[Cooperative effect of high density lipoproteins and adaptive hormones in chromatin activation in rat liver].
Fluorescent probing of rat liver chromatin with acridine orange (AO) and ethidium bromide was employed to investigate the rat liver chromatin activation under stress in vivo and in vitro. A significant increase of molar concentration of AO binding sites with chromatin in nuclei suspension was demonstrated after intensive physical exercises and partial hepatectomy. These results reveal chromatin activation under these stress conditions. For the first time the chromatin activation was shown to be a result of the cooperative effect of hydrocortisone and blood plasma high density lipoproteins (HDL). Both HDL2 and HDL3 contribute to this cooperative action. The increase of concentration of AO binding sites and simultaneous increase of the ratio of red to green fluorescence (alpha), which represents the amount of one-stranded nucleic acids, show that chromatin activation in this case is accompanied by the derepression of new genes and also by the enhanced expression of already functioning ones. Adrenaline did not change the amount of AO binding sites but increased index alpha. This evidences for the enhanced expression of already functioning genes. Hydrocortisone-dependent chromatin activation led to the increase of the binding constant of AO with DNA, while molar concentration of binding sites of the probe was practically unaltered. At the same time, cooperative effect of hydrocortisone and HDL did not alter the constants of AO binding, but the concentration of the probe binding sites with DNA was significantly increased.
Panin
L E
LE
Svechnikova
I G
IG
Maianskaia
N N
NN
D000222:Adaptation, Physiological; D000818:Animals; D002843:Chromatin / Q000187:drug effects* / Q000378:metabolism; D004837:Epinephrine / Q000494:pharmacology; D005260:Female; D006854:Hydrocortisone / Q000494:pharmacology*; D008075:Lipoproteins, HDL / Q000494:pharmacology*; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013312:Stress, Physiological / Q000378:metabolism*
D002843:Chromatin; D008075:Lipoproteins, HDL; D006854:Hydrocortisone; D004837:Epinephrine