The distribution of HCN2-positive cells in the gastrointestinal tract of mice.
HCN2 channels are involved in the spontaneous rhythmic activities of some CNS neurons and act by generating I(f)  current. The gastrointestinal (GI) tract is known to be capable of spontaneous rhythmic activity; however, the possible role of HCN2 channels in this organ has not yet been elucidated. This study investigated the distribution of HCN2-positive cells in the mouse GI tract using immunohistochemistry. To identify the nature of these HCN2 cells, anti-ChAT and anti-Kit antibodies were used to co-label neurons and the interstitial cells of Cajal (ICCs), respectively. Additionally, differences in the distribution of HCN2-positive cells within the GI tract were also analyzed. Our results showed that HCN2 channels were mainly located within the myenteric neurons of the enteric nervous system in the GI tract. Double-staining revealed that HCN2-positive neurons were labeled by ChAT, indicating that these HCN2-positive cells are also cholinergic neurons. Although the HCN2-positive cells were not stained by the anti-Kit antibody, their processes were in close proximity to ICCs around the myenteric plexus region. Moreover, several differences in the distribution of HCN2 in the stomach, small intestine and colon were partly consistent with the regional differences in the spontaneous rhythmic activities of these organs. Basing on the role HCN2, we suggested that HCN2 channels facilitate the release of Ach from cholinergic neurons to affect the GI peristalsis by acting on M receptors on the ICCs. However, the HCN2 channels are not directly involved in spontaneous slow-wave initiation by ICCs.
Department of Histology and Embryology, School of Basic Medical Sciences, Capital Medical University, Beijing, China.
Shu
S
Yang
Cheng-jie
CJ
Xiong
Hai-mei
HM
Sun
Xiao-shuang
XS
Li
Guo-quan
GQ
Zhang
Bo
B
Wu
De-shan
DS
Zhou
D000818:Animals; D017615:Enteric Nervous System; D041981:Gastrointestinal Tract / Q000033:anatomy & histology / Q000166:cytology*; D006801:Humans; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels; D007150:Immunohistochemistry; D056885:Interstitial Cells of Cajal / Q000737:chemistry / Q000166:cytology; D007473:Ion Channels / Q000032:analysis* / Q000502:physiology; D008297:Male; D051379:Mice / Q000033:anatomy & histology; D008807:Mice, Inbred BALB C; D009197:Myenteric Plexus / Q000737:chemistry* / Q000166:cytology; D009474:Neurons / Q000737:chemistry; D015221:Potassium Channels
C578710:HCN2 protein, human; C578711:Hcn2 protein, mouse; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels; D007473:Ion Channels; D015221:Potassium Channels