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

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

Rates of pyruvate utilization and lactate formation by lymphocytes from young and aged rats

The rates of pyruvate utilization and lactate formation were measured in lymphocytes obtained from mesentéric lymph nodes were incubated at-C for 1 h. The conversion of pyruvate to lactate accounted for 92.5% of the total pyruvate utilized by lymphocytes from yung rats and was 34.2% and 44.5% for adult and aged rats, respectively. Wen lymphocytes were stimulated with concanavalin. A there was an increase of 65.5% and 37.1% in the rates of pyruvate utilization by lymphocytes from young and adult rats, respectively. No changes in pyruvate utilization were observed in response to concanavalin A in lymphocytes from aged rats