Hydrogen sulfide prevents the vascular dysfunction induced by severe traumatic brain injury in rats by reducing reactive oxygen species and modulating eNOS and H2S-synthesizing enzyme expression

Reconnecting the roots of hydrogen sulfide (H2S) with medicinal chemistry: Lessons accomplished and challenges so far

Previously known for its unpleasant odour and mortality in elevated concentrations, hydrogen sulfide (H2S) is currently considered a complex molecule having significant physiological advantages. After nitric oxide (NO) and carbon monoxide (CO), H2S is regarded as the third endogenous gasotransmitter, performing many biological functions in the human body. The essential functions include but are not limited to regulating inflammation, maintaining the redox potential, cellular signalling, and metabolic processes. Moreover, an imbalance in its expression or dysfunction of its precursors and associated enzymes in its biosynthesis leads to multiple pathological conditions, including cancer, diabetes, neurodegenerative disorders, COVID-19, etc. Nonetheless, its upregulation is also reported to dysregulate normal physiological conditions and precipitate different diseases and cancer, thus acting as a "Double-edged sword." Despite this, H2S is still being widely explored for its therapeutic potential in various disease states. The present review is put forth to focus on hydrogen sulfide's dichotomous properties, emphasising its critical functions and therapeutic applications. This compilation provides a state-of-the-art analysis of the broad application of H2S donors in developing therapeutic interventions, release mechanisms, and their use in numerous diseases and disorders. Furthermore, various analytical techniques for detecting and quantifying the H2S release in biological samples via the hybrid donors are also discussed. We herein expect that an in-depth comprehension of the multiple activities of H2S can aid in discovering novel therapeutic interventions critical for holistic disease management measures in the future.

Hydrogen sulfide detection: Recent advancement and future perspectives towards fluorescence as a versatile Biophysical method

Hydrogen Sulfide (H2S) is an essential gaseous signaling molecule involved in various physiological processes, including vasodilation, neurotransmission, and anti-inflammatory responses. Accurate detection and quantification of H2S in biological systems are crucial for elucidating its physiological and pathological roles. Fluorescent probes have emerged as indispensable tools for H2S detection, offering high sensitivity, specificity, and the ability for real-time and non-invasive monitoring. This review discusses recent advances in the design and development of fluorescent probes for H2S detection, focusing on their mechanisms, properties, and applications. We explore the different strategies employed in probe design, including reduction-based mechanisms, nucleophilic addition reactions, and cleavage of sulfide bonds. Innovations such as ratiometric probes, two-photon fluorescent probes, and multi-functional probes have significantly enhanced the capabilities of H2S detection. These advancements have facilitated cellular and subcellular imaging, real-time monitoring in live organisms, and the investigation of H2S-related pathologies. Despite these progresses, challenges remain, including improving probe selectivity, stability, and biocompatibility, as well as developing methods for accurate quantification in complex biological matrices. Future research directions include designing probes with higher selectivity and sensitivity, integrating advanced computational modeling, and combining fluorescent probes with mass spectrometry for precise quantification. The continued development of sophisticated fluorescent probes will expand our understanding of H2S biology, offering new insights into its physiological and pathological roles and paving the way for novel therapeutic strategies.

Neuroprotective Effects of Sodium Nitroprusside on CKD-Induced Cognitive Dysfunction in Rats: Role of CBS and Nrf2/HO-1 Pathway

