In pancreas, the activities of several sex steroid-transforming enzymes hav
e been reported. Data have been obtained in perfused organs, total tissue h
omogenates, and subcellular organelles. These data, concurrent with the des
cription of the presence of ligand-regulated steroid receptors, as well as
the sexually dimorphic behavior of some pancreatic tumors, are clear eviden
ce in support of the participation of steroid hormones in the pancreatic fu
nction. In this study, the steroidogenic ability of the pancreas was demons
trated by two different methods: (a) in tissue homogenates, by the identifi
cation of cytochrome P-450scc gene (CYP11A) transcripts after reverse trans
cription-polymerase chain reaction amplification (RT-PCR); and (b) in isola
ted mitochondria by the glutethimide-dependent inhibition of cholesterol-pr
egnenolone biotransformation. The results obtained in a series of independe
nt experiments showed that (a) the pancreatic tissue possessed transcriptio
nal activity of the CYP11A gene, although to a lesser extent than the typic
al steroidogenic tissues, and (b) isolated mitochondria obtained from the p
ancreas were able consistently to synthesize pregnenolone; furthermore, the
addition of the specific inhibitor aminoglutethimide (AMG) blocked its syn
thesis. On the whole, these findings are interpreted as clear evidences of
the activity of the cytochrome P-450scc enzymatic complex (P450scc), respon
sible for the transformation of cholesterol into pregnenolone and considere
d the first and limiting step in steroid biosynthesis.