Patterns of spontaneous pulsatile secretion of human chorionic gonadotropin and pregnancy specific beta 1 glycoprotein by superfused placental explants in first and last trimester. Lack of episodic human placental lactogen secretion

Angiotensin II induces human placental lactogen and pregnancy-specific beta 1-glycoprotein secretion via an angiotensin AT1 receptor

The purpose of this work was to determine which subtype of angiotensin II receptors was involved in angiotensin II-induced human placental lactogen (hPL) and pregnancy-specific beta 1-glycoprotein (SP1) secretion from human placenta. The experiments were performed using placental explants and isolated trophoblast cells. They were pretreated with Dup753 (antagonist of angiotensin AT1 receptor), PD123319 (antagonist of AT2 subtype) or with CGP42112A (agonist of angiotensin AT2 receptor) before the addition of angiotensin II. The octapeptide angiotensin II significantly increased the hPL and SP1 release from both placental explants and isolated trophoblast cells. The angiotensin AT1 receptor antagonist Dup753 inhibited the angiotensin II-stimulated hPL and SP1 secretion in a dose-dependent manner but the AT2 specific ligands PD123319 and CGP42112A had no effect. This study indicates that the angiotensin AT1 receptor is the main mediator of angiotensin II in the stimulation of hPL and SP1 secretion from human placenta.

Spontaneous and gonadotropin-releasing hormone induced human chorionic gonadotropin release from superfused JAR choriocarcinoma cells

JAR choriocarcinoma cells have retained several characteristics of normal trophoblasts and have been used as an in vitro trophoblast model. The superfusion system is suitable for the study of hormone synthesis and/or secretion. JAR cells were cultured and transferred to the superfusion system in order to evaluate the spontaneous hCG secretion and the effect of GnRH. The spontaneous hCG release showed a periodic pattern with a 48 min phase interval. In our system single cells and cell-clusters were superfused and there is a possibility that cell to cell connections might have an influence on the regulation of hormone synthesis and/or secretion. GnRH in 4 x 10(-7) M and 4 x 10(-6) M concentrations or 100 mM KCl caused an immediate hCG release from the JAR cells Repeated administration of GnRH resulted in a delayed hCG release which is probably related to the relatively small amount of hCG available from the storage granules or to the phase of spontaneous secretion.