title: Interleukin-1beta-induced substance P release from rat cultured primary afferent neurons driven by two phospholipase A2 enzymes: secretory type IIA and cytosolic type IV.
abstract: We previously described that recombinant interleukin-1beta (IL-1beta) induced the significant release of substance P (SP) via a cyclooxygenase (COX) pathway in primary cultured rat dorsal root ganglion (DRG) cells. In the present study, we examined the involvement of two types of phospholipase A2 (PLA2) enzymes, which lie upstream of COX in the prostanoid-generating pathway, in the IL-1beta-induced release of SP from DRG cells. The expression of type IIA secretory PLA2 (sPLA2 -IIA) mRNA was undetectable by ribonuclease protection assay in non-treated DRG cells, while in DRG cells incubated with 1 ng/mL of IL-1beta, the expression was induced in a time-dependent manner. On the other hand, type IV cytosolic PLA2 (cPLA2 ) mRNA was constitutively expressed in the non-treated DRG cells, and treatment with 1 ng/mL of IL-1beta for 3 h significantly increased the levels of cPLA2 mRNA. The IL-1beta-induced SP release was significantly inhibited by the sPLA2 inhibitor, thioetheramide phosphorylcholine (TEA-PC), and the cPLA2 inhibitor, arachidonyl trifluoromethyl ketone (AACOCF3 ). Furthermore AACOCF3 suppressed the induction of sPLA2 -IIA mRNA expression induced by IL-1beta. These observations suggested that two types of PLA2, sPLA2 -IIA and cPLA2, were involved in the IL-1beta-induced release of SP from DRG cells, and that the functional cross-talk between the two enzymes might help to control their activity in the prostanoid-generating system in DRG cells. These events might be key steps in the inflammation-induced hyperactivity in primary afferent neurons of spinal cord.
authors.affiliation: Department of Pharmacology, Institute of Pharmaceutical Sciences, Hiroshima University School of Medicine, Kasumi, Minami-ku, Hiroshima, Japan.
authors.forename: Norimitsu
authors.initials: N
authors.lastname: Morioka
authors.forename: Kazumi
authors.initials: K
authors.lastname: Takeda
authors.forename: Kei
authors.initials: K
authors.lastname: Kumagai
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Hanada
authors.forename: Kozo
authors.initials: K
authors.lastname: Ikoma
authors.forename: Izumi
authors.initials: I
authors.lastname: Hide
authors.forename: Atsuko
authors.initials: A
authors.lastname: Inoue
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Nakata
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004790:Enzyme Induction / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005727:Ganglia, Spinal / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D054501:Group II Phospholipases A2; D054513:Group IV Phospholipases A2; D007375:Interleukin-1 / Q000494:pharmacology*; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D008297:Male; D009475:Neurons, Afferent / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D010741:Phospholipases A / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D054467:Phospholipases A2; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar; D013373:Substance P / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D007375:Interleukin-1; D007527:Isoenzymes; D012333:RNA, Messenger; D013373:Substance P; D010741:Phospholipases A; D054501:Group II Phospholipases A2; D054513:Group IV Phospholipases A2; D054467:Phospholipases A2; C516391:Pla2g4a protein, rat