The effect of estrogen on protein and RNA concentration and on de novo synthesis of RNA in the uterus of aging ovariectomized mice.

A study was made of RNA concentration and de novo synthesis and protein concentration in the uterus of ovariectomized C57BL/6J mice with and without estrogen treatment. Young adult animals (4 to 7 mo.) were compared with mice during the age period of reproductive decline (11 and 15 mo.). Concentration of RNA was significantly lower in 15-mo.-old mice than in 4- to 7- and 11-mo.-old animals. De novo RNA synthesis, as indicated by incorporation of 3H-uridine, was also lower in 15-mo.-old mice than in young adults. Estradiol -17beta increased RNA concentration at all ages studied and the percentage increase did not decline with age. De novo synthesis of RNA was also increased in response to estrogen treatment, but the response was less in 15-mo.-old mice. Protein concentration did not change with age, but the concentration decreased in the estrogen treated mice. The biochemical changes in the uterus may be associated with the declining ability of this organ to support pregnancy as it grows older.