Transient receptor potential ankyrin 1 （TRPA1） is a key player in pain and neurogenic inflammation, and is localized in nociceptive primary sensory dorsal root ganglion （DRG） neurons. TRPA1 plays a major role in t...Transient receptor potential ankyrin 1 （TRPA1） is a key player in pain and neurogenic inflammation, and is localized in nociceptive primary sensory dorsal root ganglion （DRG） neurons. TRPA1 plays a major role in the transmission of nociceptive sensory signals. The generation of neurogenic inflammation appears to involve TRPAl-evoked release of calcitonin gene-related peptide （CGRP）. However, it remains unknown whether TRPA1 or CGRP expression is affected by TRPA 1 activation. Thus, in this study, we examined TRPA 1 and CGRP expression in DRG neurons in vitro after treatment with the TRPA1 activator tbrmaldehyde or the TRPA1 blocker menthol. In addition, we examined the role of extracellular signal-regulated protein kinase 1/2 （ERK1/2） in this process. DRG neurons in culture were exposed to formaldehyde, menthol, the ERK1/2 inhibitor PD98059 ＋ formaldehyde, or PD98059 ＋ menthol. After treatment, real-time polymerase chain reaction, western blot assay and double immunofluorescence labeling were performed to evaluate TRPA1 and CGRP expression in DRG neurons. Formaldehyde elevated mRNA and protein levels of TRPA 1 and CGRP, as well as the proportion of TRPA1- and CGRP-positive neurons. In contrast, menthol reduced TRPA1 and CGRP expression. Furthermore, the effects of lbrmaldehyde, but not menthol, on CGRP expression were blocked by pretreatment with PD98059. PD98059 pretreatment did not affect TRPA1 expression in the presence of formaldehyde or menthol.展开更多
Objective To investigate the role of oxidative stress in itch-indicative scratching behavior in mice, and further- more, to define the cellular and molecular mechanisms underlying oxidative stress-mediated itch. Metho...Objective To investigate the role of oxidative stress in itch-indicative scratching behavior in mice, and further- more, to define the cellular and molecular mechanisms underlying oxidative stress-mediated itch. Methods Scratching behavior was induced by intradermal injection of the oxidants hydrogen peroxide （H202） or tert-butylhydroperoxide （tBHP） into the nape of the neck in mice. The mice were observed for 30 rain. Results Intradermal H202 （0.03%-1%） or tBHP （1-30 pmol） elicited robust scratching behavior, displaying an inverted U-shaped dose-response curve. Naloxone, an opioid receptor antagonist, but not morphine, largely suppressed the oxidant-induced scratching. Chlorpheniramine, a histamine H1 receptor antagonist, blocked histamine- but not oxidant-induced scratching, indicating the involvement of a histamine-independent mechanism in oxidant-evoked itch. Further, resiniferatoxin treatment abolished oxidant-induced scratching, suggesting an essential role of C-fibers. Notably, blockade of transient receptor potential subtype ankyrin 1 （TRPA1） with the selective TRPA1 antagonist HC-030031, or genetic deletion of Trpal but not Trpvl （subfamily V, mem- ber 1） resulted in a profound reduction in H202-evoked scratching. Finally, systemic administration of the antioxidant N- acetyl-L-cysteine or trolox （a water-soluble vitamin E analog） attenuated scratching induced by the oxidants. Conclusion Oxidative stress by different oxidants induces profound scratching behavior, which is largely histamine- and TRPV1- independent but TRPAl-dependent. Antioxidants and TRPA1 antagonists may be used to treat human itch conditions as- sociated with oxidative stress.展开更多
基金supported by the National Natural Science Foundation of China,No.81501935(to HL)the Natural Science Foundation of Shandong Province of China,No.ZR2014HQ065(to HL)
文摘Transient receptor potential ankyrin 1 （TRPA1） is a key player in pain and neurogenic inflammation, and is localized in nociceptive primary sensory dorsal root ganglion （DRG） neurons. TRPA1 plays a major role in the transmission of nociceptive sensory signals. The generation of neurogenic inflammation appears to involve TRPAl-evoked release of calcitonin gene-related peptide （CGRP）. However, it remains unknown whether TRPA1 or CGRP expression is affected by TRPA 1 activation. Thus, in this study, we examined TRPA 1 and CGRP expression in DRG neurons in vitro after treatment with the TRPA1 activator tbrmaldehyde or the TRPA1 blocker menthol. In addition, we examined the role of extracellular signal-regulated protein kinase 1/2 （ERK1/2） in this process. DRG neurons in culture were exposed to formaldehyde, menthol, the ERK1/2 inhibitor PD98059 ＋ formaldehyde, or PD98059 ＋ menthol. After treatment, real-time polymerase chain reaction, western blot assay and double immunofluorescence labeling were performed to evaluate TRPA1 and CGRP expression in DRG neurons. Formaldehyde elevated mRNA and protein levels of TRPA 1 and CGRP, as well as the proportion of TRPA1- and CGRP-positive neurons. In contrast, menthol reduced TRPA1 and CGRP expression. Furthermore, the effects of lbrmaldehyde, but not menthol, on CGRP expression were blocked by pretreatment with PD98059. PD98059 pretreatment did not affect TRPA1 expression in the presence of formaldehyde or menthol.
基金supported by grants from the US National Institutes of Health (R01-DE17794,R01-NS54362 and R01-NS67686)
文摘Objective To investigate the role of oxidative stress in itch-indicative scratching behavior in mice, and further- more, to define the cellular and molecular mechanisms underlying oxidative stress-mediated itch. Methods Scratching behavior was induced by intradermal injection of the oxidants hydrogen peroxide （H202） or tert-butylhydroperoxide （tBHP） into the nape of the neck in mice. The mice were observed for 30 rain. Results Intradermal H202 （0.03%-1%） or tBHP （1-30 pmol） elicited robust scratching behavior, displaying an inverted U-shaped dose-response curve. Naloxone, an opioid receptor antagonist, but not morphine, largely suppressed the oxidant-induced scratching. Chlorpheniramine, a histamine H1 receptor antagonist, blocked histamine- but not oxidant-induced scratching, indicating the involvement of a histamine-independent mechanism in oxidant-evoked itch. Further, resiniferatoxin treatment abolished oxidant-induced scratching, suggesting an essential role of C-fibers. Notably, blockade of transient receptor potential subtype ankyrin 1 （TRPA1） with the selective TRPA1 antagonist HC-030031, or genetic deletion of Trpal but not Trpvl （subfamily V, mem- ber 1） resulted in a profound reduction in H202-evoked scratching. Finally, systemic administration of the antioxidant N- acetyl-L-cysteine or trolox （a water-soluble vitamin E analog） attenuated scratching induced by the oxidants. Conclusion Oxidative stress by different oxidants induces profound scratching behavior, which is largely histamine- and TRPV1- independent but TRPAl-dependent. Antioxidants and TRPA1 antagonists may be used to treat human itch conditions as- sociated with oxidative stress.
