The Use of the Antiprogesterone Compound RU 486 to Control Timing of Parturition in Rats

  • M. J. Bosc
  • G. Germain
  • A. Nicolle
  • D. Philibert
  • E. E. Baulieu
Chapter
Part of the Reproductive Biology book series (RBIO)

Abstract

The end of progesterone inhibition is a prerequisite for parturition in rats (Deansley, 1956). In this species, birth is preceded by a drop in uterine progesterone (Davies and Ryan, 1973) and by low blood-progesterone concentrations during the last 25–26 hours (Sherwood et al., 1983). Therefore, an antiprogesterone compound might be used to control the time of birth. To test this possibility, a single dose of RU 486 (10 mg/rat in 0.2 ml of ethanol) was given subcutaneously to rats late in pregnancy. Ninety nine pregnant rats, isolated at mating (day 1 of pregnancy) and fed ad libitum, were submitted to eight hours daily of light (lights on from 12 noon to 8 p.m.) from day eight of gestation. RU 486 was given to five groups as follows: at 8 a.m. on day 21 (group A), at 12 noon on day 21 (group B), at 7 p.m. on day 21 (group C), at 8 a.m. on day 22 (group D) and at 12 noon on day 22 (group E). In the sixth group (T), the solvent was given once at each of the preceding times. As previously observed (Bosc and Nicolle, 1980), group T births were distributed in two periods with 2/3 of the rats giving birth in the late light phase of day 22 (mean time 6 p.m.) and 1/3 after lights on on day 23 (mean time 4 p.m.). The rats treated on day 22 (groups D and E) had a similar distribution.

Keywords

Progesterone Concentration Fertility Control Birth Timing Human Fertility Sixth Group 
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References

  1. Bosc, M. J., Nicolle, A., 1980, Influence of photoperiod on the time of parturition in the rat. I-Effect of the length of day illumination on normal or adrenalectomized animals, Reprod. Nutr. Develop., 20: 735.CrossRefGoogle Scholar
  2. Davies I. J., Ryan, R. J., 1973, The modulation of progesterone concentration in the myometrium of the pregnant rat by changes in cytoplasmic “receptor” protein activity, Endocrinology, 92: 394.PubMedCrossRefGoogle Scholar
  3. Deansley, R., 1956, The endocrinology of pregnant and fetal life in: “Marshall’s Physiology of Reproduction,” A. S. Parkes, ed., Longmans, Green and Co., London.Google Scholar
  4. Sherwood, O. D., Downing S. J., Golost, G., Gordon W. L., and Tarbell, M. K., 1983, Influence of light-dark cycle on antepartum serum relaxin and progesterone immunoactivity levels and birth in the rat, Endocrinology, 113: 997.PubMedCrossRefGoogle Scholar

Copyright information

© Plenum Press, New York 1985

Authors and Affiliations

  • M. J. Bosc
    • 1
  • G. Germain
    • 2
    • 3
    • 4
    • 5
  • A. Nicolle
    • 1
  • D. Philibert
    • 3
  • E. E. Baulieu
    • 4
  1. 1.Station de Physiologie de la ReproductionI.N.R.A. NouzillyMonnaieFrance
  2. 2.Clinique Universitaire BaudelocqueI.N.S.E.R.M. U. 262Paris Cedex, 14France
  3. 3.Laboratoires Roussel-UclafRomainvilleFrance
  4. 4.Faculte de Medecine Paris-SudLab. Hormones I.N.S.E.R.M. U. 33BicetreFrance
  5. 5.Station Centrale de Physiologie AnimaleC.N.R.Z. de l’I.N.R.A.Jouy en JosasFrance

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