Co-ordinate actions of FSH and insulin-like growth factor-I on LH receptor expression in rat granulosa cells

M. Kanzaki, M. A. Hattori, R. Horiuchi, I. Kojima

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)

Abstract

The actions of FSH and Insulin-like growth factor-I (IGF-I) were studied in cultured rat ovarian granulosa cells. Cells became differentiated and expressed LH receptors when they were incubated for 72 h with 200 μg FSH/l (high FSH) but not 20 μg FSH/l (low FSH). Treatment with high but not low FSH increased the release of both immunoreactive and bioactive IGF-I into the medium. A combination of low FSH and IGF-I reproduced the effect of high FSH on LH receptor expression. We then examined the critical time when low FSH and IGF-I exerted their effects. In the presence of continuous low FSH, IGF- I was capable of inducing LH receptor expression even when added 24 h after the addition of low FSH. However, when IGF-I was added at 36 h, LH receptor expression measured at 72 h was greatly reduced. In contrast to the action of IGF-I, continuous exposure to low FSH was required for LH receptor expression, and IGF-I had no effect when FSH was not included for the entire 72 h of culture. DNA synthesis as assessed by both [3H]thymidine incorporation and nuclear bromodeoxyuridine labelling was moderate at the beginning of culture and markedly reduced at 24 h both in the presence and absence of either high FSH or low FSH plus IGF-I. In the presence of either high FSH or a combination of low FSH plus IGF-I, DNA synthesis remained decreased for up to 72 h whereas it began to increase in the absence of either high FSH or a combination of low FSH plus IGF-I. A similar increase in DNA synthesis was observed after 48 h when granulosa cells were treated with low FSH alone, which did not induce LH receptor expression. These results indicate that 1) growth and differentiation of granulosa cells are regulated inversely; 2) FSH and IGF-I act together to induce LH receptor expression; and 3) action of IGF-I is dependent on the presence of FSH.

Original languageEnglish
Pages (from-to)301-308
Number of pages8
JournalJournal of Endocrinology
Volume141
Issue number2
DOIs
Publication statusPublished - 1994
Externally publishedYes

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Endocrinology

Fingerprint Dive into the research topics of 'Co-ordinate actions of FSH and insulin-like growth factor-I on LH receptor expression in rat granulosa cells'. Together they form a unique fingerprint.

Cite this