact of H2S breathing on cardiovascular function remains incompletely understood. In this study, the authors investigated the cardiovascular and metabolic effects of inhaled H2S in a murine model. METHODS The impact of breathing H2S on cardiovascular function was examined using telemetry and echocardiography in awake mice. The effects of breathing H2S on carbon dioxide production and oxygen consumption were measured at room temperature and in a warmed environment. RESULTS Breathing H2S at 80 parts per million by volume at 27 degrees C ambient temperature for 6 h markedly reduced heart rate, core body temperature, respiratory rate, and physical activity, whereas blood pressure remained unchanged. Echocardiography demonstrated that H2S exposure decreased both heart rate and cardiac output but preserved stroke volume. Breathing H2S for 6 h at 35 degrees C ambient temperature (to prevent hypothermia) decreased heart rate, physical activity, respiratory rate, and cardiac output without altering stroke volume or body temperature. H2S breathing seems to induce bradycardia by depressing sinus node activity. Breathing H2S for 30 min decreased whole body oxygen consumption and carbon dioxide production at either 27 degrees or 35 degrees C ambient temperature. Both parameters returned to baseline levels within 10 min after the cessation of H2S breathing. CONCLUSIONS Inhalation of H2S at either 27 degrees or 35 degrees C reversibly depresses cardiovascular function without changing blood pressure in mice. Breathing H2S also induces a rapidly reversible reduction of metabolic rate at either body temperature.
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Affiliation(s)
- Gian Paolo Volpato
- Anesthesia Center for Critical Care Research, Department of Anesthesia and Critical Care, Massachusetts General Hospital, Boston, Massachusetts, USA
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Umemura K, Kimura H. Hydrogen sulfide enhances reducing activity in neurons: neurotrophic role of H2S in the brain? Antioxid Redox Signal 2007; 9:2035-41. [PMID: 17822366 DOI: 10.1089/ars.2007.1802] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Hydrogen sulfide (H2S) can enzymatically be produced from cysteine in the brain. H2S functions as a synaptic modulator as well as a neuroprotectant from oxidative stress in the brain. Here we show that H2S specifically enhances the reducing activity in neurons and mouse neuroblastoma Neuro2a cells. An inhibitor of protein tyrosine kinase, genistein, suppresses the effect of H2S, suggesting that tyrosine kinase may be involved in the enhancement of reducing activity by H2S. The H2S-specific enhancement of the reducing activity in neurons may lead to a neurotrophic role in the brain.
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Affiliation(s)
- Ken Umemura
- National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo, Japan
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Blachier F, Mariotti F, Huneau JF, Tomé D. Effects of amino acid-derived luminal metabolites on the colonic epithelium and physiopathological consequences. Amino Acids 2006; 33:547-62. [PMID: 17146590 DOI: 10.1007/s00726-006-0477-9] [Citation(s) in RCA: 301] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2006] [Accepted: 11/09/2006] [Indexed: 02/07/2023]
Abstract
Depending on the amount of alimentary proteins, between 6 and 18 g nitrogenous material per day enter the large intestine lumen through the ileocaecal junction. This material is used as substrates by the flora resulting eventually in the presence of a complex mixture of metabolites including ammonia, hydrogen sulfide, short and branched-chain fatty acids, amines; phenolic, indolic and N-nitroso compounds. The beneficial versus deleterious effects of these compounds on the colonic epithelium depend on parameters such as their luminal concentrations, the duration of the colonic stasis, the detoxication capacity of epithelial cells in response to increase of metabolite concentrations, the cellular metabolic utilization of these metabolites as well as their effects on colonocyte intermediary and oxidative metabolism. Furthermore, the effects of metabolites on electrolyte movements through the colonic epithelium must as well be taken into consideration for such an evaluation. The situation is further complicated by the fact that other non-nitrogenous compounds are believed to interfere with these various phenomenons. Finally, the pathological consequences of the presence of excessive concentrations of these compounds are related to the short- and, most important, long-term effects of these compounds on the rapid colonic epithelium renewing and homeostasis.
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Affiliation(s)
- F Blachier
- Unité Mixte de Recherche de Physiologie de la Nutrition et du Comportement Alimentaire, Institut National de la Recherche Agronomique - Institut National Agronomique Paris-Grignon, Paris, France.
