螯虾尾神经节光敏神经元反应的适应特性及信号通路检测

Adaptation of Photosensitive Neuron Response to Maintained Illumination on Caudal Ganglion and Ascending Pathway in Crayfish

520nm光照诱发克氏原螯虾尾神经节光敏神经元反应,发现2min后出现明显适应现象。适应期间,用550nm检测光刺激引起的效应随适应发展逐渐减弱。胞外高[Mg2+]不抑制此光敏反应;高[Mg2+]、高[Ca2+]均显著增加适应速率;低[Na+]显著降低适应速率,但能被胞外高[Ca2+]所拮抗。检测光敏神经元的上行传入通路,未见通过下咽神经节,提示可能有中枢启动运动反射环路。统计239例成体螯虾光敏神经元反应检出率。

Crayfish A6 ganglion responses to 520?nm monochrome illumination with an increase in discharging frequency,which shows an obvious adaptation after 2?min.During the adaptation period the responses to test\|illuminations decline.This characteristic response can not be suppressed by extracellular high \[Mg 2+ \],but be accelerated by it alternatively.Extracellular high \[Ca 2+ \] can accelerate the adaptation.It seems there is no chemical synapses involved in the adaptation.Extracellular low \ can delay the time course of adaptation,and the effect of low \ can be diminished by the extracellular high \[Ca 2+ \].Also,we did not observe transportation of the characteristic response across hypopharyngeal ganglion.This suggested a central reflex model that was initiated by the photosensitive neuron in crayfish CNS perhaps.Statistics from 239 samples imply a possibility during development course of crayfish:the neuron reserves photosensitive potential to response to illumination;or gradually eliminates its function in adult stage.