GABA-like immunoreactivity in the cochlea of the developing mouse.
GABA-like immunoreactivity in the cochlea of the developing mouse.
复制标题
发育中小鼠耳蜗中的 GABA 样免疫反应性。
DOI：
10.1007/bf01474546
复制
发表时间：
1989
期刊：
影响因子：
--
通讯作者：
Sobkowicz,HM
中科院分区：
文献类型：
--
作者：
Whitlon,DS;Sobkowicz,HM
用免疫组织化学方法研究了出生后发育的小鼠耳蜗表组织中的GABA样免疫反应，并对成年小鼠耳蜗表面的GAD免疫反应进行了研究。GABA阳性纤维在出生时就已经存在；它们既支配内、外毛细胞，也支配一些螺旋神经节细胞。通过神经节内束进入的GABA阳性纤维将侧支发送到螺旋神经节和毛细胞区。沿着螺旋神经元中央突起进入的纤维主要终止于螺旋神经节细胞之间。少数螺旋神经元在出生时显示出GABA阳性的胞周环。在年长的动物中，末端出现在少数螺旋神经节细胞上，要么呈环状，要么呈刷状。早期的GABA阳性纤维在第二天左右到达内毛细胞，在第七天左右到达外毛细胞(仅在上回)。在12日龄的动物中，隧道纤维分布在外毛细胞区；它们的侧枝在四到八个细胞范围的节段内与外毛细胞接触，将末端分布得很高，直到网状板。在年长的动物中，纤维(GABA和GAD阳性)可能支配单个垂直排列的外毛细胞。在成熟期和成年期，耳蜗内螺旋束的GABA阳性成分明显，并沿整个耳蜗长分布，而外毛细胞的神经支配仅包括中、顶回。GABA阳性神经细胞出现在小前庭神经元中，偶尔出现在第八神经核细胞中，仅例外出现在螺旋神经节中。在成年动物中，GAD阳性细胞虽然不常见，但在螺旋神经元中也可观察到。在发育中的动物中，GABA阳性纤维产生了暂时性的形成：(1)在放射束下面和之间有一个卷曲的神经丛；(2)一个稀疏的神经丛，与内螺旋束连续，在内螺旋沟的上平面上运行。在神经元生长锥体和一些沿血管走行的纤维中也观察到了GABA样免疫反应。综上所述，GABA免疫反应纤维似乎通过两条途径到达耳蜗区：通过神经节内束，少量通过螺旋神经节的中央束。这些纤维支配感觉细胞和一些螺旋神经元。在前庭神经节、VIIIth神经核和螺旋神经元中偶尔出现GABA阳性神经元，增加了内耳局部GABA能回路的可能性。
GABA-like immunoreactivity was studied in surface preparations of cochleas from postnatal developing mice, and GAD-like immunoreactivity was studied in the adult. GABA-positive fibres are already present at birth; they innervate both the inner and outer hair cells and some spiral ganglion cells. The GABA-positive fibres that enter via the intraganglionic bundle send collaterals to the spiral ganglion and to the hair cell region. Fibres that enter along the central processes of spiral neurons end predominantly among the spiral ganglion cells. A few spiral neurons display pericellular rings of GABA-positive boutons at birth. In older animals, the endings occur on a small number of spiral ganglion cells either as rings or as brush formations. The early GABA-positive fibres reach the inner hair cells around the second day and the outer hair cells (of the upper turns only) around the seventh day. In 12-day animals, tunnel fibres arborize in the outer hair cell region; their collaterals make contacts with the outer hair cells within four to eight cell-wide segments, distributing the endings high, up to the reticular plate. In older animals, fibres (both GABA- and GAD-positive) may innervate single vertical rows of outer hair cells. In the maturing and the adult cochlea, the GABA-positive component of the inner spiral bundle is conspicuous and extends along the entire cochlear length, but the innervation of the outer hair cells comprises only the mid and apical turns.GABA-positive nerve cells occur among the small vestibular neurons, occasionally among the cells of eighth nerve nucleus and only exceptionally in the spiral ganglion. In the adult animal, GAD-positive cells, although uncommon, were observed among the spiral neurons.In the developing animal, GABA-positive fibres give rise to transitory formations: (1) a convoluted plexus running beneath and among the radial bundles and (2) a sparse plexus, continuous with the inner spiral bundle and running in the upper plane of the inner spiral sulcus. GABA-like immunoreactivity was also observed in neuronal growth cones and in some fibres running along blood vessels.In conclusion, GABA immunoreactive fibres appear to reach the cochlea by two routes: via the intraganglionic bundle and to a much lesser extent via the central bundles of the spiral ganglion. The fibres innervate sensory cells and also some spiral neurons. The occasional presence of GABA-positive neurons in the vestibular ganglion, in the VIIIth nerve nucleus, and exceptionally among the spiral neurons raises the possibility of a local GABAergic circuitry within the inner ear.