The relation between cortisol binding and glutamine synthetase induction in the neural retina of the chick embryo.

Abstract

Cortisol induces high levels of glutamine synthetase (EC 6.3.2.1) activity in the embryonic neural retina of chick embryos. This response to the hormone is impaired when the tissue is dissociated to a single cell suspenion and is gradually lost when the cells are maintained in monolayer cultures. To elucidate the mechanism that controls this tissue-specific function, the interaction of [3H]cortisol with retinal cell suspensions and retinal monolayers was studied and compared to the interaction of the hormone with the responsive intact tissue in culture. The growth rate of neural retina cells, dissociated from the 10-day-old embryonic tissue, is higher than that of the intact tissue; there is a 2-fold increase when grown in suspension cultures and a 3- to 4-fold increase when grown in monolayers. Under these conditions, retinal cells in suspension retain the full binding capacity characteristic to the intact tissue in culture. The translocation of the hormone-receptor complexes to the nucleus is also uncha...