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SUMMARY The effects of human pituitary extracts upon steroid biosynthesis by pieces of human adrenal tissue incubated in Krebs—Ringer bicarbonate buffer have been studied. Experiments with both adult and foetal adrenal tissue have been carried out. Radioactive precursor (either [7-3H]pregnenolone or [4-14C] progesterone) was added to each incubation vessel and the synthesis of radioactively labelled products was estimated by reverse isotope dilution. Individual steroids were characterized by paper and thin-layer chromatography; the radiochemical purity of cortisol, androstenedione, dehydroepiandrostenedione (DHA) and DHA sulphate was established following derivative formation. There was no consistent effect of the pituitary preparations upon the biosynthesis of cortisol, DHA or DHA sulphate, nor upon the ratio of cortisol to the combined production of DHA and DHA sulphate. However, the production of androstenedione from both [7-3H]pregnenolone and [4-14C]progesterone was significantly increased in the presence of pituitary and gonadotrophic preparations.

SUMMARY Human adrenal tissue was sliced and incubated with 25 μc [7α-3H]-pregnenolone. The percentage conversion of radioactive precursor to dehydroepiandrosterone (DHA), DHA sulphate, androstenedione, 11β-hydroxyandrostenedione, cortisol and 11-deoxycortisol was estimated by the reverse isotope dilution technique. Incubations of both adult and foetal adrenal slices gave reproducible results. The duration of the incubation period was an important factor affecting the pattern of radioactive steroids synthesized, the adult adrenal pattern being dissimilar to that of the foetal adrenal. A direct proportional relationship between the weight of the incubated tissue and the biosynthesis of cortisol from exogenous [7α-3H]-pregnenolone was not established. The production of DHA sulphate relative to free DHA increased markedly from 12 to 27 weeks gestation. When incubated for 2 hr. the combined production of DHA and DHA sulphate relative to cortisol and androstenedione decreased with gestational age. There was evidence for considerable 3β-hydroxysteroid dehydrogenase activity in foetal adrenals at 12 to 27 weeks gestation.

SUMMARY Adrenals from foetuses of 13 to 27 weeks gestation were sliced and incubated with 5 μC of [4-14C]progesterone for 2 hr. The biosynthesis of cortisol, 11-deoxycortisol, androstenedione and 11β-hydroxyandrostenedione was estimated by reverse isotope dilution. Cortisol was the major product identified and the production of both cortisol and 11β-hydroxyandrostenedione increased with gestational age in approximate proportion to the increasing adrenal weight. The ratio of (cortisol plus 11-deoxycortisol) to (androstenedione plus 11β-hydroxyandrostenedione) was constant at 13, 16 and 27 weeks gestation. The production of cortisol and androstenedione from progesterone and from pregnenolone by adrenal tissue from a 27-week-old foetus is compared.

SUMMARY Foetal rat adrenals were grown in primary tissue culture. The effects of ethidium bromide on the adrenocorticotrophin (ACTH)-induced differentiation of the mitochondria of the cortical cells were examined. Ethidium bromide (1 μg/ml/day for 4 days) inhibited the morphological transformation of the mitochondria normally induced by ACTH. At the same time the steroid 11β-hydroxylating activity, which is associated with the inner mitochondrial membrane, was either partially or completely blocked. The ethidium bromide-treated cells contained mitochondria of varying sizes and with poorly developed inner membranes. The biochemical and morphological effects of ethidium bromide on the cortical cell mitochondria were only partially reversible.