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[Apoptosis: a possible mechanism of suppressing parathyroid hyperplasia by calcimimetics]

Masahide Mizobuchi1, Fumie Saji, Kazuhiro Shiizaki

  • 1Nephrology and Blood Purification Medicine, Wakayama Medical University.

Clinical Calcium
|November 8, 2005
PubMed

Insights

Calcimimetic compounds like NPS R-568 reduce parathyroid hormone (PTH) secretion. This compound also induces apoptosis, or programmed cell death, in hyperfunctional parathyroid cells in vitro.

Area of Science:

  • Nephrology
  • Endocrinology
  • Cell Biology

Background:

  • The precise mechanisms by which calcimimetic compounds inhibit parathyroid cell proliferation remain unclear.
  • Hyperparathyroidism is a common complication of chronic kidney disease, often characterized by parathyroid cell hyperplasia.

Purpose of the Study:

  • To investigate the in vitro effects of the calcimimetic compound NPS R-568 on parathyroid cell growth and survival.
  • To compare the effects of NPS R-568 with calcitriol on parathyroid hormone secretion and apoptosis.

Main Methods:

  • Primary rat parathyroid glands from subtotally nephrectomized rats on a high-phosphorus diet were utilized.
  • Glands were incubated with NPS R-568 (10-4 M), calcitriol (10-7 M), or vehicle control for 6 hours.
  • Parathyroid hormone (PTH) levels in the medium and cell apoptosis (TUNEL assay) were assessed.

Main Results:

  • Both NPS R-568 and calcitriol significantly reduced medium PTH levels compared to controls.
  • Calcitriol treatment did not alter the rate of apoptosis compared to vehicle or untreated groups.
  • NPS R-568 significantly increased the number of TUNEL-positive cells, indicating enhanced apoptosis.

Conclusions:

  • The calcimimetic compound NPS R-568 effectively reduces PTH secretion.
  • NPS R-568 induces apoptosis in hyperfunctional parathyroid cells in vitro, suggesting a novel mechanism for controlling parathyroid cell growth.

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