Neuroscience 2003 Abstract
| Presentation Number: | 799.9 |
|---|---|
| Abstract Title: | Multiple muscarine-sensitive conductances prime hippocampal CA1 oriens/alveus interneurons for local circuit oscillations. |
| Authors: |
Statland, J. M.*1,2
; Lawrence, J. J.2
; Grinspan, Z. M.1
; McBain, C. J.2
1HHMI, NIH, Bethesda, MD 2LCMN, NICHD, NIH, Bethesda, MD |
| Primary Theme and Topics |
Synaptic Transmission and Excitability - G-Protein linked Receptors -- Muscarinic receptors |
| Secondary Theme and Topics | Synaptic Transmission and Excitability<br />- Synaptic Transmission<br />-- Postsynaptic mechanisms: Excitatory |
| Session: |
799. Muscarinic Receptors Poster |
| Presentation Time: | Wednesday, November 12, 2003 8:00 AM-9:00 AM |
| Location: | Morial Convention Center - Hall F-I, Board # D79 |
| Keywords: | voltage clamp, M Current, AHP, ADP |
Cholinergic stimulation from the septum induces theta oscillations in the hippocampus. In this study, we use patch clamp recording from acute mouse slices to investigate muscarine-induced changes in intrinsic membrane conductances in CA1 oriens/alveus (OA) interneurons. The M-current (IM) is a voltage-gated potassium conductance that plays a key role in control of cell excitability. In 11 of 17 cells, bath application of 10μM muscarine caused a 72.5±6.8% inhibition of IM (p<0.0001) and an increase in action potential (AP) firing of 7.2±2.2 Hz (p=0.008). The same cells also showed a loss of accommodation that was not completely explained by inhibition of IM. The slow afterhyperpolarization (sIAHP) is a Ca2+-dependent potassium conductance. Muscarine inhibited the sIAHP by 74.1±6.0% (p=0.001, n=9), which unmasked a Ca2+/Na+ dependent inward afterdepolarization (IADP) that could be demonstrated in the absence of muscarine by addition of 10mM TEA. The timing of the shift in the balance between the sIAHP and IADP during wash-in of muscarine paralleled the loss of accommodation. Another population of cells were inhibited by muscarine (6 of 17). The leak current (IK(Leak)) is a voltage independent conductance that sets the resting membrane potential. Muscarine induced an increase in leak of 27.0±7.4% (p=0.009), which was accompanied by a decrease in AP firing of 1.8±0.54 Hz (p=0.02). We propose that activation of the septal cholinergic system causes a shift in the balance between the IM, sIAHP , and IK(Leak), in OA interneurons. If the changes in IM and sIAHP predominate, the net effect is to engage the hippocampal network by increasing AP reliability to synaptic inputs. However, domination by IK(Leak) reduces AP reliability, promoting disengagement from the network. Thus, the same neurotransmitter may differentially affect subsets of OA interneurons to enable a theta-permissive state.
Supported by NIH, HHMI and HFSP
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2003 Neuroscience Meeting Planner. New Orleans, LA: Society for Neuroscience, 2003. Online.
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