Evaluation of the bilateral cardiac afferent distribution at the spinal and vagal ganglia by retrograde labeling

Akgul Caglar T., Durdu Z., Turhan M., Gunal M., AYDIN M., ÖZTÜRK G., ...More

Brain Research, vol.1751, 2021 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 1751
  • Publication Date: 2021
  • Doi Number: 10.1016/j.brainres.2020.147201
  • Journal Name: Brain Research
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, PASCAL, Animal Behavior Abstracts, Aquatic Science & Fisheries Abstracts (ASFA), BIOSIS, CAB Abstracts, Chemical Abstracts Core, EMBASE, Linguistics & Language Behavior Abstracts, MEDLINE, Psycinfo, Veterinary Science Database
  • Keywords: Di-8-ANEPPQ, Mouse heart, Retrograde labeling, Cardiac sensory neurons, Afferents, Mapping
  • Istanbul Medipol University Affiliated: Yes


The identity of sensory neurons innervating the heart tissue and the extent of information reported to the brain via these neurons are poorly understood. In order to evaluate the multidimensional distribution and abundance of the cardiac spinal and vagal afferents, we assessed the retrograde labeling efficiency of various tracers, and mapped the cardiac afferents qualitatively and quantitatively at the bilateral nodose ganglia (NGs) and dorsal root ganglia (DRGs). From the five different retrograde tracers evaluated, Di-8-ANEPPQ yielded reproducibly the highest labeling efficiency of cardiac afferents. We demonstrated specific cardiac afferents at NGs and C4 to T11 DRG segments. Next, the 2D reconstruction of the tissue sections and 3D imaging of the whole NGs and DRGs revealed homogeneous and bilateral distribution of cardiac afferents. The quantitative analyses of the labeled cardiac afferents demonstrated approximately 5–6% of the soma in NGs that were equally distributed bilaterally. The neuronal character of Di-8-ANEPPQ labeled cells were validated by coimmunostaning with pan-neuronal marker Tuj-1. In addition, the cell diameters of labeled cardiac sensory neurons were found smaller than 20 μm, implying the nociceptor phenotype confirmed by co-labeling with TRPV1 and Di-8-ANEPPQ. Importantly, co-labeling with two distinct tracers Di-8-ANEPPQ and WGA-647 demonstrated exclusively the same cardiac afferents in DRGs and NGs, validating our findings. Collectively, our findings revealed the cardiac afferents in NGs bilaterally and DRGs with the highest labeling efficiency reported, spatial distribution and quantitation at both 2D and 3D levels, furthering our understanding of this novel neuron population.