Analgesic effect of dimethyl trisulfide in mice is mediated by TRPA1 and sst4 receptors

Aedes aegypti salivary gland extract alleviates acute itching by blocking TRPA1 channels

Aedes aegypti (Ae. aegypti) saliva induces a variety of anti-inflammatory and immunomodulatory activities. Interestingly, although it is known that mosquito bites cause allergic reactions in sensitised hosts, the primary exposure of humans to Ae. aegypti does not evoke significant itching. Whether active components in the saliva of Ae. aegypti can counteract the normal itch reaction to injury produced by a histaminergic or non-histaminergic pathway in vertebrate hosts is unknown. This study investigated the effects of Ae. aegypti mosquito salivary gland extract (SGE) on sensitive reactions such as itching and associated skin inflammation. Acute pruritus and plasma extravasation were induced in mice by the intradermal injection of either compound 48/80 (C48/80), the Mas-related G protein-coupled receptor (Mrgpr) agonist chloroquine (CQ), or the transient receptor potential ankyrin 1 (TRPA1) agonist allyl isothiocyanate (AITC). The i.d. co-injection of Ae. aegypti SGE inhibited itching, plasma extravasation, and neutrophil influx evoked by C48/80, but it did not significantly affect mast cell degranulation in situ or in vitro. Additionally, SGE partially reduced CQ- and AITC-induced pruritus in vivo, suggesting that SGE affects pruriceptive nerve firing independently of the histaminergic pathway. Activation of TRPA1 significantly increased intracellular Ca²⁺ in TRPA-1-transfected HEK293t lineage, which was attenuated by SGE addition. We showed for the first time that Ae. aegypti SGE exerts anti-pruriceptive effects, which are partially regulated by the histamine-independent itch TRPA1 pathway. Thus, SGE may possess bioactive molecules with therapeutic potential for treating nonhistaminergic itch.

Elucidation of the binding mode of organic polysulfides on the human TRPA1 receptor

Introduction: Previous studies have established that endogenous inorganic polysulfides have significant biological actions activating the Transient Receptor Potential Ankyrin 1 (TRPA1) receptor. Organic polysulfides exert similar effects, but they are much more stable molecules, therefore these compounds are more suitable as drugs. In this study, we aimed to better understand the mechanism of action of organic polysulfides by identification of their binding site on the TRPA1 receptor. Methods: Polysulfides can readily interact with the thiol side chain of the cysteine residues of the protein. To investigate their role in the TRPA1 activation, we replaced several cysteine residues by alanine via site-directed mutagenesis. We searched for TRPA1 mutant variants with decreased or lost activating effect of the polysulfides, but with other functions remaining intact (such as the effects of non-electrophilic agonists and antagonists). The binding properties of the mutant receptors were analyzed by in silico molecular docking. Functional changes were tested by in vitro methods: calcium sensitive fluorescent flow cytometry, whole-cell patch-clamp and radioactive calcium-45 liquid scintillation counting. Results: The cysteines forming the conventional binding site of electrophilic agonists, namely C621, C641 and C665 also bind the organic polysulfides, with the key role of C621. However, only their combined mutation abolished completely the organic polysulfide-induced activation of the receptor. Discussion: Since previous papers provided evidence that organic polysulfides exert analgesic and anti-inflammatory actions in different in vivo animal models, we anticipate that the development of TRPA1-targeted, organic polysulfide-based drugs will be promoted by this identification of the binding site.

Prodrugs of sulfide and persulfide species: Implications in their different pharmacological activities

Reactive sulfur species (RSS), such as H₂S, hydrogen polysulfide (H₂S_n, n ≥ 2), and hydropersulfides (RSS_nH, n ≥ 1), are known to mediate diverse signaling pathways and possess a plethora of exciting therapeutic opportunities. Historically, due to the rapid inter-conversion among those species in vivo, the biological differences of distinct sulfur species were often overlooked. These species were considered to enrich the global sulfur pool in almost an equal fashion. However, advancement in this field has revealed that sulfur species at different oxidation states result in different pharmacological effects including scavenging reactive oxygen species (ROS), activating ion channels, and exhibiting analgesic effects. Here, we summarize recent advances in studying the biological and pharmacological differences of distinct sulfur species; discuss this phenomenon from the view of chemical properties and sulfur signaling pathways; and lay out a roadmap to transforming such new knowledge into general principles in developing sulfur-based therapeutics.

