Histamine Sensitization of the Voltage-Gated Sodium Channel Nav1.7 Contributes to Histaminergic Itch in Mice.

Itch, a common clinical symptom of many skin diseases, severely impairs the life quality of patients. Nav1.7, a subtype of voltage-gated sodium channels mainly expressed in primary sensory neurons, is responsible for the amplification of threshold currents that trigger action potential (AP) generation. Gain-of-function mutation of Nav1.7 leads to paroxysmal itch, while pharmacological inhibition of Nav1.7 alleviates histamine-dependent itch. However, the crosstalk between histamine and Nav1.7 that leads to itch is unclear. In the present study, we demonstrated that in the dorsal root ganglion (DRG) neurons from histamine-dependent itch model mice induced by compound 48/80, tetrodotoxin-sensitive (TTX-S) but not TTX-resistant Na+ currents were activated at more hyperpolarized membrane potentials compared to those on DRG neurons from vehicle-treated mice. Meanwhile, bath application of histamine shifted the activation voltages of TTX-S Na+ currents to the hyperpolarized direction, increased the AP frequency, and reduced the current threshold required to elicit APs. Further mechanistic studies demonstrated that selective activation of H1 but not H2 and H4 receptors mimicked histamine effect on TTX-S Na+ channels in DRG neurons. The protein kinase C (PKC) inhibitor GO 8963, but not the PKA inhibitor H89, normalized histamine-sensitized TTX-S Na+ channels. We also demonstrated that histamine shifted the activation voltages of Na+ currents to the hyperpolarized direction in Chinese hamster ovary (CHO) cells expressing Nav1.7. Importantly, selective inhibition of Nav1.7 by PF-05089771 significantly relieved the scratching frequency in a histamine-dependent itch model induced by compound 48/80. Taken together, these data suggest that activation of H1 receptors by histamine sensitizes Nav1.7 channels through the PKC pathway in DRG neurons that contributes to histamine-dependent itch.

The Protective Effect of Different Polar Solvent Extracts of Er Miao San on Rats with Adjuvant Arthritis.

OBJECTIVE: The aim of this study was to evaluate the antiarthritic effects of different polar solvent extracts of Er Miao San (EMS) on model rats with adjuvant arthritis (AA) and screen the effective pats of EMS in the treatment of arthritis. METHODS: Four different polar solvent extracts of EMS such as petroleum ether (PE), methylene chloride (CH2Cl2), ethyl acetate (EtOAc), and n-butanol (n-butanol (. RESULTS: Administration of EtOAc and CH2Cl2 parts remarkably inhibited the paw swelling, decreased the index of arthritis, decreased the body weight loss, and improved the changes of histopathology. Furthermore, the concentrations of proinflammatory cytokines (TNF-α, IL-1ß, and IL-6) were significantly lower, while the anti-inflammatory cytokine (IL-10) was remarkably higher compared with that in the model group. And the result of UHPLC analysis indicated that the effective parts of EMS contain berberine and atractylodin. CONCLUSIONS: EtOAc and CH2Cl2 are the effective parts of EMS that can improve arthritis. In particular, berberine and atractylodin may be responsible for the antiarthritic activity of EMS. This research provided pharmacological and chemical foundation for the application of EMS in treating rheumatoid arthritis (RA).

Er Miao San, a traditional Chinese herbal formula, attenuates complete Freund's adjuvant-induced arthritis in rats by regulating Th17/Treg cells.

Context: Er Miao San (EMS) is a traditional Chinese medicine composed of Atractylodis Rhizoma and Phellodendri Cortex in a 1:1 weight ratio. EMS has been used to treat rheumatism in China for many years.Objective: To evaluate the anti-arthritic activity of EMS extract on adjuvant-induced arthritis (AA) in Sprague-Dawley rats and to clarify its mechanisms of action.Materials and methods: EMS (0.75, 1.5 and 3 g/kg, once daily) was orally administered from day 18 after immunization to day 31. The effects of EMS on AA rats were evaluated by histopathological examination, paw swelling and polyarthritis index. The proliferation of fibroblast-like synoviocyte (FLS) and T cells was detected by CCK-8. The percentages of Th17 cells and Treg cells in splenocytes were determined by flow cytometry. Levels of cytokines in serum were detected by ELISA.Results: EMS treatment significantly decreased the paw volume (from 1.20 to 0.81), polyarthritis index (from 9.56 to 4.46) and alleviated ankle joint histopathology in AA rats. EMS inhibited the proliferation of FLS and T cells. Furthermore, EMS treatment decreased Th17 cells (from 4.62 to 2.08%) and increased Treg cells (from 2.77 to 4.75%) in splenocytes. The levels of IL-17A, TNF-α and IL-6 were remarkably decreased in the serum of EMS-treated rats, whereas the levels of IL-10 and TGF-ß1 were significantly increased.Conclusions: EMS exhibits anti-arthritic activity in the AA model by regulating the balance of cytokines and the ratio of Th17 and Treg cells. These insights may provide an experimental basis for the clinical treatment of RA.

Anti-Inflammatory Effects of Different Elution Fractions of Er-Miao-San on Acute Inflammation Induced by Carrageenan in Rat Paw Tissue.

BACKGROUND Er-Miao-San (EMS) is used in traditional Chinese medicine. This study aimed to investigate the effect of different elution fractions of EMS on acute inflammation induced by carrageenan in the rat paw and the possible mechanisms of action. MATERIAL AND METHODS Different aqueous fractions of EMS added to an AB-8 macroporous resin column and eluted with 0, 30%, 60%, and 90% ethanol. The content of berberine was evaluated by ultra-performance liquid chromatography (UPLC). Following injection of carrageenan and elution fractions of EMS into the rat paw, the volume of edema, levels of prostaglandin E2 (PGE2), tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1ß, and IL-10 in the rat tissue were quantified by enzyme-linked immunosorbent assay (ELISA). Myeloperoxidase (MPO) activity and nitric oxide (NO) levels were measured by spectrophotometry. RESULTS The 60% and 90% ethanol elution fractions of EMS contained berberine, and both inhibited edema after carrageenan injection, with inhibitory rates of 31.04-40.86% and 48.84-52.18%, respectively, and with a significant reduction in MPO activity and NO production. The 60% ethanol elution fraction of EMS significantly decreased IL-1ß levels and increased IL-10 levels, and the 30%, 60%, and 90% ethanol EMS elution fractions considerably reduced the levels of TNF-alpha. The 60% and 90% ethanol EMS elution fractions significantly reduced PGE2 levels in the rat paw. CONCLUSIONS The 60% and 90% ethanol elution fractions of EMS had an anti-inflammatory effect following injection of carrageenan in the rat paw.