Mechanisum Of Progesterone's Negative Regulation On The Luteinising Hormone Surge

Objective: Preventing premature LH surge is a key technique for in vitro fertilizationembryo transfer(IVF-ET).Our lab reported that progesterone can effectively control premature ovulation and block spontaneous LH surge.Different from traditional downregulation protocols which act at pituitary Gn RH receptor,progesterone target at hypothalamus,causing hormone secretion closer to physiological state.This new target provides new ideas for the development of hyperstimulate drugs.However,the mechanism of progesterone block LH surge is still unclear.The in-depth study of its mechanism will not only help to deepen the understanding of basic reproductive physiology,but also find new drug regulatory targets.Methods: 320 patients were enrolled in a prospective randomized controlled trial to investigate the consistant inhibition of LH by progesterone in PPOS protocol.We observed the endocrine characteristics,clinical ovulation and pregnancy outcomes by adding clomiphene to PPOS protocol;Moreover,investigate the neuroendocrine mechanism of progesterone inhibition of LH surge,C57BL6 mice were used to establish an effective animal model.Ovariectomized and estradiol-capsule embedded mice were coadministed with progesterone and estradiol benzoate for continuesly 2 days after the mice showed a diestrous smear.Based on this model,The inhibitory neurotransmitter dynorphin and ?-aminobutyric acid(GABA)antagonists were micro-perfused in the anterior ventral paraventricular(AVPV)nucleus of the mice to investigate whether they are involved in progesterone preventing LH surge model;To further explore the mechanism of LH surge occurrence,and to lay the foundation for further study,we used optogenetic technique to inject the light-sensitive AAV-EF1a-double floxedh Ch R2(H134R)EYFP-WPRE-HGHp A(#20298)virus in the arcuate(ARC)nucleus of kiss-cre mice,while implanted the optic fiber into the AVPV,stimulate the the terminal of ARC project to AVPV with different light frequencies and different hormone backgrounds(at different estrous cycles).Results:(1)Prospective randomized controlled studies have shown that clomiphene can alleviate the incidence of profound pituitary suppression in PPOS protocol;(2)Simultaneous administration of estrogen and progesterone in OVX mice can effectively inhibit LH surge;(3)AVPV GBAB-A instead of GABA-B antagonist micro-infusion can rescue the LH surge inhibited by progesterone;(4)AVPV dynorphin antagonist can counteract progesterone's inhibition on LH surge;(5)At the level of the hypothalamus,high-frequency light-stimulated ARC nucleus,center of LH pulse release,can also induce the appearance of the LH surge.Conclusions: 1.The anti-positive feedback of progesterone and the negative feedback of estrogen may have some relationships on neural signaling pathways;2.Progesterone inhibits LH surge is associated with an increase in GBAB-A rather than GABA-B signaling in AVPV;3.Progesterone's estinguish effect on LH surge is associated with an increase in dynorphin signaling pathway in AVPV;4 LH pulse control centrer arcuate nucleus also participates in the occurrence of the LH surge release.