title: Histological identification of phrenic afferent projections to the spinal cord.
abstract: Limited data are available regarding the spinal projections of afferent fibers in the phrenic nerve. We describe a method that robustly labels phrenic afferent spinal projections in adult rats. The proximal end of the cut phrenic nerve was secured in a microtube filled with a transganglionic tracer (cholera toxin β-subunit, CT-β, or Cascade Blue) and tissues harvested 96-h later. Robust CT-β labeling occurred in C3-C5 dorsal root ganglia cell bodies and phrenic afferent projections were identified in the mid-cervical dorsal horn (laminae I-III), intermediate grey matter (laminae IV, VII) and near the central canal (laminae X). Afferent fiber labeling was reduced or absent when CT-β was delivered to the intrapleural space or directly to the hemidiaphragm. Soaking the phrenic nerve with Cascade Blue also produced robust labeling of mid-cervical dorsal root ganglia cells bodies, and primary afferent fibers were observed in spinal grey matter and dorsal white matter. Our results show that the 'nerve soak' method effectively labels both phrenic motoneurons and phrenic afferent projections, and show that primary afferents project throughout the ipsilateral mid-cervical gray matter.
authors.affiliation: University of Florida, College of Public Health and Health Professions, McKnight Brain Institute, Department of Physical Therapy, PO Box 100154, 100 S. Newell Dr, Gainesville, FL 32610, United States; Center for Respiratory Research and Rehabilitation, University of Florida, Gainesville, FL 32610, United States.
authors.forename: Jayakrishnan
authors.initials: J
authors.lastname: Nair
authors.affiliation: Department of Neurobiology & Anatomy, College of Medicine, Drexel University, 2900, W. Queen Lane, Philadelphia, PA 19129, United States.
authors.forename: Tatiana
authors.initials: T
authors.lastname: Bezdudnaya
authors.affiliation: Department of Neurobiology & Anatomy, College of Medicine, Drexel University, 2900, W. Queen Lane, Philadelphia, PA 19129, United States.
authors.forename: Lyandysha V
authors.initials: LV
authors.lastname: Zholudeva
authors.affiliation: Department of Neurobiology & Anatomy, College of Medicine, Drexel University, 2900, W. Queen Lane, Philadelphia, PA 19129, United States.
authors.forename: Megan R
authors.initials: MR
authors.lastname: Detloff
authors.affiliation: University of Florida, College of Medicine, McKnight Brain Institute, Department of Neuroscience, PO Box 100244, 100 S. Newell Dr, Gainesville FL 32610, United States; Center for Respiratory Research and Rehabilitation, University of Florida, Gainesville, FL 32610, United States.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Reier
authors.affiliation: Department of Neurobiology & Anatomy, College of Medicine, Drexel University, 2900, W. Queen Lane, Philadelphia, PA 19129, United States. Electronic address: mlane.neuro@gmail.com.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Lane
authors.affiliation: University of Florida, College of Public Health and Health Professions, McKnight Brain Institute, Department of Physical Therapy, PO Box 100154, 100 S. Newell Dr, Gainesville, FL 32610, United States; Center for Respiratory Research and Rehabilitation, University of Florida, Gainesville, FL 32610, United States. Electronic address: ddf@phhp.ufl.edu.
authors.forename: David D
authors.initials: DD
authors.lastname: Fuller
mesh_terms: D000344:Afferent Pathways / Q000502:physiology*; D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D002772:Cholera Toxin / Q000378:metabolism; D005260:Female; D007839:Functional Laterality; D005727:Ganglia, Spinal / Q000166:cytology; D037102:Lectins / Q000378:metabolism; D008297:Male; D009475:Neurons, Afferent / Q000502:physiology*; D010791:Phrenic Nerve / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000166:cytology / Q000502:physiology*
chemical_list: D037102:Lectins; D002772:Cholera Toxin; D015740:Calcitonin Gene-Related Peptide
keywords: Afferent; Cascade blue; Cholera toxin; Phrenic; Spinal