Conversion Of Corticosterone Research Articles

18-Hydrocorticosterone Biosynthesis in an Aldosterone Secreting Tumor and in the Surrounding Nontumorous Adrenal Gland

A greater than normal concentration of aldosterone has been found in adrenal tumors from patients with primary aldosteronism (1). 18-Hydroxycorticosterone is probably an intermediary product in the conversion of corticosterone to aldosterone (2). This conversion takes place in the zona glomerulosa. The parallel changes in secretion rates of aldosterone and 18-hydroxycorticosterone which have been observed in man under a variety of conditions support the intermediary role of 18-hydroxycorticosterone (3). However, 18-hydroxycorticosterone is also synthesized in the fasciculata-reticularis zones of the cow adrenal gland (4), and to a lesser degree, in the inner zones of the rat adrenal gland (5).The present report describes the conversion of corticosterone-4-14C to 18-hydroxycorticosterone and aldosterone by an aldosterone producing tumor and the surrounding nontumorous adrenal tissue. Only the mitochondrial fraction of both tissues contained converting activity. The tumor converted 4 times more corticostero...

A steroid inhibitory effect on adrenal mitochondria.

Corticosterone has been reported to inhibit the in vitro incorporation of 14Cleucine into rat adrenal protein. In the present study this inhibition of 14C-leucine incorporation by corticosterone in adrenal homogenates was reversed by the addition of .5 mM ATP and an ATP generating system. Corticosterone 100 μg/ml inhibited respiration in “coupled” adrenal mitochondria in the presence of 5 mM ketoglutarate but not with 5 mM succinate, suggesting a block at the DPNH oxidase site. Rotenone, a specific inhibitor at this site, also inhibited adrenal protein synthesis and blocked the ACTH stimulation of corticosterone production in rat adrenal quarters. The conversion of corticosterone to aldosterone was inhibited by testosterone 100 μg/ml in the presence of both succinate and TPNH as substrates. Further studies suggested that testosterone was a competitive inhibitor for the conversion of corticosterone to aldosterone. These data suggest that steroids inhibit adrenal protein synthesis and block the ACTH stimula...