[Insulin-like growth factor-I (IGF-I) as a local regulator of proliferation and differentiation of villous trophoblasts in early pregnancy].
In order to elucidate the role of insulin-like growth factor-I (IGF-I) in human placental growth and function, the effects of IGF-I on the proliferation and differentiation of villous trophoblasts were investigated in vitro using an organ culture system of human early placental tissues. Explants of trophoblastic tissues obtained from 4-5 week and 6-12 week placentas were cultured with or without IGF-I (1 ng/ml, 100 ng/ml), in the presence or absence of 10(-8) M triiodo-L-thyronine (T3) respectively, in a serum-free condition. The possible effect IGF-I on the proliferative activity of the cells was examined by immunocytochemical techniques with a monoclonal antibody to proliferating cell nuclear antigen (PCNA), while the possible effect of IGF-I on the differentiated function was assessed by determining the ability to secrete hCG and hPL. In the 4-5 week placentas, IGF-I and IGF-I receptor were almost exclusively localized in cytotrophoblasts and IGF-I augmented the proliferative activity of cytotrophoblasts without affecting the ability to secrete hCG and hPL. By contrast, in the 6-12 week placentas, IGF-I and IGF-I receptor were localized in both cytotrophoblasts and syncytiotrophoblasts and IGF-I stimulated the secretion of hCG and hPL following the enhancement of the proliferative activity of cytotrophoblasts. In column chromatography of the serum-free medium obtained following a 5-day culture of trophoblasts, an elution peak of immunoreactive IGF-I was found in the fractions similar to the elution of 125I-IGF-I. The eluted amount of immunoreactive IGF-I was increased by the addition of 10(-8) MT3 to the medium.(ABSTRACT TRUNCATED AT 250 WORDS)
Murata
K
K
Department of Obstetrics and Gynecology, Kobe University School of Medicine.
Maruo
T
T
Matsuo
H
H
Mochizuki
M
M
D002455:Cell Division / Q000502:physiology; D006063:Chorionic Gonadotropin / Q000378:metabolism; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000502:physiology*; D009924:Organ Culture Techniques; D011247:Pregnancy; D011388:Prolactin / Q000378:metabolism; D017526:Receptor, IGF Type 1 / Q000032:analysis; D014284:Triiodothyronine / Q000494:pharmacology; D014327:Trophoblasts / Q000737:chemistry / Q000166:cytology / Q000502:physiology*
D006063:Chorionic Gonadotropin; D014284:Triiodothyronine; D007334:Insulin-Like Growth Factor I; D011388:Prolactin; D017526:Receptor, IGF Type 1