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VD Castracane1 *, MC Henson2 *, TL Gimpel1 , BA Tawwater1
Dept of OB/GYN, Texas Tech Univ Health Sciences Center, Amarillo, Texas 1
Dept of OB/GYN, Tulane Univ School of Medicine, New Orleans, Louisiana 2
We have used different immunoassays which recognize either pituitary (pit) GH alone or pit and placental (plac) GH to estimate serum GH levels in pregnant (PRG) women (Endocr Abst 1997). The baboon is an excellent nonhuman primate model for human reproductive endocrinology and has not been studied for changes in pit and plac GH during PRG. We have utilized a GH RIA which recognizes both pit and plac GH in the human and a specific IRMA chemiluminescent assay which only recognizes pit GH (DPC, Los Angeles, CA). Non-PRG baboon samples were analyzed by both GH methods with a good correlation between methods. Serum GH in PRG baboons showed elevated levels with the RIA but not with the IRMA assay. We have also measured immunofunctional GH (IFGH) (DSL, Webster, TX), a sandwich assay which uses as its second binding protein the GH binding protein that is present in the circulation. This assay recognizes predominantly, if not exclusively, unbound GH. In women, IFGH increases greater toward the end of PRG than does plac GH alone. In normal PRG baboons, serum samples were obtained 60-160 days of gestation. Pit GH remains low throughout PRG (<5 mg/ml) but is slightly higher than in women. Plac GH levels were between 10-20 ng/ml, higher than in women. Whether this is related to immunological recognition because of species specificity or an actual low level of pit production of GH through PRG is not defined in this protocol. IFGH is generally low in early PRG but increases after 100 days of gestation. We have reported a similar late PRG increase in women (Endocr Absts 1998). The baboon is a useful model to study GH dynamics during PRG and assays used in women can be applied to the baboon.
This abstract is being presented on Tuesday, August 3 at 8:00 AM to 10:15 AM at CUB 2nd Floor Ballroom.