Studies Concerning the Inhibition of Glucose Metabolism in Thymus Lymphocytes by Cortisol and Epinephrine

Thymus lymphocytes from adrenalectomized rats were used to study the documented inhibitory effect of glucocorticoids on glucose metabolism of lymphoid tissue. Cortisol (10^–6.M) depressed glucose uptake, lactate production, and glycogen levels during aerobic incubation of the cells. The depression of glucose uptake by cortisol was greater than the decrease in production of ¹⁴CO₂ from ¹⁴C—glucose, resulting in an increased specific yield of ¹⁴CO₂ in the presence of steroid. The fraction of glucose metabolized by the pentose phosphate pathway was increased by cortisol, but the absolute amount of glucose metabolized by this pathway was not altered by the steroid. Cortisol was without effect on anaerobic glycolysis; however, the lack of inhibition was not due to damage to the cells during anoxia since incubation of thymocytes without oxygen for 1 hr at 37 C did not prevent inhibition of aerobic glucose metabolism by the subsequent addition of cortisol.

The addition of epinephrine at a concentration of 10^-6M significantly decreased glucose uptake and lactate production only in the presence of cortisol, suggesting that epinephrine can affect glucose metabolism of thymocytes only if the cells have been exposed to glucocorticoid. (Endocrinology91: 233, 1972)