Investigation of the Role of the TRPA1 Ion Channel in Conveying the Effect of Dimethyl Trisulfide on Vascular and Histological Changes in Serum-Transfer Arthritis

Rheumatoid arthritis (RA) is one of the most prevalent autoimmune diseases. Its therapy is often challenging, even in the era of biologicals. Previously, we observed the anti-inflammatory effects of garlic-derived organic polysulfide dimethyl trisulfide (DMTS). Some of these effects were mediated by activation of the TRPA1 ion channel. TRPA1 was mostly expressed in a subset of nociceptor neurons. We decided to investigate the action of DMTS in K/BxN serum-transfer arthritis, which is a relevant model of RA. TRPA1 gene knockout (KO) and wild-type (WT) mice were used. The interaction of DMTS and TRPA1 was examined using a patch clamp in CHO cells. Arthritis was characterized by mechanical hyperalgesia, paw swelling, movement range of the ankle joint, hanging performance, plasma extravasation rate, myeloperoxidase activity, and histological changes in the tibiotarsal joint. DMTS activated TRPA1 channels dose-dependently. DMTS treatment reduced paw swelling and plasma extravasation in both TRPA1 WT and KO animals. DMTS-treated TRPA1 KO animals developed milder collagen deposition in the inflamed joints than WT ones. TRPA1 WT mice did not exhibit significant cartilage damage compared to ones administered a vehicle. We concluded that DMTS and related substances might evolve into novel complementary therapeutic aids for RA patients.

Prodrugs of Persulfide and Sulfide: Is There a Pharmacological Difference between the Two in the Context of Rapid Exchanges among Various Sulfur Species In Vivo?

Sulfide and persulfide are chemically different and one might expect persulfide to be more effective in mediating sulfur signaling because persulfide can directly modify protein cysteine residue. However, rapid scrambling, and interconversions occur among sulfur species. Then there is the question of whether the chemical reactivity differences between sulfide and persulfide would translate into pharmacological differences. Utilizing a delivery system to generate pure hydrogen sulfide (H₂ S), hydrogen persulfide (H₂ S₂ ), and N-acetyl-l-cysteine persulfide (N-CysSSH), we examined the activities of sulfide and persulfide in vitro and in vivo. Persulfide prodrugs exhibited increased activities compared to the H₂ S prodrug. In particular, the H₂ S₂ prodrug offers much-elevated analgesic effects compared to the H₂ S prodrug in vivo. Persulfide prodrugs also possess a reduced level of toxicity compared to the H₂ S prodrug in vivo, indicating persulfide might represent a better therapeutic paradigm than H₂ S.

The Role of TRPA1 Channels in the Central Processing of Odours Contributing to the Behavioural Responses of Mice

Transient receptor potential ankyrin 1 (TRPA1), a nonselective cation channel, contributes to several (patho)physiological processes. Smell loss is an early sign in several neurodegenerative disorders, such as multiple sclerosis, Parkinson’s and Alzheimer’s diseases; therefore, we focused on its role in olfaction and social behaviour with the aim to reveal its potential therapeutic use. The presence of Trpa1 mRNA was studied along the olfactory tract of mice by combined RNAscope in situ hybridisation and immunohistochemistry. The aversive effects of fox and cat odour were examined in parallel with stress hormone levels. In vitro calcium imaging was applied to test if these substances can directly activate TRPA1 receptors. The role of TRPA1 in social behaviour was investigated by comparing Trpa1 wild-type and knockout mice (KO). Trpa1 mRNA was detected in the olfactory bulb and piriform cortex, while its expression was weak in the olfactory epithelium. Fox, but not cat odour directly activated TRPA1 channels in TRPA1-overexpressing Chinese Hamster Ovary cell lines. Accordingly, KO animals showed less aversion against fox, but not cat odour. The social interest of KO mice was reduced during social habituation–dishabituation and social interaction, but not during resident–intruder tests. TRPA1 may contribute to odour processing at several points of the olfactory tract and may play an important role in shaping the social behaviour of mice. Thus, TRPA1 may influence the development of certain social disorders, serving as a potential drug target in the future.

