Effects of estrogen administration on serum testosterone in Copenhagen rats

In order to develop a standard experimental method of exogenous therapy in the Copenhagen rat, several treatment regimens were evaluated to determine their effect on the serum testosterone. Diethylstilbestrol diphosphate (DES-P) was administered either continuously in the drinking water or as a single intraperitoneal injection. Oral low-dose estrogen (0.4-1.6 microgram/ml) yielded reliable suppression of serum testosterone to castrate levels. A single intraperitoneal injection of 0.5 mg DES-P caused prompt suppression of serum testosterone with return to normal levels two weeks later.