Contribution of the environmental enrichment model in mice in understanding the links between the nervous and immune systems.

Innovative work highlights complex interactions between the brain and the immune system under physiological and pathological conditions. We will present recent data illustrating the role of T lymphocytes in the effects of Enriched Environment on brain plasticity and discuss possible modes of action of immune cells on the brain.

Brain plasticity is a remarkable ability of brain cells to adapt their structure and function in response to experience and the environment. This brain plasticity is favored by favorable living conditions that can be modeled in rodents by the Enriched Environment (EE) model. The EE consists of putting a large number of mice in large cages with many objects (nests, tunnels, wheels ...) that are changed regularly. EE induces increased voluntary physical activity, optimal conditions for the stimulation of social interactions, exploratory behavior and cognitive functions. EE has beneficial effects on the physiological processes in many systems (hormonal, cardiovascular, immune ...). EE reduces anxio-depressive behaviors, improves learning and memory. These effects are underpinned by changes in the brain, particularly the hippocampus, where more neurogenesis and synaptogenesis are observed in EE.

Innovative work highlights complex interactions between the brain and the immune system under physiological and pathological conditions. For example, in immunodeficient mice, memory performance and neurogenesis are highly impaired, suggesting an interaction between the immune system and the brain. Among the cells of the immune system, T lymphocytes (LT) seem to play a particularly important role in the mechanisms of neuronal plasticity. We will present recent data illustrating the role of LT in the effects of EE on brain plasticity and discuss possible modes of action of immune cells on the brain.