Magnesium modulates parathyroid hormone secretion and upregulates parathyroid receptor expression at moderately low calcium concentration

Abstract

BackgroundThe interest on magnesium (Mg) has grown since clinical studies have shown the efficacy of Mg-containing phosphate binders. However, some concern has arisen for the potential effect of increased serum Mg on parathyroid hormone (PTH) secretion. Our objective was to evaluate the direct effect of Mg in the regulation of the parathyroid function; specifically, PTH secretion and the expression of parathyroid cell receptors: CaR, the vitamin D receptor (VDR) and FGFR1/Klotho.MethodsThe work was performed in vitro by incubating intact rat parathyroid glands in different calcium (Ca) and Mg concentrations.ResultsIncreasing Mg concentrations from 0.5 to 2 mM produced a left shift of PTH–Ca curves. With Mg 5 mM, the secretory response was practically abolished. Mg was able to reduce PTH only if parathyroid glands were exposed to moderately low Ca concentrations; with normal–high Ca concentrations, the effect of Mg on PTH inhibition was minor or absent. After 6-h incubation at a Ca concentration of 1.0 mM, the expression of parathyroid CaR, VDR, FGFR1 and Klotho (at mRNA and protein levels) was increased with a Mg concentration of 2.0 when compared with 0.5 mM.ConclusionsMg reduces PTH secretion mainly when a moderate low calcium concentration is present; Mg also modulates parathyroid glands function through upregulation of the key cellular receptors CaR, VDR and FGF23/Klotho system.

The Effect of Increasing Dialysate Magnesium on Serum Calcification Propensity in Subjects with End Stage Kidney Disease

“…of PTH from parathyroid cells as well as increases the transcription of the Ca-sensing receptor (14). The decrease in PTH might also account for the acute decrease in PO 4 observed in the high-dialysate Mg group.…”

The influence of spironolactone on the serum electrolytes balance and renal cortical magnesium and calcium contents in cisplatin – treated rabbits

“…*P<0.05, ** P<0.01. a significantly different from C The PTH in turn is believed to regulate the magnesium homeostasis by influencing the renal magnesium reabsorption. 18 The activation of calcium receptors in the renal tubules was shown to inhibit the renal magnesium reabsorption, 19 which would further reduce the magnesium level and inhibit the PTH release ending up in depletion of the serum calcium level. Thus, the observed reduction in serum calcium could be secondary to the cisplatin-induced magnesium depletion.…”

Effects of magnesium degradation products on mesenchymal stem cell fate and osteoblastogenesis

“…Therefore, it could be postulated that Mg extract alone inhibits the noncollagenous protein colonisation of the ECM and mineralisation itself. However, these effects are [37]. In addition to its role in calcium homeostasis, VDR and its high affinity ligand (1α,25(OH)2D3 -vitamin D3) also stimulate osteoblastogenesis in MSCs in a potential autocrine/paracrine manner [38].…”