The effects of 5-bromo-2-thienyl-ethyl-ketone thiosenicarbazone on ovarian cyclicity and ovulation in the rat.

Pseudopregnant and cyclic rats were injected for 5 to 26 days with daily doses of 5 and/or 3 mg of 5-bromo-2-thienyl-ethyl-ketone thiosemicarbazone (70026) starting on Day 0 (the day of oestrus). The vaginal smear cytology, record of ovulation and ability to breed and conceive were compared with the results for corn oil-injected controls. Both doses of 70026 were found to cause a reappearance of pro-oestrous and/or oestrous vaginal smears within 4 to 6 days in the pseudopregnant rats, but ovulations did not occur. The 5-mg dose of 70026 inhibited ovulation and interrupted the oestrous cycle in cyclic rats, even though the daily 3-mg dose seemed to have little effect on ovulation, ovarian cyclicity, breeding or conception. In spite of the absence of an ovulation accompanying the induced pro-oestrous and/or oestrous vaginal smears in the pseudopregnant rats, the pattern of the vaginal smears suggested the occurrence of a 'delayed pseudopregnancy' in most of the pseudopregnant rats treated daily with 3 mg, but in few of those treated with 5 mg, 70026.