US EPA

4673915 

Journal Article 

Differential Expression Of GRP78 And HSP70 In Primary Brainstem And Cortical Astrocytes Exposed To 1, 3-Dintrobenzene 

Runkle, S. A.; Steiner, S. R.; Philbert, M. A. 

2005 

1 

Toxicological Sciences
ISSN: 1096-6080
EISSN: 1096-0929 

84 

1-S 

313 

English 

Exposure to 1, 3-dinitrobenzene (1, 3-DNB) results in a gliovascular lesion within specific brainstem nuclei. Although these regions have high energy requirements, this alone does not describe the observed pathology due to the absence of lesion in areas of similar energy demand. We investigated the possibility that acute in vitro neurotoxicity of 1, 3-DNB may be mediated through a disruptive effect by the compound on two key molecular chaperones, glucose regulated protein 78 (GRP78) and heat shock protein 70 (HSP70). Real time RT-PCR analysis of primary brainstem and cortical astrocyte cultures revealed GRP78 mRNA expression increased approximately two-fold in the brainstem, 2 hours post 1mM 1, 3-DNB exposure. Cortical GRP78 mRNA expression increased approximately two-fold, 4 hours after exposure. Regional differences in sensitivity were also observed with the positive control. Thapsigargin (1µM) induced a five-fold increase in brainstem GRP78 expression, in contrast, cortical expression levels were not significantly affected. Immunoblot analysis of brainstem astrocytes showed down-regulation of GRP78 protein expression at 0.5 and 2 hours and up-regulation to basal levels at 4 hours. No significant changes in GRP78 protein expression were observed in the cortical astrocytes after 6 hours of exposure. Immunofluorescence was used to monitor changes in HSP70 expression after 1, 3-DNB exposure in primary brainstem and cortical astrocytes. HSP70 was up-regulated at 2 hours in the cortical astrocytes and at 4 hours in the brainstem astrocytes. This data indicates that primary brainstem and cortical astrocytes respond differentially to oxidative cues after 1, 3-DNB exposure: brainstem astrocytes are significantly more sensitive. Temporal regulation of regional molecular responses to oxidative stress may underlie the differential susceptibility of brainstem astrocytes to 1, 3-DNB. 

Heat-Shock Proteins/*GENETICS
HSP70 Heat-Shock Proteins/*GENETICS
Humans
Cells, Cultured
Reverse Transcriptase Polymerase Chain Reaction
RNA, Messenger/GENETICS
Brain Stem/*DRUG EFFECTS/METABOLISM/CYTOLOGY
Cerebral Cortex/*DRUG EFFECTS/METABOLISM/CYTOLOGY
Dinitrobenzenes/*TOXICITY
Astrocytes/*DRUG EFFECTS/METABOLISM
Thapsigargin/PHARMACOLOGY
Fluorescent Antibody Technique
Gene Expression Regulation/*DRUG EFFECTS
NO CAS RN
99-65-0
67526-95-8