Behavioral characterization of a mouse model of premature immunosenescence

In previous studies we have shown that differences in life span among members of Swiss mouse populations appear to be related to their performance in a T-maze, with a slow performance ("slow" mice) being linked to an impaired immune function and a shorter life span when compared to "fast" mice, which led us to propose the slow mice as a model of immunosenescence. In the present study we demonstrate that in a tightrope test of neuromuscular vigor and coordination the slow mice show a worse performance, needing more time to complete the task. Moreover, these animals show a decreased locomotor activity and an increased level of emotionality/anxiety in three standard behavioral tests (the holeboard, the open field and the plus-maze) when compared to fast mice. All these behavioral features were most marked in the slow females. The results also indicate that slow animals show a decreased chemotaxis of macrophages and lymphocytes, as well as a reduced lymphoproliferative response to mitogens. The data supports our claim that slow or hyperemotional mice, in which immune and neurobehavioural functions appear to be impaired, may be a useful model of premature aging.