Ablation of the auditory cortex results in changes in the expression of neurotransmission-related mRNAs in the cochlea

作者：Lamas Veronica^*; Juiz Jose M; Merchan Miguel A

来源：Hearing Research, 2017, 346: 71-80.

DOI：10.1016/j.heares.2017.02.011

• Inner ear
• Descending control
• Auditory cortex
• Olivocochlear efferent system
• Postsynaptic receptors
• Homeostatic plasticity

The auditory cortex (AC) dynamically regulates responses of the Organ of Corti to sound through descending connections to both the medial (MOC) and lateral (LOC) olivocochlear efferent systems. We have recently provided evidence that AC has a reinforcement role in the responses to sound of the auditory brainstem nuclei. In a molecular level, we have shown that descending inputs from AC are needed to regulate the expression of molecules involved in outer hair cell (OHC) electromotility control, such as prestin and the alpha 10 nicotinic acetylcholine receptor (nAchR). In this report, we show that descending connections from AC to olivocochlear neurons are necessary to regulate the expression of molecules involved in cochlear afferent signaling. RT-qPCR was performed in rats at 1, 7 and 15 days after unilateral ablation of the AC, and analyzed the time course changes in gene transcripts involved in neurotransmission at the first auditory synapse. This included the glutamate metabolism enzyme glutamate decarboxylase 1 (glud1) and AMPA glutamate receptor subunits GluA2-4. In addition, gene transcripts involved in efferent regulation of type I spiral ganglion neuron (SGN) excitability mediated by LOC, such as the alpha 7 nAchR, the D2 dopamine receptor, and the alpha 1, and gamma 2 GABAA receptor subunits, were also investigated. Unilateral AC ablation induced up-regulation of GluA3 receptor subunit transcripts, whereas both GluA2 and GluA4 mRNA receptors were down-regulated already at 1 day after the ablation. Unilateral removal of the AC also resulted in up-regulation of the transcripts for alpha 7 nAchR subunit, D2 dopamine receptor, and alpha 1 GABAA receptor subunit at 1 day after the ablation. Fifteen days after the injury, AC ablations induced an up-regulation of glud1 transcripts.

• 出版日期2017-3