Chapter 5 - Hormones and Pregnancy in Eutherian Mammals

Abstract

Publisher Summary The chapter discusses the endocrinology of recurring estrous/menstrual cycles and pregnancy in primates, ruminants, swine, horses, cats, dogs, and rodents with an emphasis on hormonal signaling for maternal recognition of pregnancy and the endocrinology of pregnancy. The establishment and maintenance of pregnancy require that eutherian mammals maintain a functional corpus luteum (CL) for the production of progesterone (P4), the hormone of pregnancy. This is accomplished by species-specific mechanisms as pregnancy recognition signals, including chorionic gonadotropin in primates, estrogens in pigs, lactogenic hormones in rodents, and interferon tau in ruminants. Uterine receptivity to implantation is P4-dependent; however, a prerequisite for implantation in all species studied is loss of expression of receptors for P4 and estrogens by uterine epithelia. Thus, P4 acts via P4 receptor (PR)-positive uterine stromal cells that express one or more progestamedins—e.g., fibroblast growth factors-7 and -10 and/or hepatocyte growth factors—that act via their respective receptors on uterine epithelia and trophectoderm to regulate expression of genes in concert with other hormones such as estrogens, chorionic gonadotropin, interferons, and lactogenic hormones.