Fig. 5.

A putative role for catechol-O-methyltransferase (COMT) in modulating the response to estrogen in the myometrium during pregnancy. Decreasing levels of COMT in the myometrium in early and midpregnancy (under influence of increasing estrogen and progesterone) result in a high accumulation of 2-hydroxyestrogen (2-OHE2) (A), which acts as an antiestrogen and may promote uterine quiescence (B). Near term, levels of COMT increase in the myometrium under the influence of proinflammatory cytokines like tumor necrosis factor alpha (TNFα) and others; this increase leads to a reduction in the levels of antiestrogen 2-OHE2 (A), which induces cellular functional estrogen activation and mediates uterine contraction (B).

Wentz. Catechol-O-Methyl Transferase Regulation. Obstet Gynecol 2006.