Effects of cholinergic neuromodulation in the rat dorsal cochlear nucleus: a calcium imaging study performed on brain slices.
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1
University of Debrecen, Institute of Physiology, Hungary
In a previous study our laboratory showed that the cholinergic agonist, carbachol increased the spontaneous activity of the giant neurons of the dorsal cochlear nucleus (DCN) with electro physiological technics. The increased activity was partly due to a potassium conductance decrease mediated by M3 and M4 muscarinic cholinergic receptors situated directly on the giant cells. We also observed cholinergic modulational effect on the synaptic inputs of the giant cells. To further investigate this presynaptic effect proposed by the electrophysiological experiments, in this work we used “multy neuronal calcium imaging” on Oregon Green-AM loaded DCN slices.
We studied the effect of carbachol on the neurons of DCN in the presence of a glutamatergic, glycinergic and GABA-ergic neurotransmission blocking “cocktail” (NBQX, AP5, strychnine, bicuculline). The effect observed on the neurons - parted from each other by this pharmacological manipulation - is presumably mediated through receptors situated directly on these cells themselves. With this method we observed significant calcium event frequency increase in a number of small cells in the DCN. The average diameter of these carbachol-responding-small-cells was 7.1 micron. It suggests that these cells might be the granule cells of the DCN as they have 6-8 micron soma diameter conventionally.
Afterwards also in the presence of the glutamatergic, glycinergic and GABA-ergic neurotransmission blocking “cocktail” we examined whether the effect of carbachol can be prevented with atropine. In the case of eight of nine cells showing activity increase for carbachol, atropin prevented the effect of carbachol.
Our results point out a significant cholinerg neuro modulatory effect on some of the small cells of the DCN. According to our experimental procedure this effect seems to be mediated by muscarinic receptors situated directly on these “carbachol-responding” small cells, which might be the granule cells of the DCN.
Conference:
IBRO International Workshop 2010, Pécs, Hungary, 21 Jan - 23 Jan, 2010.
Presentation Type:
Poster Presentation
Topic:
Sensory and motor systems
Citation:
Koszeghy
A,
Pál
B,
SzXucs
G and
Rusznák
Z
(2010). Effects of cholinergic neuromodulation in the rat dorsal cochlear nucleus: a calcium imaging study performed on brain slices..
Front. Neurosci.
Conference Abstract:
IBRO International Workshop 2010.
doi: 10.3389/conf.fnins.2010.10.00239
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Received:
05 May 2010;
Published Online:
05 May 2010.
*
Correspondence:
Aron Koszeghy, University of Debrecen, Institute of Physiology, Debrecen, Hungary, aron.koeszeghy@meduniwien.ac.at