Distinct thyroid hormone-dependent expression of TrKB and p75NGFR in nonneuronal cells during the critical TH-dependent period of the cochlea

J Neurobiol. 1999 Feb 15;38(3):338-56.

Abstract

Analyzing the thyroid hormone (TH)-dependent period of the inner ear, we observed that the presence of triiodothyronine (T3) between postnatal day 3 (P3) and P12 is sufficient for functional maturation of the auditory system. Within this short time period, an unusual transient TH-dependent expression of nonneuronal neurotrophin receptors (NT-R) trkB and p75(NGFR) was observed in correlation with neuronal and morphogenetic processes. The availability of thyroid hormone was revealed to be invariably correlated with (a) a transient expression of full-length trkB in TRalpha1-, TRalpha2- and TRbeta1-expressing hair cells concomitant to the segregation of afferent fibers and the synaptogenesis of efferent fibers; and (b) a transient expression of p75(NGFR) in TRalpha1- and TRbeta1-expressing great epithelia ridge cells in direct spatiotemporal correlation with the appearance of apoptotic cells and morphogenetic maturation of the organ. For the first time, these data suggest a TH dependency of the expression of neurotrophin receptors in nonneuronal cells. A potential role of these peculiar neurotrophin receptor expression for the conversion of the biological function of TH on innervation patterning and morphogenesis during the critical TH-dependent period of the inner ear may be considered.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / physiology
  • Blotting, Western
  • Cochlea / cytology
  • Cochlea / growth & development
  • Cochlea / metabolism*
  • Evoked Potentials, Auditory / physiology
  • Immunohistochemistry
  • In Situ Hybridization
  • Precipitin Tests
  • RNA Probes
  • Rats
  • Rats, Sprague-Dawley
  • Rats, Wistar
  • Receptor Protein-Tyrosine Kinases / biosynthesis*
  • Receptor Protein-Tyrosine Kinases / genetics
  • Receptor, Ciliary Neurotrophic Factor
  • Receptor, Nerve Growth Factor
  • Receptors, Nerve Growth Factor / biosynthesis*
  • Receptors, Nerve Growth Factor / genetics
  • Thyroid Hormones / physiology*
  • Thyroxine / physiology
  • Triiodothyronine / physiology

Substances

  • RNA Probes
  • Receptor, Ciliary Neurotrophic Factor
  • Receptor, Nerve Growth Factor
  • Receptors, Nerve Growth Factor
  • Thyroid Hormones
  • Triiodothyronine
  • Receptor Protein-Tyrosine Kinases
  • Thyroxine