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Insulin-like growth factor I regulates gonadotropin responsiveness in the murine ovary.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Zhou, Jie Kumar, T. Rajendra Matzuk, Martin M. Bondy, Carolyn A. |
| Copyright Year | 1997 |
| Abstract | The present study shows that insulin-like growth factor I (IGF-I) and FSH receptor (FSHR) mRNAs are selectively coexpressed in a subset of healthy-appearing follicles in murine ovaries, irrespective of cycle stage. Aromatase gene expression, a prime marker for FSH effect, is found only in IGF-I/FSHR-positive follicles, showing that these are healthy, gonadotropin-responsive follicles. Given the striking coexpression of FSHR and IGF-I, we hypothesized that FSH was responsible for follicular IGF-I expression. We found, however, that granulosa cell IGF-I mRNA levels are not reduced in hypophysectomized (+/-PMSG) or FSH knockout mice, indicating that FSH does not have a major role in regulation of granulosa cell IGF-I gene expression. To test the alternative hypothesis that IGF-I regulates FSHR gene expression, we studied ovaries from IGF-I knockout mice. FSHR mRNA was significantly reduced in ovaries from homozygous IGF-I knockout compared with wild type mice and was restored to control values by exogenous IGF-I treatment. The functional significance of the reduced FSHR gene expression in IGF-I knockout ovaries is suggested by reduced aromatase expression and by the failure of their follicles to develop normally beyond the early antral stage. In fact, IGF-I knockout and FSH knockout ovaries appear very similar in terms of arrested follicular development. In summary, we have shown that IGF-I and FSHR are selectively coexpressed in healthy, growing murine follicles and that FSH does not affect IGF-I expression but that IGF-I augments granulosa cell FSHR expression. These data suggest that ovarian IGF-I expression serves to enhance granulosa cell FSH responsiveness by augmenting FSHR expression. |
| Starting Page | 299 |
| Ending Page | 304 |
| Page Count | 6 |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://mend.endojournals.org/content/11/13/1924.full.pdf |
| PubMed reference number | 9415397v1 |
| Volume Number | 11 |
| Issue Number | 13 |
| Journal | Molecular endocrinology |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Cardiac Arrest FSHR gene Follicle Stimulating Hormone Receptor Gene Expression Gonadotropins Growth Factor Homozygote IGF2R protein, human Ovarian Follicle Ovary Somatomedins Subgroup Urofollitropin Wild Type granulosa cell |
| Content Type | Text |
| Resource Type | Article |
