Prolactin production from proliferative phase leiomyoma.

Area of Science:

• Reproductive Endocrinology
• Molecular Biology
• Gynecologic Pathology

Background:

• Endometrial stromal cells synthesize prolactin after progesterone-induced decidualization.
• Myometrial cells may retain the capacity to synthesize prolactin, but in vivo evidence is lacking.
• Prolactin genome expression in pathological conditions, specifically leiomyomas, was investigated.

Purpose of the Study:

• To investigate prolactin synthesis in leiomyomas during the follicular phase.
• To determine if leiomyomas synthesize prolactin in vitro.
• To assess the effect of estradiol and progesterone on prolactin synthesis in leiomyomas.

Main Methods:

• Follicular phase leiomyomas were cultured in Dulbecco's modified Eagle's medium with varying hormone treatments (estradiol, progesterone).
• Prolactin synthesis was assessed using radioimmunoassay and tritium-labeled leucine incorporation.
• Prolactin was characterized by molecular weight determination (Sephadex G-100), immunoprecipitation, and bioactivity assays.

Main Results:

• Follicular phase leiomyomas contained prolactin levels exceeding normal serum values.
• Prolactin synthesis was observed in leiomyomas cultured without progesterone.
• Progesterone demonstrated a variable suppressive effect on prolactin synthesis over 144 hours.
• Leiomyoma prolactin exhibited similar molecular weight, antigenicity, and bioactivity to pituitary and decidual prolactin.

Conclusions:

• Proliferative phase leiomyomas contain elevated prolactin, presumed to be secondary to in vivo synthesis.
• In vitro studies confirmed prolactin synthesis by leiomyoma tissue.
• These findings suggest leiomyomas may contribute to local prolactin levels.