Expression of hyperpolarization-activated cyclic nucleotide-gated cation channels in rat dorsal root ganglion neurons innervating urinary bladder.
Afferent pathways innervating the urinary bladder consist of myelinated Adelta- and unmyelinated C-fibers, the neuronal cell bodies of which correspond to medium and small-sized cell populations of dorsal root ganglion (DRG) neurons, respectively. Since hyperpolarization-activated cyclic nucleotide-gated cation (HCN) channel currents have been identified in various peripheral sensory neurons, we examined the expression of isoforms of HCN channels in the L6-S1 spinal cord and bladder afferent neurons from L6-S1 DRG in rats. Among HCN-1, HCN-2 and HCN-4 channel subtypes, positive staining with HCN-2 antibodies was found in the superficial dorsal horn of the spinal cord and small- and medium-sized unidentified DRG neurons. In dye-labeled bladder afferent neurons, HCN-2-positive cells were found in approximately 60% of neurons, and HCN-2 was expressed in both small- and medium-sized neurons with a higher ratio (expression ratio: 61% and 50% of neurons, respectively) compared with unidentified DRG neurons, in which the HCN expression ratio was 47% and 21% of small- and medium-sized cells, respectively. These results suggest that HCN-2 is the predominant subtype of HCN channels, which can control neuronal excitability, in small-sized C-fiber and medium-sized Adelta fiber DRG neurons including bladder afferent neurons, and might modulate activity of bladder afferent pathways controlling the micturition reflex.
Matsuyoshi
Hiroko
H
Department of Urology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA.
Masuda
Noriyuki
N
Chancellor
Michael B
MB
Erickson
Vickie L
VL
Hirao
Yoshihiko
Y
de Groat
William C
WC
Wanaka
Akio
A
Yoshimura
Naoki
N
D000818:Animals; D048429:Cell Size; D054815:Cyclic Nucleotide-Gated Cation Channels; D005260:Female; D005456:Fluorescent Dyes; D005727:Ganglia, Spinal / Q000166:cytology / Q000378:metabolism*; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels; D007150:Immunohistochemistry; D007473:Ion Channels / Q000378:metabolism*; D009413:Nerve Fibers, Myelinated / Q000378:metabolism / Q000648:ultrastructure; D036421:Nerve Fibers, Unmyelinated / Q000378:metabolism / Q000648:ultrastructure; D009475:Neurons, Afferent / Q000166:cytology / Q000378:metabolism*; D020671:Posterior Horn Cells / Q000166:cytology / Q000378:metabolism; D015221:Potassium Channels / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012018:Reflex / Q000502:physiology; D001743:Urinary Bladder / Q000294:innervation* / Q000502:physiology; D014554:Urination / Q000502:physiology; D017833:Visceral Afferents / Q000166:cytology / Q000378:metabolism*
D054815:Cyclic Nucleotide-Gated Cation Channels; D005456:Fluorescent Dyes; C513836:HCN4 protein, rat; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels; D007473:Ion Channels; D015221:Potassium Channels