Role of endogenous zinc in the enhancement of bone protein synthesis associated with bone growth of newborn rats

Abstract

The role of endogenous zinc in protein synthesis in the bone tissues of newborn rats was investigated in the present study. Femoral–diaphyseal and metaphyseal tissues were obtained at 1, 7, 14, 21, and 28 days after birth. Many protein molecules were found to be present in the diaphyseal and metaphyseal tissues using sodium dodecyl sulfate–polyacrylamide gel electrophoresis analysis. Bone protein synthesis activity was enhanced by increasing age, and reached a plateau 21 days after birth. Protein synthesis in the diaphyseal and metaphyseal tissues obtained from 7- or 14-day-old rats was significantly decreased by the addition of dipicolinate (10⁻³ M), a chelator of zinc ion, into the reaction mixture, while it was significantly enhanced by zinc sulfate (10⁻⁴ M). When the diaphyseal and metaphyseal tissues obtained from 7- or 14-day-old rats were cultured for 48 h in a medium containing dipicolinate (10⁻³ M), bone protein synthesis was significantly reduced. This decrease was blocked completely by culture with the addition of zinc (10⁻⁴ M). Culture with zinc (10⁻⁵ and 10⁻⁴ M) alone had a stimulatory effect on the bone protein synthesis. Zinc (10⁻⁴ M)-induced increases in bone protein synthesis were completely blocked by culture with cycloheximide (10⁻⁶ M) or actinomycin D (10⁻⁷ M). The present study suggests that bone protein synthesis is enhanced with increasing age of newborn rats, and that endogenous zinc in bone tissues has a stimulatory role in the enhancement of protein synthesis with bone growth.