Dynamic expression of the TRPM subgroup of ion channels in developing mouse sensory neurons

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Abstract

Despite the significance of transient receptor potential (TRP) channels in sensory physiology, little is known of the expression and developmental regulation of the TRPM (melastatin) subgroup in sensory neurons. In order to find out if the eight TRPM subgroup members (TRPM1–TRPM8) have a possible role in the sensory nervous system, we characterized the developmental regulation of their expression in mouse dorsal root ganglion (DRG) from embryonic (E) day 12 to adulthood. Transcripts for all channels except for TRPM1 were detected in lumbar and thoracic DRG and in nodose ganglion (NG) with distinguishable expression patterns from E12 until adult. For most channels, the expression increased from E14 to adult with the exception of TRPM5, which displayed transient high levels during embryonic and early postnatal stages. Cellular localization of TRPM8 mRNA was found only in a limited subset of very small diameter neurons distinct in size from other populations. These neurons did not bind isolectin B4 (IB4) and expressed neither the neuropeptide calcitonin gene-related peptide (CGRP) nor neurofilament (NF)200. This suggests that TRPM8+ thermoreceptive sensory neurons fall into a separate group of very small sized neurons distinct from peptidergic and IB4+ subtypes of sensory neurons. Our results, showing the expression and dynamic regulation of TRPM channels during development, indicate that many TRPM subfamily members could participate during nervous system development and in the adult by determining distinct physiological properties of sensory neurons.

Section snippets

Results and discussion

There are several types of sensory neurons in the DRG with responsiveness to different kinds of external and internal stimuli. These stimuli, i.e. nociceptive, thermal or mechanical, activate different receptors and ion channels that are present in the nerve terminals at the sensory receptive fields and their expression in selective subsets of DRG neurons determines the response profile of individual neurons to a given stimuli. TRP channels are a group of non-selective cation channels that play

Experimental procedures

All procedures involving animal handling were approved by the local Ethical Committee for Animal Experiments.

Acknowledgement

We thank Johnny S. for technical support. This work was supported by Swedish Research Council, Swedish Brain Foundation, Bertil Hållsten Foundation, Linné Foundation (DBRM), ERC advanced Grant 232675 and the Karolinska Foundation.

References (31)

  • S. Thor et al.

    The homeodomain LIM Protein Isl-1 is expressed in subsets of neurons and endocrine cells in the adult rat

    Neuron

    (1991)
  • H. Zhuo et al.

    Neurochemistry of the nodose ganglion

    Prog. Neurobiol.

    (1997)
  • S. Averill et al.

    Immunocytochemical localization of trkA receptors in chemically identified subgroups of adult rat sensory neurons

    Eur. J. Neurosci.

    (1995)
  • D.O. Clary et al.

    TrkA cross-linking mimics neuronal responses to nerve growth factor

    Mol. Biol. Cell

    (1994)
  • A. Dhaka et al.

    Visualizing cold spots: TRPM8-expressing sensory neurons and their projections

    J. Neurosci.

    (2008)

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