Effects of contraceptive agents on the biochemical and protein composition of human endometrium.

An analysis of the nucleic acid and protein composition of endometrial tissue was undertaken in normal women and in patients using either steroidal oral contraceptives or intrauterine contraceptive devices (IUCD). In the presence of an IUCD, endometrial RNA/DNA and protein/DNA ratios were elevated in the secretory phase of the menstrual cycle compared to values obtained in normal women. In the oral contraceptive group, endometrial RNA/DNA and protein/DNA ratios were below the normal range in the late proliferative phase of the cycle. Typical electrophoretic profiles in the oral contraceptive group were similar to the control group, although a quantitative analysis revealed that the concentrations of certain characteristic uterine proteins were reduced. In the IUCD group, there was a preferential appearance of two proteins with approximate molecular weights of 36,000 and 26,000 daltons. Another protein with a molecular weight of 48,000 daltons, which demonstrated a cyclic change during the normal menstrual cycle, was reduced in both study groups. The results suggest that both agents studied induce changes in the macromolecular composition of the human endometrium which may relate to their contraceptive effect.