Expression of sodium channel Nav1.6 in cholinergic myenteric neurons of guinea pig proximal colon.
We wished to establish the functional identity of Na(v)1.6-expressing myenteric neurons of the guinea pig proximal colon by determining the extent of colocalization of Na(v)1.6 and selected neurochemical markers. Na(v)1.6-like immunoreactivity (-li) was primarily localized to the hillock and initial segments of myenteric neurons located near junctions with internodal fiber tracts. Immunoreactivity for Na(v)1.6 was co-localized with choline-acetyltransferase-li, representing 96% of Na(v)1.6-immunoreactive neurons; about 5% of these neurons showed co-localization with calretinin-li, but none with substance-P-li. Cholinergic neurons expressing Na(v)1.6 were amongst the smallest (somal area <300 mum(2)) of all cholinergic myenteric neurons observed. Only three of 234 Na(v)1.6-immunoreactive neurons exhibited nNOS-li, and none co-localized with calbindin-li. These data suggest that Na(v)1.6 is expressed in a small uniform population of cholinergic myenteric neurons that lie within the guinea pig proximal colon and that are likely to function as excitatory motor neurons.
Program in Neuroscience, Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, Washington State University, Pullman, WA 99164-6520, USA.
A C
AC
Bartoo
L K
LK
Sprunger
D A
DA
Schneider
D000818:Animals; D002799:Cholinergic Fibers / Q000378:metabolism*; D003106:Colon / Q000166:cytology / Q000378:metabolism*; D006168:Guinea Pigs; D007150:Immunohistochemistry; D008297:Male; D009197:Myenteric Plexus / Q000166:cytology / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D015222:Sodium Channels / Q000096:biosynthesis*
D015222:Sodium Channels