Abstract: 【ABSTRACT】 BACKGROUND ＆ AIM: To study the mechanism of estrogen in an estrogen_induced prolactinoma model. MATERIALS AND METHODS: ① Preparation of rat prolactinoma model: adult male Wistar rats were divided into 2 groups at random. Each rat in control group(n=8)received a subcutaneous blank implant. Rats in prolactinoma group(n=8) received estrogen_containing implants. After 8 weeks, all the animals were sacrificed. ② Each pituitary gland was weighed and collected for histopathological and immunocytochemical examination. ③ Serum prolactin(PRL) levels were measured by RIA method. ④ Both c_fos mRNA level and pituitary tumor transforming gene (PTTG) mRNA level in pituitary tissue were measured by RT_PCR method. RESULTS: Prolactinoma model were prepared successfully as reflected by serum PRL level, pituitary weight and immunocytochemical examination. The expression levels of both c_fos mRNA and PTTG mRNA in prolactinoma group were obviously higher than those in control group(P<0.001). CONCLUSION: Estrogen stimulated the expression of c_fos and PTTG oncogenes, which played important roles in estrogen_induced prolactinoma model.

Key words: estrogen, c_fos, pituitary tumor transforming gene(PTTG), prolactinomas