title: Differential expression of hyperpolarization-activated cyclic nucleotide-gated channel subunits during hippocampal development in the mouse.
abstract: BACKGROUND
  Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels help control the rhythmic activation of pacemaker neurons during brain development. However, little is known about the timing and cell type specificity of the expression of HCN isoforms during development of the hippocampus.
  
  
  RESULTS
  Here we examined the developmental expression of the brain-enriched HCN1, HCN2, and HCN4 isoforms of HCN channels in mouse hippocampus from embryonic to postnatal stages. All these isoforms were expressed abundantly in the hippocampus at embryonic day 14.5 and postnatal day 0. Each HCN channel isoform showed subfield-specific expression within the hippocampus from postnatal day 7, and only HCN4 was found in glial cells in the stratum lacunosum moleculare at this developmental stage. At postnatal days 21 and 56, all HCN isoforms were strongly expressed in the stratum lacunosum moleculare and the stratum pyramidale of the Cornu Ammonis (CA), as well as in the hilus of the dentate gyrus, but not in the subgranular zone. Furthermore, the immunolabeling for all these isoforms was colocalized with parvalbumin immunolabeling in interneurons of the CA field and in the dentate gyrus.
  
  
  CONCLUSIONS
  Our mapping data showing the temporal and spatial changes in the expression of HCN channels suggest that HCN1, HCN2, and HCN4 subunits may have distinct physiological roles in the developing hippocampus.
authors.affiliation: Department of Anatomy, Brain Science & Engineering Institute, Kyungpook National University Graduate School of Medicine, 2-101, Dongin-dong, Jung-gu, Daegu, 700-842, South Korea. hseo@knu.ac.kr.
authors.forename: Hyunhyo
authors.initials: H
authors.lastname: Seo
authors.affiliation: Department of Anatomy, Brain Science & Engineering Institute, Kyungpook National University Graduate School of Medicine, 2-101, Dongin-dong, Jung-gu, Daegu, 700-842, South Korea. basketmania8@naver.com.
authors.forename: Myoung-Jin
authors.initials: MJ
authors.lastname: Seol
authors.affiliation: Department of Anatomy, Brain Science & Engineering Institute, Kyungpook National University Graduate School of Medicine, 2-101, Dongin-dong, Jung-gu, Daegu, 700-842, South Korea. irislkm@knu.ac.kr.
authors.forename: Kyungmin
authors.initials: K
authors.lastname: Lee
mesh_terms: D000375:Aging / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D000089622:Doublecortin Domain Proteins; D004622:Embryo, Mammalian / Q000378:metabolism; D006624:Hippocampus / Q000254:growth & development* / Q000378:metabolism*; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels / Q000378:metabolism*; D008297:Male; D008810:Mice, Inbred C57BL; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009479:Neuropeptides / Q000378:metabolism; D010320:Parvalbumins / Q000378:metabolism; D020033:Protein Isoforms / Q000378:metabolism; D021122:Protein Subunits / Q000378:metabolism*
chemical_list: D000089622:Doublecortin Domain Proteins; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels; D008869:Microtubule-Associated Proteins; D009479:Neuropeptides; D010320:Parvalbumins; D020033:Protein Isoforms; D021122:Protein Subunits