Influence of age and stress from physical activity on the redistribution of lymphocytes

The influence of age and stress on the redistribution of lymphocytes between the intra- and extra-vascular spaces has been studied. Young (12 +/- 4 weeks) and old (68 +/- 6 weeks) mice were made to swim until exhaustion, with and without a previous period of training. Lymphocyte concentration in the blood and in the peritoneal cavity, was evaluated as well as the weight of spleen and thymus in these animals. In parallel, and as an indicator of the level of stress, quantification was made of the serum corticosterone levels and weight as well as the protein, DNA, and RNA content of the adrenal glands. Results indicate that, after being subjected to stress, the young mice present no changes in lymphocyte number in blood or peritoneal cavity. Old mice, however, after acute physical activity, present a greater lymphocyte content in the intravascular compartment, as well as a fall in the peritoneal lymphocyte concentration and spleen weight. The data could indicate that age modifies the response to stress, with an augmentation of lymphocytes in the intravascular compartment at the expense of the extravascular one.