睾丸间质细胞胰岛素样生长因子－Ⅰ基因表达的调控

Regulation of the Expression of Insulin-like Growth Factor-ⅠMessenger Ribonucleic Acid in Leydig Cells

评估了联岛素样生长因子－Ⅰ（ＩＧＦ－Ｉ）ｍＲＮＡ在大鼠睾丸Ｌｅｙｄｉｇ细胞中的基因表达。用１５％～６０％Ｐｅｒｃｏｌｌ液密度梯度离心，可将原始的间质细胞分成不同的３条带。ＩＧＦＩ．ｍＲＮＡ主要位于Ｌｅｙｄｉｇ细胞丰富组分（带３），带１和带２组分仅含少量ＩＧＦ－ＩｍＲＮＡ．Ｌｅｙｄｉｇ细胞ｍＲＮＡ具有碱基从０．８～７．５ｋｂ的多种型，在２５～５５日龄大鼠中均存在ＩＧＦ－ＩｍＲＮＡ。用Ｋｌｉｎｅｆｅｌｔｅｒ等方法高度纯化Ｌｅｙｅｉｇ细胞，发现大多数ＩＧＦ－ＩｍＲＮＡ位于这些Ｌｅｙｄｉｇ细胞，而在整个睾丸组织或其它间质细胞检测不到ＩＧＦ－ＩｍＲＮＡ。大鼠应用生长激素（ＧＨ）后，Ｌｅｙｄｉｇ细胞中ＩＧＦ－ＩｍＲＮＡ增加２倍以上，提示Ｌｅｙｄｉｇ细胞中的ＩＧＦ－ＩｍＲＮＡ亦依赖ＧＨ．Ｌｅｙｄｉｇ细胞产生的间质ＩＧＦ－Ｉ在睾丸中可能具有自分泌和旁分泌作用。

In the present study,we evaluated insulin-like growth factor-I(IGF-I)messenger RNA expression inthe rat testis,Crude interstitial cells were separated into three distinct bands on 15%～60%Percoll densitygradients. IGF-I mRNA was mainly localized in the Leydig cell-enriched fraction(band 3),while band 1 andband 2 cells did not contain significant amounts of IGF-I mRNA,Leydig cell IGF-I mRNA consisted of multi-ple species varying from 0.8 to 7.5kb and was present in rat Leydig cell of all ages examined from 25 to 55days old.To further document that IGF-I mRNAs are present in Leydig cells, the method of Klinefelter etal.was used to isolate highly purified(98%pure)Leydig cells.Most of the IGF-I mRNA was localized inthese Leydig cells,while there was no detectable IGF-ImRNA in the whole testis or other interstitial cells,Furthermore,IGF-ImRNA in Leydig cells was increased more than 2-fole by growth hormone(GH)adminis-tration in vivo. This suggests that IGF-I mRNA in Leydig cells is also GH dependent.Interstitial IGF-Ipro-duced in Leydig cells may have both autocrine and paracrine effects in the testis.