Abstract
β-Eudesmol, a sesquiterpenoid isolated from “So-jutsu” (Atractylodislanceaerhizomas), is known to have various unique effects on the nervous system. We examined in detail the mechanism by which β-eudesmol modified neuronal function using rat pheochromocytoma cells (PC-12). β-Eudesmol at concentrations of 100 and 150 μM significantly induced neurite extension in PC-12 cells, which was accompanied, at the highest concentration, by suppression of [3H]thymidine incorporation. β-Eudesmol at concentrations of 100 and 150 μM also evoked a significant increase in intracellular Ca2+concentration ([Ca2+]i) in these cells, as determined by the fura 2 assay. Much of this increase remained even after the extracellular Ca2+ was chelated by EGTA. The [Ca2+]i increase induced by β-eudesmol was partially inhibited by the phosphoinositide-specific phospholipase C (PI-PLC) inhibitor 1-[6-[[17β-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-1H-pyrrole-2,5-dione (U-73122) (2 μM) under extracellular Ca2+-free conditions. Furthermore, β-eudesmol, in a concentration-dependent fashion, caused an accumulation of inositol phosphates. β-Eudesmol (150 μM) promoted phosphorylation of both mitogen-activated protein kinase (MAPK) and cAMP-responsive element binding protein in a time-dependent manner. These phosphorylations were suppressed by the MAPK kinase inhibitor 2-(2′-amino-3′-methoxyphenol)-oxanaphthalen-4-one (PD98059) (50 μM), U-73122 (2 μM), the calmodulin inhibitorN-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide hydrochloride (W7) (1–10 μM), and the protein kinase A inhibitorN-[2-(4-bromocinnamylamino)ethyl]-5-isoquinoline (H89) (1–10 μM). β-Eudesmol-induced neurite extension was significantly inhibited by both U-73122 (2 μM) and PD98059 (30 μM), suggesting the involvement of PI-PLC and MAPK in neurite outgrowth. β-Eudesmol, being a small molecule, may therefore be a promising lead compound for potentiating neuronal function. Furthermore, the drug may be useful in helping to clarify the mechanisms underlying neuronal differentiation.
Footnotes
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This work was supported in part by grants-in-aid from the Japan Society for the Promotion of Science (01532 to Yu.O.).
- Abbreviations:
- NGF
- nerve growth factor
- AIT-082
- 4-[[3-(1,6-dihydro-6-oxo-9-purin-9-yl)-1-oxopropyl]amino]benzoic acid
- SR57746A
- 1-[2-(naphth-2-yl)ethy]-4-(3-trifluoromethyl phenyl)-1,2,5,6-tetrahydropyridine hydrochloride
- GF109203X
- 3-[1-[-3-(dimethylaminopropyl]-1H-indol-3-yl]-4-(1H-indol-3-yl)-1H-pyrrole-2,5-dione monohydrochloride
- W7
- N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide hydrochloride
- H89
- N-[2-(4-bromocinnamylamino)ethyl]-5-isoquinoline
- U-73122
- 1-[6-[[17β-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-1H-pyrrole-2,5-dione
- U-73343
- 1-[6-[[17β-3-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-2,5-pyrrolidine-dione
- PD98059
- 2-(2′-amino-3′-methoxyphenol)-oxanaphthalen-4-one
- DMEM
- Dulbecco's modified Eagle's medium
- PBS
- phosphate-buffered saline
- MTT
- 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium
- BSA
- bovine serum albumin
- MOPS
- 4-morpholinepropanesulfonic acid
- MAPK
- mitogen-activated protein kinase
- CREB
- cAMP-responsive element binding protein
- PI-PLC
- phosphoinositide-specific phospholipase C
- [Ca2+]i
- intracellular Ca2+concentration
- CaM
- calmodulin
- PKA
- protein kinase A
- PKC
- protein kinase C
- RSK
- ribosomal S6 kinase
- PC-12
- pheochromocytoma cells
- Received December 11, 2001.
- Accepted February 19, 2002.
- The American Society for Pharmacology and Experimental Therapeutics
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