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National Institute of Environmental Health Sciences

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Your Environment. Your Health.

Publication Detail

Title: Trimethylamine oxide suppresses stress-induced alteration of organic anion transport in choroid plexus.

Authors: Villalobos, Alice R A; Renfro, J Larry

Published In J Exp Biol, (2007 Feb)

Abstract: The effect of physicochemical stress on organic anion transport across the vertebrate blood-cerebrospinal fluid (CSF) barrier in the presence and absence of an endogenous cytoprotectant, trimethylamine oxide (TMAO), was investigated in isolated IVth choroid plexus (CP) of spiny dogfish shark (Squalus acanthias), an animal with naturally high levels of TMAO ( approximately 70 mmol l(-1)). Active transepithelial absorption of the organic anion, 2,4-dichlorophenoxyacetic acid (2,4-D), by IVth CP mounted in Ussing chambers was measured after in vitro stress, and a marker for the cellular stress response, inducible heat shock protein 70 (Hsp70), was assayed by immunoblot analysis. Transient heat stress (a shift from the normal 13.5 degrees C to 23.5 degrees C for 1 h) decreased 2,4-D transport by approximately 66%; however, the same stress minus TMAO (isosmotic replacement with urea) had no effect on transport rate. In the absence of TMAO, stress-induced Hsp70 accumulation was more than double that seen in the presence of TMAO. Likewise, exposure to 50 micromol l(-1) Zn for 6 h induced a twofold greater Hsp70 accumulation in the absence of TMAO than in its presence, and the higher Hsp70 level was associated with a higher 2,4-D transport rate. Heat stress and 50 micromol l(-1) Zn also induced more pronounced increases in Hsp70 mRNA in the absence of TMAO. Thus, the cellular stress response can significantly alter CP organic anion transport capacity, and an endogenous osmolyte can suppress that response.

PubMed ID: 17234624 Exiting the NIEHS site

MeSH Terms: 2,4-Dichlorophenoxyacetic Acid/metabolism*; Animals; Biological Markers/analysis; Blood-Brain Barrier/drug effects; Blood-Brain Barrier/metabolism; Choroid Plexus/anatomy & histology; Choroid Plexus/drug effects; Choroid Plexus/metabolism*; Female; HSP70 Heat-Shock Proteins/analysis; Heat Stress Disorders; Ion Transport/drug effects; Male; Methylamines/pharmacology*; Oxidants/pharmacology*; RNA, Messenger/metabolism; Squalus acanthias/metabolism*; Zinc/pharmacology

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