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Leschelle X, Goubern M, Andriamihaja M, Blottière HM, Couplan E, Gonzalez-Barroso MDM, Petit C, Pagniez A, Chaumontet C, Mignotte B, Bouillaud F, Blachier F. Adaptative metabolic response of human colonic epithelial cells to the adverse effects of the luminal compound sulfide. Biochim Biophys Acta Gen Subj 2005; 1725:201-12. [PMID: 15996823 DOI: 10.1016/j.bbagen.2005.06.002] [Citation(s) in RCA: 126] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2005] [Revised: 05/25/2005] [Accepted: 06/08/2005] [Indexed: 02/08/2023]
Abstract
Hydrogen sulfide (H(2)S), a bacterial metabolite present in the lumen of the large intestine, is able to exert deleterious effects on the colonic epithelium. The mechanisms involved are still poorly understood, the reported effect of sulfide being its capacity to reduce n-butyrate beta-oxidation in colonocytes. In this work, we studied both the acute effect of the sodium salt of H(2)S on human colonic epithelial cell metabolism and the adaptative response of these cells to the pre-treatment with this agent. Using the human colon carcinoma epithelial HT-29 Glc(-/+) cell model, we found that the acute effect of millimolar concentrations of NaHS was to inhibit l-glutamine, n-butyrate and acetate oxidation in a dose-dependent manner. Using micromolar concentrations of NaHS, a comparable effect but largely reversible was observed for O(2) consumption and cytochrome c oxidase activity. Pre-treatment with 1 mM NaHS induced several adaptative responses. Firstly, increased lactate release and decreased cellular oxygen consumption evidenced a Pasteur-like effect which only partly compensated for the altered mitochondrial ATP production. Thus, a decrease in the proliferation rate with a constant adenylate charge was observed. Secondly, in these pre-treated cells, NaHS induced a hypoxia-like effect on cytochrome c oxidase subunits I and II which were decreased. Thirdly, a mild uncoupling of mitochondrial respiration possibly resulting from an increase of UCP 2 protein was observed. The NaHS antimitotic activity was not due to cellular apoptosis and/or necrosis but to a proportional slowdown in all cell cycle phases. These results are compatible with a metabolic adaptative response of the HT-29 colonic epithelial cells to sulfide-induced O(2) consumption reduction which, through the maintenance of a constant energetic load and an increased mitochondrial proton leak, would participate in the preservation of cellular viability.
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Affiliation(s)
- Xavier Leschelle
- Laboratoire de Nutrition et Sécurité Alimentaire, Institut National de la Recherche Agronomique, 78352 Jouy en Josas cedex, France
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Doeller JE, Isbell TS, Benavides G, Koenitzer J, Patel H, Patel RP, Lancaster JR, Darley-Usmar VM, Kraus DW. Polarographic measurement of hydrogen sulfide production and consumption by mammalian tissues. Anal Biochem 2005; 341:40-51. [PMID: 15866526 DOI: 10.1016/j.ab.2005.03.024] [Citation(s) in RCA: 264] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2004] [Indexed: 11/17/2022]
Abstract
The role of nitric oxide (NO) in redox cell signaling is widely accepted. However, the biological role of another candidate small inorganic signaling molecule and the subject of this study, hydrogen sulfide (H2S), is much less known. H2S as a reductant and nucleophile has numerous potential cellular targets; however, its rapid biological oxidation suggests a fleeting cellular existence. The challenge of accurate real-time measurement of H2S at low micromolar or nanomolar concentrations in biological preparations represents a major impediment to H2S investigations. We here demonstrate the use of a novel polarographic H2S sensor (PHSS) to follow rapid changes in H2S concentration in common buffered biological solutions with a detection limit near 10 nM. The PHSS, used in combination with O2 and NO sensors in multisensor respirometry, shows stability, a high signal-to-noise ratio, and signal specificity for H2S. Preparations of rat vascular tissue exhibit H2S production on the addition of sulfhydryl-bearing amino acid substrates and H2S consumption when supplied with exogenous H2S. Taken together, these findings suggest the existence of dynamic steady-state cellular H2S levels. The PHSS should facilitate the investigation of H2S biology by providing a previously unattainable continuous record of H2S under biologically relevant conditions.
