Chronic pathophysiologic elevation of corticosterone after thermal injury or thermal injury and burn wound infection adversely affects body mass, lymphocyte numbers, and outcome.

The purpose of the present studies was to investigate the effect of glucocorticoids on catabolism and lymphocyte numbers in a rat model of thermal injury or thermal injury plus burn wound infection. Thermal injury alone caused only an acute increase in plasma corticosterone concentrations. Furthermore, body weight declined moderately (5%), and lymphocyte numbers in lymph nodes draining the burn wound and blood increased markedly, whereas splenic lymphocyte numbers declined by about 60%. By contrast uninjured rats subjected to chronic elevation of corticosterone by corticosterone pellet implantation showed large decreases in body weight and lymphocyte numbers in all tissues examined. The combination of injury and chronic corticosterone elevation resulted in body weight and lymphocyte changes intermediate between injury alone and corticosterone treatment alone. Chronic elevation of corticosterone for 4 days before burn wound infection significantly decreased survival time and survival. Burn wound infection immediately after injury caused chronic elevation of endogenous plasma corticosterone and body weight and numeric lymphocyte changes that were remarkably similar to those of uninjured rats treated with corticosterone. Finally, the glucocorticoid receptor antagonist RU 486 significantly increased survival time in thermally injured, burn wound-infected rats. These results lend support to a hypothesis that chronic elevation of plasma cortisol concentrations as observed in patients with burns may be deleterious.