The Hypothermic Effect of Hydrogen Sulfide Is Mediated by the Transient Receptor Potential Ankyrin-1 Channel in Mice

Hydrogen sulfide (H₂S) has been shown in previous studies to cause hypothermia and hypometabolism in mice, and its thermoregulatory effects were subsequently investigated. However, the molecular target through which H₂S triggers its effects on deep body temperature has remained unknown. We investigated the thermoregulatory response to fast-(Na₂S) and slow-releasing (GYY4137) H₂S donors in C57BL/6 mice, and then tested whether their effects depend on the transient receptor potential ankyrin-1 (TRPA1) channel in Trpa1 knockout (Trpa1^−/−) and wild-type (Trpa1^+/+) mice. Intracerebroventricular administration of Na₂S (0.5–1 mg/kg) caused hypothermia in C57BL/6 mice, which was mediated by cutaneous vasodilation and decreased thermogenesis. In contrast, intraperitoneal administration of Na₂S (5 mg/kg) did not cause any thermoregulatory effect. Central administration of GYY4137 (3 mg/kg) also caused hypothermia and hypometabolism. The hypothermic response to both H₂S donors was significantly (p < 0.001) attenuated in Trpa1^−/− mice compared to their Trpa1^+/+ littermates. Trpa1 mRNA transcripts could be detected with RNAscope in hypothalamic and other brain neurons within the autonomic thermoeffector pathways. In conclusion, slow- and fast-releasing H₂S donors induce hypothermia through hypometabolism and cutaneous vasodilation in mice that is mediated by TRPA1 channels located in the brain, presumably in hypothalamic neurons within the autonomic thermoeffector pathways.

Synthesis and structure-activity relationships of 3,4,5-trisubstituted-1,2,4-triazoles: high affinity and selective somatostatin receptor-4 agonists for Alzheimer's disease treatment

Somatostatin receptor-4 (SST₄) is highly expressed in brain regions affiliated with learning and memory. SST₄ agonist treatment may act to mitigate Alzheimer's disease (AD) pathology. An integrated approach to SST₄ agonist lead optimization is presented herein. High affinity and selective agonists with biological efficacy were identified through iterative cycles of a structure-based design strategy encompassing computational methods, chemistry, and preclinical pharmacology. 1,2,4-Triazole derivatives of our previously reported hit (4) showed enhanced SST₄ binding affinity, activity, and selectivity. Thirty-five compounds showed low nanomolar range SST₄ binding affinity, 12 having a K _i < 1 nM. These compounds showed >500-fold affinity for SST₄ as compared to SST_2A. SST₄ activities were consistent with the respective SST₄ binding affinities (EC₅₀ < 10 nM for 34 compounds). Compound 208 (SST₄ K _i = 0.7 nM; EC₅₀ = 2.5 nM; >600-fold selectivity over SST_2A) display a favorable physiochemical profile, and was advanced to learning and memory behavior evaluations in the senescence accelerated mouse-prone 8 model of AD-related cognitive decline. Chronic administration enhanced learning with i.p. dosing (1 mg kg^-1) compared to vehicle. Chronic administration enhanced memory with both i.p. (0.01, 0.1, 1 mg kg^-1) and oral (0.01, 10 mg kg^-1) dosing compared to vehicle. This study identified a novel series of SST₄ agonists with high affinity, selectivity, and biological activity that may be useful in the treatment of AD.

