Yang Q Z, Hatton G I
Neuroscience Program, Michigan State University, East Lansing 48824-1117.
Brain Res. 1988 Oct 25;463(1):47-56. doi: 10.1016/0006-8993(88)90525-2.
Transfer of the fluorescent dye, Lucifer yellow (LY), from an intracellularly injected neuron to one or more other neurons is accepted as indirect evidence of electrotonic interactions among such dye coupled cells. Direct evidence requires that at least two coupled cells be recorded from simultaneously and such evidence in the CNS has been gained only for hippocampal pyramidal neurons. Since interpretations of the functional significance of dye coupling among magnocellular neuroendocrine cells depend upon its relation to electrical coupling, we sought to obtain direct evidence for electrotonic interactions in such neurons. Over 150 pairs of supraoptic nucleus (SON) neurons in hypothalamic slices were recorded from intracellularly using one LY and one potassium acetate electrode in each instance. Of these, 9 pairs were studied in sufficient detail to determine that they were electrically coupled. Most of the remaining pairs were determined not to be coupled. In each coupled pair of cells, membrane voltage changes due to spontaneously occurring or current evoked action potentials, as well as current evoked hyperpolarizations, in one cell were reflected in similar, though attenuated changes in the other cell. All of these changes occurred simultaneously in the two neurons. Spontaneously arising postsynaptic potentials in the two cells were temporally uncorrelated. In each case that electrical coupling was observed, dye coupling resulted from LY injection. Coupling ratios ranged from 0.05 to 0.2. Capacitative coupling between the recording electrodes as an artifact was ruled out since cells in the same tissue penetration as the coupled cell showed no responses to membrane voltage changes in the primary cell; no responses were seen with the second electrode placed extracellularly or in the medium; and similar coupling potentials were also seen when one cell was recorded without a second electrode present. We conclude that electrical coupling exists among magnocellular neurons of the SON and that the incidence of dye coupling is a reasonable estimate of the incidence of electrical coupling. These electrotonic interactions probably play important roles in the coordination of firing among magnocellular neurosecretory neurons.
荧光染料路西法黄（LY）从细胞内注射的神经元转移至一个或多个其他神经元，被视为这类染料偶联细胞间电紧张相互作用的间接证据。直接证据要求同时记录至少两个偶联细胞，而在中枢神经系统中，仅对海马锥体细胞获得了此类证据。由于对视上核神经内分泌细胞间染料偶联功能意义的解释取决于其与电偶联的关系，我们试图获取这类神经元电紧张相互作用的直接证据。在每一例实验中，使用一个LY电极和一个醋酸钾电极，从下丘脑切片中的150多对视上核（SON）神经元进行细胞内记录。其中，9对被详细研究以确定它们是电偶联的。其余大多数对被确定为非偶联。在每一对偶联细胞中，一个细胞中由自发产生或电流诱发的动作电位以及电流诱发的超极化所引起的膜电压变化，在另一个细胞中表现为类似但减弱的变化。所有这些变化在两个神经元中同时发生。两个细胞中自发产生的突触后电位在时间上不相关。在每一例观察到电偶联的情况下，染料偶联都是由LY注射导致的。偶联比率范围为0.05至0.2。由于与偶联细胞在同一组织穿刺中的细胞对主细胞的膜电压变化无反应；将第二个电极置于细胞外或培养基中时无反应；并且当记录一个细胞而不使用第二个电极时也观察到类似的偶联电位，因此排除了记录电极间电容性偶联作为假象的可能性。我们得出结论，SON的大细胞神经元之间存在电偶联，并且染料偶联的发生率是电偶联发生率的合理估计。这些电紧张相互作用可能在大细胞神经分泌神经元的放电协调中起重要作用。
