下丘脑KNDy神经元在介导孕激素抑制LH峰发生中的作用机制

The control of premature LH surge to prevent early ovulation is essential to in vitro fertilization-embryo transfer. In our clinic, we found that the introduction of progesterone to suppress spontaneous LH surge in ovarian stimulation protocol is effective and efficient in achieving satisfactory embryological and clinical pregnancy outcome. Previous researches have shown that progesterone can block LH surge by relying on the feedback loop of the hypothalamus without interfering with its functions. However, the mechanism behind this is still largely unknown. In recent years, the understanding of hypothalamic kisspeptin neurons has advanced tremendously; scientists are increasingly concerned with the changes in GnRH/LH secretion patterns by progesterone through different kisspeptin/KNDy neurons in the brain, but a complete ovulation induction animal model is still lacking. Our study proposes a hypothesis based on an animal model we have successfully built: In addition to acting on AVPV brain neurons, progesterone can also block LH surge through progesterone receptors expressed on the ARC brain region of KNDy neurons. We aim to discover whether hypothalamic KNDy neurons are involved in the inhibition of LH surge under the action of progesterone by administering estrogen and/or progesterone receptor antagonists in the rat ARC neucleus, and by giving different dosage of progesterone to elucidate the relationship between the KNDy neurons in the ARC nucleus and LH surge inhibition by progesterone. This research will be an innovation in the field of neuroendocrinology, and provide scientific evidence for the optimization of key steps in ovulation stimulation.

控制LH峰避免提早排卵是体外受精胚胎移植的关键。我们发现在超排卵中添加孕激素(P)能阻断自发性LH峰，临床上已证明更加安全高效。P通过下丘脑水平抑制LH峰同时不阻断垂体功能，此过程机理尚未明确。随着对下丘脑kisspeptin神经元的了解，人们越来越关注P通过不同脑区kisspeptin/KNDy神经元对GnRH/LH分泌模式的改变，但都缺乏促排卵的完整动物研究模型。本项目在已建立该种模型及研究的基础上提出假说:除了AVPV脑区神经元外，表达在ARC脑区KNDy神经元上的孕激素受体也可能参与P抑制LH峰的作用。本项目拟进一步通过在性腺轴完整大鼠的ARC核团（KNDy神经元所在）注射雌激素和/或孕激素受体拮抗剂、给予不同剂量P等，明确下丘脑KNDy神经元在P作用下是否参与抑制LH峰及其相关分子机制，这将是神经内分泌领域的理论创新，为优化促排卵中关键步骤提供科学依据。

临床发现高孕激素促排卵方案可有效抑制排卵前LH峰的发生。为了确认该现象并探索其神经生物学机制，我们首先在大、小鼠上建立模拟临床高孕激素促排卵方案的研究模型，验证高孕激素对LH峰的抑制作用；然后在该模型上进一步明确了下丘脑介导孕激素抑制LH峰和脉冲的核团，并通过光/化学遗传学特异性操控GnRH神经元活性，进一步明确LH峰和脉冲的下丘脑调控机制；接着借助光遗传学技术特异性操控从ARC核团投射到AVPV脑区的kiss神经元投射，发现ARC核团“KNDy”中的kisspeptin神经元通过AVPV核团间接参与LH峰的发生，并结合药理学发现神经递质谷氨酸参与该调控；最后通过AVPV脑区核团灌注等药理学技术发现孕激素可能通过促进AVPV核团释放GABA、Dynorphin等抑制性神经递质来抑制LH峰的发生。以上研究结果为高孕激素促排卵方案在临床进一步改进，优化和推广提供了坚实的理论依据和指导。