Corticosteroid and thyrotropin-releasing hormone effects on preterm sheep lung function

Ikegami, Machiko; Polk, Daniel H.; Tabor, Bannie L.; Lewis, Jon C.; Yamada, Takako; Jobe, Alan H.

doi:10.1152/jappl.1991.70.5.2268

Cited by 70 publications

(37 citation statements)

References 34 publications

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“…As wa s seen for the ca rdiov ascular effects, it is po ssible that a low er dos e of T 4 may hav e augmented the FFA responses as had been anticipated. Th e results of the thyroid hormone assa ys demonstrate that anten atal BETA exp osure augments fet al umbilical and postnatal circulating T3 level s. The mechanism for this effect is presumed to be induction of the hepatic monodeiodinase activity responsible for T 4 to T 3 conversion (8,42). The dose of T 4 we used in combination with BETA in the present study blunted both the prenatal and postnatal increase in T 3 , presum ably via suppress ion of thyroidal T 4 secretion.…”

Section: Ol---lij-----------------supporting

confidence: 49%

Postnatal Cardiovascular and Metabolic Responses to a Single Intramuscular Dose of Betamethasone in Fetal Sheep Born Prematurely by Cesarean Section

et al. 1995

Pediatr Res

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Although the benefits of antenatal hormone treatment are well accepted, most studies have reported only pulmonary effects. There is evidence of beneficial cardiovascular and metabolic effects in studies using chronically catheterized animals; however because of the route of administration, the results are not directly applicable to clinical strategies. We previously demons trated sign ificant pulmonary effects in animals treated antenatally with a single, direct fetal, intramuscular injection of glucocorticoids . Th is study was performed to determine the effects of a single fetal injection of betamethasone (BETA) alone or in combination with thyroxine (T 4 ) on cardiovascular and metabolic respons es after preterm birth . Hemodynamic and metabolic response s at birth were determined in fetuses (126-d gestation; term = 150 d) treated with ultrasound-guided intramuscular injections of 0.5 mg/kg BETA (n = 7), BETA plus 60 g/kg T 4 (n = 7), or saline (SAL, n = 9). After 48 h, lambs were delivered by cesarean section and studied for 3 h. BETA treatment increased mean arterial blood pressure [56 ± 6 (SEM) versus 42 ± 3 mm Hg], heart rate (152 ± 5 versus 123 ± 4 beats/min), and cardiac Multiple studies have documented improved outcomes of preterm human infants born to mothers treated antenatally with glucocor ticoids. Most studies have focused primarily on pulmonary effects, although secondary outcome variables and retrospective metanalysis of clinical and other demographic data indicate beneficial effects in other organ systems (1, 2). Maternal corticosteroid treatment reduces nonrespiratory morbidities such as intraventricular hemorrhage, necrotizing enterocolitis, and patent ductus arteriosus. The mechanism(s) for these varied clinical outcomes is uncertain .In previous studies using chronically catheterized fetal sheep we demonstrated that antenatal corticosteroid infusion signifi- Responses of BETA + T 4 -treated animals were not different from animals treated with BETA alone. Glucose and FFA were simila r among all groups. The increase in catecholamine levels normally seen at birth was significantly attenuated in both the BETA and BETA + T 4 -treated animal s. A single, intramuscular injec tion of glucocorticoids 48 h before delive ry improves cardiovascular responses to preterm birth . This effect is not augmented by concomitant admi nistration of T4 ' (Pediatr Res 38: 709-715, 1995) Abbrev iations BETA, betamethasone T 4 , thyroxine T 3 , triiodothyronine SAL , saline TRH, thyrotropin-releasing hormone ANOVA, analysis of variance

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Section: Ol---lij-----------------supporting

confidence: 49%

Postnatal Cardiovascular and Metabolic Responses to a Single Intramuscular Dose of Betamethasone in Fetal Sheep Born Prematurely by Cesarean Section

et al. 1995

Pediatr Res

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“…The observation by Ikegami et al (17) that prenatal corticosteroids improve lung function measures without changing surfactant pool sizes and our finding that corticosteroids induce an increase in catalase activity raise the issue of cause and effect. The induction of lung catalase activity by corticosteroids and the catalase activity of natural surfactant both have the potential to reduce pulmonary oxygen toxicity.…”

Section: Discussionmentioning

confidence: 59%

“…Animals used in this study were the sheep used for lung function studies reported by Ikegami et al (17). In brief, date-mated mixed Western breed sheep with twin pregnancies underwent hysterotomy at 121 + 1 d gestation (term is 150 d).…”

