Morphological and enzymatic changes caused by a long-term treatment of female rats with a low dose of gonadoliberin agonist and antagonist.
Summary of the study--general tendencies in gonadoliberin (GnRH) agonist (dalarelin)-and GnRH antagonist (cetrorelix)-treated groups compared with proestrus rats Evaluated parameter GnRH agonist GnRH (dalarelin) antagonist Sex hormone (cetrorelix) concentration 17[beta]-estradiol [down arrow] * [down arrow] * progesterone n.s.
(1) Nonstandard abbreviations: hCG, human chorionic gonadotropin; free [beta], free [beta]-subunit; free [alpha], free u-subunit; and GnRH,
gonadoliberin.
In the late follicular phase, the increase in estradiol is important in the development of the midcycle LH surge, and exerts a positive feedback effect and enhances LH responsiveness to
gonadoliberin (GnRH).
(4) The goal of the stimulation with exogenous gonadotropins, combined with the administration of
gonadoliberin analogs (GnRHa) in patients undergoing in vitro fertilization and embryo transfer (IVF-ET), either with clomiphene citrate or with gonadotropins alone, is to induce the ovaries to produce multiple retrievable oocytes to raise pregnancy rates [1-141.