INSULIN-LIKE GROWTH FACTOR-I ENHANCES LUTEINIZING-HORMONE BINDING TO RAT OVARIAN THECA-INTERSTITIAL CELLS
INSULIN-LIKE GROWTH FACTOR-I ENHANCES LUTEINIZING-HORMONE BINDING TO RAT OVARIAN THECA-INTERSTITIAL CELLS
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DOI：
10.1172/jci114745
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发表时间：
1990-08-01
影响因子：
15.9
通讯作者：
ROSENFIELD, RL
中科院分区：
文献类型：
--
作者：
CARA, JF;FAN, J;ROSENFIELD, RL
We tested the hypothesis that insulin-like growth factor-I (IGF-I) stimulates ovarian androgen production by increasing theca-interstitial cell luteinizing hormone (LH) binding affinity and/or binding capacity. We then investigated the role of transcriptional and translational events in mediating these actions of IGF-I. LH bound to saturable, high affinity binding sites on rat ovarian theca-interstitial cells. Preincubation with LH produced a decrease in LH binding capacity with no effect on LH binding affinity. Treatment with IGF-I, both in the absence and presence of LH, increased LH binding capacity 1.5 to 2-fold with no change in LH binding affinity. Androgen production was increased progressively by LH, suggesting that LH-stimulated steroidogenesis is not tightly coupled to LH receptor downregulation. IGF-I increased androgen synthesis in proprotion to its upregulation of LH binding capacity. Transcriptional inhibition with dichlorobenzimidazole riboside inhibited the IGF-I-mediated increase in LH capacity but had no effect on androgen production. Translational inhibition with cycloheximide inhibited both the IGF-I-mediated increase in LH binding and stimulation of androgen synthesis. We conclude that IGF-I incrreases theca-interstitial cell LH binding capacity and reverses the LH-induced downregulation of LH binding sites. The enhancement of LH binding by IGF-I is compatibile with transcriptional mediation whereas the effect of IGF-I on androgen synthesis appears to be mediated by a direct effect of the peptide on the translational process(es) involved in steroidogensis.
