The Direct Mammotrophic Action of Lactogenic Hormone

Abstract

SummaryThirty oophorectornized, virgin rabbits, injected subcutaneously 5 days weekly for 4 weeks with 200 I.U. of estrone and 1 I.U. of progesterone showed prolactational mammary growth approximating that of a 3-weeks′ pregnant rabbit. Three days after the last of these injections, 5 different levels of lactogenic hormone were tested on groups of 6 rabbits. The hormone was given intraductally in such a way that an individual sector in each animal received a constant volume of fluid (1.0 cc). Of the different doses of hormone tested, 6 and 3 I.U. caused localized sector lactation in all 6 animals; 1.5 I.U. in 5 of 6; and 0.75 I.U. in 3 of 6 animals. None of the 6 animals injected with 0.37 I.U. lactated; nor did the uninjected or control-injected sectors in any animal lactate. This experiment demonstrates for the first time that the hypophysial lactogenic hormone has a direct mammotrophic effect just as it was previously shown to have a direct crop sac stimulating action. With all other factors essentiall...