Prostaglandin E and F2αReceptors in Human Uterine Leiomyomas

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Abstract
Human uterine leiomyomas specifically bound less (P < 0.01) [3H]prostaglandin Ex (pHlPGEj) and [3H]PGF2α than adjacent normal myometria [leiomyomas: mean [3H]PGE1, 16.4 (range, 11.1–25.2) fmol/mg protein; mean [3H]PGF2α, 4.7 (range, 0.8–12.1) fmol/mg protein; adjacent normal myometria: mean [3H]PGE1; 41.7 (range 27.1–60.7) fmol/mg protein; mean [3H]PGF2α, 7.8 (range, 4.3–16.3) fmol/mg protein]. The lower binding of both [3H]PGs by leiomyomas was due to lower numbers of available high and low affinity sites. Leiomyomas and normal adjacent myometria bound 4–7 times more [3H]PGEi than [3H]PGF2α, and this appears to be due to high affinity and high numbers of low affinity PGE sites. The smooth muscle content was lower (P < 0.01) in leiomyomas (mean, 28.0%; range, 9.7–45.5%) than that of adjacent normal myometria (mean, 58.9; range, 51.4–71.2%). In summary, this is the first demonstration of PGE and PGF2α receptors in human uterine leiomyomas. Lower receptor numbers in leiomyomas appear to be due to the lower smooth muscle content of the tissue.