Fetal Rat Lung Development: Lipids and Surface Tension Properties After Decapitation in utero

Wr, Blackburn; Dm, Potter; Travers, Henry; Ll, Gassenheimer; Rhoades, Rodney A.

doi:10.3181/00379727-140-36572

Cited by 6 publications

(4 citation statements)

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“…This model permits satisfactory fetal growth (4) and has a counterpart in humans, viz., congenital anencephaly of genetic etiology. A s mentioned previously, studies by Blackburn et al (2)(3)(4) have demonstrated that fetal anencephaly in rats is accompanied by retarded lung development based on impaired cytodifferentiation, high surface tension of lung extracts, and low pulmonary PC concentration. In the present investigation, we have extended those observations by assessing selected biochemical features of lung differentiation-in late Plasma corticosterone, the principal circulating glucocorticoid of the rat, was measured in representative control and anencephalic fetuses.…”

Section: Discussionmentioning

confidence: 99%

“…The animals were anesthetized with ether and subjected to surgery at 16-17 days gestation as described previously (2,3). Following decapitation of half the fetuses per litter (the remainder serving as controls), fetuses were generally allowed to develop without further intervention until harvesting.…”

Section: Methodsmentioning

confidence: 99%

“…This experimental model has provided considerable information on the role of adrenocorticoids in regulating liver glycogen metabolism (15) and has been employed by Blackburn and associates (2,3) to investigate fetal lung development. In the latter studies, it has been demonstrated that lungs of anencephalic rat fetuses show: ( I ) morphologic abnormalities characterized by increased cellularity, retarded cytodifferentiation, and a decreased number o f osrniophilic lamellar bodies in type I1 pneurnonocytes; ( 2 ) functional impairment evidenced by an inability of minced lung samples to lower surface tension to normal levels, suggesting surfactant deficiency, and (3) chemical changes, including a decreased concentration of lung phosphatidylcholine and a reduction in the palmitic acid content of isolated PC.…”

Section: Speculationmentioning

confidence: 99%

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Lung Phosphatidylcholine Synthesis and Cholinephosphotransferase Activity in Anencephalic Rat Fetuses with Corticosteroid Deficiency

1977

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SummaryAdrenocortical insufficiency was produced in rat fetuses by surgical decapitation. These animals show low plasma corticosterone levels compared to littermate controls. Lung slices from anencephalic fetuses were found to have reduced incorporation of ['4C]choline into phosphatidylcholine, hence diminished choline pathway activity; this abnormality was present at 21 days of gestation but not at term. Cholinephosphotransferase (CPT), the terminal catalyst of the choline pathway, also showed diminished activity in lungs of anencephalic fetuses, with a mean of 120 pmol/min/mg protein compared to a control value of 190. Dexamethasone treatment of these animals for 6-12 hr led to enhanced choline incorporation rates. Corticosteroid administration also restored CPT activity and even elevated the enzyme to a mean level (340 pmol/min/mg protein) greater than that found in normal fetuses at 21-22 days of gestation. The early pulmonary biochemical effects of dexamethasone in this model were not accompanied by recognizable ultrastructural changes. SpeculationIt is proposed that glucocorticoids act to influence the timing of l~n~biorhemical development relative to phosphatidylcholin~ svnthesis. Increased amounts of the hormone amear to be suffis e n t but not necessary for this effect since aig'mented choline pathway rates eventually occur in the absence of the corticosteroid stimulus.The low surface tension achieved during expiration by the pulmonary surfactant system is essential for maintenance of alveolar integrity and prevention of the neonatal respiratory distress syndrome (1,8). Synthesis of the major surfactant phospholipid, phosphatidylcholine PC or lecithin (1 ,2-diacyl-sn-glycero-3-phosphorylcholine), is accomplished de novo in fetal lung by incorporation of CDP-choline into 1 ,2-diacylglycerol (7, 9). Investigations by several groups with many species have demonstrated that corticosteroids influence fetal lung development, leading to early increases in the following: ( I ) functional surfactant (19), (2) PC concentration (1 1). (3) PC synthesis per se from choline (6, l l ) , and (4) the apparent number of osmiophilic lamellar bodies in type I1 pneumonocytes (25). Such maturational changes are accompanied by, and are at least partially attributable to, corticosteroid-mediated induction of cholinephosphotransferase or CPT (CDP-cholinc: 1 -2-diglyceride choline phosphotransferase. EC. 2.7.8.2) (1 1).Although adrenocortical insufficiency is rarely encountered in developing fetuses, Jost and Picon (18) have described a model of fetal panhypopituitarism which is produced surgically by decapitating rat fetuses prior to the 18th day of gestation. This experimental model has provided considerable information on the role of adrenocorticoids in regulating liver glycogen metabolism (15) and has been employed by Blackburn and associates (2,3) to investigate fetal lung development. In the latter studies, it has been demonstrated that lungs of anencephalic rat fetuses show: ( I ) morphologic abnormalities characterized b...

