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Nitric oxide regulates the firing rate of neuronal subtypes in the guinea pig ventral cochlear nucleus
Author(s) -
Hockley Adam,
Berger Joel I.,
Smith Paul A.,
Palmer Alan R.,
Wallace Mark N.
Publication year - 2020
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/ejn.14572
Subject(s) - nmda receptor , chemistry , nitric oxide , endogeny , nitric oxide synthase , biophysics , cochlear nucleus , long term potentiation , neuroscience , nucleus , glutamate receptor , biology , biochemistry , receptor , organic chemistry
The gaseous free radical, nitric oxide ( NO ) acts as a ubiquitous neuromodulator, contributing to synaptic plasticity in a complex way that can involve either long term potentiation or depression. It is produced by neuronal nitric oxide synthase ( nNOS ) which is presynaptically expressed and also located postsynaptically in the membrane and cytoplasm of a subpopulation of each major neuronal type in the ventral cochlear nucleus ( VCN ). We have used iontophoresis in vivo to study the effect of the NOS inhibitor L‐ NAME (L‐ NG ‐Nitroarginine methyl ester) and the NO donors SIN ‐1 (3‐Morpholinosydnonimine hydrochloride) and SNOG (S‐Nitrosoglutathione) on VCN units under urethane anaesthesia. Collectively, both donors produced increases and decreases in driven and spontaneous firing rates of some neurones. Inhibition of endogenous NO production with L‐ NAME evoked a consistent increase in driven firing rates in 18% of units without much effect on spontaneous rate. This reduction of gain produced by endogenous NO was mirrored when studying the effect of L‐ NAME on NMDA ( N ‐Methyl‐D‐aspartic acid)‐evoked excitation, with 30% of units showing enhanced NMDA ‐evoked excitation during L‐ NAME application (reduced NO levels). Approximately 25% of neurones contain nNOS and the NO produced can modulate the firing rate of the main principal cells: medium stellates (choppers), large stellates (onset responses) and bushy cells (primary‐like responses). The main endogenous role of NO seems to be to partly suppress driven firing rates associated with NMDA channel activity but there is scope for it to increase neural gain if there were a pathological increase in its production following hearing loss.