Phosphorylation of TRPV1 by neurokinin-1 receptor agonist exaggerates the capsaicin-mediated substance P release from cultured rat dorsal root ganglion neurons.
The present study was conducted to determine whether the activation of neurokinin-1 receptor (NK-1R) by its agonist (GR73632) enhances the capsaicin-evoked substance P (SP) release using a radioimmunoassay. A pre-exposure to GR73632 enhanced the capsaicin-evoked SP release in a time- and dose-dependent manner. The augmentation of capsaicin-evoked SP release by GR73632 was completely inhibited by pharmacological blockade of NK-1R or transient receptor potential vanilloid receptor subtype 1 (TRPV1), and was partially attenuated by the inhibition of either protein kinase C (PKC), cyclooxygenase (COX) or phospholipase C (PLC), p38 or p42/44 mitogen-activated protein (MAP) kinase, but not protein kinase A. This augmentation of SP release was further increased by inhibition of c-Jun NH2-terminal kinase. A short-term (10min) exposure to GR73632 resulted in an increase in the TRPV1 phosphorylation. The increase in the TRPV1 phosphorylated forms induced by a 60-min exposure to GR73632 was completely abolished by the inhibition of either PKC, COX or PLC, p38 or p42/44 MAP kinases. Immunocytochemistry study demonstrated that the NK-1R and TRPV1 were mainly co-expressed in the small-sized neurons. These findings suggest that the activation of NK-1R by its agonist, by sensitizing the TRPV1 through the PKC phosphorylation of TRPV1, may play a role in the enhancement of the capsaicin-evoked SP release from cultured rat DRG neurons.
Tang
He-Bin
HB
Department of Pharmacology, Graduate School of Biomedical Sciences, Hiroshima University, Kasumi 1-2-3, Minami-ku, Hiroshima 734-8553, Japan.
Li
Yu-Sang
YS
Miyano
Kanako
K
Nakata
Yoshihiro
Y
D000704:Analysis of Variance; D000818:Animals; D001713:Biphenyl Compounds / Q000494:pharmacology; D002211:Capsaicin / Q000494:pharmacology; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005727:Ganglia, Spinal / Q000166:cytology*; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D010446:Peptide Fragments / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D018040:Receptors, Neurokinin-1 / Q000819:agonists* / Q000378:metabolism; D013373:Substance P / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology; D050916:TRPV Cation Channels / Q000378:metabolism*; D013997:Time Factors
D001713:Biphenyl Compounds; D004791:Enzyme Inhibitors; D010446:Peptide Fragments; D018040:Receptors, Neurokinin-1; D050916:TRPV Cation Channels; C493922:Trpv1 protein, rat; C068032:GR 73632; D013373:Substance P; D002211:Capsaicin; C066892:CP 96345