Circadian Synchronization of Liver Regeneration in Adult Rats: The Role Played by Adrenal Hormones

摘要: The role played by the adrenal hormones in regulation of liver proliferation adult rats was investigated under various experimental conditions. In untreated control groups, cell growth very low and endogenous corticosterone levels showed a clearly-defined circadian rhythm with peak evening. Adrenalectomy depressed level immediately rate increased significantly. We were able to prevent this effect repeated injections at physiological doses. After 1/3 hepatectomy sham-operation, blood maintained its normal pattern exception transient increase during first two post-operative hours. After kind, negative correlation found exist between hormone waves DNA synthesis; subsequent mitoses appeared successive decreasing amplitude, maximum value being reached morning. In submitted an adrenalectomy simultaneously, fell significantly after peak. regenerating completely different from that induced alone. rise labelling index began earlier rose higher values; it then followed single large mitotic wave without any rhythm. These results favour hypothesis have significant on regeneration. Circadian changes responsible for nycthemeral observed partial hepatectomy. show marked inhibition G1-S transition, particularly evening, when concentration highest. Also discussed is relationship corticoids ‘chalones’, which synergetically inhibit passage G0 into cycle.