Involvement of sensory neurons in bone defect repair in rats

J Electron Microsc (Tokyo). 2011 Dec;60(6):393-400. doi: 10.1093/jmicro/dfr075. Epub 2011 Nov 13.

Abstract

We investigated bone repair in sensory-denervated rats, compared with controls, to elucidate the involvement of sensory neurons. Nine-week-old male Wistar rats received subcutaneous injections of capsaicin to denervate sensory neurons. Rats treated with the same amount of vehicle served as controls. A standardized bone defect was created on the parietal bone. We measured the amount of repaired bone with quantitative radiographic analysis and the mRNA expressions of osteocalcin and cathepsin K with real-time polymerase chain reaction (PCR). Quantitative radiographic analysis showed that the standard deviations and coefficients of variation for the amount of repaired bone were much higher in the capsaicin-treated group than in the control group at any time point, which means that larger individual differences in the amount of repaired bone were found in capsaicin-treated rats than controls. Furthermore, radiographs showed radiolucency in pre-existing bone surrounding the standardized defect only in the capsaicin-treated group, and histological observation demonstrated some multinuclear cells corresponding to the radiolucent area. Real-time PCR indicated that there was no significant difference in the mRNA expression levels of osteocalcin and cathepsin K between the control group and the capsaicin-treated group. These results suggest that capsaicin-induced sensory denervation affects the bone defect repair.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biomarkers
  • Bone Regeneration*
  • Capsaicin / administration & dosage
  • Cathepsin K / genetics
  • Cathepsin K / metabolism
  • Gene Expression Regulation
  • Injections, Subcutaneous
  • Male
  • Osteocalcin / genetics
  • Osteocalcin / metabolism
  • Osteoclasts / metabolism
  • Osteoclasts / pathology
  • Parietal Bone / diagnostic imaging
  • Parietal Bone / drug effects*
  • Parietal Bone / injuries*
  • Parietal Bone / pathology
  • RNA, Messenger / genetics
  • RNA, Messenger / isolation & purification
  • RNA, Messenger / metabolism
  • Radiography
  • Rats
  • Rats, Wistar
  • Real-Time Polymerase Chain Reaction
  • Sensory Receptor Cells / drug effects*
  • Sensory Receptor Cells / pathology

Substances

  • Biomarkers
  • RNA, Messenger
  • Osteocalcin
  • Cathepsin K
  • Capsaicin