The Synthesis of Prostaglandins from Persistent Proliferative Endometrium

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Abstract
The pattern of prostaglandins (PGs) synthesized by persistent proliferative endometrium of women with excessive menstrual bleeding (>50 ml) associated with anovulatory cycles was compared to endometrium collected from women with normal menstrual blood loss (2a in normal and persistent proliferative endometrium were lower than the levels of PGF2a found in normal secretory endometrium (P < 0.005 for both normal and persistent proliferative endometria). When incubated with exogenous [l-14C]arachidonic acid (9.1 nmol), normal secretory endometrium synthesized more PGF2a and PGE2 than did normal proliferative endometrium, but the amounts of PGF2a and PGE2 released by persistent proliferative endometrium were similar to those obtained by normal secretory endometrium. These findings suggest that persistent proliferative and normal secretory endometria have the same PG synthetase activity, and that the low endogenous concentrations of PGF2a in the former arise from a lack of endogenous precursor. PGF2a has predominantly vasoconstricting properties, and a reduced capacity to synthesize this PG by persistent proliferative endometrium may result in excessive menstrual bleeding, as was suggested by the inverse correlation between the ratio of the endogenous concentrations of PGF2a, and PGE and the menstrual blood loss (r = −0.7; P < 0.0005; n = 26).