猫听觉脑干上橄榄复合体投射神经元的分布

Distribution of projection neurons of the superior olivary complex in the auditory brainstem in cats

目的:探讨猫上橄榄复合体各个核团内橄榄耳蜗神经元的分布和形态。方法:将8只成年猫随机分成两组,实验组5只,于左侧耳蜗内注射霍乱毒素B亚单位(cholera toxin B subunit,CTB),右侧耳蜗注射荧光金(fluoro-gold,FG);对照组3只,于双侧耳蜗注射生理盐水。取脑干组织切片,经免疫组化ABC方法和DAB显色后观察被标记的橄榄耳蜗神经元。结果:实验组猫橄榄耳蜗神经元总数为2518个,其中外侧橄榄耳蜗(lateral olivocochlear,LOC)神经元1738个,占69.0%,主要分布于脑桥中部,以同侧投射占优势。内侧橄榄耳蜗(medial olivocochlear,MOC)神经元780个(31.0%),主要位于背内侧橄榄旁核(dorsomedial periolivary nucleus,DMPO)、内侧斜方体核(medial nucleus of the trapezoid body,MNTB)以及腹侧斜方体核(ventral nucleus of the trapezoid body,VNTB),在脑桥嘴侧分布密集,其发出的纤维以对侧投射占优势。结论:猫的橄榄耳蜗神经元分布LOC神经元向同侧投射为主;而MOC神经元则为对侧投射优势,且MOC神经元分布较LOC神经元更靠近脑桥嘴侧。

Objective To investigate the distribution and morphology of olivocochlear neurons of superior olivary complex in cats. Methods Eight adult cats were divided into 2 groups randomly. Cholera toxin B subunit was injected to the left cochlea and fluoro-gold was injected to the right cochlea in the experimental group （n = 5 ）. Saline was injected to bilateral cochlea in the control group （n = 3 ）. Brainstem tissue was sectioned serially. All of the sections were immunohistochemically treated with ABC and stained with DAB, and then the labelled olivocochlear neurons were observed. Results The labelled olivocochlear neurons in the experimental group were 2 518 in total. Of them, the number of lateral olivoeochlear （LOC） neurons was 1 738 （69. 0% ） , mainly located in the middle of the pons, predominately projected ipsilaterally. The total of medial olivocochlear （ MOC ） neurons was 780 （31% ） , mainly located in dorsomedial periolivary nucleus, medial nucleus of the trapezoid body and ventral nucleus of the trapezoid body, mainly distributed in the rostral extent of the pons, predominately projected contralaterally. Conclusion In the distribution of olivocochlear neurons in cats, LOC neurons mainly project to the ipsilateral. While the projection of MOC neurons is predominately contralateral, the distribution of MOC neurons is more adjacent to the rostral extent of the pons than LOC neurons.