Figure 3

EE2 treatment reduces circulatory testosterone concentration through abolishing LH-mediated signaling. EE2 inhibits circulatory testosterone level in vivo. (A) Representative result of RIA of plasma testosterone concentration from male rats upon subcutaneous injection with EE2 once daily for 1 week. Blood samples were harvested on days 0, 3 and 7 by tail artery collection under anesthesia. Plasma samples were collected at the end of time points, and then the plasma was isolated for analysis of the concentration of testosterone using RIA (n = 6). (B) Quantification of the area under curve (AUC) during the period of EE2 injection is shown. (C) Representative result of RIA of plasma testosterone concentration on day 4 of EE2 injection. Rats were administered with hCG (5 IU/kg, arrow) through the right jugular vein (RJV). Blood was collected through the RJV at each time interval. Plasma samples were isolated and the concentration of testosterone was measured using RIA (n = 4-6). (D) Quantification of the AUC during hCG administration is shown. Data represent means ± SEM. *P < 0.05, **P < 0.01 as compared with the EE2-untreated group. ⁺P < 0.05, ⁺⁺P < 0.01 as compared with the vehicle corresponding group.