Rat thecal/interstitial cells express transforming growth factor-beta type 1 and 2, but only type 2 is regulated by...

We previously demonstrated that granulosa cells from diethylstilbestrol-primed immature rats expressed transforming growth factor-beta 2 (TGF beta 2), but not TGF beta 1, mRNA and that its expression was regulated by FSH in vitro. The present studies were designed, therefore, to establish whether thecal/interstitial cells (TIC) from diethylstilbestrol-primed immature rats express more than one subtype of TGF beta mRNA and gene product and whether the levels of expression/production in vitro were regulated by LH/hCG. Reverse transcription-polymerase chain reaction (RT-PCR) analysis of total RNA indicated that TIC expressed both TGF beta 1 and TGF beta 2 mRNA. In response to hCG (200 ng/ml), TIC expressed TGF beta 2 mRNA levels that were 51% of control levels; TGF beta 1 mRNA levels were not altered. In response to cholera toxin (10(-9) M), TIC expression of TGF beta 2 and TGF beta 1 mRNA levels was 10% and 55% of control values, respectively. Western blot analysis established that both TGF beta 1 and TGF beta 2 were secreted in vitro. hCG and cholera toxin reduced secretion of TGF beta bioactivity by 55% and 90%, respectively. In summary, these results indicate: 1) TIC express both TGF beta 1 and TGF beta 2 mRNA; 2) TIC expression of TGF beta 2, but not TGF beta 1, mRNA is regulated by hCG in vitro; 3) TIC secrete both TGF beta 1 and TGF beta 2, and 4) TIC secretion in vitro of TGF beta activity is gonadotropin regulated.