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The MAP kinase cascade is activated prior to the induction of gliosis in the 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of dopaminergic neurotoxicity.

Authors
O'Callaghan-JP; Martin-PA; Mass-MJ
Source
Ann NY Acad Sci 1998 May; 844:40-49
NIOSHTIC No.
20025462
Abstract
Injury to the central nervous system (CNS) provokes microglial activation and astrocytic hypertrophy at the site of damage. The signaling events that underlie these cellular responses remain unknown. Recent evidence has implicated tyrosine phosphorylation systems, in general, and the mitogen-activated protein kinase (MAP kinase) cascade, in particular, in the mediation of growth-associated events linked to neural degeneration, such as glial action. Moreover, an increase in the mRNA coding for the 14.3.3 protein, a known regulator of the MAP kinase pathway, appears to be involved in methamphetamine neurotoxicity. To examine the potential role of these protein kinase pathways in drug-induced damage to the CNS, we used the dopaminergic neurotoxicant, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), and to damage nerve terminals in the mouse neostriatum and elicit a glial reaction. The onset of reactive gliosis then was verified by Northern blot analysis of glial fibrillary acidic protein (GFAP) mRNA and qualified by enzyme-linked immunosorbent assay (ELISA) of GFAP (protein). A single administration of MPTP (12.5 mg/kg, subcutaneously (s.c.)) to the C57B1/66J mouse resulted in a 10-fold increase in GFAP mRNA by 1 day and a 4-fold increase in GFAP (protein) by 2 days. To determine the potential role of protein tyrosine phosphorylation and MAP kinase activation in these events, blots of striatal homogenates were probed with antibodies directed against phospho-tyr 204 and phospho-thr 202, residues corresponding to the active sites of p42/44 MAP kinase. After mice were sacrificed by focused microwave irradiation to preserve steady-state phosphorylation, proteins from striatal homogenates were resolved by sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE). Immunoblots of these samples showed a number of phosphotyrosine-labeled bands, but there were no apparent differences between control and MPTP groups. In contrast, phospho-MAP kinase was elevated over 1.5 fold, 3-6 hours post MPTP. These findings are suggestive of a role of the MAP kinase cascade in the early phase of injury-induced glial activation.
Keywords
Models; Neurotoxic-effects; Neurotoxicity; Neurotoxicology; Neurotoxins; Injuries; Central-nervous-system-disorders; Sampling; Laboratory-animals; Animals; Animal-studies
Contact
James P. O'Callaghan, Ph.D., Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, HELD/TMBB, 1095 Willowdale Road, Morgantown, WV 26505
CODEN
ANYAA9
CAS No.
55520-40-6
Publication Date
19980530
Document Type
Journal Article
Email Address
jdo5@cdc.gov
Fiscal Year
1998
NTIS Accession No.
NTIS Price
ISBN No.
9781573311458
ISSN
0077-8923
NIOSH Division
HELD
Source Name
Annals of the New York Academy of Sciences, The Neurochemistry of Drugs of Abuse
State
WV; NC
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