Neuroscience 2003 Abstract
| Presentation Number: | 377.19 |
|---|---|
| Abstract Title: | Histamine inhibits thalamic reticular/perigeniculate neurons by activating a chloride conductance. |
| Authors: |
Broberger, C.*1
; Lee, K.1
; McCormick, D. A.1
1Dept. of NeuroBiol., Yale Univ. Sch. Med, New Haven, CT |
| Primary Theme and Topics |
Sensory Systems - Tactile/Somatosensory -- Cortex and thalamocortical relationships |
| Secondary Theme and Topics | Synaptic Transmission and Excitability<br />- Neurotransmitters<br />-- Catecholamines |
| Session: |
377. Modulation & Plasticity of Intrinsic Membrane Properties I Poster |
| Presentation Time: | Monday, November 10, 2003 10:00 AM-11:00 AM |
| Location: | Morial Convention Center - Hall F-I, Board # F85 |
| Keywords: | thalamus, AROUSAL, tuberomammillary, sleep spindles |
Histaminergic terminals innervate the thalamus, suggesting that histamine-induced arousal may in part be mediated via the thalamocortical network. Here we investigated the actions of histamine on neurons in the perigeniculate/thalamic reticular nucleus. Intra- and extracellular recordings were performed on an in vitro slice preparation of the ferret geniculate complex and/or thalamus. Local application of histamine resulted in decreased input resistance and, depending on resting membrane potential, either a hyper- or depolarization towards -73 mV. This effect was resistant to local application of tetrodotoxin, suggesting the involvement of direct postsynaptic actions. Blocking the histamine H2 receptor with the antagonist tiotidine abolished the histamine response, whereas the effects on membrane potential and input resistance remained intact in the presence of the H1 and H3 antagonists, diphenhydramine and thiopyramide, respectively. The change in membrane potential was associated with a current that reversed around -73 mV when recorded with either 2 M potassium acetate or 3 M cesium acetate-filled electrodes; the same reversal potential was observed when histamine was substituted with the GABAA agonist muscimol. When electrodes filled with 3 M potassium chloride were used in order to load cells with Cl-, the reversal potential of both the histamine and muscimol responses shifted to more depolarized membrane potentials to a similar extent. These data indicate that histamine H2 receptors in the reticular/perigeniculate thalamus couple to a chloride, rather than a potassium, conductance, and that activation of this conductance inhibits the neurons. Notably, bath application of histamine resulted in the cessation of sleep spindle activity as observed with extracellular multi-unit recordings, suggesting that increased thalamic histaminergic tone may have prominent functional consequences.
Supported by The NIH, Wenner-Gren Foundation and Fulbright Commission
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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