Activation of the mitogen-activated protein kinase cascade through nitric oxide synthesis as a mechanism of neuritogenic effect of genipin in PC12h cells.
Prominent neurite outgrowth induced by genipin, a plant-derived iridoid, was substantially inhibited by addition of NG-nitro-L-arginine methyl ester (L-NAME), a nitric oxide (NO) synthase (NOS) inhibitor, and carboxy-PTIO, an NO scavenger, in PC12h cells. Increases of the NADPH-diaphorase activity and neuronal and inducible NOS proteins in cells preceded the neurite outgrowth after addition of genipin to medium. NO donors could induce the neurite outgrowth dose-dependently in the cells. On the other hand, an inhibitor of soluble guanylate cyclase (SGC), which is known to be a stimulatory target of NO, abolished greatly the genipin-induced neurite outgrowth. Addition of extracellular signal-regulated kinase (ERK) kinase inhibitors could almost completely abolish the neurite induction. L-NAME remarkably depressed genipin-stimulated phosphorylation of ERK-1 and -2. A neuritogenic effect of nerve growth factor (NGF) in PC12h cells was also remarkably inhibited by the NOS inhibitor, NO scavenger and SGC inhibitor. These findings suggest that induced NO production followed by cyclic GMP-mediated stimulation of the mitogen-activated protein kinase (MAPK) cascade is implicated in the neuritogenesis by genipin and NGF in PC12h cells.
Yamazaki
M
M
Department of Biodynamics, Faculty of Pharmaceutical Sciences, Hokuriku University, Ishikawa, Japan. m-yamazaki@hokuriku-u.ac.jp
Chiba
K
K
Mohri
T
T
Hatanaka
H
H
D000818:Animals; D004789:Enzyme Activation / Q000187:drug effects; D004790:Enzyme Induction; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016166:Free Radical Scavengers; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors; D057889:Iridoid Glycosides; D039823:Iridoids; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D020932:Nerve Growth Factor / Q000494:pharmacology; D016501:Neurites / Q000187:drug effects* / Q000648:ultrastructure; D009569:Nitric Oxide / Q000096:biosynthesis* / Q000502:physiology; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D016716:PC12 Cells / Q000201:enzymology / Q000648:ultrastructure*; D010766:Phosphorylation; D011714:Pyrans / Q000494:pharmacology*; D051381:Rats
D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D057889:Iridoid Glycosides; D039823:Iridoids; D020030:Nitric Oxide Donors; D011714:Pyrans; D009569:Nitric Oxide; D020932:Nerve Growth Factor; C007834:genipin; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496322:Nos1 protein, rat; C496318:Nos2 protein, rat; C496316:Nos3 protein, rat; D020928:Mitogen-Activated Protein Kinases; D006162:Guanylate Cyclase; D019331:NG-Nitroarginine Methyl Ester