| Autor: |
Kishi, Hiroshi, Minegishi, Takashi, Tano, Mari, Abe, Yumiko, Ibuki, Yoshito, Miyamoto, Kaoru |
| Zdroj: |
FEBS Letters; January 1997, Vol. 402 Issue: 2-3 p198-202, 5p |
| Abstrakt: |
Initial experiments established the experimental conditions necessary for the induction of LH receptor mRNA down‐regulation in granulosa cells isolated from diethylstilbestrol (DES)‐primed immature rats. LH/hCG receptor mRNA was first induced in granulosa cells by incubating them for 24 h with FSH. Exposure of granulosa cells to a second dose of gonadotropin caused a decrease in LH/hCG receptor mRNA and binding levels after 4 h. This effect was transient, by 12 h the mRNA levels had returned to control levels, and by 24 h the mRNA levels were higher than the control. To evaluate the ability of cAMP to down‐regulate the receptor, cells were exposed to 8‐Br‐cAMP. The pattern of sustained decrease in LH/hCG receptor mRNA levels seen with 8‐Br‐cAMP was similar to that with gonadotropins. The presence of activin with FSH or hCG is more effective than FSH or hCG alone in inducing LH/hCG receptor down‐regulation in rat granulosa cells. The LH/hCG receptor mRNA levels decreased in a dose‐dependent manner in the presence of increasing concentrations (30–100 ng/ml) of activin with FSH. These observations indicate that an increase in cAMP causes down‐regulation of LH/hCG receptor mRNA and contributes to the effect of FSH and hCG, whereas basal cAMP activity is required for LH/hCG receptor mRNA expression. |
| Databáze: |
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