MICROPENIS IN HYPOGONADOTROPIC HYPOGONADISM - RESPONSE OF THE PENILE ANDROGEN RECEPTOR TO TESTOSTERONE TREATMENT

Purpose: We determine whether testosterone therapy alters penile andro gen receptor expression within the hypogonadotropic hypogonadal (HPG) micropenis. Materials and Methods: In protocol 1 a strain of mice with micropenis due to congenital HPG and wild type litter mates were divi ded into testosterone treated and untreated groups. Treatment was init iated on day 15 of life. On day 90 of life (day 75 of treatment) the m ice were sacrificed, and the penises were removed and weighed. In prot ocol 2 microphallic mice treated with testosterone were sacrificed on days 0, 6, 30, 60 and 75 after the initiation of treatment. Untreated HPG and wild type litter mates served as controls. At autopsy the peni s was removed and weighed, and androgen receptor content was determine d by Western immunoblotting. Results: Testosterone treatment resulted in 6-fold up regulation in HPG penile androgen receptor, approximately 1.4-fold higher than in the normal wild type pubescent penis. Testost erone induced and wild type pubescent penile androgen receptor up regu lation was maintained for approximately 75 and 60 days, respectively. Despite improved HPG penile androgen receptor expression penile growth did not become normal. Average total penile weight plus or minus stan dard deviation was 7.2 +/- 3.5 mg. in untreated HPG mice. Testosterone significantly improved average HPG penile weight to 23.5 +/- 1.8 mg. (p <0.001). However, the testosterone treated micropenis failed to rea ch average normal penile size (38.6 +/-: 2.6 mg., p <0.001). Conclusio ns: Testosterone increases the concentration and duration of penile an drogen receptor expression within the HPG micropenis. Despite this imp rovement microphallic HPG penile growth does not become normal.