Galanin is a selective marker of the retrotrapezoid nucleus in rats

Ruth L. Stornetta*, Darko Spirovski, Thiago S. Moreira, Ana C. Takakura, Gavin H. West, Justin M. Gwilt, Paul M. Pilowsky, Patrice G. Guyenet

*Corresponding author for this work

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The rat retrotrapezoid nucleus (RTN) contains CO2-activated neurons that contribute to the central chemoreflex and to breathing automaticity. These neurons have two known markers, the transcription factor Phox2b and vesicular glutamate transporter 2 (VGLUT2). Noncatecholaminergic galanin-immunoreactive (ir) neurons within a region of the lower brainstem that seems identical to what is currently defined as the RTN have been previously described. Here we ask whether these galanin-expressing neurons are the same cells as the recently characterized CO2-sensitive neurons of the RTN. By using in situ hybridization, we found that pre-pro-galanin (PPGal) mRNA is expressed by an isolated cluster of neurons that is co-extensive with the RTN as defined by a population of strongly Phox2b-ir neurons devoid of tyrosine hydroxylase (Phox2b+/TH- neurons). This bilateral structure contains about 1,000 PPGal mRNA-positive neurons in the rat. The PPGal mRNA-positive neurons were Phox2b+/TH- and as susceptible to destruction by the toxin [Sar9, Met (O2)11]-substance P as the rest of the RTN/TH- cells of the RTN. CO2-activated neurons were recorded in the RTN of anesthetized rats and were labeled with biotinamide. Many of those cells (7/17, 41%, five rats) contained PPGal-mRNA. In conclusion, galanin mRNA is a very specific marker of the glutamatergic Phox2b+/TH- neurons of the RTN, but galanin mRNA identifies only half of these putative central respiratory chemo-receptors.

Original languageEnglish
Pages (from-to)373-383
Number of pages11
JournalJournal of Comparative Neurology
Issue number3
Publication statusPublished - 20 Jan 2009



  • Central chemoreceptors
  • Galanin
  • Medulla oblongata
  • Phox2b
  • Retrotrapezoid nucleus

Cite this

Stornetta, R. L., Spirovski, D., Moreira, T. S., Takakura, A. C., West, G. H., Gwilt, J. M., ... Guyenet, P. G. (2009). Galanin is a selective marker of the retrotrapezoid nucleus in rats. Journal of Comparative Neurology, 512(3), 373-383.