Prolactin injection, a new contraceptive method: experimental study.

"Prolactin injection" is presented as a new contraceptive method. The method was tested in dogs. The dogs in the test group were injected with prolactin (PRL) in a dose of 600 micrograms/kg of body weight weekly for 6 months. During this period, the testicles, semen, reproductive hormones, renal function, and serum sodium and potassium were examined periodically. Testicular biopsy was obtained after 3 and 6 months of PRL injection. These investigations were repeated during the 6 months following withdrawal of the drug. Sperm count decreased to azoospermia in 3 months after PRL administration with decrease of sperm motility and increase of abnormal forms. Testicular biopsy showed degenerated seminiferous tubules. Reproductive hormones, renal function, and serum sodium and potassium revealed insignificant change (P > 0.05). Dog mating during the period of PRL administration induced no pregnancy. After 3 months of drug withdrawal, the sperm count normalized and dog mating produced pregnancy; offsprings showed no anomalies. The study demonstrates that PRL administration has the potential to be developed as a reversible male contraceptive.