Progesterone (P4), estradiol (E2), and expression of their receptors (PGR and ESR1, respectively) by cells of the uterus regulate reproductive performance of mammals through effects on secretion and transport of nutrients into the uterine lumen. This study investigated the effect of changes in P4, E2, PGR, and ESR1 on expression of enzymes for the synthesis and secretion of polyamines. Suffolk ewes (n = 13) were synchronized to estrus (Day 0) and then, on either Day 1 (early metestrus), Day 9 (early diestrus), or Day 14 (late diestrus) of the estrous cycle, maternal blood samples were collected, and ewes were euthanized before obtaining uterine samples and uterine flushings. Endometrial expression of MAT2B and SMS mRNAs increased in late diestrus (P < 0.05). Expression of ODC1 and SMOX mRNAs decreased from early metestrus to early diestrus, and expression of ASL mRNA was lower in late diestrus than in early metestrus (P < 0.05). Immunoreactive PAOX, SAT1, and SMS proteins were localized to uterine luminal, superficial glandular, and glandular epithelia, stromal cells, myometrium, and blood vessels. Concentrations of spermidine and spermine in maternal plasma decreased from early metestrus to early diestrus and decreased further in late diestrus (P < 0.05). The abundances of spermidine and spermine in uterine flushings were less in late diestrus than early metestrus (P < 0.05). These results indicate that synthesis and secretion of polyamines are affected by P4 and E2, as well as the expression of PGR and ESR1 in the endometria of cyclic ewes.

Summary Sentence

Synthesis and secretion of polyamines are regulated by changes in progesterone (P4), estradiol (E2), and expression of their receptors (PGR and ESR1, respectively) in uterine epithelia of ewes during the estrous cycle.

Graphical Abstract

Progesterone, estradiol, and the expression of their receptors in uterine luminal, superficial glandular, and glandular epithelia affect changes in the polyamine pathway during the estrous cycle. Changes in the concentrations and abundances of polyamines in plasma and uterine flushings, respectively, and cell-specific expression of enzymes involved in polyamine synthesis in the uteri of ewes occur in response to changes in circulating levels of progesterone, estradiol, and the expression of their receptors (PGR and ESR1) in the uteri of cyclic ewes.