Submaxillary Gland Epidermal Growth Factor: A Sensitive Index of Biologic Androgen Activity

The increase in immunoreactive epidermal growth factor (EGF) concentrations in the submaxillary glands of female Balb/C mice was evaluated as a bioassay for androgenic steroids. A simple, sensitive, and specific radioimmunoassay was used to measure EGF. Testosterone and dihydrotestos-terone, injected subcutaneously in a dose of 2 mg per day, increased EGF after only 1 day. An exponential rise in EGF was observed between days 1 to 5. EGF concentrations increased more slowly from days 7 to 14. The dose-response relationship for testosterone was linear over a 300-fold dose range, and was parallel to that of dihydrotestosterone, which was 13.4 times more potent than testosterone. 3±-An-drostane- diol and 3²-androstane-diol generated steeper dose-response curves. Their potencies rela-tive to testosterone, based on a median response, were 5.0 and 0.07, respectively. The submaxillary gland EGF levels of androgen-insensitive (tfm/y) mice failed to increase in response to high doses of a long-acting testosterone preparation, further documenting the unresponsiveness of this animal. It appears that measurement of immunoreactive EGF concentrations in the submaxillary glands of female mice provides a very sensitive and relatively simple index of androgenic bioactivity. (Endocrinology95: 1019, 1974)