Tetralone derivatives are MIF tautomerase inhibitors and attenuate macrophage activation and amplify the hypothermic response in endotoxemic mice

Macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine playing crucial role in immunity. MIF exerts a unique tautomerase enzymatic activity that has relevance concerning its multiple functions and its small molecule inhibitors have been proven to block its pro-inflammatory effects. Here we demonstrate that some of the E-2-arylmethylene-1-tetralones and their heteroanalogues efficiently bind to MIF's active site and inhibit MIF tautomeric (enolase, ketolase activity) functions. A small set of the synthesised derivatives, namely compounds (4), (23), (24), (26) and (32), reduced inflammatory macrophage activation. Two of the selected compounds (24) and (26), however, markedly inhibited ROS and nitrite production, NF-κB activation, TNF-α, IL-6 and CCL-2 cytokine expression. Pre-treatment of mice with compound (24) exaggerated the hypothermic response to high dose of bacterial endotoxin. Our experiments suggest that tetralones and their derivatives inhibit MIF's tautomeric functions and regulate macrophage activation and thermal changes in severe forms of systemic inflammation.

Dimethyl Trisulfide Diminishes Traumatic Neuropathic Pain Acting on TRPA1 Receptors in Mice

Pharmacotherapy of neuropathic pain is still challenging. Our earlier work indicated an analgesic effect of dimethyl trisulfide (DMTS), which was mediated by somatostatin released from nociceptor nerve endings acting on SST₄ receptors. Somatostatin release occurred due to TRPA1 ion channel activation. In the present study, we investigated the effect of DMTS in neuropathic pain evoked by partial ligation of the sciatic nerve in mice. Expression of the mRNA of Trpa1 in murine dorsal-root-ganglion neurons was detected by RNAscope. Involvement of TRPA1 ion channels and SST₄ receptors was tested with gene-deleted animals. Macrophage activity at the site of the nerve lesion was determined by lucigenin bioluminescence. Density and activation of microglia in the spinal cord dorsal horn was verified by immunohistochemistry and image analysis. Trpa1 mRNA is expressed in peptidergic and non-peptidergic neurons in the dorsal root ganglion. DMTS ameliorated neuropathic pain in Trpa1 and Sstr4 WT mice, but not in KO ones. DMTS had no effect on macrophage activity around the damaged nerve. Microglial density in the dorsal horn was reduced by DMTS independently from TRPA1. No effect on microglial activation was detected. DMTS might offer a novel therapeutic opportunity in the complementary treatment of neuropathic pain.

Role of H2S in pain: Growing evidences of mystification

There have been studies suggesting the pain attenuating as well as pain inducing actions of hydrogen sulfide (H₂S). Exogenous administrated H₂S may be antinociceptive or pronociceptive, while the endogenous H₂S is pronociceptive. Experimental studies have shown that pharmacological inhibitors of H₂S biosynthetic enzymes may attenuate nociceptive as well as neuropathic pain. It suggests that nerve injury or inflammatory agents may induce the expression of H₂S biosynthetic enzymes to increase the endogenous production of H₂S, which acts as a pain neurotransmitter to produce pain. The endogenous H₂S may act through different mechanisms including opening of T-type calcium channels, activation of voltage-gated sodium channels, suppression of potassium channels, activation of TRPA1, TRPV1 and TRPC6 channels, upregulation of spinal NMDA receptors and sensitization of purinergic receptors. Exogenous administration of H₂S/precursors/donors attenuates or facilitates pain. It may be hypothesized that local administration of H₂S may cause pain; while it's systemic administration may attenuate pain. The doses of H₂S may also influence the pain response and H₂S in low doses may contribute in reducing pain, while H₂S in high doses may contribute in relieving pain. Accordingly, enzymatic inhibitors of H₂S synthesis or systemic administration of slow H₂S releasing agents/low dose H₂S donors may be useful in attenuating nociceptive and neuropathic pain. The present review describes the dual role of H₂S in pain attenuation and pain induction along with possible mechanisms.

