Effect of norgestrel on spermatogenesis & fertility of rats

The effect of noregstrel (d1-13beta-ethyl-17alpha-ethynyl-17beta-hydroxy-4-estren-3-one) on spermatogenesis and fertility of rats was studied. Male albino rats received norgestrel .1 or .5 mg/rat im daily for 30, 48, or 96 days. Fertility performance tests were conducted and the animals were mated to coeval female of proven fertility. Treatment was discontinued after the 96th day and the animals were sacrificed after 30 days for reversibility studies. .1 mg was ineffective in causing spermatogenic inhibition when given for 30 days but was antispermatogenic when given for 48 or 96 days. Similar effects were seen with .5 mg after 30 and 48 days of treatment, however, partial restoration of spermatogenesis occurred in 50% of the animals even after 96 days of treatment. Androgen deficiency produced at 30 days caused ponderal depression and functional impairment of accessory genital organs. It is concluded that these results cast doubt on the usefulness of norgestrel as a male contraceptive since loss of libido and inconsistent effects on spermatogenesis appear to be major contraindications.