Positive effect of FSH but not LH on early development of the dominant follicle in mares.
The effects of FSH, LH or both on follicular growth and intrafollicular free insulin-like growth factor (IGF)-1 and oestradiol were investigated in mares after the beginning of deviation (largest follicle >/= 20 mm; Hour 0). A single treatment with a gonadotropin-releasing hormone antagonist (acyline) was given at Hour 3 to suppress the concentrations of FSH and LH. Five groups (n = 5 mares per group) were evaluated in the present study: (1) control; (2) acyline treated; (3) acyline + recombinant equine (re) FSH treated; (4) acyline + reLH treated; and (5) combined acyline + reFSH + reLH treated. Beginning at Hour 3, reFSH and reLH were given at 6-h intervals in eight decreasing or increasing doses, respectively. The reFSH and reLH prevented the acyline-induced decreases in FSH and LH, respectively. Diameters and concentrations of intrafollicular free IGF-1 and oestradiol of the two largest follicles at Hour 48 did not differ significantly between the control and acyline + FSH groups, but were reduced (P < 0.05) similarly in the acyline and acyline + LH groups. The combination of reFSH and reLH was no more effective than reFSH alone. The results demonstrate a role for FSH but not LH in the growth of the largest follicle and intrafollicular concentrations of free IGF-1 and oestradiol during the 48 h after the beginning of deviation in mares.
Checura
C M
CM
Eutheria Foundation, Cross Plains, WI 53528, USA.
Beg
M A
MA
Parrish
J J
JJ
Ginther
O J
OJ
D000818:Animals; D004958:Estradiol / Q000502:physiology; D005260:Female; D005640:Follicle Stimulating Hormone / Q000008:administration & dosage / Q000097:blood / Q000502:physiology*; D006736:Horses / Q000502:physiology*; D007334:Insulin-Like Growth Factor I / Q000502:physiology; D007986:Luteinizing Hormone / Q000008:administration & dosage / Q000378:metabolism / Q000502:physiology*; D009842:Oligopeptides / Q000494:pharmacology; D006080:Ovarian Follicle / Q000187:drug effects* / Q000502:physiology; D011897:Random Allocation
D009842:Oligopeptides; D004958:Estradiol; D007334:Insulin-Like Growth Factor I; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; C109238:acyline