Effect of diazepam on the immune response of rats exposed to acute and chronic swim stress

To examine the effect of the anti-stress agent diazepam on the immune respo nse, rats were exposed either to acute swim stress, i.e., swimming once onl y for 30 minutes (non-trained swimmers), or to chronic stress with gradual progressive training for 6 weeks (trained swimmers). Both groups of animals were divided into subgroups treated before swimming with and without diaze pam, 1 mg/kg, administered i.m. The phagocytic capacity and superoxide anio n generation of the peritoneal macrophages was examined. In addition, the p roliferative response of the splenic cells (splenocytes) to concanavalin A (Con A) and phytohemagglutinin (PHA), as well as the serum corticosterone l evels were investigated. Diazepam abolished increased superoxide anion prod uction in both non-trained and trained swimmers. In non-trained swimmers, t he number of latex particles internalized by each cell was decreased and fu rther reduced by the drug. In trained rats treated with diazepam. the perce ntage of phagocytosing cells remained reduced compared to controls, whereas the drug prevented a decrease in the engulfing capacity of individual cell s. Diazepam lowered the suppressed proliferative response of the splenocyte s to PHA found in non-trained swimmers. It is concluded that diazepam modif ies the immune response of rats exposed to acute and chronic swim stress. ( C) 2000 Editions scientifiques ct medicales Elsevier SAS.