The detection and quantification, in vivo and in real time, of hydrogen sulfide in ethanol-induced lesions in rat stomachs using an ion sensitive electrode

Unmet needs in glaucoma therapy: The potential role of hydrogen sulfide and its delivery strategies

Glaucoma is an optic neuropathy disorder marked by progressive degeneration of the retinal ganglion cells (RGC). It is a leading cause of blindness worldwide, prevailing in around 2.2% of the global population. The hallmark of glaucoma, intraocular pressure (IOP), is governed by the aqueous humor dynamics which plays a crucial role in the pathophysiology of the diesease. Glaucomatous eye has an IOP of more than 22 mmHg as compared to normotensive pressure of 10-21 mmHg. Currently used treatments focus on reducing the elevated IOP through use of classes of drugs that either increase aqueous humor outflow and/or decrease its production. However, effective treatments should not only reduce IOP, but also offer neuroprotection and regeneration of RGCs. Hydrogen Sulfide (H₂S), a gasotransmitter with several endogenous functions in mammalian tissues, is being investigated for its potential application in glaucoma. In addition to decreasing IOP by increasing aqueous humor outflow, it scavenges reactive oxygen species, upregulates the cellular antioxidant glutathione and protects RGCs from excitotoxicity. Despite the potential of H₂S in glaucoma, its delivery to anterior and posterior regions of the eye is a challenge due to its unique physicochemical properties. Firstly, development of any delivery system should not require an aqueous environment since many H₂S donors are susceptible to burst release of the gas in contact with water, causing potential toxicity and adverse effects owing to its inherent toxicity at higher concentrations. Secondly, the release of the gas from the donor needs to be sustained for a prolonged period of time to reduce dosing frequency as per the requirements of regulatory bodies. Lastly, the delivery system should provide adequate bioavailability throughout its period of application. Hence, an ideal delivery system should aim to tackle all the above challenges related to barriers of ocular delivery and physicochemical properties of H₂S itself. This review discusses the therapeutic potential of H₂S, its delivery challenges and strategies to overcome the associated chalenges.

Disrupted H2S Signaling by Cigarette Smoking and Alcohol Drinking: Evidence from Cellular, Animal, and Clinical Studies

The role of endogenous hydrogen sulfide (H₂S) as an antioxidant regulator has sparked interest in its function within inflammatory diseases. Cigarette and alcohol use are major causes of premature death, resulting from chronic oxidative stress and subsequent tissue damage. The activation of the Nrf2 antioxidant response by H₂S suggests that this novel gasotransmitter may function to prevent or potentially reverse disease progression caused by cigarette smoking or alcohol use. The purpose of this study is to review the interrelationship between H₂S signaling and cigarette smoking or alcohol drinking. Based on the databases of cellular, animal, and clinical studies from Pubmed using the keywords of H₂S, smoking, and/or alcohol, this review article provides a comprehensive insight into disrupted H₂S signaling by alcohol drinking and cigarette smoking-caused disorders. Major signaling and metabolic pathways involved in H₂S-derived antioxidant and anti-inflammatory responses are further reviewed. H₂S supplementation may prove to be an invaluable asset in treating or preventing diseases in those suffering from cigarette or alcohol addiction.

Gasotransmitters in pregnancy: from conception to uterine involution

Gasotransmitters are endogenous small gaseous messengers exemplified by nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S or sulfide). Gasotransmitters are implicated in myriad physiologic functions including many aspects of reproduction. Our objective was to comprehensively review basic mechanisms and functions of gasotransmitters during pregnancy from conception to uterine involution and highlight future research opportunities. We searched PubMed and Web of Science databases using combinations of keywords nitric oxide, carbon monoxide, sulfide, placenta, uterus, labor, and pregnancy. We included English language publications on human and animal studies from any date through August 2018 and retained basic and translational articles with relevant original findings. All gasotransmitters activate cGMP signaling. NO and sulfide also covalently modify target protein cysteines. Protein kinases and ion channels transduce gasotransmitter signals, and co-expressed gasotransmitters can be synergistic or antagonistic depending on cell type. Gasotransmitters influence tubal transit, placentation, cervical remodeling, and myometrial contractility. NO, CO, and sulfide dilate resistance vessels, suppress inflammation, and relax myometrium to promote uterine quiescence and normal placentation. Cervical remodeling and rupture of fetal membranes coincide with enhanced oxidation and altered gasotransmitter metabolism. Mechanisms mediating cellular and organismal changes in pregnancy due to gasotransmitters are largely unknown. Altered gasotransmitter signaling has been reported for preeclampsia, intrauterine growth restriction, premature rupture of membranes, and preterm labor. However, in most cases specific molecular changes are not yet characterized. Nonclassical signaling pathways and the crosstalk among gasotransmitters are emerging investigation topics.