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Speculationmentioning

confidence: 99%

See 1 more Smart Citation

Lung Phosphatidylcholine Synthesis and Cholinephosphotransferase Activity in Anencephalic Rat Fetuses with Corticosteroid Deficiency

1977

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“…Blackburn et al (1) have succeeded in bringing about a delay in lung maturation in mice by their decapitation. Burke et al (2) describe an anencephalic newborn with mature lungs, and state that normal adrenal function of fetal adrenal glands is not necessary for the production or liberation of active lecithin in the surfactant.…”

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confidence: 99%

Role of Fetal Adrenal Glands

Peleg¹,

Goldman²,

Elian³

1978

Gynecol Obstet Invest

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The role of fetal adrenals in the maturation of fetal lungs is not clear as yet. The anencephalic baby, with rudimentary adrenal glands, may be considered an excellent model for the study of this subject. The maturation of fetal lungs was determined in 3 anencephalic monsters and in 2 microencephalic babies. As a measure of fetal pulmonary maturation the foam test and lecithin/sphingomyelin ratio (L/S) were used, as determined in the amniotic fluid. In the anencephalic babies, fetal pulmonary maturation was lacking, while in the microencephalic infants there were definite signs of lung maturation.

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Lung development and the pulmonary surfactant system: Hormonal influences

Hitchcock

1980

Anat. Rec.

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The effect of hormones on developmental events is not a new area of scientific investigation. However, in the last decade, the developing lung has been the focus of an increasing amount of basic and applied research. Inadequate development of the newborn's respiratory system precludes extra-uterine existence; indeed, such respiratory inadequacy has been a leading cause of death in premature infants. Tremendous strides have been made in understanding the basic cell biology of the developing lung. Much has been learned about the source, composition, and function of pulmonary surfactant, a surface-active material produced by the lung and essential to alveolar stability. Deficient stores of this material is a major etiologic factor in the respiratory distress syndrome of the newborn (RDS). This fact, coupled with observations that certain hormones can accelerate lung development and the consequent availability of adequate stores of pulmonary surfactant, has led to a large body of literaturae dealing with the effects of hormones (and other agents) on lung development. It is the purpose of this literature review (1) to discuss the various kinds of investigations which have linked surfactant synthesis to the type II pulmonary epithelial cell; and (2) to review the current status of research dealing with the effects of glucocorticoids and thyroid hormones on lung maturation.

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Fetal Rat Lung Development: Lipids and Surface Tension Properties After Decapitation in utero

Cited by 6 publications

References 0 publications

Lung Phosphatidylcholine Synthesis and Cholinephosphotransferase Activity in Anencephalic Rat Fetuses with Corticosteroid Deficiency

Lung Phosphatidylcholine Synthesis and Cholinephosphotransferase Activity in Anencephalic Rat Fetuses with Corticosteroid Deficiency

Role of Fetal Adrenal Glands

Lung development and the pulmonary surfactant system: Hormonal influences

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