The effect of the anti-progestin RU 486 on early pregnancy in the long-tailed macaque (Macaca fascicularis).
The efficacy of various doses of RU 486 in terminating pregnancy before and after the luteal-placental shift (LPS) in the long-tailed macaque (Macaca fascicularis) was assessed through sonographic examination and measurements of steroid hormones and their metabolites. Intramuscular injection of 1.0, 2.5, 12.5, or 25.0 mg/kg was administered either from gestational day (GD) 15-18 (Group 1; N = 11) or GD 23-26 (Group 2; N = 9). The timing of treatment was determined by the detection of the preovulatory estrogen peak via daily urinary estrone conjugate (E1C) measurements. In Group 1, a 90.9% pregnancy loss was observed (10/11); seven animals aborted during GD 15-20, two animals indicated early embryonic death with retained gestational sacs, one animal aborted on GD 56, and one pregnancy was maintained. In Group 2, an 88.9% pregnancy loss was observed (8/9); eight animals aborted between GD 26-29, and one pregnancy was unaffected. Hormone profiles appeared to fall secondarily to the loss of trophoblast function. These results indicate: (a) RU 486 was more effective after the LPS; and (b) the primary effect of RU 486 appeared to be at the level of the products of conception.
Department of Veterinary Anatomy, University of Nairobi.
G E
GE
Owiti
A F
AF
Tarantal
B L
BL
Lasley
A G
AG
Hendrickx
D000019:Abortifacient Agents / Q000494:pharmacology*; D000021:Abortifacient Agents, Steroidal / Q000494:pharmacology*; D000818:Animals; D003281:Contraceptives, Postcoital / Q000494:pharmacology*; D003283:Contraceptives, Postcoital, Synthetic / Q000494:pharmacology*; D003338:Corpus Luteum / Q000502:physiology; D004963:Estrenes / Q000008:administration & dosage / Q000494:pharmacology*; D004970:Estrone / Q000652:urine; D005260:Female; D008252:Macaca fascicularis; D015735:Mifepristone; D010920:Placenta / Q000502:physiology; D011247:Pregnancy; D011374:Progesterone / Q000097:blood
D000019:Abortifacient Agents; D000021:Abortifacient Agents, Steroidal; D003281:Contraceptives, Postcoital; D003283:Contraceptives, Postcoital, Synthetic; D004963:Estrenes; D004970:Estrone; D015735:Mifepristone; D011374:Progesterone