Prolactin-Like Substance of Human Placenta

Publisher Website
Google Scholar
Abstract
Implantation of placentae of several stages of pregnancy beneath the skin near the crop of pigeons always caused considerable hyperemia, thickening and opacity of the mucous membrane. Placental extract in saline caused negative crop reaction. Placental extracts prepared by Bonsens and White''s method, Li''s method and Lyon''s method always caused negative crop reaction. The three extracts prepared by our method from full-term human placentae with the iso-electric point at pH 5.0, pH 5.8 and pH 6.0 caused always positive crop reaction, 1 mg. of them being equivalent to 1/2, 1 and 2 pigeon units, respectively. Positive reaction also followed intramuscular injection of 20 mg. of pH 5.0 and pH 5.9 fractions and 10 mg. of pH 6.0 fraction. Only the pH 5.8 fraction caused lactation upon injection into the lactiferous tubules of pseudo-pregnant rabbits. When injected in post-puerperal rabbits with completely stopped lactation, all the fractions caused resumption of lactation. When injected in puerperal women, all the fractions caused increase of secreted milk over that in the non-treated controls. No side-effect of the administration was perceptible. The chemical properties of the fractions were determined. The results pointed to the inference that it consisted in a prolactin-like protein.