Serotonergic modulation of inhibitory synaptic transmission in mouse inferiorcolliculus
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- OBARA Nobuyuki
- Department of Otolaryngology–Head and Neck Surgery Hokkaido University Graduate School ofMedicine, Sapporo 060-8638, Japan Department of Neurobiology, Hokkaido University Graduate School ofMedicine, Sapporo 060-8638, Japan
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- KAMIYA Haruyuki
- Department of Neurobiology, Hokkaido University Graduate School ofMedicine, Sapporo 060-8638, Japan
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- FUKUDA Satoshi
- Department of Otolaryngology–Head and Neck Surgery Hokkaido University Graduate School ofMedicine, Sapporo 060-8638, Japan
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Abstract
The inferior colliculus (IC) transmits the ascending auditory signal to the thalamic medial geniculatenucleus. Previous studies have reported that serotonergic input originating from the raphe nucleihas a strong influence on signal processing within the central nucleus of the IC. To identifythe cellular target for the serotonergic modulation in the IC, we examined the effect of serotoninas well as selective serotonin reuptake inhibitor (SSRI) fluvoxamine on spontaneous GABAergicand glycinergic inhibitory postsynaptic currents (sIPSCs) recorded with whole-cell recordings.Consistent with earlier studies, we confirmed that serotonin robustly enhanced the frequency, butnot amplitude, of GABAergic sIPSCs. It should be noted that the application of fluvoxamine alonemarginally increased the frequency of GABAergic sIPSCs. These findings suggest that serotonin isendogenously released even in slice preparations, and it negatively modulates the tone of activityof inhibitory neurons within IC. We also examined the effect of serotonin and fluvoxamine on glycinergicsIPSCs and found that serotonin has a significantly weaker effect on glycinergic sIPSCsthan on GABAergic sIPSCs. The differential sensitivity of the GABAergic and glycinergic sIPSCsto serotonin implies that serotonergic input plays a specific role in auditory information processing.Moreover, it suggests that the serotonergic input may contribute to pathological conditionssuch as tinnitus.
Journal
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- Biomedical Research
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Biomedical Research 35 (1), 81-84, 2014
Biomedical Research Press