Estrogen Stimulates both Prolactin and Growth Hormone mRNAs Expression in the MtT/F4 Transplantable Pituitary Tumor

Abstract

Abstract

The effects of 17β-estradiol (E₂) on MtT/F4 pituitary tumor growth and on prolactin (PRL) and growth hormone mRNA expression were analyzed in F344 female rats. E₂ (10 mg) stimulated pituitary PRL cell hyperplasia and PRL mRNA, but inhibited growth of the transplantable tumors. The expression of both PRL and growth hormone mRNA levels was increased in the MtT/F4 tumors. The effects of E₂ on increasing PRL mRNA levels were more marked in the pituitary compared with the tumors. These results indicate that estrogens stimulate proliferation and PRL expression in the pituitary while inhibiting cell proliferation in the MtT/F4 tumor. E₂ also stimulated both growth hormone and PRL mRNA expression in the MtT/F4 transplantable tumor.