DEXAMETHASONE SUPPRESSION TEST - CORTICOSTEROID RECEPTORS REGULATION IN MONONUCLEAR LEUKOCYTES OF YOUNG AND AGED SUBJECTS

The dexamethasone suppression test (DST) is considered an indicator of the Junction of the adrenal pituitary axis. The effect of the steroid is mediated by its binding to corticosteroid receptors. We previously suggested that the measurement of corticosteroid receptors in lymphoc ytes is an index of an analogous pattern in brain. In the present stud y, corticosteroid Type I and Type II receptors in mononuclear leukocyt es were measured in 10 elderly subjects and in 9 young adults, before and after overnight DST (1 mg). Receptors were measured by radiorecept or assay. In ail the subjects, dexamethasone was able to suppress plas ma cortisol. The number of Type I and Type II receptors before the tes t was lower in elderly subjects than in adults. In the control group, dexamethasone produced a significant depression of Type I receptors (f rom 267 +/- 72 to 169 +/- 71 receptors per cell), which can be interpr eted as a primary involvement of Type I receptors in the response to d examethasone; Type II receptors decreased in half the subjects (from 2 849 +/- 703 to 2345 +/- 569 receptors per cell). In elderly healthy su bjects, Type II receptors were also significantly decreased (from 1796 +/- 671 to 720 +/- 345). We suggest that in young subjects Type II re ceptors are initially up-regulated by dexamethasone, and then down-reg ulated, while in aged subjects an up-regulation cannot be achieved, as suggested by the higher values of plasma cortisol usually found in ag ing subjects. (C) 1996, Editrice Kurtis