Adenosine A2A receptors are expressed by GABAergic neurons of medulla oblongata in developing rat

Brain Res. 2006 Feb 3;1071(1):42-53. doi: 10.1016/j.brainres.2005.11.077. Epub 2006 Jan 17.

Abstract

During early development, adenosine contributes to the occurrence of respiratory depression and recurrent apneas. Recent physiological studies indicate that GABAergic mechanisms may be involved in this inhibitory action of adenosine, via their A(2A) receptors. In the present study, in situ hybridization with ribonucleotide probes for A(2A) receptor (A(2A)R) mRNA was combined with the immunolabeling technique for parvalbumin and transneuronal retrograde tracing method using green fluorescent protein expressing pseudorabies virus (GFP-PRV) to (1) characterize age-dependent changes in the expression of adenosine A(2A)Rs mRNA in brain stem regions where GABAergic neurons are located; (2) determine whether GABA-containing neurons express A(2A)R mRNA traits, and (3) identify whether bulbospinal GABAergic neurons projecting to phrenic nuclei contain A(2A)R mRNA. Results revealed expression of A(2A) receptors in regions of medulla oblongata containing GABAergic neurons, namely in the ventral aspect of the medulla, within the Bötzinger region and caudal to it, the gigantocellular reticular nucleus, midline neurons and the caudal ventrolateral medulla oblongata. Furthermore, a subpopulation of identified GABAergic neurons, projecting to the phrenic motor nuclei, possess A(2A)R mRNA. It is concluded that adenosine A(2A)Rs expressed by GABAergic neurons are likely to play a role in mediating adenosine-induced respiratory depression.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • Age Factors
  • Animals
  • Blotting, Northern / methods
  • Cell Count / methods
  • Diaphragm / innervation
  • Diaphragm / metabolism
  • Diaphragm / virology
  • Gene Expression Regulation, Developmental / physiology*
  • Glutamate Decarboxylase / genetics
  • Glutamate Decarboxylase / metabolism
  • Green Fluorescent Proteins / metabolism
  • Herpesvirus 1, Suid / physiology
  • Immunohistochemistry / methods
  • In Situ Hybridization / methods
  • Medulla Oblongata / cytology*
  • Medulla Oblongata / growth & development
  • Models, Neurological
  • Neural Pathways / metabolism
  • Neural Pathways / virology
  • Neurons / metabolism*
  • Parvalbumins / genetics
  • Parvalbumins / metabolism
  • RNA, Messenger / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, Adenosine A2 / genetics
  • Receptors, Adenosine A2 / metabolism*
  • Reverse Transcriptase Polymerase Chain Reaction / methods
  • Statistics, Nonparametric
  • gamma-Aminobutyric Acid / metabolism*

Substances

  • Parvalbumins
  • RNA, Messenger
  • Receptors, Adenosine A2
  • Green Fluorescent Proteins
  • gamma-Aminobutyric Acid
  • Glutamate Decarboxylase