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Affiliation(s)
- Jeannette E Doeller
- Department of Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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Dombkowski RA, Russell MJ, Schulman AA, Doellman MM, Olson KR. Vertebrate phylogeny of hydrogen sulfide vasoactivity. Am J Physiol Regul Integr Comp Physiol 2004; 288:R243-52. [PMID: 15345473 DOI: 10.1152/ajpregu.00324.2004] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hydrogen sulfide (H(2)S) is a recently identified endogenous vasodilator in mammals. In steelhead/rainbow trout (Oncorhynchus mykiss, Osteichthyes), H(2)S produces both dose-dependent dilation and a unique dose-dependent constriction. In this study, we examined H(2)S vasoactivity in all vertebrate classes to determine whether H(2)S is universally vasoactive and to identify phylogenetic and/or environmental trends. H(2)S was generated from NaHS and examined in unstimulated and precontracted systemic and, when applicable, pulmonary arteries (PA) from Pacific hagfish (Eptatretus stouti, Agnatha), sea lamprey (Petromyzon marinus, Agnatha), sandbar shark (Carcharhinus milberti, Chondrichthyes), marine toad (Bufo marinus, Amphibia), American alligator (Alligator mississippiensis, Reptilia), Pekin duck (Anas platyrhynchos domesticus, Aves), and white rat (Rattus rattus, Mammalia). In otherwise unstimulated vessels, NaHS produced 1) a dose-dependent relaxation in Pacific hagfish dorsal aorta; 2) a dose-dependent contraction in sea lamprey dorsal aorta, marine toad aorta, alligator aorta and PA, duck aorta, and rat thoracic aorta; 3) a threshold relaxation in shark ventral aorta, dorsal aorta, and afferent branchial artery; and 4) a multiphasic contraction-relaxation-contraction in the marine toad PA, duck PA, and rat PA. Precontraction of these vessels with another agonist did not affect the general pattern of NaHS vasoactivity with the exception of the rat aorta, where relaxation was now dominant. These results show that H(2)S is a phylogenetically ancient and versatile vasoregulatory molecule that appears to have been opportunistically engaged to suit both organ-specific and species-specific homeostatic requirements.
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Affiliation(s)
- Ryan A Dombkowski
- South Bend Center for Medical Education, Indiana University School of Medicine, University of Notre Dame, Notre Dame, IN 46556, USA
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Teague B, Asiedu S, Moore PK. The smooth muscle relaxant effect of hydrogen sulphide in vitro: evidence for a physiological role to control intestinal contractility. Br J Pharmacol 2003. [PMID: 12208769 DOI: 10.1038/sj.bjp.0704858/abstract] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
1. Sodium hydrogen sulphide (NaHS), a donor of hydrogen sulphide (H(2)S), produced dose-related relaxation of the rabbit isolated ileum (EC(50), 76.4+/-7.9 microM) and rat vas deferens (EC(50), 64.8+/-5.4 microM) and reduced ACh-mediated contraction of the guinea-pig isolated ileum. 2. NaHS also reduced the response of the guinea-pig (EC(50), 80.0+/-5.7 microM) and rat (EC(50), 108.2+/-11.2 microM) ileum preparations to electrical stimulation of the intramural nerves. In guinea-pig ileum this effect was spontaneously reversible and mimicked by sodium nitroprusside (SNP, EC(50), 2.1 microM). Combination of NaHS (20 microM) with SNP (0.5 microM) produced a greater than additive inhibition of the twitch response of the ileum to electrical stimulation. 3. The inhibitory effect of NaHS on the field-stimulated guinea-pig ileum was unaffected by pretreatment with L-NAME (100 microM), indomethacin (10 microM), naloxone (1 microM) or glibenclamide (100 microM). Furthermore, NaHS (200 microM) did not affect the contractile response of the ileum to KCl (10 to 60 mM). 4. Propargylglycine (PAG, 1 mM) and beta-cyanoalanine (BCA, 1 mM) (inhibitors of cystathionine-gamma-lyase) but not aminooxyacetic acid (AOAA, 1 mM) (inhibitor of cystathionine-beta-synthetase) caused a slowly developing increase in the contraction of the guinea-pig ileum to field stimulation. This effect was reversed by cysteine (1 mM). 5. These results show that NaHS relaxes gastrointestinal and urogenital smooth muscle and suggest that H(2)S is responsible for these effects. The possibility that endogenous H(2)S, formed as a consequence of activation of intramural nerves, plays a part in controlling the contractility of the guinea-pig ileum is discussed.