Chronic kidney disease (CKD) is a conceivable new risk factor for cognitive disorder and dementia. Uremic toxicity, oxidative stress, and peripheral-central inflammation have been considered important mediators of CKD-induced nervous disorders. Nitric oxide (NO) is a retrograde neurotransmitter in synapses, and has vital roles in intracellular signaling in neurons. This research aims to determine the effectiveness of NO in CKD-induced cognitive deficits by considering the nuclear factor-erythroid factor 2-related factor 2 (Nrf2)/ heme oxygenase-1 (HO-1) signaling pathway and the important roles of cystathionine beta-synthase (CBS, H2S producing enzyme). Forty rats were divided into four experimental groups: sham, five-sixth (5/6) nephrectomy (5/6Nx, CKD), CKD + NO donor (Sodium nitroprusside, SNP), CKD + SNP and a CBS inhibitor (amino-oxy acetic acid, AOAA). To assess the neurocognitive abilities, eleven weeks after 5/6Nx, behavioral tests (Novel object recognition test, Passive avoidance test, and Barnes maze test) were done. Twelfth week after 5/6Nx, blood urea nitrogen (BUN) and serum creatinine (sCr) levels, as well as the nuclear factor-erythroid factor 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1) expression levels and neuronal injury in the hippocampus and prefrontal cortex were assessed. As predicted, the levels of BUN and sCr (both P < 0.001) and neuronal injury in the hippocampus (P < 0.001 for CA1; CA3; DG) and prefrontal cortex (P < 0.001) increased in CKD rats as well as 5/6Nx induced reduction of Nrf2 (both P < 0.001) /HO-1(P < 0.001; P < 0.01 respectively) pathway activity in the hippocampus and prefrontal cortex in CKD rats. Moreover, CKD leads to cognitive disorder and memory loss (Novel object recognition test (NOR) (P < 0.001), Passive avoidance test (PA) (P < 0.001) and Barnes maze (BA) (Escape latency (P < 0.001); Error (P < 0.001)). SNP treatment significantly improved Nrf2 (both P < 0.001) /HO-1 (P < 0.001; P < 0.05 respectively) pathways and neuronal injury (P < 0.001 for CA1; CA3; DG) in the hippocampus and prefrontal cortex in CKD rats as well as enhanced learning and memory ability in CKD rats. However, ameliorating effects of SNP on cognitive disorder (NOR (P < 0.05), PA (P < 0.001) and BA (Escape latency (P < 0.05); Error (P < 0.001)) and Nrf2 (P < 0.01; P < 0.001 in the hippocampus and prefrontal cortex respectively) /HO-1 (P < 0.05 in both) signaling pathway activity were nullified by CBS inhibitor and H2S reduction. In conclusion, this study demonstrated that NO improved CKD-induced cognitive impairment and neuronal death which is may be depended to CBS activity and endogenous H2S levels.

Biomaterials and tissue engineering in traumatic brain injury: novel perspectives on promoting neural regeneration

Traumatic brain injury is a serious medical condition that can be attributed to falls, motor vehicle accidents, sports injuries and acts of violence, causing a series of neural injuries and neuropsychiatric symptoms. However, limited accessibility to the injury sites, complicated histological and anatomical structure, intricate cellular and extracellular milieu, lack of regenerative capacity in the native cells, vast variety of damage routes, and the insufficient time available for treatment have restricted the widespread application of several therapeutic methods in cases of central nervous system injury. Tissue engineering and regenerative medicine have emerged as innovative approaches in the field of nerve regeneration. By combining biomaterials, stem cells, and growth factors, these approaches have provided a platform for developing effective treatments for neural injuries, which can offer the potential to restore neural function, improve patient outcomes, and reduce the need for drugs and invasive surgical procedures. Biomaterials have shown advantages in promoting neural development, inhibiting glial scar formation, and providing a suitable biomimetic neural microenvironment, which makes their application promising in the field of neural regeneration. For instance, bioactive scaffolds loaded with stem cells can provide a biocompatible and biodegradable milieu. Furthermore, stem cells-derived exosomes combine the advantages of stem cells, avoid the risk of immune rejection, cooperate with biomaterials to enhance their biological functions, and exert stable functions, thereby inducing angiogenesis and neural regeneration in patients with traumatic brain injury and promoting the recovery of brain function. Unfortunately, biomaterials have shown positive effects in the laboratory, but when similar materials are used in clinical studies of human central nervous system regeneration, their efficacy is unsatisfactory. Here, we review the characteristics and properties of various bioactive materials, followed by the introduction of applications based on biochemistry and cell molecules, and discuss the emerging role of biomaterials in promoting neural regeneration. Further, we summarize the adaptive biomaterials infused with exosomes produced from stem cells and stem cells themselves for the treatment of traumatic brain injury. Finally, we present the main limitations of biomaterials for the treatment of traumatic brain injury and offer insights into their future potential.

