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This Article Full Text Full Text (PDF) All Versions of this Article: 582/2/597    most recent jphysiol.2007.135319v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Fayuk, D. Articles by Yakel, J. L. Search for Related Content PubMed PubMed Citation Articles by Fayuk, D. Articles by Yakel, J. L. Related Collections Neuroscience

¹ Laboratory of Neurobiology, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, PO Box 12233, Research Triangle Park, NC 27709, USA

Neuronal nicotinic acetylcholine receptors (nAChRs) are in the superfamily of Cys-loop ligand-gated ion channels, which are widely expressed in the brain. Among the many different subtypes of nAChRs known to be expressed in the rat brain, the 7-containing nAChRs are considered to be the most permeable to Ca²⁺. Utilizing highly localized and rapid iontophoretic agonist delivery, combined with patch-clamp electrophysiology and fura-2 fluorescence imaging techniques, we examined the 7 nAChR-mediated currents and [Ca²⁺]_i transients in the dendrites of rat hippocampal CA1 interneurons in the slice. We found that in the dendrites, whereas the amplitudes of the current responses were smaller and the decay kinetics faster than the responses in the soma, the amplitudes of the [Ca²⁺]_i signals were significantly larger. Cultured hippocampal neurons were studied since the dendritic field lies in the same focal plane, which allowed for a broader investigation of the spatiotemporal dynamics of [Ca²⁺]_i signalling. In cultured neurons, the [Ca²⁺]_i signals in the dendrites were similar to those in slices. Interestingly in cultures, even though the amplitude of the 7 nAChR-mediated currents dramatically decreased with distance from the soma (from 20–250 µm), the amplitude of the [Ca²⁺]_i signals did not correlate with distance. This indicates that the relative efficacy of 7 nAChR activation to increase [Ca²⁺]_i levels in dendrites increased severalfold with distance from the soma. These results may have implications for the role that 7 nAChRs have in regulating various signal transduction cascades, synaptic plasticity, and memory processes, via significant changes in [Ca²⁺]_i levels.

(Received 25 April 2007; accepted after revision 14 May 2007; first published online 17 May 2007)
Corresponding author J. L. Yakel: NIEHS, F2–08, PO Box 12233, 111 T. W. Alexander Drive, Research Triangle Park, NC 27709, USA. Email: yakel{at}niehs.nih.gov

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