Delay of Parturition in Rats by Various Progestational Steroids

Edgren, Richard A.; Peterson, DeAnn L.

doi:10.3181/00379727-123-31626

Cited by 3 publications

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“…Among several methods for experimental prolongation of pregnancy like application of progesterone [14] or choriongonadotrophin [1,21], the use of synthetic gestagens, as recommended by E d g r en and P eterson [8], is the most reliable one. The pregnancy of rats can be prolonged by ad ministration of chlormadinone acetate or norethisterone acetate, as is shown in this paper.…”

Section: Discussionmentioning

confidence: 99%

“…The postmature fetuses showed several changes similar to human postmature newborns with signs of placental insufficiency. A pro-longed gestation can be induced by application of progesterone or synthetic gestagens in pregnant animals [8,14,19]. In this paper we report the effects of prolonged gestation in rats, induced by application of synthetic gestagens, the weight of the pregnant animals, the placentas, the fetuses and fetal mortality.…”

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Intrauterine Dystrophy in Rats Due to Placental Insufficiency Caused by Hormonally Induced Prolonged Gestation

Bührdel¹,

Willgerodt²,

Keller³

et al. 1974

Neonatology

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The duration of pregnancy in rats can be prolonged beyond day 26 after conception by administration of synthetic gestagens. The fetal mortality increased with prolonged duration of gestation to 24.8% on day 24 and 54.6% on day 25. Nearly all the fetuses were dead on day 26. On day 24 some of the litter mates and on day 25 all of the living ones were markedly hypotrophic. A placental insufficiency is suggested as causing the increasing mortality and the hypotrophy of the fetuses. The placental weight increases up to the 20th day of gestation, decreases slightly thereafter and does so markedly beyond the 24th day. An increase of water content is characteristic for the postmature litter mates.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Intrauterine Dystrophy in Rats Due to Placental Insufficiency Caused by Hormonally Induced Prolonged Gestation

Bührdel¹,

Willgerodt²,

Keller³

et al. 1974

Neonatology

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“…This injection was repeated daily from the 15th day of gestation until the animals were decapi tated on day 24. Spontaneous birth can be delayed by daily injection of chlormadinoneacetate from the 15th day of gestation (5,8). Other animals were paired on the 2nd and 3rd day of the experiment and formed groups II and I, respectively.…”

mentioning

confidence: 99%

Postnatal Development of Rats Born Preterm and Postterm

Bührdel¹,

Willgerodt²,

Keller³

et al. 1978

Neonatology

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Litters with 3 preterm, 3 term and 3 postterm littermates have been fed by one mother each. Fetal body weight continues to increase in utero if the normal gestational period is extended by 1 day. But this intrauterine weight gain is smaller than the postnatal weight gains of term rats of the same conceptional ages. While the body weights of term and postterm rats increase rapidly immediately after birth, there is a lag phase of 3 days in preterm animals. This delay in weight gain is not caught up during a period of 30 postnatal days. This appears to be due to malnutrition in the early postnatal period. After the 20th day of life, the weight gain markedly increases in all groups, indicating the effect of supplemental feeding in the weaning period.

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Hormones, Sex Hormones

Gunnet

Dixon

2000

Kirk-Othmer Encyclopedia of Chemical Technology

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Progestins are a class of steroids named for their role in maintaining pregnancy. Naturally occurring progestins, such as progesterone, are 21‐carbon steroids having the basic pregnane structure. Synthetic progestins are derived from four structural groups; ie, 5α‐prenanes, 5α‐androstanes, estranes, and gonanes. They are produced by chemical and microbial degradation of naturally occurring steroids and by total synthesis. Structure–activity relationships of progestins have been explored using computer‐aided techniques. The principal use of progestins is in contraception, prescribed alone or in combination with estrogens, where they act primarily to prevent uncontrolled estrogen stimulation of the uterine endometrium. Progestins have other uses based on their antiestrogenic effects. They are known to cause a conformational change in receptors. When bound to an agonist, progestin receptors act as transcription factors, altering the rate of expression of various genes. New antiprogestins with improved receptor specificity are becoming available and may eventually be used in some of the same therapeutic areas as progestin agonists.

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Delay of Parturition in Rats by Various Progestational Steroids

Cited by 3 publications

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Intrauterine Dystrophy in Rats Due to Placental Insufficiency Caused by Hormonally Induced Prolonged Gestation

Intrauterine Dystrophy in Rats Due to Placental Insufficiency Caused by Hormonally Induced Prolonged Gestation

Postnatal Development of Rats Born Preterm and Postterm

Hormones, Sex Hormones

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