Relationship Between Luteinizing Hormone and Decidual Luteotropin in the Maintenance of Luteal Steroidogenesis 1

Open Access
Publisher Website
Google Scholar
Abstract
Between Days 6–11 of pregnancy or pseudopregnancy, the decidual tissue of the rat produces a prolactin-like hormone, decidual luteotropin, which can sustain luteal progesterone production when prolactin is suppressed. However, this effect is dependent upon the presence of the pituitary. The present investigation was undertaken to determine whether decidual luteotropin and luteinizing hormone (LH) act together to sustain luteal steroidogenesis and if so, to find out whether the need for LH is due to the inability of the decidual tissue to produce LH-like material and/or whether LH affects decidual luteotropin production. Pseudopregnant rats with or without decidual tissue were hypophysectomized on Day 8 and treated with either 1.5 IU human chorionic gonadotropin (hCG)/day or with vehicle. Within 24 h, serum progesterone dropped in both vehicle-treated groups and decidual luteotropin levels declined by 80% in the decidual tissue. Human CG administration had no effect on progesterone production in the control group. Yet in rats with decidual tissue, hCG stimulated progesterone production for at least 48 h and maintained the decidual tissue content of decidual luteotropin. Progesterone, but not hCG treatment, maintained decidual luteotropin concentrations in ovariectomized rats. To compare the luteotropic activity of the decidual tissue with that of the placenta, pregnant or pseudopregnant rats with decidual tissue were hypophysectomized on Day 8 and treated with 1.5 IU hCG. Control groups had decidual tissue or placentas removed and were similarly treated. Human CG stimulated progesterone production only in rats with placental or decidual tissue.However, progesterone began to drop from Day 11 in rats with decidual tissue but remained elevated in pregnant rats and continued to increase despite cessation of hCG treatment. In addition, no hCG-like activity was detectable in Day 9 decidual tissue or in media from a 4-h decidual tissue incubation. In summary, results of this investigation demonstrate that in the absence of prolactin, LH and decidual luteotropin act in concert to sustain progesterone production between Days 8–11. The progesterone that is formed then acts on the decidual tissue to sustain decidual luteotropin production. The results also suggest that the requirement of LU may be due to the inability of the decidual tissue to secrete a LH-like hormone.

This publication has 0 references indexed in Scilit: