Functional Impairment Of The Primary Visual Cortex Of Young Mice By High-sugar Diet And Its Mechanism

Excessive intake of monosaccharides has long been recognized as a threat to human health,and adolescents are more sensitive to sugar as a critical period of growth and development.Many studies have shown that a high-sugar diet may do a lot of harm to the health of teenagers.As one of the important windows for human to perceive the outside world,the visual system plays an important role in teenagers’ perception ability.Many studies have confirmed that high-sugar diet may impair visual function,but the current research on the effects of high-sugar diet on visual function mainly focuses on the front of the visual pathway,focusing on the eye system and the optic ganglion,the posterior of the visual pathway,such as the central cortex,has not been reported.To gain a more comprehensive understanding of the effects of high-sugar diet on visual pathways in adolescents,we investigated the effects of high-sugar diet on the primary visual cortex(V1)in young mice.In this study,we first examined the effects of high-sugar diet on the ability of orientation discrimination in young mice by using the GO/NO-GO paradigm.The results showed that after two months of high-sugar feeding,the ability of young mice to orientation discrimination decreased significantly.Based on the in vivo multi-channel electrophysiological recordings,this study further analyzed the response characteristics of single uint in V1,the results showed that the spontaneous activity was increased,the ability of orientation tuning was decreased,and the high cut-off spatial frequency was decreased in the mice fed with high-sugar diet compared with that in the control group,the response variability of neurons increased while the signal-to-noise ratio(SNR)decreased significantly.The results of neuronal noise correlation analysis showed that the correlation of V1 neuron pairs in mice fed with high-sugar diet was significantly up-regulated.By further analyzing the changes of SNR and response variability,it is found that SNR and response variability of population neurons are obviously changed,and the ability of neural network to process information is decreased.In order to exclude the influence of retinal lesions on the experimental results,the retinal microvascular lesions of mice were examined by panoramic fundus photography before the behavioral experiments,and after the experiments,the retinal tissue sections of mice were stained with HE and the changes in the thickness of each retinal cell layer were compared,and there was no difference between the mice in the high-sugar diet group and the control group.These results suggest that the response properties of individual neurons in the primary visual cortex of young mice fed a high-sugar diet,as well as the ability of neural networks to process information,are impaired;Furthermore,it affected the ability of orientation discrimination of mice.This study confirms that high-sugar diets adversely affect the cerebral cortex of adolescents,complementing previous studies that have found that high-sugar diets affect the brain,it also provides a new evidence for the effect of high-sugar diet on visual pathway in adolescents,and provides a mechanistic insight into the effect of high-sugar diet on V1 and other brain regions.