A new non-hormonal antifertility drug DL-204: I. Effects on testes and accessory glands of reproduction in male rats.

The effect of DL-204, 2-(3-ethoxyphenyl)-5,6-dihydro-5-triazole (5,1a)-isoquinoline, a non-hormonal post-implantational anti-fertility drug, on tissue weights, nucleic acids and total protein concentrations in the testes, ventral prostate and seminal vesicles were evaluated in immature and sexually mature rats, while changes in DNA synthesis were studied only in the immature rats. Treatment of 21-day-old rats at doses of 5mg and 10mg/kg bw once daily for 15 days had no effect on body weight but reduced the weights of testes and accessory glands of reproduction. The concentration of DNA increased while RNA and protein decreased significantly. Treatment of adult rats with DL-204 at a dose of 10mg/kg bw had no effect on body and testes weights but reduced ventral prostate and seminal vesicle weights. The concentration of RNA and protein decreased significantly, while DNA concentration was not altered. DL-204 treatment resulted in drastic decrease of RNA/DNA ratio, reflecting ribosomal loss and cytoplasmic shrinkage. The effects observed after DL-204 treatment are comparable to post-castration changes. DL-204 may be acting on testes and accessory reproductive organs by blocking androgen biosynthesis and/or by antagonizing the action of androgens. It may be acting directly on the normal function of the hypothalamo-pituitary-gonadal axis.