Stimulation of ovine placental transport of calcium and magnesium by mid‐molecule fragments of human parathyroid hormone‐related protein

Care, A. D.; Abbas, S. K.; Pickard, D. W.; Barri, M. E. S.; Drinkhill, MJ; Findlay, JB; White, Iain R.; Caple, I. W.

doi:10.1113/expphysiol.1990.sp003437

Cited by 202 publications

(83 citation statements)

References 4 publications

(7 reference statements)

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Section: Discussionmentioning

confidence: 99%

“…In fetal sheep PTHrP is responsible, at least in part, for maintaining the differential gradient between high fetal serum calcium and that of the maternal circulation (Rodda et al, 1988;Abbas et al, 1989;Care et al, 1990). A midmolecule fragment of PTHrP was suggested to be responsible for placental transport of calcium in sheep (Care et al, 1990), a region which appeared to be present in Sparus saccus through interaction with antibody specific to the midmolecule 50-69 residues. Whether PTHrP is also functionally involved in calcium storage or mobilization in the saccus remains to be determined, but it is possible that it may be a factor which helps to maintain calcium concentrations in the CSF within strict limits, because the lumen of the saccus is continuous with that of the third ventricle of the diencephalon of the midbrain.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Immunochemical Detection of Parathyroid Hormone-Related Protein in the Saccus Vasculosus of a Teleost Fish

Devlin¹,

Danks

Faulkner³

et al. 1996

General and Comparative Endocrinology

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Using antisera to regions of human parathyroid hormone-related protein (PTHrP) the saccus vasculosus (SV) of the sea bream (Sparus aurata) has been shown to contain immunoreactive PTHrP. By immunohistochemistry (IHC) the epithelial coronet cells in fixed and waxembedded SV tissue reacted with antisera to the prepro region of human PTHrP (−13 to +2), the N-terminus PTHrP (1-16), and the midmolecule PTHrP (50-69). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of saccus extracts and incubation media contained two major proteins of 14.3 and 15 kDa. By Western blotting these two proteins both reacted with the three antisera used for IHC, suggesting that they are immunochemically similar to human PTHrP (1-84). Ultrastructurally the coronet cells of Sparus saccus vasculosus resembled coronet cells described for other teleosts, with an abundant smooth endoplasmic reticulum (SER) which was more highly organized in the coronets. IHC at EM level showed reaction mainly with the membranes of the SER. These results suggest that S. aurata saccus vasculosus may produce a PTHrP-like molecule similar to human PTHrP.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Immunochemical Detection of Parathyroid Hormone-Related Protein in the Saccus Vasculosus of a Teleost Fish

Devlin¹,

Danks

Faulkner³

et al. 1996

General and Comparative Endocrinology

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“…We have no direct evidence that PTHrP of parathyroid origin regulates placental calcium transport in the pig, as it does in the sheep (Rodda et al 1988;Abbas, Pickard, Rodda, Heath, Hammonds, Wood, Caple, Martin & Care, 1989;Care, Abbas, Pickard, Barri, Drinkhill, Findlay, White & Caple, 1990), but PTHrP derived from the placenta itself may have a local action on calcium transport to the fetus. Thyroparathyroidectomy of the ovine fetus, with thyroxine replacements, results in reversal of the placental calcium gradient (Care, Caple, Abbas & Pickard, 1986).…”

Section: Analysesmentioning

confidence: 94%

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 use of specific antibodies against different epitopes in the molecule has confirmed the heterogeneity. Ovine studies have shown that it is the midregion PTHrp, and not the amino-terminal region, that is functionally active during pregnancy (24). The consideration of this regional selectivity, together with the use of two-site IRMAs, has improved the accuracy of the measurements.…”

Section: Pth and Pthrpmentioning

confidence: 99%

ENDOCRINOLOGY IN PREGNANCY: Bone metabolic changes during pregnancy: a period of vulnerability to osteoporosis and fracture

Sanz-Salvador

Garcı́a-Pérez

Tarı́n

et al. 2015

European Journal of Endocrinology

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Changes in bone density and bone markers suggest that pregnancy is associated with deterioration of bone mass in the mother. The metabolism of calcium resets to allow for the needs imposed by the building of the fetal skeleton. The fetus contributes to the process through the output of regulators from the placenta. Understanding of the whole process is limited, but some changes are unambiguous. There is an increase in the circulating levels of vitamin D, but its functional impact is unclear. Fetal parathyroid hormone (PTH) and PTH-related peptide (PTHrp) play an indirect role through support of a calcium gradient that creates hypercalcemia in the fetus. Placental GH, which increases up to the end of pregnancy, may exert some anabolic effects, either directly or through the regulation of the IGF1 production. Other key regulators of bone metabolism, such as estrogens or prolactin, are elevated during pregnancy, but their role is uncertain. An increase in the ratio of receptor activator of nuclear factor kappa B ligand (RANKL) to osteoprotegerin (OPG) acts as an additional pro-resorbing factor in bone. The increase in bone resorption may lead to osteoporosis and fragility fracture, which have been diagnosed, although rarely. However, the condition is transitory as long-term studies do not link the number of pregnancies with osteoporosis. Prevention is limited by the lack of identifiable risk factors. When fractures are diagnosed, rest, analgesics, or, when indicated, orthopedic intervention have demonstrated efficacy. Systemic treatment with anti-osteoporotic drugs is effective, but the potential harm to the fetus imposes caution in their use.

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Stimulation of ovine placental transport of calcium and magnesium by mid‐molecule fragments of human parathyroid hormone‐related protein

Abstract: SUMMARYPerfusion in situ of the placenta of intact or previously parathyroidectomized fetal lambs has been used to assess the ability of three mid-molecule fragments of the human parathyroid hormone-related protein (PTHrP)

Cited by 202 publications

References 4 publications

Immunochemical Detection of Parathyroid Hormone-Related Protein in the Saccus Vasculosus of a Teleost Fish

Immunochemical Detection of Parathyroid Hormone-Related Protein in the Saccus Vasculosus of a Teleost Fish

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

ENDOCRINOLOGY IN PREGNANCY: Bone metabolic changes during pregnancy: a period of vulnerability to osteoporosis and fracture

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