| Background: Retina is an important organ for visual information transmission and processing,but the exact mechanism for processing external light information in retina is still unclear.The neural projection pathways of retina are mainly composed of doubal-level synaptic connections formed by photoreceptor cells(cone and rod cells),bipolar cells and ganglion cells.Photoreceptors receive light information from the outside world,while ganglion cells transmit the processed retinal information to different visual centers of the brain through the optic nerve formed by their axons.Therefore,the optic nerve is the only information output pathway of the retina.Traditional theories hold that visual information transmission depends on electrical and chemical signals.Recent studies have shown that excitatory neurotransmitter glutamate(Glu)can induce biophotonic activities in brain slice,which may play an important role in the process of neuronal information transmission and processing.Therefore,we speculate that the information processing mechanism of the retina to the external light may be related to the biophotonic activity and transmission.In order to explore the relationship between the biophoton activity and the visual signal processing and transmission mechanisms of retina,we studied the characteristics of biophotonic activity and transmission as well as the regulation mechanisms in retina by using the double-level synaptic connection pathways formed by photoreceptor cells,bipolar cells and ganglion cells as the research model.Research methods: By using isolated rat "retina-sclera-optic nerve stump specimens" as experimental tissue materials and ultra-weak biophoton imaging system(UBIS),we first observed the characteristics of glutamate-induced biophotonic acitivities emitted from the optic nerve stump,and then explored regulation mechanism of different neurotransmitters,such as gamma-aminobutyric acid(GABA),5-hydroxytryptamine(5-HT),dopamine(DA),norepinephrine(NE)and acetylcholine(ACh),on the glutamate action.Results and conclusion: After image acquisition,data processing and analysis,it was found that:(1)50 mM Glu-induced biophotonic emission from the optic nerve stump presented characteristic changes(initiation,maintenance and washing);(2)GABA at the different concentrations(60 mM,125 mM,250 mM and 500 mM)had a concentration-dependent enhancement effect on the glutamate-induced biophotonic emission from the optic nerve stump;(3)DA at the different concentrations(0.5 mM,2.5 mM,5 mM,10 mM and 20 mM)had dual effects of enhancement and inhibition on the glutamate-induced biophotonic emission from the optic nerve stump.DA at concentration of 0.5 mM had a transient inhibition effect and then a significant enhancement.The effect was not obvious at 2.5 mM,and a transient inhibition and then maintained stability were found at 5 mM,while the significant inhibitory effects were showed at 10 mM and 20 mM DA;(4)5-HT at the different concentrations(25 ?M,50 ?M,100 ?M,200 ?M and 400 ?M)presented a concentration-dependent inhibitory effect on the glutamate-induced biophotonic emission from the optic nerve stump;(5)The effects of NE(0.1 mM,1 mM and 10 mM)on the glutamate-induced biophotonic emission from the optic nerve stump presented a significant inhibition at the concentrations of 0.1 mM and 1 mM,but a significant enhanced at the concentrations of 10 mM;(6)The effects of ACh(1 ?M,0.1 mM and 10 mM)on the glutamate-induced biophotonic emission from the optic nerve stump showed significant changes from the decline to stabilization,and then have a significant enhanced,however,the decline presents a concentration-dependent enhancement effect.These experimental results indicated that the biophotonic activity and transmission induced by glutamate,the most abundant excitatory neurotransmitter in retina,forms the basic biophotonic information streams,which may play an important role in the transmission of retinal information,whereas the positive and negative regulatory effects of other neurotransmitters on the glutamate-induced biophotonic activity and transmission may be involved in the regulation of visual information.Our findings may provide new evidence for further understanding of the mechanism of "photon quantum brain" and new ideas for better understanding of the vision mechanism and developing visual artificial intelligence products.In addition,the "retina-sclera-optic nerve stump specimens" used provide a unique in vitro experimental model for further elucidating the mechanism of biophoton transmission and regulation in the retinal neuroal circuits. |
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