A comparative study of the early effects of phenobarbital and 3-methylcholanthrene on the synthesis and transport of ribonucleic acid in rat liver.

Kumar, Ashwani and Rao, MR and Padmanaban, G (1980) A comparative study of the early effects of phenobarbital and 3-methylcholanthrene on the synthesis and transport of ribonucleic acid in rat liver. In: Biochemical Journal, 186 (1). pp. 81-87.

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Abstract

At 2-3 h after phenobaribtal administration, the drug has no effect on nucleoplasmic RNA synthesis and decreases nucleolar RNA synthesis. However, at this time there is an increase in the labelling of cytoplasmic poly(A)-containing RNA, even though there is decreased labelling of total polyribosomal RNA. The decrease in labelling of nucleolar and total polyribosomal RNA owing to phenobarbital is a transient phenomenon. Under similar conditions, 3-methylcholanthrene has no effect on nucleolar RNA synthesis, but leads to an increase in synthesis of nucleoplasmic and cytoplasmic poly(A)-containing RNA. Cytosol isolated from phenobarbital-treated, but not from 3-methyl-cholanthrene-treated, animals facilitates an enhanced transport of RNA from nuclei. At the time points investigated, 3-methylcholanthrene or its metabolite shows a 10-15-fold higher concentration in the chromatin than that of phenobarbital or its metabolite. It is suggested that the primary effect of phenobarbital is at the cytoplasmic level, promoting the transport of RNA from the nuclei, which can act as a trigger for enhanced transcription at later periods. 3-Methylcholanthrene or its metabolite directly binds to the chromatin and evokes a selective transcriptional response.

Item Type:	Journal Article
Publication:	Biochemical Journal
Publisher:	Portland Press
Additional Information:	Copyright of this article belongs to Portland Press.
Department/Centre:	Division of Biological Sciences > Biochemistry
Date Deposited:	21 Jan 2010 07:37
Last Modified:	19 Sep 2010 05:51
URI:	http://eprints.iisc.ac.in/id/eprint/24753

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