Characterization and physiological variation in prostaglandin, prostacyclin and thromboxane synthesis by corpora lutea, non-luteal and uterine tissues during pseudopregnancy in the rabbit.

To determine if luteal as well as uterine prostaglandin production is associated with luteal regression, the conversion of (14C) arachidonic acid into prostaglandin (PG) F2 alpha, PGE2, PGD2, prostacyclin (measured as its stable metabolite 6-keto-PGF1 alpha) and thromboxane (measured as its stable metabolite TXB2) was characterized and measured in microsomes from the uterus, corpora lutea and nonluteal tissue of the rabbit on days 8, 12 and 15 of pseudopregnancy. PGF2 alpha production was increased on day 15 compared to days 8 or 12 of pseudopregnancy in corpora lutea and in the uterus. In uterine microsomes, 6-keto-PGF1 alpha production was also elevated on day 15. No significant changes in the production of PGF2 alpha, TXB2 or PGD2 were observed with uterine or luteal microsomes. Arachidonic acid metabolism by microsomes from nonluteal tissue was not significantly different on any day examined. These results suggest that intraluteal, as well as uterine PGF2 alpha production may contribute physiologically to the final phase of luteal regression.