The role of hydrogen sulfide in gastric mucosal damage

Gastrointestinal disease is a major global threat to public health. In the past few decades, numerous studies have focuses on the application of small molecule gases in the disease treatment. Increasing evidence has shown that hydrogen sulfide (H₂S) has anti-inflammatory and anti-oxidative effects, and can regulate gastric mucosal blood flow in the gastric mucosa. After gastric mucosa damage, the level of H₂S in the stomach decreases. Administration of H₂S can protect and repair the damaged gastric mucosa. Therefore, H₂S is a new target for the repair and treatment of gastric mucosa damage. In this review, we introduce the roles of H₂S in the treatment of gastric mucosa damage and provide the potential strategies for further clinical treatment.

Real-time in vivo detection techniques for neurotransmitters: a review

Functional synapses in the central nervous system depend on a chemical signal exchange process that involves neurotransmitter delivery between neurons and receptor cells in the neuro system.

Novel Applications of Lead Acetate and Flow Cytometry Methods for Detection of Sulfur-Containing Molecules

Hydrogen sulfide (H₂S) is the most recently established gaseous vasodilator, enzymatically produced from cysteine metabolism, involved in a number of pathophysiological processes. However, its accurate detection in vivo is critical due to its volatility and tendency to form sulfane sulfur derivatives, thus limiting the data interpretation of its biological roles. We developed new applications of the simple and rapid method to measure H₂S release in cell culture systems, based on the lead acetate strip test. This test, previously prevalently used in microbiology, was compared with the agar trap method, applied, in parallel, on both cell cultures and cell-free samples. Sulfane sulfur represents the major species derived from intracellular H₂S. Various fluorescent probes are available for quantitation of H₂S derivatives intracellularly. We present here an alternative to the classic imaging method for sulfane sulfur evaluation, running on a flow cytometer, based on SSP4 probe labeling. Flow cytometry turned out to be more direct, fully quantitative and less time-consuming compared to microscopy and more precise with respect to the fluorescence multi-plate reader assay. The new application methods for H₂S determination appear to be fully suitable for the analysis of H₂S release and sulfane sulfur content in biological samples.

Hydrogen sulfide exposure induces jejunum injury via CYP450s/ROS pathway in broilers

Hydrogen sulfide (H₂S) is generally recognized as a highly poisonous environmental and industrial pollutant. Previous toxicological studies of H₂S are mainly focused on the nervous and cardiovascular system. There are few reports on the H₂S toxicity effects on jejunum to our knowledge. Our study examined the morphological changes and antioxidant functions of broiler jejunum after the 42-day exposure to H₂S. Effects of H₂S on morphological damage and immune function in the broiler jejunum were analyzed from the perspective of CYP450s and oxidative stress via transcriptomics and quantitative real-time PCR (qRT-PCR). It was found that the activities of GPx, CAT, SOD, and T-AOC and the level of GSH were observably decreased (P < 0.05), while the contents of MDA and H₂O₂ were remarkably increased (P < 0.05) in the jejunums of broilers exposed to H₂S, which undergone a process of oxidative stress, and typical inflammatory changes and apoptosis could be observed. Transcriptional profiling results showed that 208 genes were significantly up-regulated while 295 genes were remarkably down-regulated in H₂S group. The expression of CYP450s, inflammation and apoptosis-related genes were also significantly increased. In conclusion, H₂S led to the redox homeostasis disorder through CYP450s differential expression in broiler jejunum. The jejunal inflammatory response, apoptosis along with the immune dysfunction were subsequently observed, which eventually caused jejunal morphology and functional damage. The present study further enriches and perfects the mechanism theory of H₂S toxicity on broilers, which may be valuable for the risk assessment of H₂S and human health protection.