Prolactin production by human endometrium during the normal menstrual cycle

Area of Science:

• Reproductive Biology
• Endocrinology
• Cellular Biology

Background:

• Prolactin (PRL) synthesis has been documented in human decidua from term pregnancies.
• The presence and synthesis of PRL in non-pregnant endometrium remain less understood.

Purpose of the Study:

• To investigate the in vitro production and tissue content of prolactin (PRL) in both "decidualized" and "non-decidualized" human endometrium.
• To determine if PRL synthesis occurs in the endometrium outside of pregnancy and its relationship with the menstrual cycle.

Main Methods:

• Endometrial tissue samples were collected throughout the menstrual cycle and dated histologically.
• Radioimmunoassay (RIA) was used to quantify PRL content in tissue and incubation medium.
• Cycloheximide was added to assess the role of de novo protein synthesis in PRL accumulation.

Main Results:

• No detectable PRL was found in proliferative endometrium or early secretory endometrium (prior to day 22).
• Significant increases in PRL tissue and medium content were observed in the late secretory phase (days 22-26).
• Cycloheximide inhibited the net increase in PRL, indicating active synthesis.

Conclusions:

• Human endometrium synthesizes prolactin (PRL) during the normal menstrual cycle.
• The onset and level of PRL synthesis are associated with the progression of endometrial decidualization in the luteal phase.