Tiras N P, Mikheeva I B, Pakhotin P I, Moshkov D A
Laboratory of Neuronal Ultrastructure, RAS Institute of Theoretical and Experimental Biophysics, Educational Centre of Biophysics and Physiology, Pushchino State University.
Morfologiia. 2002;122(6):19-24.
In newly-hatched goldfish the adapted state was developed using repeated short-term stimulation of the vestibular apparatus. It differed from the non-adapted state by the absence of fatigue during the turns of fishes produced by unilateral tail fin flicks in ring channel. Electrophysiological study of Mauthner neurons (MN) in adapted goldfish using the slices of medulla oblongata incubated in vitro, has shown the preservation of the amplitude of the extracellular responses after prolonged orthodromic electric stimulation of acoustic nerve, which suppressed the responses of non-adapted MN. Thus, the resistance against fatigue has developed also at the level of MN. Using electron microscopy it was demonstrated that adapted MN following the prolonged electric stimulation in vitro were characterized by the resistance of specialized desmosome-like contacts, similar to what was earlier observed in these neurons in vivo. The data obtained suggest that indirect evaluation of MN functional state in goldfish by counting the number of turns performed by it in narrow ring channel, corresponds to the direct morpho-functional assessment of MN state. This form of innate behavior of freely moving fish seems to be the result of MN excitation.
在新孵化的金鱼中，通过对前庭器官进行反复的短期刺激来建立适应状态。它与非适应状态的不同之处在于，在环形通道中通过单侧尾鳍轻弹使鱼转弯时，适应状态下不存在疲劳现象。利用体外孵育的延髓切片对适应后的金鱼的莫纳神经元（MN）进行电生理研究发现，在对听神经进行长时间的顺向电刺激后，适应后的MN的细胞外反应幅度得以保留，而这种刺激会抑制非适应状态下MN的反应。因此，在MN水平也产生了抗疲劳能力。利用电子显微镜观察发现，体外长时间电刺激后的适应MN的特征是特殊的桥粒样连接具有抗性，这与之前在这些神经元的体内观察结果相似。所获得的数据表明，通过计算金鱼在狭窄环形通道中转弯的次数来间接评估MN的功能状态，与对MN状态进行直接的形态功能评估结果相符。自由游动鱼类的这种先天行为形式似乎是MN兴奋的结果。
