LOCALIZATION AND TEMPORAL EXPRESSION OF PROLACTIN RECEPTOR IN HUMAN ENDOMETRIUM

Extrapituitary PRL is synthesized by the decidualized endometrial stro mal cells from the mid to late secretory phase in the nonpregnant cycl e and throughout pregnancy. The function of PRL in the uterus is unkno wn, but the temporal expression indicates a role in implantation and p lacentation. PRL is a powerful immunoregulatory agent, and thus, a rol e in modulating endometrial leukocytes may be envisaged. To investigat e the site of action of PRL, immunohistochemistry was conducted to loc alize the PRL receptor (PRL-R). In addition, ribonucleic acid was extr acted and reverse transcriptase-PCR for PRL-R was conducted. PRL-R pro tein was immunolocalized to the glandular epithelium and a subset of s tromal cells from the mid to late secretory phase of the menstrual cyc le and in early decidua. PRL-R transcripts were also detected from the late secretory phase and first trimester decidua. These findings indi cate that the receptor is expressed in a temporal pattern similar to t hat of PRL. PRL-R expression in the glandular epithelium is consistent with a role in regulating glandular activity. Furthermore, immunoreac tivity for PRL-R in a subset of stromal cells may be evidence for para crine interactions between decidualized cells or an immunoregulatory r ole for PRL.