The coexistence of VGluT2 and neurotensin or leu-enkephalin in the medullary dorsal horn: a confocal and electron microscopic immunohistochemical study in the rat

Neurosci Lett. 2015 Jan 1:584:390-4. doi: 10.1016/j.neulet.2014.11.008. Epub 2014 Nov 11.

Abstract

Neuropeptides such as neurotensin (NT), and enkephalin (ENK) in the medullary dorsal horn (MDH) are involved in excitatory synaptic transmission to modulate nociceptive information. However, morphological evidence indicating that NT or ENK coexists with glutamate in the MDH is still meager. Using fluorescent immunohistochemistry, the results showed that double labeling of NT or ENK terminals with VGluT2 is mainly concentrated in the lamina II of the MDH, and many axon terminals exhibiting NT or ENK immunoreactivity in the superficial layers of the MDH showed VGluT2 immunoreactivity. Electron microscopy confirmed the coexpression of NT or ENK and VGluT2 in axon terminals within the laminae I and II of the MDH. These axon terminals make asymmetrical synapses with immunonegative neuronal cell bodies and dendrites. The findings suggest that glutamate is coreleased with NT or ENK from axon terminals of interneurons in the superficial layers of the MDH.

Keywords: Enkephalin; Fluorescent immunohistochemistry; Medullary dorsal horn; Neurotensin; Rat; The second vesicular glutamate transporter.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Enkephalin, Leucine / metabolism*
  • Glutamic Acid / metabolism
  • Immunohistochemistry
  • Medulla Oblongata / metabolism*
  • Microscopy, Confocal
  • Microscopy, Electron
  • Neurotensin / metabolism*
  • Posterior Horn Cells / metabolism*
  • Presynaptic Terminals / metabolism
  • Rats, Wistar
  • Vesicular Glutamate Transport Protein 2 / metabolism*

Substances

  • Slc17a6 protein, rat
  • Vesicular Glutamate Transport Protein 2
  • Neurotensin
  • Glutamic Acid
  • Enkephalin, Leucine