Sperm output and serum testosterone in rabbits given prostaglandin F2α or E2

Two experiments were conducted, the first to compare sperm output and the second to determine serum testosterone in rabbits given PGF₂α or PGE₂. In the first, six rabbits were ejaculated twice each Monday, Wednesday and Friday for 5 weeks. Each rabbit was given subcutaneously (sc) each of the following treatments five times: 1) saline, 2) 5 mg PGF₂α and 3) 5 mg PGE₂. Treatments were given, half at 4 hr and half at 2 hr before first ejaculations. Both PGF₂α and PGE₂ caused increased (50% and 84%) sperm content of first ejacula, without significantly altering characteristics of second ejacula. The extra sperm in first ejacula was a function of increased sperm density, because seminal volume was unaltered.In the second experiment, 15 rabbits were bled at 0.5-hr intervals for 9 hr and given (sc): 1) saline at 1 and 3 hr (n=4), 2) 2.5 mg PGF₂α at 1 and 3 hr (n=4), 3) 2.5 mg PGE₂ at 1 and 3 hr (n=4) or 4) 5 mg PGF₂α at 1 hr after the onset of blood sampling. In saline-treated controls, episodic surges of testosterone occurred on the average every 5 hours. After the injection of 2.5 or 5.0 mg PGF₂α, serum testosterone began to rise at 0.5 hr, peaked (8 to 13 ng/ml) at 1 hr and approached a nadir (0.5 ng/ml) within 4 hours. The second injection of 2.5 mg PGF₂α failed to significantly affect serum testosterone. PGE₂ treatment was followed by significantly depressed serum testosterone; only 1 of these 4 rabbits had any surge of testosterone for the 8 hr after treatment. In conclusion, PGF₂α and PGE₂ both increased sperm output, but PGF₂α increased serum testosterone while PGE₂ depressed serum testosterone. Thus, the sperm output effect of these prostaglandins probably is independent of the acute changes in testosterone secretion.