Effects of insulin, growth hormone, IGF-I and IGF-II on phenylalanine extraction in the chicken embryo cultured in vitro.

1. To evaluate growth-promoting potencies of bovine insulin, bovine growth hormone (bGH), and recombinant human insulin like growth factor (rhIGF)-I and -II in the chicken, phenylalanine extraction from a synthetic serum-free culture medium into whole-embryos was measured. 2. The chicken embryos at 7 days of age were cultured in a rotatory embryo culture apparatus under a gas phase of 95% O2 and 5% CO2 at 37 degrees C for varying periods of time, and the change in phenylalanine contents in the medium was determined fluorimetrically. 3. Bovine insulin enhanced the phenylalanine extraction when added to the medium at 250 ng/ml whereas no significant change was observed below this concentration. 4. Intact bGH did not show any significant effect on the phenylalanine extraction in its intact form at the concentrations tested. However, bGH partially digested with trypsin increased the phenylalanine extraction. 5. The rhIGF-I enhanced the phenylalanine extraction significantly at 50 ng/ml with no significant increase below this level, whereas rhIGF-II showed no significant increase in phenylalanine extraction at any doses tested. 6. It was concluded that the whole-embryo culture was a quick and convenient system for searching physiologically active compounds that may have growth-promoting potency in the chicken.