Lactogenic Activity of Mammalian Growth Hormones in vitro

Summary

Growth hormone preparations from several mammalian species were investigated for their ability to initiate secretion in organ cultures of prelactating mammary tissue from strain C3H and A mice. All the growth hormones studies showed some degree of activity in C3H mammary tissues. Bovine, ovine and porcine GH were 20-50% as active as ovine prolactin, although the prolactin content of the preparations was shown to be low. Simian and human GH, whose prolactin-like activity in other systems is well-known, showed activity equal to or greater than ovine prolactin in C3H mammary tissues. On the other hand, a single human GH preparation (one of three studied) was the only GH to show significant activity in strain A mammary tissues. These results suggest an intrinsic lactogenic activity of GH, particularly well-marked in the case of human GH, whose expression in mouse mammary gland cultures is in part determined by the genetic background of the tissues.