Dynamic Changes and Effects of H2S, IGF-1, and GH in the Traumatic Brain Injury

The aim of this study was to examine the expression changes of H2S, IGF-1, and GH in traumatic brain injury (TBI) patients and to detect their neuroprotective functions after TBI. In this study, we first collected cerebrospinal fluid (CSF) and plasma from TBI patients at different times after injury and evaluated the concentrations of H2S, IGF-1, and GH. In vitro studies were using the scratch-induced injury model and cell-cell interaction model (HT22 hippocampal neurons co-cultured with LPS-induced BV2 microglia cells). In vivo studies were using the controlled cortical impact (CCI) model in mice. Cell viability was assessed by CCK-8 assay. Pro-inflammatory cytokines expression was determined by qRT-PCR, ELISA, and nitric oxide production. Western blot was performed to assess the expression of CBS, CSE, IGF-1, and GHRH. Moreover, the recovery of TBI mice was evaluated for behavioral function by applying the modified Neurological Severity Score (mNSS), the Rotarod test, and the Morris water maze. We discovered that serum H2S, CSF H2S, and serum IGF-1 concentrations were all adversely associated with the severity of the TBI, while the concentrations of IGF-1 and GH in CSF and GH in the serum were all positively related to TBI severity. Experiments in vitro and in vivo indicated that treatment with NaHS (H2S donor), IGF-1, and MR-409 (GHRH agonist) showed protective effects after TBI. This study gives novel information on the functions of H2S, IGF-1, and GH in TBI.

Salidroside enhances NO bioavailability and modulates arginine metabolism to alleviate pulmonary arterial hypertension

BACKGROUND

Salidroside (SAL), derived from Rhodiola, shows protective effects in pulmonary arterial hypertension (PAH) models, but its mechanisms are not fully elucidated.

OBJECTIVES

Investigate the therapeutic effects and the mechanism of SAL on PAH.

METHODS

Monocrotaline was used to establish a PAH rat model. SAL's impact on oxidative stress and inflammatory responses in lung tissues was analyzed using immunohistochemistry, ELISA, and Western blot. Untargeted metabolomics explored SAL's metabolic regulatory mechanisms.

RESULTS

SAL significantly reduced mean pulmonary artery pressure, right ventricular hypertrophy, collagen deposition, and fibrosis in the PAH rats. It enhanced antioxidant enzyme levels, reduced inflammatory cytokines, and improved NO bioavailability by upregulating endothelial nitric oxide synthase (eNOS), soluble guanylate cyclase (sGC), cyclic guanosine monophosphate (cGMP), and protein kinase G (PKG) and decreases the expression of endothelin-1 (ET-1). Metabolomics indicated SAL restored metabolic balance in PAH rats, particularly in arginine metabolism.

CONCLUSIONS

SAL alleviates PAH by modulating arginine metabolism, enhancing NO synthesis, and improving pulmonary vascular remodeling.

The role of hydrogen sulfide regulation of ferroptosis in different diseases

Ferroptosis is a programmed cell death that relies on iron and lipid peroxidation. It differs from other forms of programmed cell death such as necrosis, apoptosis and autophagy. More and more evidence indicates that ferroptosis participates in many types of diseases, such as neurodegenerative diseases, ischemia-reperfusion injury, cardiovascular diseases and so on. Hence, clarifying the role and mechanism of ferroptosis in diseases is of great significance for further understanding the pathogenesis and treatment of some diseases. Hydrogen sulfide (H2S) is a colorless and flammable gas with the smell of rotten eggs. Many years ago, H2S was considered as a toxic gas. however, in recent years, increasing evidence indicates that it is the third important gas signaling molecule after nitric oxide and carbon monoxide. H2S has various physiological and pathological functions such as antioxidant stress, anti-inflammatory, anti-apoptotic and anti-tumor, and can participate in various diseases. It has been reported that H2S regulation of ferroptosis plays an important role in many types of diseases, however, the related mechanisms are not fully clear. In this review, we reviewed the recent literature about the role of H2S regulation of ferroptosis in diseases, and analyzed the relevant mechanisms, hoping to provide references for future in-depth researches.

