Neuroscience 2005 Abstract
| Presentation Number: | 377.13 |
|---|---|
| Abstract Title: | Activity-dependent regulation of HCN1 channel transport in axons of rat perforant path. |
| Authors: |
Bender, R. A.*1
; Kretz, O.2
; Patel, N. A.1
; Richichi, C.1
; Frotscher, M.2
; Baram, T. Z.1
1Dept Pediatrics Anat & Neurobiol, Univ. of California, Irvine, Irvine, CA 2Germany, Med Sci I, Room B160, 92697, |
| Primary Theme and Topics |
Neural Excitability, Synapses, and Glia: Cellular Mechanisms - Ion Channels -- HCN and non-selective cation channels |
| Secondary Theme and Topics | Development<br />- Synaptogenesis and Activity-Dependent Development<br />-- Synaptogenesis and activity-dependent plasticity |
| Session: |
377. HCN and Nonselective Cation Channels Poster |
| Presentation Time: | Monday, November 14, 2005 8:00 AM-9:00 AM |
| Location: | Washington Convention Center - Hall A-C, Board # D38 |
| Keywords: | Entorhinal cortex, hippocampus, organotypic culture, ion channel |
Rationale: Expression of HCN channels in hippocampus is developmentally regulated, suggesting that these channels contribute to age-specific network functions (Bender, Neuroscience, 2001). We recently found that sub-cellular transport of the HCN1 channel isoform can also be age-dependent: In immature rats, HCN1 channels are abundantly expressed in the perforant path, in axons of entorhinal cortex (EC) layer II neurons. This expression weakens and virtually disappears with age (Bender, SFN, 2004). Because neuronal activity influences expression of HCN channels in developing hippocampus (Brewster, J Neurosci, 2002), we examined whether neuronal activity governs also the sub-cellular transport of these channels, using organotypic slice cultures, in which normal neuronal activity was maintained or blocked.
Methods: Entorhino-hippocampal slice cultures were explanted on P4 and cultured for 7 days, with or without TTX (0.1 *micro*M) in the culture medium. HCN1 protein and mRNA expression were analyzed using immunohistochemistry (ICC) and in situ hybridization, respectively. Electron microscopy and immuno-gold ICC were carried out in vivo, to determine the precise sub-cellular location of the HCN1 channel molecules.
Results: HCN1 immunoreactivity was detected in dentate gyrus molecular layer (the perforant path termination zone). Electron microscopy revealed that, in immature hippocampus, the channel is localized specifically to axon terminals and presynaptic zones. Elimination of neuronal activity (action potentials) for a week using TTX increased HCN1 signal significantly (~25%). This was not a result of increased HCN1 expression in EC layer II neurons (TTX-treated vs control cultures, p=0.68).
Conclusion: Neuronal activity is an important determinant of the amount of HCN1 channels that is transported to perforant path axons. This effect is independent of mRNA expression levels.
Methods: Entorhino-hippocampal slice cultures were explanted on P4 and cultured for 7 days, with or without TTX (0.1 *micro*M) in the culture medium. HCN1 protein and mRNA expression were analyzed using immunohistochemistry (ICC) and in situ hybridization, respectively. Electron microscopy and immuno-gold ICC were carried out in vivo, to determine the precise sub-cellular location of the HCN1 channel molecules.
Results: HCN1 immunoreactivity was detected in dentate gyrus molecular layer (the perforant path termination zone). Electron microscopy revealed that, in immature hippocampus, the channel is localized specifically to axon terminals and presynaptic zones. Elimination of neuronal activity (action potentials) for a week using TTX increased HCN1 signal significantly (~25%). This was not a result of increased HCN1 expression in EC layer II neurons (TTX-treated vs control cultures, p=0.68).
Conclusion: Neuronal activity is an important determinant of the amount of HCN1 channels that is transported to perforant path axons. This effect is independent of mRNA expression levels.
Supported by NIH 35439
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2005 Neuroscience Meeting Planner. Washington, DC: Society for Neuroscience, 2005. Online.
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