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Characterisation of hyperpolarization-activated currents (I(h)) in the medial septum/diagonal band complex in the mouse.
Brain Res. 2004 Apr 23; 1006(1):74-86.BR

Abstract

Hyperpolarization-activated cyclic nucleotide gated (HCN) channel subunits are distributed widely, but selectively, in the central nervous system, and underlie hyperpolarization-activated currents (I(h)) that contribute to rhythmicity in a variety of neurons. This study investigates, using current and voltage-clamp techniques in brain slices from young mice, the properties of I(h) currents in medial septum/diagonal band (MS/DB) neurons. Subsets of neurons in this complex, including GABAergic and cholinergic neurons, innervate the hippocampal formation, and play a role in modulating hippocampal theta rhythm. In support of a potential role for I(h) in regulating MS/DB firing properties and consequently hippocampal neuron rhythmicity, I(h) currents were present in around 60% of midline MS/DB complex neurons. The I(h) currents were sensitive to the selective blocker ZD7288 (10 microM). The I(h) current had a time constant of activation of around 220 ms (at -130 mV), and tail current analysis revealed a half-activation voltage of -98 mV. Notably, the amplitude and kinetics of I(h) currents in MS/DB neurons were insensitive to the cAMP membrane permeable analogue 8-bromo-cAMP (1 mM), and application of muscarine (100 microM). Immunofluoresence using antibodies against HCN1, 2 and 4 channel subunits revealed that all three HCN subunits are expressed in neurons in the MS/DB, including neurons that express the calcium binding protein parvalbumin (marker of fast spiking GABAergic septo-hippocampal projection neurons). The results demonstrate, for the first time, that specific HCN channel subunits are likely to be coexpressed in subsets of MS/DB neurons, and that the resultant I(h) currents show both similarities, and differences, to previously described I(h) currents in other CNS neurons.

Authors+Show Affiliations

School of Biomedical Sciences, University of Leeds, Worsley Building, Leeds LS2 9NQ, UK. n.p.morris@leeds.ac.ukNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

15047026

Citation

Morris, Neil P., et al. "Characterisation of Hyperpolarization-activated Currents (I(h)) in the Medial Septum/diagonal Band Complex in the Mouse." Brain Research, vol. 1006, no. 1, 2004, pp. 74-86.
Morris NP, Fyffe RE, Robertson B. Characterisation of hyperpolarization-activated currents (I(h)) in the medial septum/diagonal band complex in the mouse. Brain Res. 2004;1006(1):74-86.
Morris, N. P., Fyffe, R. E., & Robertson, B. (2004). Characterisation of hyperpolarization-activated currents (I(h)) in the medial septum/diagonal band complex in the mouse. Brain Research, 1006(1), 74-86.
Morris NP, Fyffe RE, Robertson B. Characterisation of Hyperpolarization-activated Currents (I(h)) in the Medial Septum/diagonal Band Complex in the Mouse. Brain Res. 2004 Apr 23;1006(1):74-86. PubMed PMID: 15047026.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Characterisation of hyperpolarization-activated currents (I(h)) in the medial septum/diagonal band complex in the mouse. AU - Morris,Neil P, AU - Fyffe,Robert E W, AU - Robertson,Brian, PY - 2004/01/30/accepted PY - 2004/3/30/pubmed PY - 2004/6/21/medline PY - 2004/3/30/entrez SP - 74 EP - 86 JF - Brain research JO - Brain Res VL - 1006 IS - 1 N2 - Hyperpolarization-activated cyclic nucleotide gated (HCN) channel subunits are distributed widely, but selectively, in the central nervous system, and underlie hyperpolarization-activated currents (I(h)) that contribute to rhythmicity in a variety of neurons. This study investigates, using current and voltage-clamp techniques in brain slices from young mice, the properties of I(h) currents in medial septum/diagonal band (MS/DB) neurons. Subsets of neurons in this complex, including GABAergic and cholinergic neurons, innervate the hippocampal formation, and play a role in modulating hippocampal theta rhythm. In support of a potential role for I(h) in regulating MS/DB firing properties and consequently hippocampal neuron rhythmicity, I(h) currents were present in around 60% of midline MS/DB complex neurons. The I(h) currents were sensitive to the selective blocker ZD7288 (10 microM). The I(h) current had a time constant of activation of around 220 ms (at -130 mV), and tail current analysis revealed a half-activation voltage of -98 mV. Notably, the amplitude and kinetics of I(h) currents in MS/DB neurons were insensitive to the cAMP membrane permeable analogue 8-bromo-cAMP (1 mM), and application of muscarine (100 microM). Immunofluoresence using antibodies against HCN1, 2 and 4 channel subunits revealed that all three HCN subunits are expressed in neurons in the MS/DB, including neurons that express the calcium binding protein parvalbumin (marker of fast spiking GABAergic septo-hippocampal projection neurons). The results demonstrate, for the first time, that specific HCN channel subunits are likely to be coexpressed in subsets of MS/DB neurons, and that the resultant I(h) currents show both similarities, and differences, to previously described I(h) currents in other CNS neurons. SN - 0006-8993 UR - https://www.unboundmedicine.com/medline/citation/15047026/Characterisation_of_hyperpolarization_activated_currents__I_h___in_the_medial_septum/diagonal_band_complex_in_the_mouse_ DB - PRIME DP - Unbound Medicine ER -