IN RAT ADRENAL GLANDS

Minced rat adrenal glands were incubated in vitro with [4-14C]proges-terone and [16-3H]pregnenolone separately and together for 4 and 6 hr. periods. The yields of corticosterone, 11-deoxycorticosterone, and 18-hy-droxy-11-deoxycorticosterone from both precursors, and of progesterone from [16-3H]pregnenolone, were estimated. In three incubations the change of these yields with time was also investigated. The results obtained sug-gest that in contrast to the human adrenal, and possibly those of other species, there is no distinction between the roles of progesterone and pregnenolone as precursors of corticosteroids in the rat adrenal gland. They suggest also that in the normal rat adrenal gland pregnenolone is trans-formed as follows:,corticosterone pregnenolone-> progesterone- * 11-deoxycorticosterone ^ 18-hydroxy-ll-deoxycorticosterone Alternative pathways seem to be relatively unimportant