Effects of Cortisol on the Metabolism of Glucose by Lymphoid Tissue.

Jedeikin and White (1) reported that the over-all oxidation of uniformly labeled glucose-% to carbon dioxide by suspensions of rat thymic lymphocytes was inhibited by 31% by cortisol (lop4 M) ; similar depressions of glucose oxidation were observed in suspensions of rat lymphosarcoma cells. In addition, injection of cortisol into normal or adrenalectomized rats led to a decreased oxidation of glucose by thymocytes studied in vitro thereafter (1). Extension of these studies by Blecher and White (2) with malignant lymphoid tissue led to the suggestion that loci of action of adrenal corticoids in inhibiting the over-all oxidation of glucose resided in intermediate steps of glycolysis. Bartlett, Morita, and Munck (3) reported that the injection of cortisol into adrenalectomized rats inhibited by about 30% the incorporation of injected glucose into thymus tissue fractions as determined shortly (l+ hours) after substrate administration. In addition, Morita and Munck (4) reported that, 2 hours after administration in vivo of cortisol to fasted, adrenalectomized rats, the ability of thymocytes in vitro to take up glucose from the incubation medium was depressed by 40%. Furthermore, the presence in vitro of cortisol (1OP M) was reported (4)l to inhibit the uptake of glucose by rat thymocytes by about 28%; the inhibitory effects of lower concentrations of cortisol (IOP to 10P7 M) were less significant (22 and 770, respectively). Since the loci of action of adrenal glucocorticoids in depressing glucose utilization by rat thymocytes remained in doubt (inhibition of uptake or of further metabolism), the present studies were undertaken to examine the effects of these steroids on the uptake, oxidation to carbon dioxide, and conversion to lipids and cell protein of glucose-6-W by suspensions of thymic lymphocytes obtained from normal and adrenalectomized rats. It was observed that all parameters of glucose metabolism, except that of uptake of glucose by the cells, were inhibited by cortisol in vitro, and increased by prior adrenalectomy of donor animals; the uptake of glucose was unaffected by cortisol in vitro over a wide range of concentrations, or by prior adrenalectomy of donor animals.