title: Substance P release evoked by capsaicin or potassium from rat cultured dorsal root ganglion neurons is conversely modulated with bradykinin.
abstract: To clarify the molecular mechanism of substance P (SP) release from dorsal root ganglion (DRG) neurons, we investigated the involvement of several intracellular effectors in the regulation of SP release evoked by capsaicin, potassium or/and bradykinin. Bradykinin-evoked SP release from cultured adult rat DRG neurons was attenuated by either the mitogen-activated protein kinase kinase (MEK) inhibitor (U0126) or cycloheximide. As the long-term exposure of DRG neurons to bradykinin (3 h) resulted in extracellular signal-regulated kinase (ERK) phosphorylation at an early stage and thereafter induced cyclooxygenase-2 (COX-2) protein expression, which both contribute to the SP release triggered by bradykinin B2 receptor. The long-term exposure of DRG neurons to bradykinin enhanced the SP release by capsaicin, but attenuated that by potassium. Interestingly, the inositol 1,4,5-triphosphate (IP3)-induced calcium release blocker [2-aminoethyl diphenylborinate (2-APB)] not only inhibited the potassium-evoked SP release, but also completely abolished the enhancement of capsaicin-induced SP release by bradykinin from cultured DRG neurons. Together, these findings suggest that the molecular mechanisms of SP release by bradykinin involve the activation of MEK, and also require the de novo protein synthesis of COX-2 in DRG neurons. The IP3-dependent calcium release could be involved in the processes of the regulation by bradykinin of capsaicin-triggered SP release.
authors.affiliation: Department of Pharmacology, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan.
authors.forename: He-Bin
authors.initials: HB
authors.lastname: Tang
authors.forename: Atsuko
authors.initials: A
authors.lastname: Inoue
authors.forename: Mikiko
authors.initials: M
authors.lastname: Iwasa
authors.forename: Izumi
authors.initials: I
authors.lastname: Hide
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Nakata
mesh_terms: D000818:Animals; D001896:Boron Compounds / Q000494:pharmacology; D001920:Bradykinin / Q000378:metabolism* / Q000494:pharmacology; D002211:Capsaicin / Q000494:pharmacology*; D002478:Cells, Cultured; D051546:Cyclooxygenase 2 / Q000187:drug effects / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000187:drug effects / Q000378:metabolism; D005727:Ganglia, Spinal / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism / Q000494:pharmacology; D048369:MAP Kinase Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D010146:Pain / Q000378:metabolism / Q000503:physiopathology; D011188:Potassium / Q000378:metabolism* / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D043782:Receptor, Bradykinin B2 / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013373:Substance P / Q000378:metabolism*; D010738:Type C Phospholipases / Q000378:metabolism
chemical_list: D001896:Boron Compounds; D004791:Enzyme Inhibitors; D011500:Protein Synthesis Inhibitors; D043782:Receptor, Bradykinin B2; D013373:Substance P; D011189:Potassium Chloride; D015544:Inositol 1,4,5-Trisphosphate; C109986:2-aminoethoxydiphenyl borate; D051546:Cyclooxygenase 2; D048049:Extracellular Signal-Regulated MAP Kinases; D048369:MAP Kinase Kinase 1; D010738:Type C Phospholipases; D011188:Potassium; D002211:Capsaicin; D001920:Bradykinin