A delayed ovulation of Progestin-Primed Ovarian Stimulation (PPOS) by down-regulating the LHCGR/PGR pathway

Abstract

Abstract PPOS as a new clinic ovulation stimulation protocol, its role in ovulation and regulatory mechanism is not clear. The clinical PPOS protocol was simulated in mice, and it had a delayed ovulation than the control group at 12.5 hours after hCG trigger. The suppressed LH level of PPOS group led to the reduced expression of LHCGR on the preovulatory follicles before trigger, and significantly decreased the following progesterone synthesis, blood progesterone level and progesterone-receptor (PGR) expression within 4-6 hours after hCG trigger. Furthermore, the important ovulatory genes regulated by PGR including ADAMTS1, VEGF-A and EDN2 were downregulated in the PPOS group, ultimately delaying the ovulation. Meanwhile, the distribution of ovulation trigger–OPU time intervals with oocyte retrieval rate (>70%) and mature oocyte rate (>80%) in patients using PPOS also indirectly indicate the delayed ovulation. This research provides the crucial evidence for patients using PPOS when arranging the OPU time interval.