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Cholinergic modulation of medial vestibular nucleus neurons of the gerbil in vitro Belzile, Denise
Abstract
The actions of various cholinergic agonists on 135 medial vestibular nucleus (MVN) neurons were investigated in in vitro brainstem preparations from young gerbils (p10-p15). Changes in conductance and membrane potential were determined using the whole cell patch clamp technique. Both muscarinic agonists (oxotremorine at concentrations of 5-20 µM) and mixed cholinergic agonists (acetylcholine and carbachol at concentrations of 10-20 µM) produced complex responses in the neurons. The membrane responses persisted on blockade of action potentials by application of 0.3 µM TTX. Increases and decreases in conductance with depolarizations and hyperpolarizations of the membrane potential were observed with all three drugs. There was no correlation between the changes in conductance and the changes in membrane potential. In order to examine the nicotinic responses of MVN neurons, the effects of acetylcholine and carbachol were studied during blockade of muscarinic receptors with the antagonist scopolamine (10 µM). Once again, a variety of membrane changes were observed, indicating a nicotinic response in these neurons. Acetylcholine applied simultaneously with the nicotinic blocker, mecamylamine (10 µM), also produced a mixed response in these neurons, indicating the presence of muscarinic receptors in this nucleus. The simultaneous application of scopolamine and mecamylamine failed to completely block the response of MVN neurons to acetylcholine. Both antagonists were found to have direct effects on MVN neurons, suggesting that endogenous acetylcholine is present within the slice preparation, and may affect the MVN in vivo. The results of these studies imply a more complex role for acetylcholine in the MVN than previously imagined. In addition, we have demonstrated a significant nicotinic response within these cells.
Item Metadata
Title |
Cholinergic modulation of medial vestibular nucleus neurons of the gerbil in vitro
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1999
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Description |
The actions of various cholinergic agonists on 135 medial vestibular nucleus (MVN) neurons
were investigated in in vitro brainstem preparations from young gerbils (p10-p15). Changes
in conductance and membrane potential were determined using the whole cell patch clamp
technique. Both muscarinic agonists (oxotremorine at concentrations of 5-20 µM) and mixed
cholinergic agonists (acetylcholine and carbachol at concentrations of 10-20 µM) produced
complex responses in the neurons. The membrane responses persisted on blockade of action
potentials by application of 0.3 µM TTX. Increases and decreases in conductance with
depolarizations and hyperpolarizations of the membrane potential were observed with all
three drugs. There was no correlation between the changes in conductance and the changes in
membrane potential. In order to examine the nicotinic responses of MVN neurons, the
effects of acetylcholine and carbachol were studied during blockade of muscarinic receptors
with the antagonist scopolamine (10 µM). Once again, a variety of membrane changes were
observed, indicating a nicotinic response in these neurons. Acetylcholine applied
simultaneously with the nicotinic blocker, mecamylamine (10 µM), also produced a mixed
response in these neurons, indicating the presence of muscarinic receptors in this nucleus.
The simultaneous application of scopolamine and mecamylamine failed to completely block
the response of MVN neurons to acetylcholine. Both antagonists were found to have direct
effects on MVN neurons, suggesting that endogenous acetylcholine is present within the slice
preparation, and may affect the MVN in vivo. The results of these studies imply a more
complex role for acetylcholine in the MVN than previously imagined. In addition, we have
demonstrated a significant nicotinic response within these cells.
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Extent |
4794107 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-06-12
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0099312
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
1999-11
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
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Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.