下丘脑长投射GnRH神经元介导孕激素抑制LH峰和脉冲的作用机制

提前排卵是试管婴儿失败的常见原因，故控制LH峰很关键。高孕激素（P）促排卵能通过下丘脑而非垂体阻断自发性LH峰，其机制尚不清楚。我们前期发现：P作用于下丘脑AVPV和ARN脑区进而调控其下游GnRH神经元以分别抑制LH峰和脉冲；但GnRH神经元在下丘脑长距离投射，其胞体(rPOA脑区)和轴树突（MBH脑区）的功能很关键且不同。我们猜测：P最终通过调控GnRH神经元的胞体和轴树突来分别抑制LH峰和脉冲。本研究用GnRH-Cre小鼠和hM4D(Gi)、hM3D(Gq)病毒建立可操控GnRH神经元活性的化学遗传性技术；在POA、MBH脑区或腹腔注射CNO抑制GnRH神经元的胞体、轴树突活性或两者活性，明确其调控LH峰和脉冲的机制；然后在高孕激素促排卵小鼠的不同脑区给以CNO反向激活，验证能否能恢复P对LH峰和脉冲的抑制。这将为此原创性促排卵方案的推广提供科学依据，并为神经内分泌领域带来理论创新。

Early ovulation is a common cause of IVF failures, so controlling the LH peak is critical. High progesterone (P) ovulation induction can block spontaneous LH peak through hypothalamus rather than pituitary, the mechanism of which is unclear. Our previous research found that Progesterone separately acts on the AVPV and ARN brain area and regulate their downstream GnRH neurons to inhibit LH peaks and pulses. However, GnRH neurons has a long distant projection in the hypothalamus, and their cellular bodies (in the rPOA) and dendrons (in the MBH) play different roles in this regulation. We hypothesized that Progesterone eventually separately inhibited LH peaks and pulses by the cell bodies and dendrons of GnRH neurons. In this study, GnRH-cre mice and hM4D(Gi) and hM3D(Gq) viruses were used to establish chemogenetics to control the activity of GnRH neurons. Then CNO was injected into POA, MBH brain area or intraperitoneal cavity to inhibit the cell body, axonal dendritic activity or both activity of GnRH neurons, to explore their regulation effect on LH peak and pulse. Then CNO with reverse activation was performed in different brain regions of Progestin-primed Ovary Stimulation (PPOS) mice, to see whether this could rescue the progesterone inhibiting on LH peaks and pulses. It will provide a scientific basis for the promotion of this original PPOS protocol and bring theoretical innovations to the field of neuroendocrinology.