AJP - Endocrinology and Metabolism, Vol 262, Issue 6 E869-E874, Copyright © 1992 by American Physiological Society
Studies of adrenal steroidogenic enzymes in guinea pigs
P. H. Provencher, Y. Tremblay, B. Belanger and A. Belanger
Le Centre Hospitalier, Universite Laval Research Center, Quebec, Canada.
In the present study we found that 3 beta-hydroxysteroid dehydrogenase
4-ene-5-ene-isomerase (3 beta-HSD), 17-hydroxylase and 17,20-lyase
(P-450c17), and 21-hydroxylase (P-450c21) activities in a suspension of
cells from guinea pig zona reticularis (RE) were 10- to 15-fold less than
those measured in cells from zona fasciculata-glomerulosa (FG). Whereas the
secretion of cortisol and C-19 steroids was remarkably increased during
treatment of FG cells with adrenocorticotropic hormone (ACTH), no response
could be detected when using cells from zona RE. By contrast, the
measurement of a series of C-21 and C-19 steroids shows that the
concentrations of several steroids were greater in the zona RE than in the
zona FG. In addition, using Northern blot analysis, we have observed that
the basal steady-state levels of mRNA for cholesterol side-chain cleavage
(P-450scc), 3 beta-HSD, P-450c21, P-450c17, and P-450c11 were in the same
range in the two zones and an administration of ACTH caused, in both zona
FG and zona RE, a two- to threefold decrease in P-450c17 and P-450c21
steady-state mRNA levels, whereas P-450c11, 3 beta-HSD, and P-450scc
steady-state mRNA levels remained unchanged. Our data suggest the presence
of some factor(s) capable of rapidly deactivating the steroidogenic enzymes
in the zona RE.
