Zhang D X, Li L, Kelly J B, Wu S H
Department of Psychology, Carleton University, Ottawa, Ont, Canada.
Hear Res. 1998 Mar;117(1-2):1-12. doi: 10.1016/s0378-5955(97)00202-5.
The objective of the present study was to provide direct evidence regarding GABAergic projections from the nuclei of the lateral lemniscus to the central nucleus of the inferior colliculus (ICC), and from the ICC to the opposite ICC. Projections of GABAergic neurons in the rat were investigated by a combination of fluorogold (FG) retrograde tracing and GABA immunocytochemistry. FG was first injected into a frequency-defined region (11-13 kHz) in the center of the ICC, and 1-2 weeks was allowed for retrograde transport. Vibratome sections were then cut through the brainstem and stained with GABA antibody. Double-labeling was taken as evidence of GABAergic neurons projecting to the ICC. The results from FG retrograde labeling alone showed that neurons in the dorsal nucleus of the lateral lemniscus (DNLL) bilaterally, in the intermediate and ventral nucleus of the lateral lemniscus (INLL and VNLL) ipsilaterally, and in the ICC contralaterally project to the ICC. GABA immunostaining alone showed substantial numbers of GABA positive neurons in the nuclei of the lateral lemniscus and the inferior colliculus. FG and GABA double-labeled neurons were present in all nuclei of the lateral lemniscus that project to the ICC. The greatest concentration of double-labeled neurons was found bilaterally in the DNLL, suggesting a prominent GABAergic projection from the DNLL to the ICC. The presence of many double-labeled neurons in the ipsilateral INLL and VNLL suggests that there are also GABAergic inputs from the INLL and VNLL to the ICC. No double-labeled neurons were found in the contralateral ICC, which suggests the possibility of a prominent non-GABAergic projection.
本研究的目的是提供直接证据，证明从外侧丘系核到下丘中央核（ICC）以及从ICC到对侧ICC的γ-氨基丁酸能投射。通过荧光金（FG）逆行追踪和γ-氨基丁酸免疫细胞化学相结合的方法，研究了大鼠γ-氨基丁酸能神经元的投射。首先将FG注入ICC中央的一个频率定义区域（11-13千赫兹），并给予1-2周的时间进行逆行运输。然后用振动切片机切取脑干切片，并用γ-氨基丁酸抗体进行染色。双重标记被视为γ-氨基丁酸能神经元投射到ICC的证据。仅FG逆行标记的结果显示，双侧外侧丘系背核（DNLL）、同侧外侧丘系中间核和腹核（INLL和VNLL）以及对侧ICC中的神经元投射到ICC。仅γ-氨基丁酸免疫染色显示外侧丘系核和下丘中有大量γ-氨基丁酸阳性神经元。投射到ICC的外侧丘系所有核中均存在FG和γ-氨基丁酸双重标记的神经元。在双侧DNLL中发现双重标记神经元的浓度最高，表明从DNLL到ICC存在显著的γ-氨基丁酸能投射。同侧INLL和VNLL中存在许多双重标记神经元，表明从INLL和VNLL到ICC也存在γ-氨基丁酸能输入。在对侧ICC中未发现双重标记神经元，这表明可能存在显著的非γ-氨基丁酸能投射。
