Changes in serum α2u-globulin levels in castrated male rats treated with testosterone propionate in a Hershberger assay

The Hershberger assay has been proposed as a candidate screening test method for the detection of androgenic and anti-androgenic chemicals and is being validated presently under the test guideline programme of the Organization for Economic Cooperation and Development (OECD). Rat a,alpha(2u)-globulin is male rat-specific protein appearing in their serum and urine, and the protein is known to be induced by androgens. We investigated the usefulness of measuring serum alpha(2u)-globulin levels as a parameter for the androgenic activity of chemicals tested in the Hershberger assay. The serum alpha(2u)-globulin level was measured after the administration of testosterone propionate at dosages of 0, 20, 100 or 500 mu g kg(-1) day(-1) for ten consecutive days in the castrated male rats. The ventral prostate, balbocavernosus/levator ani muscles, glans penis and Cowper's gland were collected and weighed. Although all the androgen-responsive organ weights were increased significantly at dosages of 100 and 500 mu g kg(-1), day(-1) the serum alpha(2u)-globulin level was increased significantly only at a dosage of 500 mu g kg(-1) day. These results show that the serum alpha(2u)-globulin level may be a useful biomarker for detecting androgenic activity caused by test chemicals, but it is less sensitive than the organ weights of androgen-responsive tissues in the Hershberger assay. (c) Copyright 2005 John Wiley T Sons, Ltd.