Schwarz D W, Schwarz I E, Hu K
Division of Otolaryngology, University of British Columbia, Vancouver, Canada.
J Otolaryngol. 1989 Feb;18(1):28-31.
It is likely that several mechanisms contribute to the efferent control of cochlear and vestibular function. Different effects are probably mediated by different neuronal transmitters. In spite of a number of transmitter candidates, it is still widely assumed that the entire efferent system can be globally characterized as cholinergic. We attempted to label retrogradely identified efferent neurons in the brainstem with a monoclonal antibody against choline acetyltransferase (ChAT), the acetylcholine (ACh) synthesizing enzyme. Only a portion of the vestibular efferents could thus be shown to be cholinergic in the rat. Medial cochlear efferents, terminating under outer hair cells, may also be cholinergic since they stain intensely for acetylcholine esterase (AChE) after pre-treatment with the AChE inhibitor diisopropylfluorophosphate (DFP). The lateral cochlear efferents terminating under inner hair cells, as well as more than half of the vestibular efferent neuron population, reacted negatively with either method designed to identify cholinergic neurons. Half of the lateral olivo-cochlear neuron population filled retrogradely with tritiated gamma-amino butyric acid [( 3H]-GABA). These cells were similar in size and distribution to neurons staining for the GABA synthesizing enzyme glutamic acid decarboxylase (GAD). Retrograde transport of [3H]-aspartate from the inner ear to the brainstem was seen in half of the lateral olivocochlear population, as well as in part of the efferent vestibular population in group E and in the caudal pontine reticular nucleus (CPR). Since various peptides have also been located in efferent neurons, this system is chemically diversified. Several distinct mechanisms of efferent control with presumably differing functions must, therefore, exist.
可能有多种机制参与耳蜗和前庭功能的传出控制。不同的效应可能由不同的神经递质介导。尽管有多种递质候选物，但人们仍然普遍认为整个传出系统可总体上被视为胆碱能系统。我们试图用一种针对胆碱乙酰转移酶（ChAT，乙酰胆碱（ACh）合成酶）的单克隆抗体对脑干中逆行鉴定的传出神经元进行标记。结果显示，在大鼠中只有一部分前庭传出纤维是胆碱能的。终止于外毛细胞下方的内侧耳蜗传出纤维也可能是胆碱能的，因为在用乙酰胆碱酯酶（AChE）抑制剂二异丙基氟磷酸酯（DFP）预处理后，它们对乙酰胆碱酯酶有强烈染色。终止于内毛细胞下方的外侧耳蜗传出纤维，以及超过一半的前庭传出神经元群体，对任何一种旨在鉴定胆碱能神经元的方法均呈阴性反应。外侧橄榄耳蜗神经元群体的一半被逆行标记上了氚化γ-氨基丁酸[（3H）-GABA]。这些细胞在大小和分布上与那些对GABA合成酶谷氨酸脱羧酶（GAD）染色的神经元相似。在外侧橄榄耳蜗群体的一半，以及E组的部分前庭传出群体和脑桥尾侧网状核（CPR）中，观察到了[3H]-天冬氨酸从内耳到脑干的逆行运输。由于在传出神经元中也发现了多种肽类，因此该系统在化学组成上具有多样性。因此，必然存在几种具有不同功能的传出控制的不同机制。
