Effect of Dibutyryl Cyclic Amp and Oestradiol on Incorporation of [3h]leucine Into the Proteins of Luminal Fluid of the Rat Uterus

Abstract

An injection of 12-5 nmol dibutyryl cyclic AMP (dbcAMP) into each uterine horn of ovariectomized rats maintained on progesterone alone, enhanced incorporation of [3H]leucine into uterine luminal proteins. A value of 11-73 X 10(3) c.p.m. [3H]leucine incorporated/rat was found after injection of dbcAMP compared with 3-69 X 10(3) c.p.m./rat after injection of saline. An injection of 1-0 microgram oestradiol, in contrast, gave 58-05 X 10(3) c.p.m./rat. Electrophoretic analysis showed that the radioactively labelled proteins found after an injection of dbcAMP or oestradiol were qualitatively similar to those detected on day 5 of pregnancy, the day of blastocyst implantation. The nucleotide thus apparently elicits a uterine response similar to that observed after an injection of oestradiol.

Hormone involvement in the establishment of pregnancy

“…Since implantation did not follow, blastocyst activation may have arisen by the direct action of cyclic AMP or through a restricted oestrogen-mimicking action on the luminal epitheUum, thereby removing the implantation inhibition characteristic of the epithelium during diapause. The actions of oestradiol and dbcAMP are also similar in their ability to induce synthesis of specific uterine luminal proteins (Surani & Webb, 1977). In the experiments above in which cyclic nucleotides were administered to assess their influence on implantation, cellular uptake was assumed but not demonstrated.…”

Affinity of uterine luminal proteins for rat blastocysts

“…The detailed procedure for the recovery of uterine luminal proteins has been described elsewhere (Surani & Webb, 1977). About 30 µg protein were obtained from each pregnant rat at 12:00 h on Day 5 of pregnancy.…”