The distribution of estrogen receptors in the urinary tract of the male rabbit. An immunohistochemical and biochemical study.

The distribution of estrogen receptors (ER) in the urinary system in the male rabbit were investigated in 18 mature and healthy rabbits by immunohistochemical examination of tissue samples taken from renal pelvis, mid-ureter, bladder-top, posterior urethra and the prostate. ER were detected in 17 out of 18 cases in the urothelial lining and the subepithelial stromal cells of the posterior urethra; and in 15 out of 18 cases in prostatic stromal cells. ER was not found in bladder-top, mid-ureter or renal pelvis. Receptor determination in the isolated cytosolic and nuclear fraction, showed that the mean prostatic receptor density were 151.5 f mol/mg protein in the nuclear and 51.4 in the cytosolic fraction. The corresponding mean values obtained from the posterior urethra were 128.2 and 88.9 f mol/mg protein. We conclude, that ER can be demonstrated in the urinary system of the male rabbit, and these are restricted to the posterior urethra and the prostatic stromal tissue.