Decreased Nav1.9 channel expression in Hirschsprung's disease.
OBJECTIVE
Voltage-gated sodium channel subtype 9 (Nav1.9) are expressed in dorsal root ganglion neurons and are known to be involved in pain during inflammation. Animal studies have reported Nav1.9 channel expression in myenteric intrinsic primary afferent neurons (IPANs). More recently, a study involving Nav1.9 knockout mice showed clear evidence of colonic dysmotility. However, there are no data regarding the expression of these channels in the human intestine, thus, the aim of our study was to determine Nav1.9 channel expression within the human colon and to elucidate if Nav1.9 channel expression is altered in Hirschsprung's disease (HD).


METHODS
HD tissue specimens (n=10) were collected at the time of pull-through surgery, while normal controls were obtained at the time of colostomy closure in patients with imperforate anus (n=10). Nav1.9 immunofluorescence was visualized using confocal microscopy to assess the distribution of the protein. Western blot analysis was undertaken to determine Nav1.9 protein quantification.


RESULTS
Confocal microscopy revealed Nav1.9-immunoreactive neurons within the submucosal and myenteric plexus in normal controls, with a reduction in the HD specimens. Calbindin double-labeling showed that Nav1.9-immunoreactive neurons were IPANs. Nav1.9 channels were also seen to be co-localized on smooth muscle cells in all tissues. Western blotting revealed high levels of Nav1.9 protein expression in normal controls, while there was a marked decrease in Nav1.9 protein expression in the HD tissue.


CONCLUSIONS
Our results show the expression of Nav1.9 channels within the human colon for the first time. Furthermore, Nav1.9 channel expression is decreased in HD versus normal controls.
National Children's Research Centre, Our Lady's Children's Hospital Crumlin, Dublin, Ireland.
Anne-Marie
AM
O'Donnell
National Children's Research Centre, Our Lady's Children's Hospital Crumlin, Dublin, Ireland.
David
D
Coyle
National Children's Research Centre, Our Lady's Children's Hospital Crumlin, Dublin, Ireland. Electronic address: prem.puri@ucd.ie.
Prem
P
Puri
D015415:Biomarkers / Q000378:metabolism; D015153:Blotting, Western; D016022:Case-Control Studies; D003106:Colon / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006627:Hirschsprung Disease / Q000378:metabolism*; D006801:Humans; D018613:Microscopy, Confocal; D062558:NAV1.9 Voltage-Gated Sodium Channel / Q000378:metabolism
D015415:Biomarkers; D062558:NAV1.9 Voltage-Gated Sodium Channel; C491886:SCN11A protein, human
Enteric nervous; Hirschsprung's disease; Nav1.9; Voltage-gated sodium channels