Vesicular glutamate transporter 2 is expressed in different nerve fibre populations that selectively contact pulmonary neuroepithelial bodies

Histochem Cell Biol. 2004 Jan;121(1):1-12. doi: 10.1007/s00418-003-0609-1. Epub 2003 Dec 16.

Abstract

Pulmonary neuroepithelial body (NEB) receptors in rats receive at least four different nerve fibre populations. In addition to a spinal sensory innervation that contacts NEBs at their basal side, extensive vagal nodose sensory terminals and separate nitrergic and cholinergic nerve endings protrude between NEB cells. In the present study, antibodies against the vesicular glutamate transporter 2 (VGLUT2), a transmembrane protein responsible for loading glutamate into synaptic vesicles, were used to investigate whether some of the nerve terminals contacting NEBs in rat lungs might use glutamate as a neurotransmitter. VGLUT2 immunoreactivity (IR) was detected in extensive intraepithelial arborising nerve terminals that appeared to contact most of the NEBs. Multiple immunostaining showed VGLUT2 IR in the vagal nodose and spinal sensory nerve terminals contacting NEBs, and in another, most likely sensory, intraepithelial nerve fibre population, the origin and further characteristics of which remain to be elucidated. At least part of the VGLUT2-immunoreactive nerve fibres that contact NEBs were shown to be myelinated. The expression of VGLUT2 indicates that glutamate is stored and released as a neurotransmitter in terminals of several pulmonary (sensory) nerve fibre populations that selectively relate to the complex NEB receptors. The present study strongly suggests an involvement of glutamatergic mechanisms in the peripheral transduction of sensory stimuli from the lungs, via the release of glutamate from nerve terminals, thereby modulating the activity of NEB receptor cells or the excitability of afferent nerves.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Carrier Proteins / biosynthesis*
  • Epithelial Cells / cytology*
  • Epithelial Cells / physiology
  • Glutamic Acid / metabolism
  • Glutamic Acid / physiology
  • Histocytochemistry
  • Lung / cytology*
  • Lung / innervation*
  • Lung / physiology
  • Membrane Transport Proteins*
  • Nerve Fibers / chemistry
  • Nerve Fibers / metabolism*
  • Neurosecretory Systems / cytology*
  • Neurosecretory Systems / physiology
  • Nodose Ganglion / cytology
  • Nodose Ganglion / physiology
  • Presynaptic Terminals / metabolism
  • Presynaptic Terminals / ultrastructure
  • Rats
  • Rats, Wistar
  • Vagus Nerve / cytology
  • Vagus Nerve / physiology
  • Vesicular Glutamate Transport Protein 2
  • Vesicular Transport Proteins*

Substances

  • Carrier Proteins
  • Membrane Transport Proteins
  • Slc17a6 protein, rat
  • Vesicular Glutamate Transport Protein 2
  • Vesicular Transport Proteins
  • Glutamic Acid