Cytology and immunocytochemistry of the nucleus of the lateral line lobe in the electric fish Gnathonemus petersii (mormyridae): Evidence suggesting that GABAergic synapses mediate an inhibitory corollary discharge
Cytology and immunocytochemistry of the nucleus of the lateral line lobe in the electric fish Gnathonemus petersii (mormyridae): Evidence suggesting that GABAergic synapses mediate an inhibitory corollary discharge
复制标题
电鱼 Gnathonemus petersii（mormyridae）侧线叶核的细胞学和免疫细胞化学：表明 GABA 能突触介导抑制性伴随放电的证据
作者：
E. Mugnaini;L. Maler
节器是在桑鱼中发现的低阈值电感受器，主要参与通讯，如果不是完全参与的话。外侧线叶的斜方脑核(NLll)是丘脑神经传入纤维的靶核。NLL内的细胞接受一些中等大小的带有圆形突触小泡的终末(分为勺形、大棒状、小棒状和小棒状)，它们形成联系(缝隙连接)和与圆形突触小泡相关的不对称的化学突触。此外，这些末端发出细小的侧支，在nLLL神经元上终止为小的突触；这些突触也有圆形的小泡，形成混合的(电紧张性和化学的)突触。此外，nLLL中的细胞接受来自许多小突触的突触输入，这些小突触含有多形性小泡并形成对称性突触。我们在nLLL内没有发现任何中间神经元。我们的超微结构分析表明，nLL1神经元上的突触只属于两个传入纤维系统，nLL1神经元的接线图极其简单。我们研究了谷氨酸脱羧酶(GAD)在NLLL中的免疫定位，GAD是合成GABA所必需的酶，也是这种广泛分布的抑制性神经递质的有用标记物。GAD免疫反应仅局限于具有多形性小泡的小突起。GAD也见于投射到nLL1的核，这里称为丘脑下核(SL)，它可能向nLL1传递相应的放电信号。这种GABA能投射可能与这些细胞中描述的与电子器官放电指令相关的有效抑制有关。
Knollenorgans, Low‐threshold electoreceptors found in mormyrid fish, are involved primarily, if not exclusively, in communication. The rhombencephalic nucleus of the lateral line lobe (nLLL) is the target nucleus of knollenorgan afferents. Cells in the nLLL receive a few medium size to large endings with round synaptic vesicles (classified as spoon; large club; small club‐, and rodlet‐shaped endings) with which they form nexus (gap junction) and asymmetrical chemical synapses associated with the round synaptic vesicles. In addition these endings emit thin collaterals which terminate as small boutons on nLLL neurons; these boutons also have round vesicles and make mixed (electrotonic and chemical) synapse. In addition, cells in the nLLL receive synaptic input from numerous small boutons containing pleomorphic vesicles and making symmetric synapses. We have not found any interneurons within nLLL. Our ultrastructural analysis suggests that boutons synapsing on nLLL neurons belong to only two afferent fiber systems and that the wiring diagram of nLLL is extremely simple. We have studied the immunolocalization in nLLL of glutamic acid decarboxylase (GAD), the enzyme essential for the synthesis of GABA that is also a useful marker for this widely distributed inhibitory neurotransmitter. GAD immunoreactivity was confined to the small boutons with pleomorphic vesicles. GAD was also found in a nucleus projecting to the nLLL, here named the sublemniscal nucleus (SL), which probably conveys corollary discharge signals to the nLLL. This GABAergic projection may be responsible for the potent inhibition associated with the electric organ discharge command that has been described in these cells.