Sodium Hydrosulfide Reverts Chronic Stress-Induced Cardiovascular Alterations by Reducing Oxidative Stress

ABSTRACT

Chronic stress induces a group of unrecognized cardiovascular impairments, including elevated hemodynamic variables and vascular dysfunction. Moreover, hydrogen sulfide (H 2 S), a gasotransmitter that regulates the cardiovascular system decreases under chronic stress. Thus, this study assessed the impact of sodium hydrosulfide (NaHS) (H 2 S donor) on chronic restraint stress (CRS)-induced cardiovascular changes. For that purpose, male Wistar rats were restrained for 2 hours a day in a transparent acrylic tube over 8 weeks. Then, body weight, relative adrenal gland weight, serum corticosterone, H 2 S-synthesizing enzymes, endothelial nitric oxide synthetize expression, reactive oxygen species levels, lipid peroxidation, and reduced glutathione-to-oxidized glutathione (GSH 2 :GSSG) ratio were determined in the thoracic aorta. The hemodynamic variables were measured in vivo by the plethysmograph method. The vascular function was evaluated in vitro as vasorelaxant responses induced by carbachol or sodium nitroprusside, and norepinephrine (NE)-mediated vasocontractile responses in the thoracic aorta. CRS increased (1) relative adrenal gland weight; (2) hemodynamic variables; (3) vasoconstrictor responses induced by NE, (4) reactive oxygen species levels, and (5) lipid peroxidation in the thoracic aorta. In addition, CRS decreased (1) body weight; (2) vasorelaxant responses induced by carbachol; (3) GSH content, and (4) GSH 2 :GSSG ratio. Notably, NaHS administration (5.6 mg/kg) restored hemodynamic variables and lipid peroxidation and attenuated the vasoconstrictor responses induced by NE in the thoracic aorta. In addition, NaHS treatment increased relative adrenal gland weight and the GSH 2 :GSSG ratio. Taken together, our results demonstrate that NaHS alleviates CRS-induced hypertension by reducing oxidative stress and restoring vascular function in the thoracic aorta.

Lateral fluid percussion injury: A rat model of experimental traumatic brain injury

Traumatic brain injury (TBI) represents one of the leading causes of disability and death worldwide. The annual economic impact of TBI-including direct and indirect costs-is high, particularly impacting low- and middle-income countries. Despite extensive research, a comprehensive understanding of the primary and secondary TBI pathophysiology, followed by the development of promising therapeutic approaches, remains limited. These fundamental caveats in knowledge have motivated the development of various experimental models to explore the molecular mechanisms underpinning the pathogenesis of TBI. In this context, the Lateral Fluid Percussion Injury (LFPI) model produces a brain injury that mimics most of the neurological and systemic aspects observed in human TBI. Moreover, its high reproducibility makes the LFPI model one of the most widely used rodent-based TBI models. In this chapter, we provide a detailed surgical protocol of the LFPI model used to induce TBI in adult Wistar rats. We further highlight the neuroscore test as a valuable tool for the evaluation of TBI-induced sensorimotor consequences and their severity in rats. Lastly, we briefly summarize the current knowledge on the pathological aspects and functional outcomes observed in the LFPI-induced TBI model in rodents.

