Prostaglandin F2 alpha synthesis and metabolism by luteal phase endometrium in vitro

Differences in prostaglandin (PG) F2 alpha synthesis and degradation were sought between early luteal endometrium (histology day 15 to 22, n = 6) and late luteal endometrium (histology day 23 to 28, n = 6). In addition, alterations in PGF2 alpha synthesis and degradation in response to 17 beta-estradiol (E2) and progesterone (P) were examined to clarify the mechanism of steroid modulation of endometrial PG production (n = 12). Endometrium was maintained in tissue culture and the concentration of PGF2 alpha and 13,14 dehydro-15 keto F2 alpha (DHKF2 alpha) was determined in spent media by radioimmunoassay. Prostaglandin F2 alpha and DHKF2 alpha output from luteal endometrium exposed to P and E2 + P were both significantly reduced when compared with no addition or E2 treatments. This implies that the modulation of PGF2 alpha output by P in vitro is secondary to altered synthesis. There was an increase in PGF2 alpha output from late luteal endometrium when compared with early luteal endometrium in the P and E2 + P treatments, but DHKF2 alpha remained unchanged. These data imply that the temporal increase in PGF2 alpha output is the result of alterations in both PG synthesis and catabolism.