Neurodegenerative diseases(NDs)are closely related to the central nervous system and characterized by morphological abnormalities and progressive loss of function in specific neuron groups.The main NDs include Alzheimer's disease,Parkinson's disease,amyotrophic lateral sclerosis,multiple sclerosis and Huntington's disease.However,no direct therapies for NDs exist.In recent years,single cell RNA-sequencing(scRNA-seq)has been widely used in various NDs.The pathogenesis of NDs is closely related to morphology of immune cells,and the pathogenesis mainly involves mitochondrial function,glucose metabolism,inflammation,and synaptic transmission.Induced pluripotent stem cells are a potential therapy for NDs.Ultimately,we review the application of scRNA-seq to various NDs and provide a reference for prevention and treatment of NDs.

Objective To explore the mechanisms of circadian rhythm disorder(CRD)on behavior and testicular spermatogenic capacity in adolescent mice.Methods Thirty SPF grade C57 mice were selected and randomly di-vided into the control and CRD groups with 15 mice in each group.The control group kept 12 h dark/12 h bright circulating light,and the CRD group kept 24 h light.The trial lasted for 61 days.The growth curves of mice in each group were counted;the elevated plus maze test and open field test were performed to detect mice behavior;neuronal morphology was visualized by Nissl staining.The distribution of ionized calcium-binding adapter molecule 1(Iba1)and neuron-specific nuclear protein(NeuN)in the hypothalamus were detected by immunofluorescence and Western blot.Expression of testosterone synthesis-related genes steroidogenic acute regulatory protein(StAR)and hydroxy-delta-5-steroid dehydrogenase,3 beta-and steroid delta-isomerase 1(HSD3B1)and spermatogenesis-related genes gametogenetin binding protein 2(GGNBP2)and deleted in azoospermia-like(DAZL)were deter-mined by RT-qPCR.Results The weight of the CRD group was significantly higher than that of control group at 61 days;in the elevated plus maze test,the time,frequency,and percentage of time in the open arm of the CRD group were significantly less than those of the control group;in the open field test,there was no significant differ-ence in movement distance between the two groups;however,the residence time of the central area in the CRD group was significantly less than that in the control group;the frequency of entering the central area in the CRD group was significantly less than that in the control group.Nissl staining results showed that the positive cells in the CRD group were significantly lower than the control group.Immunofluorescence and Western blot results showed that Iba1 protein expression was up-regulated and NeuN protein expression was down-regulated in the hypothalamus of the CRD group.In the RT-qPCR experiment,the expression of HSD3B1 in the CRD group was significantly low-er than that of the control group;the expression of GGNBP2 and DAZL in the CRD group was significantly lower than that in the control group.Conclusion The CRD treatment can not only lead to depressive behavior in adoles-cent mice but also reduce the development of reproductive system in male adolescent mice.