In vivo effect of glucocorticoids on the rates of pyruvate utilization and lactate formation by incubated lymphocytes

RESUMO

Although the immunosuppressive effect of glucocorticoids has been widely reported, the mechanism of action of these hormones on the immune system has not been fully established. In the present study, the effect of glucocorticoids on the rates of pyruvate utilization and lactate production by lymphocytes obtained from rat mesenteric lymph nodes was investigated. Adult rats were injected withh dexamethasone ( 1 mg/kg, ip) daily for dfays. A stressed group which received a corresponding volume of 0.9% saline and control rats not injected were also included. All treatments were carried out at 17:00 h. Stress or administration of dexamethasone reduced the rate of pyruvate utilization by 505 and 625, respectively. The hormonal injection increased ther rate of lactate production by 575, whereas the stressed group showed a 2.4-fold increase of the conversion of pyruvate to lactate, as compared to control rats. These findings suggest that glucorticoids regulate pyruvate metabolism in lymphocytes and that an additional neurohormonal factor released during stress may also participate in the control of lactate production