Retrograde labeling of phrenic motoneurons by intrapleural injection

Carlos B. Mantilla, Wen Zhi Zhan, Gary C. Sieck

Research output: Contribution to journalArticlepeer-review

87 Scopus citations


Studies of motoneuron plasticity during development or in response to injury or disease rely on the ability to correctly identify motoneurons innervating specific muscle groups. Commonly, injections of retrograde tracer molecules into a target muscle or into a transected nerve are used to label specific motoneuron pools. However, intramuscular injection does not consistently label all motoneurons in the target pool; and either injection site may involve additional surgical procedures and muscle or nerve perturbations. For instance, retrograde labeling of phrenic motoneurons by injection into the diaphragm muscle is commonly employed in studies of plasticity in respiratory motor control. Diaphragm intramuscular injection involves a laparotomy, and this additional surgery may limit the ability to conduct labeling studies particularly in small animals. In the present study, we provide validation of a novel method for phrenic motoneuron labeling using intrapleural injection of Alexa 488-conjugated cholera toxin subunit B. Only phrenic motoneurons were labeled in the cervical spinal cord as verified by co-staining with rhodamine-conjugated dextran injected into the diaphragm muscle or applied via phrenic nerve dip. Thoracic intercostal motoneurons and some dorsal root ganglia neurons were also labeled by intrapleural injection, but there was no evidence of trans-synaptic labeling. Phrenic motoneuron labeling was not present if the phrenic nerve was transected prior to intrapleural injection. This novel method is ideally suited for morphological studies and analyses of mRNA expression in isolated phrenic motoneurons using techniques such as laser capture microdissection.

Original languageEnglish (US)
Pages (from-to)244-249
Number of pages6
JournalJournal of Neuroscience Methods
Issue number2
StatePublished - Sep 15 2009


  • Diaphragm muscle
  • Phrenic motoneurons
  • Respiratory plasticity
  • Retrograde tracer

ASJC Scopus subject areas

  • Neuroscience(all)


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