Mechanisms of specific regulation of gonadotropn subunits expression by pulsatile GnRH stimulation

PACAP及其受体作为下丘脑-垂体释放因子和垂体内自分泌-旁分泌因子，不仅在中枢神经系统中表达，而且在外周器官中也有表达，具有刺激垂体激素合成和释放的功能。PACAP刺激促性腺激素分泌细胞的促性腺激素α、促黄体生成素β和促性腺激素释放激素β亚基以及促性腺激素释放激素受体及其自身的PACAP I型受体(PAC1R)的表达。GnRH被认为是促性腺激素分泌的关键成分，它反过来刺激促性腺激素细胞中PACAP和PAC1R的表达。此外，PAC1R存在于产生GnRH的神经细胞中，PACAP调节GnRH神经元的功能。显然，PACAP通过直接或间接地通过调节GnRH的释放来调节促性腺激素，从而发挥生殖功能。

PACAP and its receptor are expressed not only in the central nervous system, but also in peripheral organs and function to stimulate pituitary hormone synthesis and release as both hypothalamic-pituitary releasing factor as well as an autocrine-paracrine factor within the pituitary. PACAP stimulates the expression of the gonadotropin alpha, LH betand FSH beta subunits as well as the GnRH receptor and its own PACAP type I receptor (PAC1R) in gonadotropin-secreting pituitary cells. In turn, GnRH, which has been known as a crucial component of gonadotropin secretion, stimulates the expression of PACAP and PAC1R in gonadotrophs. In addition, PAC1R presents in GnRH-producing neuronal cells and PACAP modulates the functions of GnRH neurons. It is evident that PACAP plays a role in reproductive function through regulating gonadotropins directly or indirectly by modulating GnRH release.