Insulin-like growth factor I gene expression by primary cultures of ovarian cells: Insulin and dexamethasone dependence

Luis F. Botero, Charles Roberts, Derek LeRoith, Eli Y. Adashi, Eleuterio R. Hernandez

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

A growing body of information now supports the existence of a complete intraovarian insulin-like growth Factor I (IGF-I) system replete with ligands, receptors, and binding protein(s). However, studies concerned with the regulation of ovarian IGF-I gene expression remain scarce. It was thus the objective of this communication to evaluate the expression of the IGF-I gene in the immature rat ovary under in vitro conditions. Whole ovarian dispersates or isolated granulosa cells were cultured for up to 96 h under serum-free conditions in the absence or presence of the indicated experimental agents. Extracted total RNA was subjected to a sensitive solution hybridization/RNase protection assay using 32P-labeled rat IGF-I and/or type I IGF receptor antisense RNA probes. Cultured in the absence or presence of FSH (100 ng/ml), whole ovarian dispersates (or isolated granulosa cells) displayed time-dependent (FSH-independent) decrements in the relative abundance of IGF-I transcripts apparent as early as 3 h after the onset of culture. No evidence of recovery was apparent by 96 h of culture. The apparent lack of an FSH effect did not reflect diminished biopotency as attested to by the ability of the hormone to promote time-dependent increments in the accumulation of progesterone. Importantly, the apparent decrease in ovarian IGF-I gene expression proved to be IGF-I specific in that type I IGF receptor transcripts displayed a substantial and sustained (for up to 96 h) FSH-independent increase beginning at the 24-h time point. At no point were IGF-II transcripts detected. The apparent decrease in the expression of IGF-I did not reflect the lack of extracellular matrix support in that neither laminin, collagen, nor whole serum supported sustained ovarian IGF-I gene expression. Treatment of whole ovarian dispersates with pharmacological concentrations of either insulin (1 μg/ml) or dexamethasone (10-7 M) did not reverse the decline in IGF-I gene expression. Importantly, however, the combined application of both insulin and dexamethasone resulted in virtually complete preservation of IGF-I gene expression, the relative abundance of the corresponding transcripts proving uniform throughout. Taken together, these in vitro observations reveal irreversible (FSH-independent) decrements in ovarian IGF-I (but not type I IGF receptor) gene expression, the preservation of which required the concurrent provision of both insulin and dexamethasone.

Original languageEnglish (US)
Pages (from-to)2703-2708
Number of pages6
JournalEndocrinology
Volume132
Issue number6
StatePublished - Jun 1993
Externally publishedYes

Fingerprint

Primary Cell Culture
Insulin-Like Growth Factor I
Dexamethasone
Insulin
Gene Expression
IGF Type 1 Receptor
Granulosa Cells
RNA Probes
Antisense RNA
Insulin-Like Growth Factor II
Laminin
Ribonucleases
Serum
Extracellular Matrix
Progesterone
Ovary
Carrier Proteins
Collagen

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

Insulin-like growth factor I gene expression by primary cultures of ovarian cells : Insulin and dexamethasone dependence. / Botero, Luis F.; Roberts, Charles; LeRoith, Derek; Adashi, Eli Y.; Hernandez, Eleuterio R.

In: Endocrinology, Vol. 132, No. 6, 06.1993, p. 2703-2708.

Research output: Contribution to journalArticle

Botero, Luis F. ; Roberts, Charles ; LeRoith, Derek ; Adashi, Eli Y. ; Hernandez, Eleuterio R. / Insulin-like growth factor I gene expression by primary cultures of ovarian cells : Insulin and dexamethasone dependence. In: Endocrinology. 1993 ; Vol. 132, No. 6. pp. 2703-2708.
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