Immune and endocrine aspects of physical and social environmental variations in groups of male rabbits in seminatural conditions

Endocrine and immune parameters, namely glucocorticoid receptors (GcR) and IFN-gamma production in peripheral blood mononuclear cells (PBMC), and cort icosterone in plasma, were studied in groups of four male rabbits observed in seminatural conditions in relation to agonistic behaviour and to seasona l variations. These parameters were selected on the basis of the findings t hat the presence of GcR in PBMC gives an indication of the in vivo biologic al effects of glucocorticoids and that PBMC cytokine production and plasma corticosterone are related to social behaviour. The frequency of active and passive behaviours was used to rank the animals. Seasonal variations were present for agonistic behaviours (Attack, Follow, Chase) and For plasma cor ticosterone, which were significantly higher in winter. IFN-gamma productio n in PBMC was increased after social interactions in both seasons, while pl asma corticosterone was increased only in winter: GcR capacity in PBMC was decreased after social interactions. The results indicate that social and p hysical environmental factors are correlated with immune-endocrine function s.