Fig. 6

Prolonged anesthesia caused synaptic elimination in the hippocampus by complement-mediated synaptic elimination and decreased dendritic spines and their genes. A Prolonged anesthesia increased complement-mediated synaptic elimination in the hippocampal CA1 region. Complement C1qa (green) colocalized with PSD95 (red) puncta was elevated after prolonged anesthesia. Scale bar = 10 μm. B Prolonged anesthesia reduced synaptic density in the hippocampal CA1 region. SYN1 (red), as a marker of synaptic density, was sharply decreased after prolonged anesthesia. Scale bar = 10 μm. C SEM (scanning electron microscope) identifies ultrastructural alteration of synapses in the hippocampal. Synaptic vesicles were reduced, and postsynaptic membrane continuity was interrupted after prolonged anesthesia. Scale bar = 500 nm. D The number of C1qa-colocalized PSD95 between both groups (n = 4 per group). E Prolonged anesthesia reduced the number of synapses. The synapse was marked by presynaptic (SYP) and postsynaptic protein (PSD95). Synapse partially enlarged as shown in panel E. Scale bar = 10 μm. F Synaptic density in the hippocampal CA1 region between both groups (n = 5 per group). G The number of synapses in the hippocampal CA1 region between both groups (n = 4 per group). H, I Prolonged anesthesia downregulated genes of the dendrite (H) and dendritic spines (I). In panels H to I, the horizontal axis is the z-score of the sample, and the vertical axis is the gene. The warmer the color block is, the higher the expression level is, and the colder the color block is, the lower the expression level is (n = 3 per group). J Golgi staining in the hippocampal CA1 region. Scale bar = 100 μm. K Prolonged anesthesia triggered the loss of dendritic spines. L Maximal intersection number per neuron between groups (n = 3 per group). M Sholl analysis discovered that prolonged anesthesia decreased maximal intersection number per neuron between groups. Scale bar = 50 μm. N The number of dendritic spines in the hippocampus between groups (n = 4 per group). Data was shown as Mean ± SD, with *P < 0.05 or *P < 0.001; Sevo group vs. control group. Arrows represent synaptic puncta or colocalization