Rapid modulation of ovarian 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase gene expression by prolactin and human chorionic gonadotropin in the hypophysectomized rat.

In order to better understand the role of prolactin (PRL) and luteinizing hormone (LH) on progesterone biosynthesis in the ovary, we have investigated the time course (1-9 days) of the effect of PRL and human chorionic gonadotropin (hCG) on ovarian 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase (3 beta-HSD) expression in the hypophysectomized rat. As evaluated by quantitative in situ hybridization using a 35S labelled type I 3 beta-HSD cDNA probe, the administration of hCG for 2, 3 and 9 days induced increases of 63%, 145% and 146% above control, respectively, in 3 beta-HSD mRNA levels in ovarian interstitial cells. The absence of apparent effect of the gonadotropin in other ovarian cell types could explain the small modulation of ovarian 3 beta-HSD protein content and enzymatic activity observed in total ovarian tissue. On the other hand, treatment with PRL caused a rapid decrease in 3 beta-HSD mRNA levels in corpus luteum by 23%, 63%, 76% and 78% (P < 0.01) following 1, 2, 5 and 9 days of treatment, respectively. The short-term inhibitory effect of PRL was also observed on ovarian immunoreactive 3 beta-HSD protein, as measured by Western blot analysis, and on 3 beta-HSD activity measured by the conversion of [14C]dehydroepiandrosterone into [14C]androstenedione.(ABSTRACT TRUNCATED AT 250 WORDS)