Topography of Human Uterine Prostaglandin E and F2αReceptors and Their Profiles during Pathological States*

Abstract

The topography of prostaglandin (PG) E and F_2α receptors in uteri of premenopausal women was investigated by dividing uteri into six equal longitudinal strips and further dividing each strip into approximately 1-cm segments. Tissue for determination of smooth muscle content using the Trichrome stain was taken from each section, and the remainder was homogenized for binding studies with ³H-labeled PGs. The [³H] PGE₁ binding (mean, 41.5 fmol/mg protein; range, 23.1–58.3) was about 8-fold greater in the fundus than [³H]PGF_2α binding (mean, 4.8 fmol/mg protein; range, 1.3–13.0), and this trend was found in most uterine sections. The binding of both ³H-labeled PGs decreased from fundus to cervix, and this decrease was similar to the decrease in smooth muscle content. Scatchard analysis revealed apparent dissociation constants (K_ds) of 1.4 and 76 nM and apparent specific binding capacities (Ns) of 25 and 488 fmol/mg protein for [³H]PGE₂, and K_d values of 11.5 and 81 nM and Ns values of 19.4 and 58 fmol/mg protein for [³H]PGF_2α in the uterine fundus. The Kd values for [³H]PGE₂ were similar in other sections of the uterus, but the Ns values were smaller in the lower uterine body and cervical end. While the phase of the menstrual cycle did not influence [³H]PG binding, the diagnosis of abnormal uterine bleeding compared to dysmenorrhea was associated with an increase in [³H]PGE₁ binding (P < 0.05).