THE INTRASPLENIC INJECTION OF ESTROGENS AND THEIR ESTERS

Abstract

[alpha]-Estradiol, [alpha]-estradiol-3-benzoate, [alpha]-estradiol dipropionate, equilin, estrone and estrone-3-benzoate were slightly less effective in the spleen divorced from the portal circulation than when injected subcut. They were markedly less effective when injected into the spleen in situ. [alpha]-Estradiol-3-benzoate-17-butyrate was equally effective when administered subcut. or in the spleen in situ. a-Estradiol-17-caprylate and [alpha]-estradiol-3-benzoate-17-butyrate were more effective in the spleen divorced from the portal circulation than when injected subcut. a-Estradiol-17-caprylate was less effective in the spleen in situ than in the spleen divorced from the portal circulation. The liver was a site of extensive inactivation of estrogen. The degree of inactivation was governed, in part at least, by the individual estrogen. The esters of [alpha]-estradiol were at least partially absorbed as such from the spleen. Esterification protected [alpha]-estradiol from inactivation by the liver, the 17 hydroxyl being more important than the 3 hydroxyl. The possible explanation of the results and their significance is discussed.