Propagation in vitro of functional rat adrenal cortical cells: Modifications of the differentiated state by culture conditions

Abstract

Adrenal cortical cells obtained from adult rats were propagated as monolayers in vitro for up to 6 weeks. Depending on the culture regime, these cells could be maintained consistently in two distinct states of differentiation. Cells that were subcultured by tryptic dissociation and grown in 25% fetal calf serum assumed a fibroblast-like morphology but differed from fibroblasts of connective tissue origin in histochemistry, steroid metabolism, response to adrenocorticotrophic hormone (ACTH), and life-span. A limited expression of adrenocortical function was suggested by the presence of lipid, of Δ5-3β-hydroxysteroid and glucose-6-phosphate dehydrogenases, the production of small amounts of corticosteroids, and the ability to respond to ACTH. If cells were subcultured by mechanical dissociation from confluent primary adrenal cultures and grown in media containing 10% horse serum, they assumed an epithelial morphology resembling adrenal cortical parenchyma. Their more intense reaction for lipid and dehydrogenases, higher rate of steroid metabolism, and synthesis of the tissue-specific hormone, corticosterone, indicated a degree of differentiation not attained by the adrenal cells in the fibroblast-like form. It would appear that the adrenal cortical phenotype is expressed more completely in monolayer cultures under conditions where cell to cell contact and the integrity of cell surfaces are maximally maintained.