Merchán-Pérez A, Gil-Loyzaga P, López-Sánchez J, Eybalin M, Valderrama F J
Departamento de Ciencias Morfológicas, Universidad Complutense, Madrid, Spain.
Brain Res Dev Brain Res. 1993 Nov 19;76(1):33-41. doi: 10.1016/0165-3806(93)90120-y.
Cochlear efferent innervation originates in two different groups of neurons located in the superior olivary complex. A first group of olivocochlear neurons (lateral efferent neurons) lies in the lateral superior olive. They send axons to the organ of Corti, where they synapse with radial afferent dendrites of primary auditory neurons, postsynaptic to the inner hair cells. The second group of neurons (medial efferent neurons) is found in medial subnuclei of the superior olivary complex and sends axons to synapse with outer hair cells. Subpopulations of both medial and lateral olivocochlear neurons probably use gamma-aminobutyric acid (GABA) as a neurotransmitter. We have used an immunoperoxidase technique to detect GABA-like immunoreactivity (GABA-LI) in postnatal maturing rat cochleas. The GABA-LI appeared in the inner hair cell region by P3 (P1 = birth) and reached a mature appearance by P15-P16. In the outer hair cell region, GABA-like immunoreactive fibers and terminals could not be identified until P9 and they were only found in the apical end of the cochlea. There was a dual gradient of maturation of GABA-LI in the cochlea. The GABA-LI appeared first at the cochlear base and then extended towards the apex. It also appeared earlier (about a week) in the inner hair cell region than in the outer hair cell region. This dual gradient of maturation is in close agreement with previous data concerning the maturation of the cochlea.
耳蜗传出神经支配起源于位于上橄榄复合体的两组不同神经元。第一组橄榄耳蜗神经元（外侧传出神经元）位于外侧上橄榄核。它们将轴突发送至柯蒂氏器，在那里与初级听觉神经元的放射状传入树突形成突触，这些树突是内毛细胞的突触后结构。第二组神经元（内侧传出神经元）位于上橄榄复合体的内侧亚核，并将轴突发送至外毛细胞形成突触。内侧和外侧橄榄耳蜗神经元的亚群可能都使用γ-氨基丁酸（GABA）作为神经递质。我们使用免疫过氧化物酶技术检测出生后成熟大鼠耳蜗中的GABA样免疫反应性（GABA-LI）。GABA-LI在出生后第3天（P1 =出生）出现在内毛细胞区域，并在出生后第15 - 16天达到成熟状态。在外毛细胞区域，直到出生后第9天才能识别出GABA样免疫反应性纤维和终末，并且它们仅在耳蜗的顶端被发现。耳蜗中GABA-LI的成熟存在双重梯度。GABA-LI首先出现在耳蜗底部，然后向顶端延伸。它在内毛细胞区域也比在外毛细胞区域出现得更早（约一周）。这种成熟的双重梯度与先前关于耳蜗成熟的数据密切一致。