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Affiliation(s)
- B Teague
- Centre for Cardiovascular Biology and Medicine, King's College, University of London, London SE1 1UL, UK
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Teague B, Asiedu S, Moore PK. The smooth muscle relaxant effect of hydrogen sulphide in vitro: evidence for a physiological role to control intestinal contractility. Br J Pharmacol 2002; 137:139-45. [PMID: 12208769 PMCID: PMC1573483 DOI: 10.1038/sj.bjp.0704858] [Citation(s) in RCA: 217] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2002] [Revised: 06/26/2002] [Accepted: 06/27/2002] [Indexed: 01/02/2023] Open
Abstract
1. Sodium hydrogen sulphide (NaHS), a donor of hydrogen sulphide (H(2)S), produced dose-related relaxation of the rabbit isolated ileum (EC(50), 76.4+/-7.9 microM) and rat vas deferens (EC(50), 64.8+/-5.4 microM) and reduced ACh-mediated contraction of the guinea-pig isolated ileum. 2. NaHS also reduced the response of the guinea-pig (EC(50), 80.0+/-5.7 microM) and rat (EC(50), 108.2+/-11.2 microM) ileum preparations to electrical stimulation of the intramural nerves. In guinea-pig ileum this effect was spontaneously reversible and mimicked by sodium nitroprusside (SNP, EC(50), 2.1 microM). Combination of NaHS (20 microM) with SNP (0.5 microM) produced a greater than additive inhibition of the twitch response of the ileum to electrical stimulation. 3. The inhibitory effect of NaHS on the field-stimulated guinea-pig ileum was unaffected by pretreatment with L-NAME (100 microM), indomethacin (10 microM), naloxone (1 microM) or glibenclamide (100 microM). Furthermore, NaHS (200 microM) did not affect the contractile response of the ileum to KCl (10 to 60 mM). 4. Propargylglycine (PAG, 1 mM) and beta-cyanoalanine (BCA, 1 mM) (inhibitors of cystathionine-gamma-lyase) but not aminooxyacetic acid (AOAA, 1 mM) (inhibitor of cystathionine-beta-synthetase) caused a slowly developing increase in the contraction of the guinea-pig ileum to field stimulation. This effect was reversed by cysteine (1 mM). 5. These results show that NaHS relaxes gastrointestinal and urogenital smooth muscle and suggest that H(2)S is responsible for these effects. The possibility that endogenous H(2)S, formed as a consequence of activation of intramural nerves, plays a part in controlling the contractility of the guinea-pig ileum is discussed.
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Affiliation(s)
- B Teague
- Centre for Cardiovascular Biology and Medicine, King's College, University of London, London SE1 1UL
| | - S Asiedu
- Centre for Cardiovascular Biology and Medicine, King's College, University of London, London SE1 1UL
| | - P K Moore
- Centre for Cardiovascular Biology and Medicine, King's College, University of London, London SE1 1UL
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Brenneman KA, Meleason DF, Sar M, Marshall MW, James RA, Gross EA, Martin JT, Dorman DC. Olfactory mucosal necrosis in male CD rats following acute inhalation exposure to hydrogen sulfide: reversibility and the possible role of regional metabolism. Toxicol Pathol 2002; 30:200-8. [PMID: 11950163 DOI: 10.1080/019262302753559533] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Hydrogen sulfide (H2S) is a potent inhibitor of cytochrome oxidase (CO) and is associated with dysosmia and anosmia in humans and nasal lesions in exposed rodents. An improved understanding of the pathogenesis of these lesions is needed to determine their toxicological relevance. We exposed 10-week-old male CD rats to 0, 30, 80, 200, or 400 ppm H2S for 3 hours/day for 1 or 5 days consecutively. The nose was histologically examined 24 hours after H2S exposure, and lesion recovery was assessed at 2 and 6 weeks following the 5-day exposure. A single 3-hour exposure to > or = 80 ppm H2S resulted in regeneration of the respiratory mucosa and full thickness necrosis of the olfactory mucosa localized to the ventral and dorsal meatus, respectively. Repeated exposure to the same concentrations caused necrosis of the olfactory mucosa with early mucosal regeneration that extended from the dorsal medial meatus to the caudal regions of the ethmoid recess. Acute exposure to 400 ppm H2S induced severe mitochondrial swelling in sustentacular cells and olfactory neurons, which progressed to olfactory epithelial necrosis and sloughing. CO immunoreactive cells were more frequently observed in regions of the olfactory mucosa commonly affected by H2S than in regions that were not. These findings demonstrate that acute exposure to >80 ppm H2S resulted in reversible lesions in the respiratory and olfactory mucosae of the CD rat and that CO immunoreactivity may be a susceptibility factor for H2S-induced olfactory toxicity in the rat.
