豚鼠上橄榄外侧核γ－氨基丁酸阳性神经元向耳蜗和耳蜗核的分支投射

为探讨豚鼠上橄榄外侧核内γ－氨基丁酸（ＧＡＢＡ）阳性神经元是否同时支配同侧Ｃｏｒｔｉ器和耳蜗核，采用逆行追踪的方法，将Ｆａｓｔｂｌｕｅ（ＦＢ）和Ｄｉａｍｉｄｉｎｅ黄（ＤＹ）两种不同性质的荧光素分别注入耳蜗鼓阶及同侧耳蜗核，观察上橄榄外侧核内ＧＡＢＡ阳性神经元的分支投射。结果发现，同侧上橄榄外侧核内ＦＢ单标细胞占标记细胞的８０．８％；ＤＹ单标细胞占１２．４％；ＦＢ－ＤＹ双标细胞占６％；ＧＡＢＡ、ＦＢ、ＤＹ三标阳性细胞占０．７％。对侧上橄榄外侧核内ＦＢ、ＤＹ单标细胞均较少，未见双标细胞。结果表明，豚鼠上橄榄外侧核内有ＧＡＢＡ免疫反应阳性神经元向同侧的Ｃｏｒｔｉ器和耳蜗核并行投射，但数量较少，支配Ｃｏｒｔｉ器和耳蜗核的传出神经纤维，分别来自不同的听觉传出神经核团。

Collateral Projections of Gamma-Aminohutyric Acid Positive Neurons from the Lateral Superior Nucleus to the Cochlea and Cochlear Nucleus in Guinea Pigs

Collateral projections of gamma-amiobutyric acid (GABA)neurons from the lateral supe rior olivary nucleus (LSO)to the cochlea and cochlear nuclei in the guinea pigs were studied by injection of two retrograde fluorescent neuronal tracers. For experiments, fast blue( FB)was injected into the scala tyrnpani of one cochlea and diamidine yellow(DY)was injected into coChlear nuclei of the same side. The results showed that the FB-labelled cells and DY-labelled cells constituted approximately 80.8%and 12.4%, respectively;FB and DY double-labelled cells constituted about 6%; FB and DY labelled cells with GABA constituted about 0.7%in the ipsilateral LSO. In the contralateral LSO, the FB and DY labelled cells were less than those of ipsilateraI LSO and no FB-DY double-labelled cells could be found. Our results suggest that there are collateral projections of GABA neurons from ipsilater-al LSO to the organ of Corti and cochlear nuclei in the guinea pig, even though the numbers are few. The results also show that the efferent projections to the cochlea and cochlear nuclei generally come fromtwo different auditorv neuronaI nuclei.