title: The expression of hyperpolarization-activated cyclic nucleotide-gated channel 1 (HCN1) and HCN2 in the rat trigeminal ganglion, sensory root, and dental pulp.
abstract: Hyperpolarization-activated cyclic nucleotide-gated channel 1 (HCN1) and 2 (HCN2) are abundantly expressed in primary sensory neurons and contribute to neuronal excitability and pathological pain. We studied the expression of HCN1 and HCN2 in the rat trigeminal ganglion (TG) neurons and axons in the dental pulp, and the changes in their expression following inflammation, using light- and electron-microscopic immunocytochemistry and quantitative analysis. HCN1 and HCN2 were expressed predominantly in large-sized, neurofilament 200-immunopositive (+) or parvalbumin+ soma in the TG whereas they were expressed mostly in unmyelinated and small myelinated axons in the sensory root. The expression was particularly strong along the plasma membrane in the soma. In the dental pulp, majority of HCN1+ and HCN2+ axons coexpressed calcitonin gene-related peptide. They were expressed mainly in the peripheral pulp and pulp horn where the axons branch extensively in the dental pulp. The expression of HCN1 and HCN2 in TG neurons increased significantly in rats with experimentally induced inflammation of the dental pulp. Our findings support the notion that HCN1 and HCN2 are expressed mainly by both the soma of mechanosensitive neurons in the TG and peripheral axons of nociceptive neurons in the sensory root, and may play a role in the mechanisms of inflammatory pain from the dental pulp.
authors: Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu 700-412, Republic of Korea.
authors: Y S
authors: YS
authors: Cho
authors: Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu 700-412, Republic of Korea.
authors: Y S
authors: YS
authors: Kim
authors: Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu 700-412, Republic of Korea.
authors: S J
authors: SJ
authors: Moozhayil
authors: Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu 700-412, Republic of Korea.
authors: E S
authors: ES
authors: Yang
authors: Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu 700-412, Republic of Korea. Electronic address: ycbae@knu.ac.kr.
authors: Y C
authors: YC
authors: Bae
mesh_terms: D000818:Animals; D001369:Axons / Q000378:metabolism / Q000648:ultrastructure; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D003782:Dental Pulp / Q000378:metabolism* / Q000648:ultrastructure; D003788:Dental Pulp Diseases / Q000378:metabolism / Q000473:pathology; D004195:Disease Models, Animal; D005620:Freund's Adjuvant; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels / Q000378:metabolism*; D007249:Inflammation / Q000378:metabolism / Q000473:pathology; D008297:Male; D009413:Nerve Fibers, Myelinated / Q000378:metabolism / Q000648:ultrastructure; D016900:Neurofilament Proteins / Q000378:metabolism; D010320:Parvalbumins / Q000378:metabolism; D015221:Potassium Channels / Q000378:metabolism*; D017207:Rats, Sprague-Dawley; D011984:Sensory Receptor Cells / Q000378:metabolism* / Q000648:ultrastructure; D012668:Trigeminal Ganglion / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: C578667:Hcn1 protein, rat; C578712:Hcn2 protein, rat; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels; D016900:Neurofilament Proteins; D010320:Parvalbumins; D015221:Potassium Channels; C051774:neurofilament protein H; D005620:Freund's Adjuvant; D015740:Calcitonin Gene-Related Peptide
keywords: HCN; axon type; dental pulp; inflammation; trigeminal ganglion; ultrastructure