Anodal transcranial direct current stimulation affects auditory cortex plasticity in normal-hearing and noise-exposed rats

作者：Paciello Fabiola; Podda Maria Vittoria^*; Rolesi Rolando; Cocco Sara; Petrosini Laura; Troiani Diana; Fetoni Anna Rita^*; Paludetti Gaetano; Grassi Claudio

来源：Brain Stimulation, 2018, 11(5): 1008-1023.

DOI：10.1016/j.brs.2018.05.017

• Auditory cortex
• Brain-derived neurotrophic factor
• Dendritic spines
• Personalized medicine
• Synaptic transmission
• tDCS

Background: Transcranial direct current stimulation (tDCS) is a non-invasive tool capable to modulate cortical functions by affecting neuronal excitability and synaptic plasticity.
Objective: Here we investigated the effects of anodal tDCS on auditory cortex (ACx) in normal-hearing rats and following a paradigm of noise-induced hearing loss (NIHL), that causes morphological alterations in ACx pyramidal neurons.
Methods: Male rats exposed to intense pure tone (10 kHz) were subsequently subjected to unilateral anodal tDCS of ACx and changes in dendritic morphology and spines were assessed by Golgi-Cox staining 30 days after the onset of the acoustic trauma. Molecular and functional changes were investigated by Western immunoblotting, immunofluorescence experiments and electrophysiological recordings in brain slices.
Results: We found that NIHL altered dendritic morphology by decreasing spine density, mostly in layer 2/3 pyramidal neurons. Interestingly, tDCS increased ACx spine density, targeting apical dendrites of layer 2/3 and 5/6 pyramidal neurons in rats with normal auditory function and both apical and basal arborizations in layer 2/3 of NIHL rats. Twenty-four hours after tDCS, Bdnf and synaptophysin levels in ACx increased both in normal-hearing and noise-exposed rats. Field recordings showed that basal synaptic transmission at layer 2/3 horizontal connections was significantly reduced in noise-exposed rats compared to normal-hearing animals and, notably, input-output curves of noise-exposed animals subjected to tDCS were similar to those of normal-hearing rats.
Conclusions: Our findings provide novel evidence that anodal tDCS affects structural plasticity in the ACx suggesting that it might be beneficial in treating cortical alterations due to cochlear damage.

• 出版日期2018-10