Reduced DNA synthesis in primary cultures of hepatocytes from old mice is restored by thymus grafts.
We previously observed in vivo that a neonatal thymus grafted into old mice can correct age-related changes such as occurrence of hepatocyte tetraploid nuclei and impaired isoproterenol-induced DNA synthesis in submandibular glands. The aim of the present paper was to study the influence of age and thymus on basal and beta-adrenergic-stimulated DNA synthesis using primary cultures of mouse hepatocytes. In the absence of any adrenergic agents, cells from young mice show peak DNA synthesis between 36 and 48 h; old mice show a similar time course, but the peak is significantly reduced statistically. The main result is represented by the behavior of hepatocytes from old thymus-grafted mice, which recover the levels of [3H]-thymidine incorporation toward young-like values. Grafted animals also show a correction of total DNA content that is increased in old mice. The addition of isoproterenol does not modify the DNA synthetic pattern, whereas the antagonist propranolol causes a slight but statistically significant decrease.
Basso
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A
Gerontological Research Department, Italian National Research Centers on Aging, Ancona, Italy.
Piantanelli
L
L
Rossolini
G
G
Roth
G S
GS
D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000375:Aging / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn / Q000097:blood; D001790:Blood Physiological Phenomena; D002417:Cattle / Q000097:blood; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis*; D007545:Isoproterenol / Q000494:pharmacology; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D011433:Propranolol / Q000494:pharmacology; D011506:Proteins / Q000378:metabolism; D013950:Thymus Gland / Q000637:transplantation*
D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D011506:Proteins; D004247:DNA; D011433:Propranolol; D007545:Isoproterenol