Modulation of acetylation of chromosomal proteins of the brain of rats of various ages by epinephrine and estradiol

Abstract

In vitro acetylation of histones and non histone chromosomal proteins (NHCP) and their modulation by epinephrine and estradiol were studied by incubating slices of cerebral hemisphere of young (2-), adult (15-) and old (84-week) female rats with ¹⁴C-sodium acetate. Acetylation of histones decreases with increasing age. Both epinephrine and estradiol stimulate acetylation in the young. Stimulation by epinephrine is greatly decreased in the adult, and it has no effect in the old. Estradiol has no effect in adult and old rats. Acetylation of H3, H4 and H2B histones decreases with age, but not of H1 and H2A. Epinephrine and estradiol significantly stimulate acetylation of H1 and H3 respectively in the young. Acetylation of NHCP is high in the young and decreases precipitously with increasing age. Both epinephrine and estradiol stimulate acetylation of NHCP in young, but not in adult and old rats. Such age-related alterations in acetylation of chromosomal proteins by hormones and other effectors may be responsible for differential activation and repression of genes and cause aging.