Effects of early gestation GH administration on placental and fetal development in sheep.
Ovine GH (oGH) is synthesized in placental tissue during maximal placental growth and development. Our objectives were to localize oGH mRNA in the placenta, and study the impact of exogenous GH on twin pregnancies during the normal window (35-55 days of gestational age; dGA) of placental expression. In situ hybridization localized oGH mRNA in uterine luminal epithelium but not in tissues of fetal origin. While maternal GH and IGF-I concentrations were increased (P<0.001) approximately tenfold, uterine, uterine fluid, placental, and fetal weights were unaffected by treatment at either 55 or 135 dGA. Fetal length, liver weight, and liver weight per kg of body weight were unaffected by maternal GH treatment. However, in the cotyledon, IGF-binding protein (BP)-1 and IGFBP-4 mRNA concentrations were increased (P<0.05), while IGFBP-2 mRNA was decreased (P<0.05). The concentration of mRNA for IGFBP-3 was unaffected by treatment. Within the caruncle, IGFBP-1 mRNA was decreased (P<0.05), while IGFBP-3 and IGFBP-4 mRNA were increased (P<0.05), and IGFBP-2 mRNA was unchanged due to GH treatment. While our data indicate that elevated maternal GH and IGF-I concentrations during early and mid-gestation do not enhance placental and fetal growth in twin pregnancies, localization of GH mRNA in uterine luminal epithelium could explain GHs transitory expression from 35 to 55 dGA, since by the end of this period the majority of the uterine luminal epithelium has fused with chorionic binucleate cells forming the placental syncytium.
Wright
Casey D
CD
Animal Reproduction and Biotechnology Laboratory, Department of Biomedical Sciences, Colorado State University, ARBL-Foothills Campus, Campus Delivery 1683, Fort Collins, Colorado 80-523-1683, USA.
Orbus
Ryan J
RJ
Regnault
Timothy R H
TR
Anthony
Russell V
RV
D000818:Animals; D005260:Female; D047109:Fetal Development / Q000187:drug effects*; D013006:Growth Hormone / Q000097:blood / Q000235:genetics / Q000494:pharmacology*; D017403:In Situ Hybridization; D018969:Insulin-Like Growth Factor Binding Proteins / Q000235:genetics; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D010920:Placenta / Q000187:drug effects* / Q000378:metabolism; D011247:Pregnancy; D012333:RNA, Messenger / Q000032:analysis; D012756:Sheep
D018969:Insulin-Like Growth Factor Binding Proteins; D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone