Controlled ovulation of the dominant follicle: a critical role for LH in the late follicular phase of the menstrual cycle.
BACKGROUND
A method was sought to control ovulation of the dominant follicle and to test the importance of LH during the late follicular phase of the menstrual cycle. Menstrual cycles of rhesus monkeys were monitored, and treatment initiated at the late follicular phase (after dominant follicle selection, before ovulation).


METHODS
The 2-day treatment consisted of GnRH antagonist plus either r-hFSH and r-hLH (1:1 or 2:1 dose ratio) or r-hFSH alone. In addition, half of the females received an ovulatory bolus of hCG.


RESULTS
When treatment was initiated at estradiol levels >120 pg/ml, neither the endogenous LH surge, ovulation nor luteal function were controlled. However, when treatment was initiated at estradiol levels 80-120 pg/ml using either 1:1 or 2:1 dose ratios of FSH:LH, the LH surge was prevented, and ovulation occurred following hCG treatment. FSH-only treatment also prevented the LH surge, but follicle development appeared abnormal, and hCG failed to stimulate ovulation.


CONCLUSIONS
Control over the naturally dominant follicle is possible during the late follicular phase using an abbreviated GnRH antagonist, FSH+LH protocol. This method offers a model to investigate periovulatory events and their regulation by gonadotrophins/local factors during the natural menstrual cycle in primates.
Young
Kelly A
KA
Division of Reproductive Sciences, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, Oregon 97006, USA.
Chaffin
Charles L
CL
Molskness
Theodore A
TA
Stouffer
Richard L
RL
D000818:Animals; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D005498:Follicular Phase / Q000502:physiology*; D007987:Gonadotropin-Releasing Hormone / Q000037:antagonists & inhibitors; D006801:Humans; D007986:Luteinizing Hormone / Q000008:administration & dosage / Q000494:pharmacology / Q000502:physiology*; D008253:Macaca mulatta; D006080:Ovarian Follicle / Q000187:drug effects / Q000502:physiology*; D010062:Ovulation Induction / Q000379:methods*; D011994:Recombinant Proteins / Q000494:pharmacology
D006063:Chorionic Gonadotropin; D011994:Recombinant Proteins; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone