title: Possible involvement of cytosolic phospholipase A(2) in cell death induced by 1-methyl-4-phenylpyridinium ion, a dopaminergic neurotoxin, in GH3 cells.
abstract: Previously we reported that 1-methyl-4-phenylpyridinium ion (MPP(+)), a dopaminergic neurotoxin, induced apoptosis of GH3 cells established from rat anterior pituitary. In the present study, the role of MPP(+) along with that of other apoptotic factors such as Ca(2+) and H(2)O(2) in cell death was examined. Ionomycin induced DNA fragmentation and lactate dehydrogenase (LDH) leakage in GH3 cells. H(2)O(2) also induced LDH leakage. Co-addition of MPP(+), in conditions where MPP(+) had no effect by itself, enhanced ionomycin- and H(2)O(2)-induced cell death. Because the stimulation of phospholipase A(2) (PLA(2)) causing arachidonic acid (AA) release has been proposed to be involved in neuronal cell death, the effect of MPP(+) on AA release in GH3 cells was investigated. MPP(+) treatment for 8 h enhanced ionomycin- and H(2)O(2)-stimulated AA release mediated by activation of cytosolic PLA(2) in a concentration-dependent manner, although MPP(+) by itself had no effect on AA release. An inhibitor of cytosolic PLA(2) inhibited MPP(+)-induced cell death. These findings suggest a synergistic effect of MPP(+) on Ca(2+)- and H(2)O(2)-induced cell death, and the involvement of cytosolic PLA(2) activation in MPP(+)-induced cell death in GH3 cells. Pretreatment with a caspase inhibitor or EGF did not modify the ionomycin- or H(2)O(2)-induced AA release, or enhancement by MPP(+), but the pretreatment inhibited the cell death in the presence and absence of MPP(+). The involvement of caspase(s) on activation of PLA(2) by MPP(+) was excluded, and EGF inhibited MPP(+)-induced cell death downstream of the AA release.
authors.affiliation: Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Yoshinaga
authors.forename: Y
authors.initials: Y
authors.lastname: Yasuda
authors.forename: T
authors.initials: T
authors.lastname: Murayama
authors.forename: Y
authors.initials: Y
authors.lastname: Nomura
mesh_terms: D015655:1-Methyl-4-phenylpyridinium / Q000037:antagonists & inhibitors / Q000633:toxicity*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D016718:Arachidonic Acid / Q000378:metabolism; D001095:Arachidonic Acids / Q000494:pharmacology; D003600:Cytosol / Q000201:enzymology; D053938:DNA Fragmentation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000633:toxicity; D007770:L-Lactate Dehydrogenase; D009498:Neurotoxins / Q000633:toxicity; D010741:Phospholipases A / Q000378:metabolism*; D010911:Pituitary Neoplasms; D051381:Rats; D014407:Tumor Cells, Cultured
chemical_list: D001095:Arachidonic Acids; D004791:Enzyme Inhibitors; D009498:Neurotoxins; C081565:arachidonyltrifluoromethane; D016718:Arachidonic Acid; D006861:Hydrogen Peroxide; D007770:L-Lactate Dehydrogenase; D010741:Phospholipases A; D015655:1-Methyl-4-phenylpyridinium