Dexamethasone reduces steady state insulin-like growth factor I messenger ribonucleic acid levels in rat neuronal and glial cells in primary culture

Martin Adamo, Haim Werner, Wendy Farnsworth, Charles T. Roberts, Mohan Raizada, Derek LeRoith

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Abstract

Insulin-like growth factor I (IGF-I) mRNA was demonstrated in primary cultures of neuronal and glial cells from rat brain. On Northern blots, a rat IGF-I cDNA probe hybridized to RNA species of 7.5, 1.7, and 0.8-1.2 kilobases in total and poly(A)+ RNA from both cell types. Solution hybridization/ RNase protection assays were performed using an antisense riboprobe complementary to the 5′-untranslated region as well as part of the coding region of rat IGF-I mRNA. These studies indicated that two of the previously described three possible alternative 5′-untranslated splicing variants (classes A and C) were expressed in neuronal and glial cells, with class C transcripts predominating. Neuronal cells also possessed extremely low levels of class B transcripts. Treatment of neuronal cell cultures with the synthetic glucocorticoid dexamethasone reduced IGF-I mRNA levels by 60%. Glial cell IGF-I mRNA levels were reduced by dexamethasone by up to 40%. These results suggest that glucocorticoid-induced reductions in IGF-I production could occur at the level of transcription and may underlie some of the actions of glucocorticoids in causing growth retardation and inhibition of cell proliferation.

Original languageEnglish (US)
Pages (from-to)2565-2570
Number of pages6
JournalEndocrinology
Volume123
Issue number5
DOIs
Publication statusPublished - Nov 1988

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ASJC Scopus subject areas

  • Endocrinology

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