Hydrogen sulfide donors across time: From origins to cutting-edge applications

This review aims to analyze the developmental trajectory of hydrogen sulfide (H2S) donors over the past three decades and explore the historical background, research hotspots, and emerging trends in related fields from a temporal perspective. A total of 5092 literature articles on H2S donors were retrieved from the Web of Science Core Collection (WoSCC), encompassing 1303 journals, 20638 authors, 10992 institutions, and 459 countries and regions. Utilizing CiteSpace as a bibliometric tool, historical features, evolving active topics, and emerging trends in the field of H2S donors were identified. Over the past 30 years, the field of H2S donors has remained in a prominent stage. This article discusses both inorganic and organic types of H2S donors, including NaHS and Na2S, GYY4137, AP39, and AP123, as well as briefly outlines research and applications of H2S donors in nanotechnology, advanced materials, composite materials, nanostructures, and optical properties. Mechanistically, the review outlines how H2S donors regulate cellular signal transduction, anti-inflammatory responses, neuroprotection, and other pathways within the organism by modulating protein S-sulfhydration, antioxidant effects, and interactions with metal proteins. In terms of applications, the review summarizes the extensive use of H2S donors in biomedical research, encompassing cardiovascular, neurological, anti-inflammatory, and anti-cancer characteristics, as well as their potential applications in the treatment of metabolic diseases. Finally, challenges and limitations faced by H2S donor research are discussed, and potential future research directions are proposed.

Hydrogen sulfide ameliorates hypertension and vascular dysfunction induced by insulin resistance in rats by reducing oxidative stress and activating eNOS

Hydrogen sulfide (H2S) is a gasotransmitter implied in metabolic diseases, insulin resistance, obesity, and type 2 Diabetes Mellitus. This study aimed to determine the effect of chronic administration of sodium hydrosulfide (NaHS; inorganic H2S donor), L-Cysteine (L-Cys; substrate of H2S producing enzymes) and DL-Propargylglycine (DL-PAG; cystathionine-gamma-lyase inhibitor) on the vascular dysfunction induced by insulin resistance in rat thoracic aorta. For this purpose, 72 animals were divided into two main sets that received: 1) tap water (control group; n = 12); and 2) fructose 15% w/v in drinking water [insulin resistance group (IR); n = 60] for 20 weeks. After 16 weeks, the group 2 was divided into five subgroups (n = 12 each), which received daily i. p. injections during 4 weeks of: 1) non-treatment (control); 2) vehicle (phosphate buffer saline; PBS, 1 ml/kg); 3) NaHS (5.6 mg/kg); 4) L-Cys (300 mg/kg); and (5) DL-PAG (10 mg/kg). Hemodynamic variables, metabolic variables, vascular function, ROS levels and the expression of p-eNOS and eNOS were determined. IR induced: 1) hyperinsulinemia; 2) increased HOMA-index; 3) decreased Matsuda index; 4) hypertension, vascular dysfunction, increased ROS levels; 5) increased iNOS, and 6) decreased CSE, p-eNOS and eNOS expression. Furthermore, IR did not affect contractile responses to norepinephrine. Interestingly, NaHS and L-Cys treatment, reversed IR-induced impairments and DL-PAG treatment decreased and increased the HOMA and Matsuda index, respectively. Taken together, these results suggest that NaHS and L-Cys decrease the metabolic and vascular alterations induced by insulin resistance by reducing oxidative stress and activating eNOS. Thus, hydrogen sulfide may have a therapeutic application.

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

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

Protective Roles of Hydrogen Sulfide in Alzheimer's Disease and Traumatic Brain Injury

The gaseous signaling molecule hydrogen sulfide (H2S) critically modulates a plethora of physiological processes across evolutionary boundaries. These include responses to stress and other neuromodulatory effects that are typically dysregulated in aging, disease, and injury. H2S has a particularly prominent role in modulating neuronal health and survival under both normal and pathologic conditions. Although toxic and even fatal at very high concentrations, emerging evidence has also revealed a pronounced neuroprotective role for lower doses of endogenously generated or exogenously administered H2S. Unlike traditional neurotransmitters, H2S is a gas and, therefore, is unable to be stored in vesicles for targeted delivery. Instead, it exerts its physiologic effects through the persulfidation/sulfhydration of target proteins on reactive cysteine residues. Here, we review the latest discoveries on the neuroprotective roles of H2S in Alzheimer's disease (AD) and traumatic brain injury, which is one the greatest risk factors for AD.