Section: Methodsmentioning

confidence: 99%

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Corticosteroids, Thyrotropin-Releasing Hormone, and Antioxidant Enzymes in Preterm Lamb Lungs

et al. 1991

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ABSTRACT. Forty-three twin lamb fetuses of 121 f: 1 d gestation were catheterized and received i.v. saline (n = 8), 0.75 mg/kg/h cortisol for 60 h (n = IS), 5 ~g / k g thyrotropin-releasing hormone (TRH) every 12 h for five doses (n = 9), or cortisol and TRH (n = 11) before delivery at 128 + 1 d. After delivery, the lambs were randomized for natural sheep surfactant treatment or sham treatment, ventilated for 75 min, and killed. Superoxide dismutase, catalase, and glutathione peroxidase activities were measured in fetal lung tissue. Superoxide dismutase and catalase activities were increased in both the corticosteroid (p < 0.001) and the corticosteroid with TRH ( p < 0.01) groups.Glutathione peroxidase activity was higher after prenatal corticosteroid treatment, but statistical significance was not reached ( p = 0.06). Although prenatal exposure to corticosteroids increased superoxide dismutase, catalase, and glutathione peroxidase activities, TRH alone or TRH added to corticosteroids provided no additional benefit. Lambs treated with surfactant had higher lung catalase activities than lambs that did not receive surfactant, probably secondary to the presence of catalase activity in the surfactant preparation. Increased pulmonary antioxidant enzyme activity may be an additional feature of the overall beneficial effect of corticosteroids on fetal lung development. (Pediatr Res 30: 518-521, 1991) Abbreviations GPX, glutathione peroxidase SOD, superoxide dismutase T3, triiodothyronine T4, thyroxine ~~~, -t h~r o t r o~i n -r e l e a s i n~ hormone VEI, ventilatory efficiency index Exposure of the lung to high concentrations of oxygen produces endothelial and alveolar type I cell damage associated with alveolar-capillary leakage, lung edema, and, ultimately, deterioration of lung function. Alveolar type I1 cells synthesize and secrete surfactant and maintain the integrity of the alveolar epithelium by proliferation and differentiation into type I cells

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“…ment may lead to delays in maturation of the brain (Chan and Kilby, 2000), the lung (Ikegami et al, 1991;Hume et al, 2001) and the skeletal muscles (Hausman and Watson, 1994). In altricial species characterised by low body maturity at birth, such as the rabbit, the hypothalamo-pituitary-thyroid axis (HPTA) develops after birth (Mach, 1977), and the thyroid hormones of maternal origin are detectable in fetuses long before the onset of fetal thyroid function (Obregon et al, 1984;Escobar del Rey et al, 1986).…”

mentioning

confidence: 99%

Changes in thyroxine, 3,3',5-triiodothyronine and 3,3'5'-triiodothyronine content in the thyroid gland and in serum to thyroid tissue iodothyronine ratios during ontogenesis in the fetal pig

Brzezińska-Ślebodzińska

Slebodzinski

2004

Acta Veterinaria Hungarica

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The concentrations of thyroxine (T 4 ), 3,3',5-triiodothyronine (T 3 ) and 3,3',5'-triiodothyronine (reverse T 3 ; rT 3 ) in thyroid gland tissue and serum of the fetal pig (n = 68) from day 39 to 113 of gestation were measured. Tracer quantities of iodothyronines, displaying the onset of thyroid hormone activity, were found in the thyroid tissue on day 39, i.e. before the appearance of a measurable quantity of iodothyronines in the serum. The T 4 and T 3 thyroidal content showed the first rise between days 56 and 76. Then, T 3 was increasing sharply from day 92 till birth, while T 4 content was decreasing from about day 76 to a low value between day 92 and 105, and then showing an increase shortly before birth. The rT 3 content was the highest on day 39 and then it was steadily decreasing to reach a nadir on about day 76. Measurable amounts of thyroid hormones (TH) in the serum were observed not earlier than on day 46 of gestation. Near birth, the tissues of the pig fetus are in a milieu characterised by the highest blood TH concentrations. The serum to thyroid concentration ratio for rT 3 and T 4 was generally below 1.0 until the last trimester of gestation, when it was over 5.0 for rT 3 and over 4.0 for T 4 . By contrast, the T 3 serum to thyroid ratio was below 0.5 throughout the gestation. The results show that the fetal pig thyroid displays a low rT 3 and T 4 content, but the marked T 3 elevation observed near term supports the view that a high production and secretion of T 3 near term may be a critical factor for normal postnatal adaptation to extrauterine cooling in the pig.

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Corticosteroid and thyrotropin-releasing hormone effects on preterm sheep lung function

Cited by 70 publications

References 34 publications

Postnatal Cardiovascular and Metabolic Responses to a Single Intramuscular Dose of Betamethasone in Fetal Sheep Born Prematurely by Cesarean Section

Postnatal Cardiovascular and Metabolic Responses to a Single Intramuscular Dose of Betamethasone in Fetal Sheep Born Prematurely by Cesarean Section

Corticosteroids, Thyrotropin-Releasing Hormone, and Antioxidant Enzymes in Preterm Lamb Lungs

Changes in thyroxine, 3,3',5-triiodothyronine and 3,3'5'-triiodothyronine content in the thyroid gland and in serum to thyroid tissue iodothyronine ratios during ontogenesis in the fetal pig

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