Novel concepts of human chorionic gonadotropin: reproductive system interactions and potential in the management of infertility.
OBJECTIVE
To extensively review the scientific literature on the potential sites of hCG action and the role of this hormone on reproductive processes not necessarily related to the classic hCG functions of supporting early pregnancy.


METHODS
Review of the international scientific literature and the authors' personal research experience in this area.


RESULTS
The LH/hCG receptor has an almost ubiquitous distribution in reproductive organs, thus suggesting that the actions of hCG might be more extensive than previously thought. Independently of FSH, low-dose hCG can support development and maturation of larger ovarian follicles that have acquired granulosa cells LH/hCG receptors, potentially providing effective and safer ovulation induction regimens. Human chorionic gonadotropin seems to be capable of improving uterine receptivity by enhancing endometrial quality and stromal fibroblast function. Furthermore, through its actions on insulin-like growth factor binding protein-1 and vascular endothelial growth factor, hCG might stimulate endometrial angiogenesis and growth and extend the implantation window, thus making pregnancy more likely.


CONCLUSIONS
Mounting evidence indicates that hCG could be mediating relevant actions enhancing fertility and the efficacy of therapeutic procedures used in the management of infertility. Greater understanding of the physiologic roles that hCG plays in human reproduction might suggest novel clinical applications for this traditional hormone of pregnancy.
Filicori
Marco
M
Reproductive Endocrinology Center, University of Bologna, Bologna, Italy. marco.filicori@unibo.it
Fazleabas
Asgerally T
AT
Huhtaniemi
Ilpo
I
Licht
Peter
P
Rao
Ch V
ChV
Tesarik
Jan
J
Zygmunt
Marek
M
D000818:Animals; D006063:Chorionic Gonadotropin / Q000502:physiology / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D007246:Infertility / Q000188:drug therapy* / Q000378:metabolism; D011247:Pregnancy; D027724:Reproductive Techniques, Assisted / Q000639:trends
D006063:Chorionic Gonadotropin