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This work reports the characterization and application of a new electrochemical platform modified with gold nanoparticles (AuNP) and functionalized multi-walled carbon nanotubes (f-MWCNT) film to determine melatonin (MEL). MEL is a critical sleep inductor neurohormone, categorized by Food and Drug Administration (FDA, USA) as a nutritional supplement. The AuNP were synthesized and stabilized by 3-n-propyl-(4-methylpyridinium) silsesquioxane chloride (Si4Pic+Cl-), presenting an electrostatic stabilization and a material with a positive surface charge. Thermogravimetric analysis (TGA), Fourier transform-infrared spectroscopy (FT-IR), Raman spectroscopy, and zeta (ζ) potential indicated the insertion of oxygenated functional groups and a superficial negative charge for f-MWCNT. The GCE/f-MWCNT-AuNP-Si4Pic+Cl- platform showed an electrocatalytic profile and a current increase of ca. 7.5 times. Voltammograms were obtained by square wave voltammetry (SWV); the current increased with successive additions of MEL in the linear range of 4.9 to 55.5 µmol l-1. The values of LOD and LOQ were 1.6 and 4.7 µmol l-1, respectively. The standard addition was used to quantify MEL in simulated saliva, blood serum, and urine samples. Statistical tests showed no significant differences between the data collected by voltammetry and the comparative technique, molecular absorption spectrometry. It can be concluded that the new method provides novel perspectives for MEL sensing. [ABSTRACT FROM AUTHOR]

The article focuses on exploring the use of capsaicin and cinnamaldehyde to induce scratching behavior in mice, investigating the effects of sex, concentration, and time course, with potential implications for studying pruritus mechanisms and developing new drugs. It study establishes dose- and time-response curves for capsaicin and cinnamaldehyde, demonstrating their potential as tools for investigating pruritus.

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Arrabidaea brachypoda (DC) Bureau is a medicinal plant found in Brazil. Known as "cipó-una", it is popularly used as a natural therapeutic agent against pain and inflammation. This study evaluated the chemical composition and antinociceptive activity of the dichloromethane fraction from the roots of A. brachypoda (DEAB) and its mechanism of action. The chemical composition was characterized by high-performance liquid chromatography, and this fraction is composed only of dimeric flavonoids. The antinociceptive effect was evaluated in formalin and hot plate tests after oral administration (10-100 mg/kg) in male Swiss mice. We also investigated the involvement of TRPV1 (transient receptor potential vanilloid 1), TRPA1 (transient receptor potential ankyrin 1), TRPM8 (transient receptor potential melastatin 8), and ASIC (acid-sensing ion channel), as well as the opioidergic, glutamatergic, and supraspinal pathways. Moreover, the nociceptive response was reduced (30 mg/kg) in the early and late phase of the formalin test. DEAB activity appears to involve the opioid system, TRPM8, and ASIC receptors, clearly showing that the DEAB alleviates acute pain in mice and suggesting the involvement of the TRPM8 and ASIC receptors and the opioid system in acute pain relief. [ABSTRACT FROM AUTHOR]

Objective To investigate the effect of diacerein, an anti-inflammatory drug, on body temperature and protocols of fever induction in male Wistar rats. Methods The effect of diacerein (5.0 mg/kg, s.c.) on rectal temperature (TR) changes induced by Baker's yeast (0.135 g/kg, i.p.) and PGE2 (10 ng/animal, i.t.) was evaluated. TR changes were recorded over time. The leukocyte count and TNF-α and IL-1β content were evaluated in the peritoneal fluid by means of optical microscopy and enzyme immunoassay (ELISA kits), respectively. Results The administration of diacerein to febrile animals attenuated Baker's yeast-induced fever but did not alter prostaglandin E2-induced fever. Diacerein prevented the development of Baker's yeast-induced fever and significantly attenuated the increase in peritoneal leukocytes and decreased IL-1b and TNF-α levels in peritoneal fluid. Conclusions These data suggest that diacerein partially protects against Baker's yeast-induced fever and peritoneal leukocyte migration, and indicate that this effect appears to be due to inhibition of release of cytokines (such as TNF-α and IL-1β). [ABSTRACT FROM AUTHOR]