Abstract
Salsolinol (SAL), a novel dopaminergic catechol tetrahydroisoquinoline neurotoxin, has been speculated to contribute to the etiology of Parkinson's disease and neuropathology of chronic alcoholism. Our previous studies have demonstrated that SAL induces strand scission in øX174 supercoiled DNA and oxidative base modification in calf thymus DNA in the presence of cupric ion. We now report that treatment of rat pheochromocytoma (PC12) cells with SAL causes reduced viability, which was exacerbated by Cu2+. The copper chelator bathocuproinedisulfonic acid ameliorated cytotoxicity induced by SAL and Cu2+. N-Acetyl-l-cysteine and reduced glutathione protected against SAL- plus Cu2+-mediated PC12 cell death. Cells exposed to SAL underwent apoptosis, as revealed by characteristic morphological and biochemical changes. SAL treatment resulted in increased levels of Bax with a concomitant decrease in expression of Bcl-xL. Furthermore, SAL rapidly activated c-Jun N-terminal kinase, whereas the activity of extracellular signal-regulated protein kinase remained unchanged. Transfection with Bcl-xL or Bcl-2 led to protection against SAL-mediated PC12 cell death. Although SAL alone could cause apoptotic death in PC12 cells, cells treated with SAL together with Cu2+ became necrotic. Cells exposed to both SAL and Cu2+ exhibited higher levels of intracellular reactive oxygen species, malondialdehyde, and 8-oxo-7,8-dihydro-2′-deoxyguanosine than did those treated with SAL alone. These results suggest that copper accelerates redox cycling of SAL, leading to massive production of reactive oxygen species, which can divert the SAL-induced cell death to necrosis.
Footnotes
-
This work was supported by the Academic Research Fund (GE 997-019-D0008) awarded to Y.-J.S. from the Ministry of Education, Republic of Korea. This manuscript was prepared from a dissertation by H.-J.K. in partial fulfillment of the requirement for a Masters of Science at Seoul National University. Y.S. and J.-H.J. contributed equally to this work.
- Abbreviations:
- SAL
- salsolinol
- ROS
- reactive oxygen species
- 6-OHDA
- 6-hydroxydopamine
- MAP
- mitogen-activated protein
- JNK
- c-Jun-N-terminal kinase
- ERK
- extracellular signal-mediated protein kinase
- BCS
- bathocuproinedisulfonic acid
- NAC
- N-acetyl-l-cysteine
- GSH
- reduced glutathione
- MTT
- 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide
- DAPI
- 4′,6-diamidino-2-phenylindole
- PBS
- phosphate-buffered saline
- TUNEL
- terminal deoxynucleotidyl transferase-mediated dUTP-X nick-end labeling
- DCF-DA
- 2′,7′-dichlorodihydrofluorescein diacetate
- MDA
- malondialdehyde
- 8-oxo-dGuo
- 8-oxo-7,8-dihydro-2′-deoxyguanosine
- dGuo
- deoxyguanosine
- HPLC
- high-performance liquid chromatography
- Received November 1, 2000.
- Accepted May 11, 2001.
- The American Society for Pharmacology and Experimental Therapeutics
MolPharm articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|