The role for the uterine insulin-like growth factor I in early embryonic loss after superovulation in the rat.
OBJECTIVE
To examine possible roles of the insulin-like growth factor (IGF) system in increased early embryonic loss after superovulation.


METHODS
Changes in the uterine IGF system were examined in superovulated rats. Insulin-like growth factor I (IGF-I) was infused to the right uterine horns to mimic enhanced IGF-I actions after superovulation. Uterine luminal fluids were collected after IGF-I infusions and embryos were cultured with uterine luminal fluids.


METHODS
Steroid hormones, IGF-I, IGF binding protein (IGFBP), and IGF-I receptor levels, developmental rate, and cell numbers of embryos.


RESULTS
Elevated IGF-I levels and suppressed IGFBP levels were found from days 1 to 3 of pregnancy after superovulation. Uterine luminal fluids of the IGF-I infusion and superovulation groups impaired embryo development in vitro. Anti-IGF-I antibody infusions after superovulation reversed detrimental effects of superovulation. Dialysis of uterine luminal fluids of the IGF-I infusion and superovulation groups before culture improved embryo development.


CONCLUSIONS
Enhanced IGF-I actions in the uterus after superovulation may be responsible for the increase of early embryonic loss. The detrimental factor for embryo development seems a small molecule and is likely a local product of the uterus in which IGF-I actions are enhanced.
Katagiri
S
S
Department of Obstetrics and Gynaecology, University of British Columbia, Vancouver, Canada.
Moon
Y S
YS
Yuen
B H
BH
D000818:Animals; D005314:Embryonic and Fetal Development; D004958:Estradiol / Q000097:blood; D005260:Female; D005313:Fetal Death; D018969:Insulin-Like Growth Factor Binding Proteins / Q000032:analysis; D007334:Insulin-Like Growth Factor I / Q000032:analysis / Q000502:physiology*; D010062:Ovulation Induction; D011374:Progesterone / Q000097:blood; D051381:Rats; D017207:Rats, Sprague-Dawley; D017526:Receptor, IGF Type 1 / Q000032:analysis; D013480:Superovulation; D013997:Time Factors; D014599:Uterus / Q000737:chemistry / Q000502:physiology
D018969:Insulin-Like Growth Factor Binding Proteins; D011374:Progesterone; D004958:Estradiol; D007334:Insulin-Like Growth Factor I; D017526:Receptor, IGF Type 1