EFFECT OF AGING ON LEVELS OF ZINC IN THE LYMPHOID-TISSUES OF THE RAT

To evaluate the effect of ageing on levels of zinc in the spleen and t hymus as well as in the serum of rats, we studied three groups of the animals - young adult (3 months old), middle-aged (12-months old), and aged rats (24-months old). Each group contained 10-15 animals. Zinc v alues were determined by atomic absorption spectrophotometry. Advancin g age was associated with a significant increase in spleen zinc (from 21.8 +/- 0.8 to 33.8 +/- 1.0 mu g g(-1) tissue, p < 0.001) and a signi ficant decline in thymus zinc (from 22.7 +/- 1.1 to 15.9 +/- 0.7 mu g g(-1) tissue, p < 0.001). Serum zinc also decreased significantly in t he middle-aged rats (from 2.4 +/- 0.2 to 1.7 +/- 0.1 mu g mL(-1), p < 0.01). These findings demonstrate that zinc levels in primary lymphoid tissues are affected by ageing and indicate a possible mechanism by w hich immune functions progressively decline with age.