Articles: itch.
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Itch (pruritus), specifically chronic itch associated with disease conditions, significantly impairs the patient's quality of life. At present, the mechanisms underlying this aversive experience are still unclear, and the effective treatment of itch is largely unmet. Here, we report that intragastrical administration of bulleyaconitine A (BLA), which has been used for treating chronic pain for 30 years in China, inhibited itch-like behaviors induced by intradermal injection of histamine and chloroquine in mice and rats, dose-dependently. ⋯ The behavioral change was accompanied with the potentiation of C-fiber synaptic transmission in the dorsal horn. Both the itch sensitization and synaptic potentiation were substantially attenuated by intragastrical BLA. Together, BLA was effective in inhibiting histamine-dependent and histamine-independent itches, and the mechanisms underlying these effects were involved but not limited to the inhibition of gastrin-releasing peptide (GRP)-GRPR signaling in the spinal dorsal horn.
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Randomized Controlled Trial
Doxepin cream is not effective in reducing itch in burn scar patients: A multicenter triple-blind randomized clinical crossover trial.
To evaluate the effect of doxepin hydrochloride 5% cream on reducing pruritus in burn scar patients compared to a placebo cream. ⋯ Doxepin cream was not effective in reducing pruritus in our burn patient study population.
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Toll-like receptors (TLRs) have been implicated in pain and itch regulation. TLR2, a TLR family member that detects microbial membrane components, has been implicated in pathologic pain. However, the role of TLR2 in pruritic and nociceptive responses has not been thoroughly investigated. ⋯ Finally, Pam3Csk4 and zymosan increased the [Ca2+]i in DRG neurons from wild-type mice. However, the enhancement of [Ca2+]i was largely inhibited in the DRG neurons from TRPV1 and TRPA1 KO mice. Our results demonstrate that TLR2 is involved in different itch and pain behaviors through activating TLR1/TLR2 or TLR6/TLR2 heterodimers via TRPV1 and TRPA1 channels.
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Activation of glial cells has been shown to play an important role in chronic itch. However, whether glial cells play an important role in the development of psoriasis-induced chronic itch has not been fully elucidated. This study investigated the role of spinal glial cells in psoriasis-induced chronic itch. ⋯ The results showed that the expression of microglial marker ionized calcium binding adaptor molecule-1 was significantly increased after 5% imiquimod treatment in cervical spinal cord dorsal horn (C3-C4), and the intrathecal microglial inhibitor minocycline or PLX5622 diet suppressed both spontaneous itch and microglial activation. Furthermore, we found that the number of scratches and alloknesis score in female mice was significantly greater than in male mice after 5% imiquimod treatment. Our results indicate that microglia mediate chronic psoriatic itch induced by imiquimod.