[The effect of thymosin (fraction 5) and taktivin on adrenocortical function in mice]

A study was made of the effect of the thymic factors thymosin (fraction 5) and tactivin on adrenocortical function of BALB/C mature mice. A single administration of thymosin at a dose of 1 micrograms/mouse causes a rise of the blood level of corticosterone in 3 h. Dexamethasone, a blocker of ACTH secretion, stops the thymosin effect. Thymosin does not influence adrenocortical production of corticosterone in vitro. A marked tendency to a decrease in the blood level of corticosterone is clearly observed 3 h after tactivin administration at doses of 0.1, 0.5 and 2.5 micrograms/mouse. Tactivin added to the adrenal glands in vitro causes dose-dependent suppression of corticosterone specific production. A conclusion is that both factors act in opposite directions on adrenal functioning, and their influence on the glands is mediated differently.