title: Balance between the proximal dendritic compartment and the soma determines spontaneous firing rate in midbrain dopamine neurons.
abstract: Midbrain dopamine (DA) neurons are slow intrinsic pacemakers that require the elaborate composition of many ion channels in the somatodendritic compartments. Understanding the major determinants of the spontaneous firing rate (SFR) of midbrain DA neurons is important because they determine the basal DA levels in target areas, including the striatum. As spontaneous firing occurs synchronously at the soma and dendrites, the electrical coupling between the soma and dendritic compartments has been regarded as a key determinant for the SFR. However, it is not known whether this somatodendritic coupling is served by the whole dendritic compartments or only parts of them. In the rat substantia nigra pars compacta (SNc) DA neurons, we demonstrate that the balance between the proximal dendritic compartment and the soma determines the SFR. Isolated SNc DA neurons showed a wide range of soma size and a variable number of primary dendrites but preserved a quite consistent SFR. The SFR was not correlated with soma size or with the number of primary dendrites, but it was strongly correlated with the area ratios of the proximal dendritic compartments to the somatic compartment. Tetrodotoxin puff and local Ca(2+) perturbation experiments, computer simulation, and local glutamate uncaging experiments suggest the importance of the proximal dendritic compartments in pacemaker activity. These data indicate that the proximal dendritic compartments, not the whole dendritic compartments, play a key role in the somatodendritic balance that determines the SFR in DA neurons.
authors.affiliation: Department of Physiology, Sungkyunkwan University School of Medicine, 300 Chunchun-dong, Jangan-ku, Suwon, 440-746, Korea Center For Molecular Medicine, Samsung Biomedical Research Institute, 300 Chunchun-dong, Jangan-ku, Suwon, 440-746, Korea.
authors.forename: Jinyoung
authors.initials: J
authors.lastname: Jang
authors.affiliation: Department of Physiology, Sungkyunkwan University School of Medicine, 300 Chunchun-dong, Jangan-ku, Suwon, 440-746, Korea.
authors.forename: Ki Bum
authors.initials: KB
authors.lastname: Um
authors.affiliation: Department of Physiology, Sungkyunkwan University School of Medicine, 300 Chunchun-dong, Jangan-ku, Suwon, 440-746, Korea.
authors.forename: Miae
authors.initials: M
authors.lastname: Jang
authors.affiliation: Center For Molecular Medicine, Samsung Biomedical Research Institute, 300 Chunchun-dong, Jangan-ku, Suwon, 440-746, Korea.
authors.forename: Shin Hye
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Department of Physiology, Sungkyunkwan University School of Medicine, 300 Chunchun-dong, Jangan-ku, Suwon, 440-746, Korea Center For Molecular Medicine, Samsung Biomedical Research Institute, 300 Chunchun-dong, Jangan-ku, Suwon, 440-746, Korea.
authors.forename: Hana
authors.initials: H
authors.lastname: Cho
authors.affiliation: Department of Physiology, Sungkyunkwan University School of Medicine, 300 Chunchun-dong, Jangan-ku, Suwon, 440-746, Korea Center For Molecular Medicine, Samsung Biomedical Research Institute, 300 Chunchun-dong, Jangan-ku, Suwon, 440-746, Korea.
authors.forename: Sungkwon
authors.initials: S
authors.lastname: Chung
authors.affiliation: Department of Physiology, Sungkyunkwan University School of Medicine, 300 Chunchun-dong, Jangan-ku, Suwon, 440-746, Korea Center For Molecular Medicine, Samsung Biomedical Research Institute, 300 Chunchun-dong, Jangan-ku, Suwon, 440-746, Korea mkpark@skku.edu kimhyunjin@skku.edu.
authors.forename: Hyun Jin
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Department of Physiology, Sungkyunkwan University School of Medicine, 300 Chunchun-dong, Jangan-ku, Suwon, 440-746, Korea Center For Molecular Medicine, Samsung Biomedical Research Institute, 300 Chunchun-dong, Jangan-ku, Suwon, 440-746, Korea mkpark@skku.edu kimhyunjin@skku.edu.
authors.forename: Myoung Kyu
authors.initials: MK
authors.lastname: Park
mesh_terms: D000200:Action Potentials; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D003712:Dendrites / Q000378:metabolism / Q000502:physiology*; D059290:Dopaminergic Neurons / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D008636:Mesencephalon / Q000166:cytology / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D002118:Calcium
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