Quantitative cytochemical changes induced by dexamethasone and adrenalectomy in rat liver chromatin

Physiochemical changes in the state of chromatin shortly following glucocorticoid stimulation of target cells are predicted by the proposed mechanism of steroid action. These changes had not been previously demonstrated in situ. The present experiments demonstrate that in the intact rat, or in one which has been adrenalectomized but given a moderate dose of dexamethasone, the thermal stability of liver cell chromatin is significantly reduced over the level observed in the adrenalectomized untreated animal. This alteration was rated by measuring nuclear acridine orange metachromasia following chromatin denaturation. These data also show an enhanced binding of the dye by the liver cell nuclei under the same conditions. Feulgen dye binding was also found to be enhanced by dexamethasone stimulation but to a level indicative of configurational changes in the chromatin rather than an increase in the amount of DNA in the cells.