The effect of fetal thyroparathyroidectomy on the transport of calcium across the ovine placenta to the fetus

Care, A. D.; Caple, I. W.; Abbas, S. K.; Pickard, D. W.

doi:10.1016/s0143-4004(86)80029-7

Cited by 54 publications

(24 citation statements)

References 13 publications

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“…However, the effect of TX in utero on the circulating levels of these hormones is unknown. Total plasma calcium concentration remained normal in the TX fetuses in this study, and previously, a reduction in total plasma calcium, and a reversal of the placental calcium gradient between the mother and fetus, was observed in sheep fetuses after removal of both the thyroid and the parathyroid glands, but not following TX alone with T 4 replacement (Care et al 1986, Rodda et al 1988. In addition, mutation of the calcitonin/ calcitonin gene-related peptide gene in fetal mice has no effect on skeletal weight, or growth plate morphology or gene expression, although it causes a reduction in skeletal magnesium, but not calcium, content (McDonald et al 2004).…”

Section: Discussionsupporting

confidence: 86%

Effects of hypothyroidism on the structure and mechanical properties of bone in the ovine fetus

Lanham

Fowden

Roberts³

et al. 2011

Journal of Endocrinology

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Thyroid hormones are important for normal bone growth and development in postnatal life. However, little is known about the role of thyroid hormones in the control of bone development in the fetus. Using computed tomography and mechanical testing, the structure and strength of metatarsal bones were measured in sheep fetuses in which thyroid hormone levels were altered by thyroidectomy or adrenalectomy. In intact fetuses, plasma concentrations of total calcium and the degradation products of C-terminal telopeptides of type I collagen increased between 100 and 144 days of gestation (term 145G2 days), in association with various indices of bone growth and development. Thyroid hormone deficiency induced by thyroidectomy at 105-110 days of gestation caused growth retardation of the fetus and significant changes in metatarsal bone structure and strength when analyzed at both 130 and 144 days of gestation. In hypothyroid fetuses, trabecular bone was stronger with thicker, more closely spaced trabeculae, despite lower bone mineral density. Plasma osteocalcin was reduced by fetal thyroidectomy. Removal of the fetal adrenal gland at 115-120 days of gestation, and prevention of the prepartum rises in cortisol and triiodothyronine, had no effect on bodyweight, limb lengths, metatarsal bone structure or strength, or circulating markers of bone metabolism in the fetuses studied near term. This study demonstrates that hypothyroidism in utero has significant effects on the structure and strength of bone, with different consequences for cortical and trabecular bone.

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Section: Discussionsupporting

confidence: 86%

Effects of hypothyroidism on the structure and mechanical properties of bone in the ovine fetus

Lanham

Fowden

Roberts³

et al. 2011

Journal of Endocrinology

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“…The present studies were carried out in intact fetal mice that lacked parathyroids from conception and whose mothers were heterozygous for the same genetic defect. The studies in fetal lambs involved a surgical procedure on the lambs, followed by later removal of the fetus and subsequent perfusion of the isolated placenta in situ (4,20). Because plasma PTHrP measurements were not carried out for these thyroparathyroidectomized lambs, it is not known whether the reduction in placental calcium transfer was accompanied by a reduction in plasma PTHrP.…”

Section: Discussionmentioning

confidence: 99%

Fetal parathyroids are not required to maintain placental calcium transport

Kovacs¹,

Manley²,

Moseley³

et al. 2001

J. Clin. Invest.

110

108

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“…Thyroparathyroidectomy of the ovine fetus, with thyroxine replacements, results in reversal of the placental calcium gradient (Care, Caple, Abbas & Pickard, 1986). However, our attempts to reproduce this finding in the fetal pig have been largely unsuccessful.…”

Section: Analysesmentioning

confidence: 99%

The role of parathyroid hormone‐related protein in calcium homeostasis in the fetal pig

Abbas

Ratcliffe²,

Moniz³

et al. 1994

Experimental Physiology

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The concentrations of plasma parathyroid hormone‐like bioactivity and parathyroid hormone‐related protein (1–86) (PTHrP) immunoreactivity were both higher in fetal pigs than in their mothers during the last 3 weeks of gestation. Both activities changed inversely with alterations in the plasma ionized calcium concentration. The data suggest that PTHrP may have a role in calcium homeostasis in the fetal pig, similar to its postulated role in sheep in the stimulation of calcium transport across the placenta.

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The effect of fetal thyroparathyroidectomy on the transport of calcium across the ovine placenta to the fetus

Cited by 54 publications

References 13 publications

Effects of hypothyroidism on the structure and mechanical properties of bone in the ovine fetus

Effects of hypothyroidism on the structure and mechanical properties of bone in the ovine fetus

Fetal parathyroids are not required to maintain placental calcium transport

The role of parathyroid hormone‐related protein in calcium homeostasis in the fetal pig

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