Attenuation of Serotonin-Induced Itch by Sumatriptan: Possible Involvement of Endogenous Opioids Publisher Pubmed



Haddadi NS^{1, 2} ; Foroutan A^{1, 2} ; Shakiba S^{1, 2} ; Afshari K^{1, 2} ; Ostadhadi S^{2, 3} ; Daneshpazhooh M⁴ ; Dehpour AR^{1, 2, 3} Show Affiliations
Source: Archives of Dermatological Research Published:2018

Abstract

Serotonin (5-hydroxytryptamine or 5-HT) is a neurotransmitter in itch and impaired serotonin signaling has been linked to a variety of itch conditions. Intradermal injection of 5-HT induces scratching behavior in mice through stimulation of 5-HT receptors. Previous studies have demonstrated that selective 5-HT1B/1D receptors agonists, including sumatriptan, inhibits neurotransmission. We have also reported that sumatriptan suppresses chloroquine-induced itch. Therefore, we investigated if sumatriptan has inhibitory effects on serotonin-induced itch in mice. Here, we show that intradermal and intraperitoneal administration of sumatriptan significantly reduce 5-HT-induced scratching behavior in mice. While intradermal injection of GR-127935, a selective 5-HT1B/1D receptors antagonist, reverses the anti-pruritic effects of sumatriptan. In addition, we show that intradermal and intraperitoneal naltrexone (NTX), a non-specific opioid receptor antagonist, and methylnaltrexone (MNTX), a peripherally acting opioid receptor antagonist, significantly decrease the 5-HT-induced scratching behavior. Additionally, combined treatment with sub-effective doses of sumatriptan and an opioid receptor antagonist, naltrexone, decreases 5-HT-evoked scratching responses. We conclude that sumatriptan inhibits 5-HT-induced itch by activating the peripheral 5-HT1B/1D receptors. Moreover, peripheral opioid receptors have a role in serotonin-induced itch, and anti-pruritic effects of sumatriptan seem to involve the opioid system. These data suggest that 5-HT1B/1D receptors agonists maybe useful to treat a variety of pathologic itch conditions with impaired serotonergic system. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature.