AGING AFFECTS CELLULAR ZINC AND PROTEIN-SYNTHESIS IN THE FEMORAL DIAPHYSIS OF RATS

To clarify the effect of aging on bone metabolism, alteration of the cellular zinc content and protein synthesis was examined in the femoral diaphysis of 3- and 30-week-old male rats. The cellular zinc content in bone tissue markedly decreased in 30-week-old compared to 3-week-old rats. When the bone tissue from older rats were cultured with [3H]leucine, incorporation of [3H]leucine into the acid-insoluble residues was less than for weanling rats. This decrease was partly restored by the oral administration of zinc sulfate (0.5, 1.0, and 2.0 mg Zn/100 g body weight) to elderly rats for 3 days. An increase of in vitro [3H]leucine incorporation by bone tissues obtained from the rats that had received zinc (2.0 mg/100 g) was blocked by cycloheximide (10-6 M) or dipicolinate (10-3 M), a chelator of zinc. These results suggest that bone protein synthesis declines with age, and that this decline may be based partly on the decrease in bone cellular zinc. © 1990 Springer-Verlag.