Ouda Ladislav, Burianová Jana, Balogová Zuzana, Lu Hui Pin, Syka Josef
Department of Auditory Neuroscience, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20, Prague, Czech Republic.
Medical College, National Cheng Kung University, Tainan, Taiwan.
Brain Struct Funct. 2016 Jan;221(1):617-29. doi: 10.1007/s00429-014-0929-z. Epub 2014 Nov 19.
In previous studies (Grécová et al., Eur J Neurosci 29:1921-1930, 2009; Bures et al., Eur J Neurosci 32:155-164, 2010), we demonstrated that after an early postnatal short noise exposure (8 min 125 dB, day 14) changes in the frequency tuning curves as well as changes in the coding of sound intensity are present in the inferior colliculus (IC) of adult rats. In this study, we analyze on the basis of the Golgi-Cox method the morphology of neurons in the IC, the medial geniculate body (MGB) and the auditory cortex (AC) of 3-month-old Long-Evans rats exposed to identical noise at postnatal day 14 and compare the results to littermate controls. In rats exposed to noise as pups, the mean total length of the neuronal tree was found to be larger in the external cortex and the central nucleus of the IC and in the ventral division of the MGB. In addition, the numerical density of dendritic spines was decreased on the branches of neurons in the ventral division of the MGB in noise-exposed animals. In the AC, the mean total length of the apical dendritic segments of pyramidal neurons was significantly shorter in noise-exposed rats, however, only slight differences with respect to controls were observed in the length of basal dendrites of pyramidal cells as well as in the neuronal trees of AC non-pyramidal neurons. The numerical density of dendritic spines on the branches of pyramidal AC neurons was lower in exposed rats than in controls. These findings demonstrate that early postnatal short noise exposure can induce permanent changes in the development of neurons in the central auditory system, which apparently represent morphological correlates of functional plasticity.
在先前的研究中（格雷科娃等人，《欧洲神经科学杂志》29:1921 - 1930，2009年；布雷斯等人，《欧洲神经科学杂志》32:155 - 164，2010年），我们证明了在出生后早期短暂噪声暴露（出生第14天，8分钟125分贝）后，成年大鼠下丘（IC）中存在频率调谐曲线的变化以及声音强度编码的变化。在本研究中，我们基于高尔基 - 考克斯方法分析了出生后第14天暴露于相同噪声的3个月大的朗 - 埃文斯大鼠的IC、内侧膝状体（MGB）和听觉皮层（AC）中神经元的形态，并将结果与同窝对照进行比较。在幼年时暴露于噪声的大鼠中，发现IC的外侧皮层和中央核以及MGB腹侧部的神经元树的平均总长度更大。此外，在暴露于噪声的动物中，MGB腹侧部神经元分支上的树突棘数量密度降低。在AC中，暴露于噪声的大鼠中锥体神经元顶树突段的平均总长度明显较短，然而，在锥体细胞的基底树突长度以及AC非锥体神经元的神经元树上，与对照相比仅观察到轻微差异。暴露大鼠中AC锥体神经元分支上的树突棘数量密度低于对照。这些发现表明，出生后早期短暂噪声暴露可诱导中枢听觉系统神经元发育的永久性变化，这显然代表了功能可塑性的形态学关联。