Mammalian Transient Receptor Potential TRPA1 Channels: From Structure to Disease

The transient receptor potential ankyrin (TRPA) channels are Ca²⁺-permeable nonselective cation channels remarkably conserved through the animal kingdom. Mammals have only one member, TRPA1, which is widely expressed in sensory neurons and in non-neuronal cells (such as epithelial cells and hair cells). TRPA1 owes its name to the presence of 14 ankyrin repeats located in the NH₂ terminus of the channel, an unusual structural feature that may be relevant to its interactions with intracellular components. TRPA1 is primarily involved in the detection of an extremely wide variety of exogenous stimuli that may produce cellular damage. This includes a plethora of electrophilic compounds that interact with nucleophilic amino acid residues in the channel and many other chemically unrelated compounds whose only common feature seems to be their ability to partition in the plasma membrane. TRPA1 has been reported to be activated by cold, heat, and mechanical stimuli, and its function is modulated by multiple factors, including Ca²⁺, trace metals, pH, and reactive oxygen, nitrogen, and carbonyl species. TRPA1 is involved in acute and chronic pain as well as inflammation, plays key roles in the pathophysiology of nearly all organ systems, and is an attractive target for the treatment of related diseases. Here we review the current knowledge about the mammalian TRPA1 channel, linking its unique structure, widely tuned sensory properties, and complex regulation to its roles in multiple pathophysiological conditions.

TRPA1 Ion Channel Determines Beneficial and Detrimental Effects of GYY4137 in Murine Serum-Transfer Arthritis

Modulation of nociception and inflammation by sulfide in rheumatoid arthritis and activation of transient receptor potential ankyrin 1 (TRPA1) ion channels by sulfide compounds are well documented. The present study aims to investigate TRPA1-mediated effects of sulfide donor GYY4137 in K/BxN serum-transfer arthritis, a rodent model of rheumatoid arthritis. TRPA1 and somatostatin sst4 receptor wild-type (WT) and knockout mice underwent K/BxN serum transfer and were treated daily with GYY4137. Functional and biochemical signs of inflammation were recorded, together with histological characterization. These included detection of hind paw mechanical hyperalgesia by dynamic plantar esthesiometry, hind paw volume by plethysmometry, and upside-down hanging time to failure. Hind paw erythema, edema, and passive movement range of tibiotarsal joints were scored. Somatostatin release from sensory nerve endings of TRPA1 wild-type and knockout mice in response to polysulfide was detected by radioimmunoassay. Polysulfide formation from GYY4137 was uncovered by cold cyanolysis. GYY4137 aggravated mechanical hyperalgesia in TRPA1 knockout mice but ameliorated it in wild-type ones. Arthritis score was lowered by GYY4137 in TRPA1 wild-type animals. Increased myeloperoxidase activity, plasma extravasation, and subcutaneous MIP-2 levels of hind paws were detected in TRPA1 knockout mice upon GYY4137 treatment. Genetic lack of sst4 receptors did not alter mechanical hyperalgesia, edema formation, hanging performance, arthritis score, plasma extravasation, or myeloperoxidase activity. TRPA1 WT animals exhibited smaller cartilage destruction upon GYY4137 administration. Sodium polysulfide caused TRPA1-dependent somatostatin release from murine nerve endings. Sulfide released from GYY4137 is readily converted into polysulfide by hypochlorite. Polysulfide potently activates human TRPA1 receptors expressed in Chinese hamster ovary (CHO) cells. According to our data, the protective effect of GYY4137 is mediated by TRPA1, while detrimental actions are independent of the ion channel in the K/BxN serum-transfer arthritis model in mice. At acidic pH in inflamed tissue sulfide is released from GYY4137 and reacts with neutrophil-derived hypochlorite. Resulting polysulfide might be responsible for TRPA1-mediated antinociceptive and anti-inflammatory as well as TRPA1-independent pro-inflammatory effects.

