Osteocalcin-immunoreactive primary sensory neurons in the rat spinal and trigeminal nervous systems

Hiroyuki Ichikawa, Toshiyuki Itota, Yasuhiro Torii, Kiyoshi Inoue, Tomosada Sugimoto

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19 Citations (Scopus)


Osteocalcin-immunoreactivity (OC-ir) was examined in spinal and trigeminal primary sensory neurons of the adult rat. Sixteen percent of dorsal root ganglion (DRG) neurons were immunoreactive (ir) for this protein. These neurons were mostly large and measured 594-4583 μm2 (mean ± S.D. = 2243 ±748 μm2). Thirty-four percent of DRG neurons > 1200 μm2 and 4% of those in the range 600-1200 μm2 showed the ir. Virtually all DRG neurons < 600 μm2 were devoid of OC-ir. In the trigeminal ganglion (TG), 25% of neurons exhibited the ir. Such neurons were of various sizes (range = 156- 2825 μm2, mean ± S.D.= 1234 ± 543 ±m2). Forty-five percent of TG neurons > 800 μm2 and 6% of those < 400 μm2 were immunoreactive for this protein. Twelve percent of TG neurons in the range 400-800 μm2 showed the it. In the mesencephalic trigeminal tract nucleus (Mes5), 63% of primary sensory neurons contained OC-ir. Virtually all OC-ir DRG and Mes5 neurons co- expressed parvalbumin-ir but not CGRP-ir. On the other hand, only 31% of OC- ir neurons co-expressed parvalbumin-ir and 10% co-expressed CGRP-ir in the TG. The present study indicates that DRG and Mes5 primary sensory neurons co- expressing OC- and parvalbumin-irs are spinal and trigeminal proprioceptors. OC-ir TG neurons which co-express parvalbumin- and CGRP-irs appear to include low-threshold mechanoreceptors and nociceptors, respectively.

Original languageEnglish
Pages (from-to)205-209
Number of pages5
JournalBrain Research
Issue number1-2
Publication statusPublished - Aug 14 1999


  • Calcitonin gene-related peptide
  • Dorsal root ganglion
  • Immunohistochemistry
  • Mesencephalic trigeminal tract nucleus
  • Osteocalcin
  • Parvalbumin
  • Trigeminal ganglion

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology


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