The efficacy of 5-((4-methoxyphenyl)thio)benzo[c][1,2,5] thiodiazole (MTDZ) in mitigating paclitaxel (PTX)-induced peripheral neuropathy was investigated in male and female Swiss mice. The study examined the effects of MTDZ on various pathways, including transient receptor potential cation channel subfamily V member 1 (TRPV1), glutamatergic, nitrergic, guanylate cyclase (cGMP), serotonergic, and opioidergic. Mice received intraperitoneal PTX (2 mg/kg) or vehicle on days 1, 2, and 3, followed by oral MTDZ (1 mg/kg) or vehicle from days 3 to 14. Mechanical and thermal sensitivities were assessed using Von Frey and hot plate tests on days 8, 11, and 14. The open field test evaluated locomotion and exploration on day 12. On day 15, nitrite and nitrate (NOx) levels and Ca²⁺−ATPase activity in the cerebral cortex and spinal cord were measured after euthanizing the animals. MTDZ administration reversed the heightened mechanical and thermal sensitivities induced by PTX in male and female mice without affecting locomotion or exploration. MTDZ also modulated multiple pathways, including glutamatergic, NO/L−arginine/cGMP, serotonergic (5−HT_1A/1B), opioid, and TRPV1 pathways. Additionally, MTDZ reduced NOx levels and modulated Ca²⁺−ATPase activity. In conclusion, MTDZ effectively alleviated PTX−induced peripheral neuropathy and demonstrated multi-targeted modulation of pain-related pathways. Its ability to modulate multiple pathways, reduce NOx levels, and modulate Ca²⁺−ATPase activity makes it a potential pharmacological candidate for peripheral neuropathy, acute nociceptive, and inflammatory conditions. Further research is needed to explore its therapeutic potential in these areas.

Background/Objectives: Recognizing the current limitations in rheumatoid arthritis (RA) treatments, especially in managing pain and inflammation, there is an urgent need to develop and explore new therapeutic strategies. In this study, we devised two innovative approaches using nanotechnology for treating RA. We evaluated the effectiveness of compound 4-(phenylselanyl)-2H-chromen-2-one (4-PSCO) in three forms: free, as well as in nanoemulsified (4-PSCO NE) and nanoencapsulated (4-PSCO NC) formulations. Methods: Arthritis was induced in mice by intraplantar injection of Freund’s complete adjuvant (CFA; 0.1 mL). The 4-PSCO free, 4-PSCO NE, and 4-PSCO NC (1 mg/kg, orally) treatments were administered daily for 15 days. We assessed disease signs, symptoms, mechanical and thermal sensitivities, neurobehavioral deficits, and activities of myeloperoxidase (MPO), Na⁺, K⁺-ATPase, and acetylcholinesterase (AChE), as well as oxidative stress markers. Results: Our study demonstrates, for the first time, that both 4-PSCO NC and 4-PSCO NE inhibit the clinical signs of RA in mice, including inflammation. Moreover, both formulations alleviated pain and anxiety behaviors while restoring AChE activity and decreasing oxidative stress in the cerebral cortex. Notably, only the 4-PSCO NC treatment increased the time animals spent in the open arms of the elevated plus-maze. It lowered TBARS levels in the cerebral cortex, spinal cord, and paws, showcasing its advantages over the free 4-PSCO and 4-PSCO NE. Conclusions: These findings highlight the therapeutic potential of 4-PSCO, especially the polymeric nanocapsule, as a practical option for treating both the symptoms and underlying mechanisms of RA.