Methemoglobin Forming Effect of Dimethyl Trisulfide in Mice

Dimethyl trisulfide (DMTS) is a natural organic trisulfide that has been patented as a promising antidotal candidate against cyanide (CN). The primary mode of action of DMTS is as a sulfur donor that enables the conversion of CN to thiocyanate. Recently, it was discovered that DMTS is capable of oxidizing hemoglobin (Hb) to methemoglobin (MetHb) in vitro. The goal of these experiments was to measure the extent of DMTS-induced MetHb formation in vivo. In these experiments, intramuscular (IM) injections of formulated DMTS were administered to mice. Following the IM injection, blood was drawn and analyzed for MetHb using a rapid spectrophotometric method. Methemoglobin levels peaked in a dose-dependent manner between 20 and 30 min., and then began dropping. The highest MetHb levels measured for the 50, 100, 200 and 250 mg/kg doses of DMTS were respectively 3.28, 6.12, 9.69, and 10.76% MetHb. These experiments provide the first experimental evidence that IM administered DMTS generates MetHb in vivo and provide additional evidence for the presence of a secondary therapeutic pathway for DMTS - CN scavenging by DMTS-generated MetHb.

Effects of sulfide and polysulfides transmitted by direct or signal transduction-mediated activation of TRPA1 channels

Hydrogen sulfide (H₂S) is a gaseous mediator in various physiological and pathological processes, including neuroimmune modulation, metabolic pathways, cardiovascular system, tumour growth, inflammation and pain. Now the hydrogen polysulfides (H₂S_n) have been recognised as signalling molecules modulating ion channels, transcription factors and protein kinases. Transient receptor potential (TRP) cation channels can be activated by mechanical, thermal or chemical triggers. Here, we review the current literature regarding the biological actions of sulfide and polysulfide compounds mediated by TRP channels with special emphasis on the role of TRPA1, best known as ion channels in nociceptors. However, the non‐neuronal TRPA1 channels should also be considered to play regulatory roles. Although sulfide and polysulfide effects in different pathological circumstances and TRPA1‐mediated processes have been investigated intensively, our review attempts to present the first comprehensive overview of the potential crosstalk between TRPA1 channels and sulfide‐activated signalling pathways.

Linked Articles

This article is part of a themed section on Chemical Biology of Reactive Sulfur Species. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.4/issuetoc

Investigation of Lake Hévíz Mineral Water Balneotherapy and Hévíz Mud Treatment in Murine Osteoarthritis and Rheumatoid Arthritis Models

Arthritic diseases are the most frequent causes of chronic pain and disability. Rheumatoid arthritis (RA) is an autoimmune disease characterized by synovial inflammation and progressive structural joint damage. Osteoarthritis is a degenerative process of the articular cartilage associated with hypertrophic changes in the bone. The aim of the present study was to investigate the anti-inflammatory and analgesic effects of Hévíz thermal water and mud in monosodium iodoacetate- (MIA-) (25 mg/ml, 20 μl i.a.) induced osteoarthritis and Complete Freund's adjuvant- (CFA-) (1 mg/ml, 50-50 μl s.c) induced rheumatoid arthritis murine models. The mechanonociceptive threshold of female NMRI mice (n=6- 8 mice/ group) was measured by aesthesiometry, and paw volume was monitored with plethysmometry, knee joint diameter with digital micrometer, and dynamic weight bearing on the hind limbs with a Bioseb instrument. Periarticular bone destruction was assessed by SkyScan 1176 in vivo micro-CT. Inflammatory cytokines were detected by ELISA in plasma samples. Treatments (30 min, every working day) with tap water, sand, and a combined therapy of tap water and sand served as controls. Hévíz medicinal water and combined treatment with water and mud significantly decreased the mechanical hyperalgesia and knee oedema in MIA-induced osteoarthritis model. However, balneotherapy did not influence mechanical hyperalgesia, weight bearing, or oedema formation induced by CFA. Neither medicinal water nor mud treatment ameliorated deep structural damage of the bones or the joints in the animal models. On the basis of the present findings, we conclude that balneotherapy is an effective complementary treatment to reduce the pain sensation and swelling in degenerative joint diseases such as osteoarthritis. Our experimental data are in agreement with the previous human studies that also confirmed antinociceptive and anti-inflammatory effects of thermal water and Hévíz mud treatments.

