Quantative Changes in Ribonucleic Acids and Protein During Normal Growth of Rat Placenta

Winick, Myron; Noble, Adele

doi:10.1038/212034a0

Cited by 72 publications

(19 citation statements)

References 8 publications

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“…It can be speculated that the continuous hyperglycemia is a stimulus for continued placental growth at the expense of the initiation of maturation. Some support for this hypothesis may be found in the present study, where there is an indication that DNA synthesis in the diabetic placenta continues for an additional 2-3 days after control placentas have completed DNA synthesis (34). This ability to continue to grow may reflect a relative immaturity, or dysmaturity, of this organ, similar to the large but relatively immature lung and liver of the infant of the human diabetic pregnancy.…”

Section: Discussionsupporting

confidence: 71%

Placental Growth and Glycogen Metabolism in Streptozotocin Diabetic Rats

1983

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SummaryThe present study was designed to construct a develo~mental Placental glycogen metabolism was investigated in rat pregnancies comolicated bv stre~tozotocin-induced diabetes mellitus. Both " . diabetic and control placentas had increasing glycogen concentration from day 14 to day 16, after which glycogen concentration declined rapidly. The diabetic placentas had significantly elevated glycogen concentration when compared to controls from day 16 through term (day 22). Near term, when control glycogen content fell close to zero, the diabetic placentas still had appreciable glycogen levels.Total phosphorylase activity in the diabetic placentas was significantly higher than control values from day 16-22. Phosphorylase A activity, however, was lower in the diabetic placentas late in gestation, corresponding to the increased glycogen concentration seen at that time. Diabetic placentas had increased total synthase activity on the final 3 days of gestation, although synthase A activity was lower than corresponding control values.The placentas in this model are markedly increased in size late in gestation. No difference in protein concentration or protein/ DNA ratio was noted. Total DNA content per placenta was significantly increased in the diabetic placentas after day 16 when compared to controls. Placental DNA in the diabetics continued to increase until day 18-19 of gestation, whereas DNA content in control placentas remained constant after day 16. Thus, the diabetic placentas apparently continue the process of DNA replication after DNA synthesis is complete in the controls.

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Section: Discussionsupporting

confidence: 71%

Placental Growth and Glycogen Metabolism in Streptozotocin Diabetic Rats

1983

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“…The human fetus is obviously not available for investigation, but the placenta is an available human reproductive tissue. It has been shown that normal placental growth in rats proceeds in the same way as in their fetal organs (Winick and Noble 1966). The same general pattern of cellular growth has been reported for human placenta (Winick et al 1967), although the timing is somewhat different.…”

Section: ! Introductionsupporting

confidence: 52%

The combined effect of ultrasonic exposure and protein restriction on maternal and fetal mice

Kim

Picciano

O’Brien

1983

Ultrasound in Medicine & Biology

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Abstract--This investigation was undertaken to assess the combined effects of protein restriction and ultrasonic energy exposure during pregnancy on the maternal and fetal mouse. Pregnant female mice were fed diets containing either 18% casein (control diet) or 6% casein (restricted protein diet) during gestation. All animals were subjected to the ultrasonic exposure procedure (actual: 2.5 W/cm 2 spatial peak; sham: 0 W/cm2; continuous wave for 20 sec at a frequency of l MHz) on day 8 of gestation. On day 18 of gestation, the animals were sacrificed. Products of conception were examined, and chemical analysis were performed on maternal liver, placenta and fetus.Our results suggest that there are possible influences of ultrasonic energy exposure to the mouse fetus and placenta, as indicated by the tendency toward decreases of fetal weight, placental weight, and DNA and RNA contents of both fetus and placenta, especially with restricted protein in the maternal diet during gestation.Protein restriction during pregnancy had an adverse influence on both the maternal organism and her products of conception. The nutritional needs for the fetus were not met at the expense of the maternal organism. Parameters of fetal cellular growth were reduced by gestational protein restriction indicating that there is competition for available nutrients between the fetus under time of stress. Results also show that the trends of fetal and placental growth are in the same general direction suggesting the possible usefulness of human placental tissue as a maker for fetal growth in subsequent population studies.

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“…In the rat placental DNA synthesis and accumulation cease on about day 17, whereas there are large increases in the amounts of RNA and protein between days 17 and 19 (Winick and Noble 1966). The data in Table 1 suggest that such a pattern of cellular hyperplasia followed by cellular hypertrophy does not occur in mouse placentae, since, although there was a small increase in placental protein between days 16 and 18, the RNA:DNA ratio actually decreased slightly between days 14 and 18.…”

Section: Discussionmentioning

confidence: 91%

Effects of Ovarian Hormones on Foetal and Placental Growth in the Mouse

Miller¹

1978

Aust. Jnl. Of Bio. Sci.

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The effects of ovariectomy and treatment with progesterone and oestradiol on foetal and placental growth were examined. The occurrence of cellular hypertrophy and hyperplasia in the placenta in response to treatments was determined by measuring protein, DNA and RNA: DNA ratios. In control mice, which had not been ovariectomized, the daily administration of O·01-2' 56 J1g oestradiol on days 10-15 of pregnancy caused only small decreases in the number of live foetuses and foetal and placental weights on day 16. When mice were ovariectomized on day 10, gestation was maintained by administering 5 mg progesterone daily, but terminated when only 1 mg progesterone was given daily. However, when ovariectomized mice receiving 1 mg progesterone were also given O'OlJ1g oestradiol on days 10-15, gestation was maintained and the number of live foetuses and foetal and placental weights on day 16 were normal. Increasing the daily dose of oestradiol up to 2· 56J1g in mice receiving 1 mg progesterone on days 10-15 had no effect on foetal and placental growth. In contrast, the daily administration of 0·64-2· 56J1g oestradiol to ovariectomized mice receiving 5 mg progesterone on days 10-15 terminated gestation in some mice and considerably reduced the number of live foetuses and foetal and placental weights in those mice which remained pregnant on day 16.None of the treatments increased protein, DNA or the RNA : DNA ratio in the placenta to levels above those seen in control mice. The results are discussed in relation to ovariectomy-induced placental overgrowth in the rat.

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Quantative Changes in Ribonucleic Acids and Protein During Normal Growth of Rat Placenta

Cited by 72 publications

References 8 publications

Placental Growth and Glycogen Metabolism in Streptozotocin Diabetic Rats

Placental Growth and Glycogen Metabolism in Streptozotocin Diabetic Rats

The combined effect of ultrasonic exposure and protein restriction on maternal and fetal mice

Effects of Ovarian Hormones on Foetal and Placental Growth in the Mouse

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