Low-dose 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine causes inflammatory activation of astrocytes in nuclear factor-κB reporter mice prior to loss of dopaminergic neurons

Document Type

Article

Abstract

Neuroinflammation is implicated in the progression of numerous disease states of the CNS, but early inflammatory signaling events in glial cells that may predispose neurons to injury are not easily characterized in vivo. To address this question, we exposed transgenic mice expressing a nuclear factor-κB (NF-κB)-driven enhanced green fluorescent protein (EGFP) reporter construct to low doses of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and examined inflammatory activation of astrocytes in relation to neurobehavioral and neuropathological outcomes. The highest dose of MPTP (60 mg/kg total dose) caused a decrease in locomotor activity and a reduction in stride length. No significant loss of dopaminergic neurons in the substantia nigra was apparent at any dose. In contrast, expression of tyrosine hydroxylase in striatal fibers was reduced at 60 mg/kg MPTP, as were levels of dopamine and DOPAC. Colocalized expression of EGFP and inducible nitric oxide synthase (NOS2) occurred in astrocytes at 30 and 60 mg/kg MPTP and was associated with increased protein nitration in nigral dopaminergic neurons. Inhibition of NF-κB in primary astrocytes by expression of mutant IκBα suppressed expression of NOS2 and protected cocultured neurons from astrocyte-mediated apoptosis. These data indicate that inflammatory activation of astrocytes and enhanced nitrosative stress occurs at low doses of MPTP prior to loss of dopaminergic neurons. NF-κB-mediated expression of NOS2 appears to be a sensitive indicator of neuroinflammation that correlates with MPTP-induced neurochemical and neurobehavioral deficits prior to loss of dopaminergic neurons in the subtantia nigra.

Medical Subject Headings

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (pharmacology); Analysis of Variance; Animals; Astrocytes (drug effects); Cell Death (drug effects); Coculture Techniques (methods); Disease Models, Animal; Dopamine (metabolism); Dose-Response Relationship, Drug; Glial Fibrillary Acidic Protein (metabolism); Green Fluorescent Proteins (genetics); Hindlimb (physiopathology); Inflammation (chemically induced, pathology); Male; Mice; Mice, Transgenic; Motor Activity (drug effects); Neurons (drug effects, metabolism); Neurotoxins (pharmacology); Nitric Oxide Synthase Type II (metabolism); Protein Serine-Threonine Kinases (genetics, metabolism); Substantia Nigra (drug effects, metabolism, pathology); Tyrosine (analogs & derivatives, metabolism); Tyrosine 3-Monooxygenase (metabolism); NF-kappaB-Inducing Kinase

Publication Date

3-1-2011

Publication Title

Journal of neuroscience research

E-ISSN

1097-4547

Volume

89

Issue

3

First Page

406

Last Page

17

PubMed ID

21259327

Digital Object Identifier (DOI)

10.1002/jnr.22549

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