Administration of PTH-(7-84) antagonizes the effects of PTH-(1-84) on bone in rats with moderate renal failure

M. Chris Langub, Marie Claude Monier-Faugere, Guodong Wang, John P. Williams, Nicholas J. Koszewski, Hartmut H. Malluche

Research output: Contribution to journalArticlepeer-review

102 Scopus citations


Circulating parathyroid hormone (PTH) is a mixture of PTH-1-84 and carboxy-terminal (C-PTH) fragments. Recently, the "intact" PTH assay was reported to detect not only PTH-(1-84) but also a C-PTH fragment, presumably PTH-(7-84). The purpose of this study was to determine whether PTH-(7-84) antagonizes the PTH-(1-84) effects on bone. Forty-eight rats were thyroparathyroidectomized (TPTX), eight were used as controls and the remaining TPTX rats (10/group) were nephrectomized (Nx) and subsequently given PTH-(1-84), PTH-(7-84), PTH-(1-84) and PTH-(7-84) or no PTH peptide. Another ten rats were sham-operated and served as controls. Administration of PTH-(1-84) brought serum calcium and osteoblast activity i.e., bone turnover, to normal levels. Concomitant administration of PTH-(7-84) abrogated these effects. Administration of PTH-(7-84) alone did not further suppress the levels of serum calcium and bone turnover in these TPTX-Nx rats. Moreover, radioligand binding experiments demonstrate that PTH-(7-84) binds specifically to SaOS cells and is equally displaced by both PTH-(1-84) and (7-84), but only partially displaced by PTH-(1-34). These data indicate that PTH-(7-84) antagonizes PTH-(1-84) effect not only on serum calcium but also on osteoblasts to affect bone turnover.

Original languageEnglish
Pages (from-to)1135-1138
Number of pages4
Issue number4
StatePublished - Apr 1 2003


  • Bone turnover
  • Histomorphometry
  • Parathyroid fragment
  • Parathyroid hormone
  • Rats

ASJC Scopus subject areas

  • Endocrinology


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