Is progesterone a modulator of luteal steroidogenesis in pig? A tissue culture approach.
The objective of this research was to explain, whether high levels of progesterone (P4) play a protective role against secretion of high levels of estradiol (E2) during early and midluteal phase. Luteal cells were collected from newly formed (0-3 days after ovulation), mature (8-10 days after ovulation) and regressing (12-16 days after ovulation) corpora lutea. Control cultures were grown in M199 medium supplemented with 10% calf serum, while other cultures were supplemented with either progesterone at concentrations of 10(-7)M, 10(-6)M and 10(-5)M or with testosterone in a dose of 10(-5) M combined with progesterone at the same concentrations as above. After 24 hrs cultures were terminated and media were frozen at -20 degrees C for further steroid analysis. There was no response of luteal cells isolated during the luteal phase to exogenous progesterone in terms of estradiol secretion. Progesterone given together with testosterone was without effect on estradiol secretion by luteal cells collected during the early luteal phase. Progesterone at all concentrations tested combined with 10(-5)M testosterone significantly decreased testosterone-stimulated secretion of estradiol by luteal cells isolated during the mid and late luteal phase. This study suggests that progesterone is a local paracrine or autocrine factor regulating luteal function and that progesterone might function as an inhibitor of aromatase activity.
Department of Physiology, Jagiellonian University, Kraków, Poland.
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Gregoraszczuk
D000818:Animals; D002478:Cells, Cultured; D003338:Corpus Luteum / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D046508:Culture Techniques; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D004958:Estradiol / Q000032:analysis / Q000378:metabolism*; D005260:Female; D008183:Luteal Phase / Q000502:physiology; D011374:Progesterone / Q000032:analysis / Q000494:pharmacology*; D013552:Swine / Q000378:metabolism*; D013739:Testosterone / Q000494:pharmacology; D013997:Time Factors
D013739:Testosterone; D011374:Progesterone; D004958:Estradiol