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Affiliation(s)
- Karrie A Brenneman
- CIIT Centers for Health Research, Research Triangle Park, North Carolina 27709, USA
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Abstract
Mental retardation is progressive in Down syndrome: individuals are born with normal intelligence which starts to decline linearly within the first year. This phenomenon can be observed with phenylalanine in patients with phenylketonuria, therefore it is compatible with metabolic intoxication. The toxic compound could be hydrogen sulfide. The amount of the compound is probably increased in Down syndrome by increasing active cystathionine beta synthase. This heuristic hypothesis requires further investigation.
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Affiliation(s)
- P Kamoun
- Laboratoire de Biochimie médicale B, Hôpital Necker - Enfants Malades, Paris, France.
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Struve MF, Brisbois JN, James RA, Marshall MW, Dorman DC. Neurotoxicological effects associated with short-term exposure of Sprague-Dawley rats to hydrogen sulfide. Neurotoxicology 2001; 22:375-85. [PMID: 11456338 DOI: 10.1016/s0161-813x(01)00021-3] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Although hydrogen sulfide (H2S) is a known neurotoxic hazard, only a limited number of experimental animal studies have examined its neurochemical or behavioral effects. Our aim was to determine if short-term inhalation exposure of rats to H2S would result in altered brain catecholamnine levels or impaired learning and memory. Three groups of adult male CD rats were tested; two groups were exposed by nose-only inhalation (0, 30, 80, 200, or 400 ppm H2S) and one group was exposed by whole-body inhalation (0, 10, 30, or 80 ppm H2S) for 3 h per day forfive consecutive days. The first group (n = 10 rats per concentration) was tested immediately following each daily nose-only H2S exposure for spatial learning with a Morris water maze. Core body temperatures were also monitored in these animals during and after the last H2S exposure. The second group of rats (n = 10 rats per concentration) was tested for spontaneous motor activity immediately following the fifth exposure. These rats were then euthanized and striatal, hippocampal, and hindbrain catecholamnine levels determined. A third group of rats (n = 5-7 rats per concentration) was pretrained on a multiple fixed- interval (FI) schedule and exposed whole-body. Daily performance on the FI schedule was compared for the week pre-exposure, for the exposure week immediately following daily exposures, and for the week postexposure. We observed significant reductions in motor activity, water maze performance, and body temperature following exposure only to high concentrations (> or = 80 ppm) of H2S. Exposure to H2S did not affect regional brain catecholamine concentrations or performance on the FI schedule. Additional studies using other measures of behavior and longer-term exposure to H2S may be required to more definitively address conditions under which H2S exposure results in behavioral toxicity.
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Affiliation(s)
- M F Struve
- CIIT Centers for Health Research, Research Triangle Park, NC, USA.
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Abstract
Mitochondria have long been recognized as the generators of energy for the cell. Like any other power source, however, mitochondria are highly vulnerable to inhibition or uncoupling of the energy harnessing process and run a high risk for catastrophic damage to the cell. The exquisite structural and functional characteristics of mitochondria provide a number of primary targets for xenobiotic-induced bioenergetic failure. They also provide opportunities for selective delivery of drugs to the mitochondrion. In light of the large number of natural, commercial, pharmaceutical, and environmental chemicals that manifest their toxicity by interfering with mitochondrial bioenergetics, it is important to understand the underlying mechanisms. The significance is further underscored by the recent identification of bioenergetic control points for cell replication and differentiation and the realization that mitochondria play a determinant role in cell signaling and apoptotic modes of cell death.
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Affiliation(s)
- K B Wallace
- Department of Biochemistry and Molecular Biology, University of Minnesota School of Medicine, Duluth 55812, USA.
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