Osteocytic connexin 43 is not required for the increase in bone mass induced by intermittent PTH administration in male mice

R. Pacheco-Costa, H. M. Davis, E. G. Atkinson, E. Katchburian, Lilian Plotkin, Rejane D. Reginato

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

Objective: To investigate whether osteocytic connexin 43 (Cx43) is required for the bone response to intermittent PTH administration, and whether the connexin is involved in maintaining the bone matrix. Methods: Human PTH(1-34) was injected to adult male mice expressing (Cx43fl/fl) or not osteocytic Cx43 (Cx43fl/fl;DMP1-8kb-Cre) daily (100 μg/kg/d) for 14 days. Results: Cx43fl/fl;DMP1- 8kb-Cre mice have no difference in body weight and BMD from 1 to 4 months of age. Intermittent PTH administration increased BMD and BV/TV and induced a similar increase in type I collagen, alkaline phosphatase, runx2, osteocalcin, and bone sialoprotein expression in mice from both genotypes. On the other hand, osteocytic deletion of Cx43 did not alter mRNA levels of glycosaminoglycans, proteoglycans, collagens and osteoblast-related genes. In addition, expression of collagens assessed by immunohistochemistry was not affected by deleting osteocytic Cx43. However, PTH administration increased type II collagen only in Cx43fl/flcontrol mice, whereas hormone increased type I collagen expression only in Cx43fl/fl;DMP1-8kb-Cre mice. Furthermore, PTH increased maturity of collagen fibers in control, but not in Cx43-deficient mice. Conclusion: Expression of Cx43 in osteocytes is dispensable for bone anabolism induced by intermittent PTH administration; but it can modulate, at least in part, the effect of PTH on the bone matrix environment.

Original languageEnglish (US)
Pages (from-to)45-57
Number of pages13
JournalJournal of Musculoskeletal Neuronal Interactions
Volume16
Issue number1
StatePublished - Mar 1 2016

Keywords

  • Bone matrix
  • Collagen
  • Connexin 43
  • Osteocyte
  • PTH

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Orthopedics and Sports Medicine
  • Physiology

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