A Proposed Molecular Mechanism for Physical Analgesia in Chronic Pain

Although pain is indispensable for survival, chronic pain places a heavy burden on humans. As the efficacy of opioid treatment is limited, the development of alternative methods of pain relief without medication is desirable. Recently, we have developed a novel method of physical analgesia using an adhesive “pyramidal thorn patch.” When we apply about 3 trials of these patches on the skin of a pain region, the pain region moves toward the spinal cord like a “cutaneous rabbit,” and finally, the pain vanishes. In the present review, we propose a molecular mechanism for this analgesic method or pain relief following application of the pyramidal thorn patch where firstly the mechanoreceptors and their related nerves under the skin are activated in response to touch. Transient receptor potential (TRP) channels serve as mechanosensitive channels within these mechanoreceptors. We further propose that activation of the nerves connected with the mechanoreceptors releases oxytocin, which has an antinociceptive function and activates TRP channels to hyperpolarize the pain signal nerves. We believe that our system will pave the way for alternative pain treatment.

Role of Transient Receptor Potential Ankyrin 1 Ion Channel and Somatostatin sst4 Receptor in the Antinociceptive and Anti-inflammatory Effects of Sodium Polysulfide and Dimethyl Trisulfide

Transient receptor potential ankyrin 1 (TRPA1) non-selective ligand-gated cation channels are mostly expressed in primary sensory neurons. Polysulfides (POLYs) are Janus-faced substances interacting with numerous target proteins and associated with both protective and detrimental processes. Activation of TRPA1 in sensory neurons, consequent somatostatin (SOM) liberation and action on sst4 receptors have recently emerged as mediators of the antinociceptive effect of organic trisulfide dimethyl trisulfide (DMTS). In the frame of the present study, we set out to compare the participation of this mechanism in antinociceptive and anti-inflammatory effects of inorganic sodium POLY and DMTS in carrageenan-evoked hind-paw inflammation. Inflammation of murine hind paws was induced by intraplantar injection of carrageenan (3% in 30 µL saline). Animals were treated intraperitoneally with POLY (17 µmol/kg) or DMTS (250 µmol/kg) or their respective vehicles 30 min prior paw challenge and six times afterward every 60 min. Mechanical pain threshold and swelling of the paws were measured by dynamic plantar aesthesiometry and plethysmometry at 2, 4, and 6 h after initiation of inflammation. Myeloperoxidase (MPO) activity in the hind paws were detected 6 h after challenge by luminescent imaging. Mice genetically lacking TRPA1 ion channels, sst4 receptors and their wild-type counterparts were used to examine the participation of these proteins in POLY and DMTS effects. POLY counteracted carrageenan-evoked mechanical hyperalgesia in a TRPA1 and sst4 receptor-dependent manner. POLY did not influence paw swelling and MPO activity. DMTS ameliorated all examined inflammatory parameters. Mitigation of mechanical hyperalgesia and paw swelling by DMTS were mediated through sst4 receptors. These effects were present in TRPA1 knockout animals, too. DMTS inhibited MPO activity with no participation of the sensory neuron-SOM axis. While antinociceptive effects of POLY are transmitted by activation of peptidergic nerves via TRPA1, release of SOM and its effect on sst4 receptors, those of DMTS partially rely on SOM release triggered by other routes. SOM is responsible for the inhibition of paw swelling by DMTS, but TRPA1 does not contribute to its release. Modulation of MPO activity by DMTS is independent of TRPA1 and sst4.