The Journal of Neuroscience, September 15, 2001, 21(18):7372-7383
Cholinergic Modulation of Stellate Cells in the Mammalian Ventral
Cochlear Nucleus
Kiyohiro
Fujino and
Donata
Oertel
Department of Physiology, University of Wisconsin, Madison,
Wisconsin 53706
The main source of excitation to the ventral cochlear nucleus (VCN)
is from glutamatergic auditory nerve afferents, but the VCN is also
innervated by two groups of cholinergic efferents from the ventral
nucleus of the trapezoid body. One arises from collaterals of medial
olivocochlear efferents, and the other arises from neurons that project
solely to the VCN. This study examines the action of cholinergic inputs
on stellate cells in the VCN. T stellate cells, which form one of the
ascending auditory pathways to the inferior colliculus, and D stellate
cells, which inhibit T stellate cells, are distinguished
electrophysiologically. Whole-cell recordings from stellate cells in
slices of the VCN of mice demonstrate that most T stellate cells are
excited by cholinergic agonists through three types of receptors,
whereas all D stellate cells tested were insensitive to cholinergic
agonists. Nicotinic excitation in T stellate cells has two components.
The faster component was blocked by 
-bungarotoxin and
methyllycaconitine, suggesting that receptors contained 7 subunits;
the slower component was insensitive to both. Muscarinic receptors
excite T stellate cells by blocking a voltage-insensitive, "leak"
potassium conductance. Our results suggest that cholinergic efferent
innervation enhances excitation by sounds of T stellate cells, opposing
the inhibitory action of cholinergic innervation in the cochlea that is
conveyed indirectly through the glutamatergic afferents. The inhibitory
action of D stellate cells on their targets is probably not affected by cholinergic inputs. Excitation of T stellate cells by cholinergic efferents would be expected to enhance the encoding of spectral peaks
in noise.
Key words:
cholinergic efferents; ventral cochlear nucleus; auditory
pathways; nicotinic; -bungarotoxin; muscarinic; leak potassium
conductance
Copyright © 2001 Society for Neuroscience 0270-6474/01/21187372-12$05.00/0
Previous Article | Next Article
