In vitro spatiotemporal imaging of biophotonic activities and transmission in neural circuits
作者单位：Wuhan Institute for Neuroscience and NeuroengineeringSouth-Central University for Nationalities
会议名称：《中国神经科学学会第十届全国学术会议》
会议日期：2013年
学科分类：1001[医学-基础医学(可授医学、理学学位)] 10[医学]
关 键 词：neural circuits biophotons biophotonic transmission ultra-weak photon emission imaging system glutamate microtubule
摘 要：Objective The processing of neural information in neural circuits plays a key role in neural functions.It is well accepted that neuronal communication is mediated by bioelectricity and chemical molecules via the processes called bioelectrical and chemical transmission,respectively,which mainly occur in axons and synapses.Indeed,they seem to provide reasonable explanations for the basic functions and neural encoding of the nervous system,but many unanswered questions and debates remain.It has recently been suggested that biophotons,also called ultra-weak photon emissions,may play a potential role in neural signal transmission,contributing to the understanding of the high functions of nervous system;however,the experimental analysis of biophotonic activities(emissions) in neural circuits has been hampered due to technical limitations.Methods By developing and optimizing an in vitro biophoton imaging method,we characterize the glutamate-induced biophotonic activities along the axons of cortical projection neurons and in the intrahippocampal circuits in mouse brain slices.Results We show that the long-lasting application of 50 mM glutamate to brain slices produces a gradual and significant increase of biophotonic activities and achieves the maximal effect within approximately 90 min,which then lasts for a relatively long time( 200 min).The initiation and/or maintenance of biophotonic activities by glutamate can be obviously blocked by oxygen and glucose deprivation,together with the application of a cytochrome c oxidase inhibitor(sodium azide),but only partly by an action potential inhibitor(TTX),an anesthetic(procaine),or the removal of intracellular and extracellular Ca.The detected biophotonic activities mostly originate from axons,and the hyperphospholyation of microtubule-associated protein tau leads to a significant decrease of biophotonic activities in axons.Furthermore,the application of glutamate in the hippocampal dentate gyrus results in obvious biophotonic activities in its intrahippocampal projection areas.Conclusion These results suggest that the glutamate-induced biophotonic activities reflect biophotonic transmission in neural circuits,which may be a new mechanism for the processing of neural information and neural functions.In addition,it seems that either bioelectrical or chemical transmission may only provide a basis for the initiation and maintenance of biophotonic activities and transmission.