Changes of dipeptidyl peptidase (DP IV) activity in the T lymphocytes of rats following administration of ACTH, dexamethasone and opiates.

The aim of the work was to study the effect of glucocorticoids, opiates and stressful stimuli on dipeptidyl peptidase IV (DP IV, EC 3.4.14.5) activity of T lymphocytes prepared from the thymus of intact and adrenalectomized rats. Four week old male rats of Wistar strain were used. The in vivo administration of ACTH, dexamethasone and morphine treatment resulted in an increase of DP IV activity in the cell suspension. In adrenalectomized rats ACTH treatment failed to modify the enzyme activity, however, pain or emotional stress resulted in an elevated DP IV activity. Morphine and D-Met2-Pro5-enkephalinamide resulted in a dose dependent activation of DP IV in T cells, an effect which could be modified by naloxone pretreatment. Our findings show that DP IV mechanisms in T cells are highly sensitive to exogenous and endogenous steroids, opiates and biologically active substances released in response to stress in rats.