Objective:To investigate the effects of repetitive transcranial magnetic stimulation(rTMS) on learning memory and abnormal Aβ deposition in cerebral amyloid angiopathy(CAA) model mice, and further to investigate whether the mechanism involves the transport function of glymphatic system.Methods:Eight-month-old SPF grade Tg-SWDI mice were randomly divided into the CAA group and the rTMS group according to the random number table method with 7 in each group.Seven wild-type mice of the same genetic background and age served as the control group. The mice in rTMS group received two weeks of high-frequency rTMS intervention, and the mice in CAA group and control group were only restrained without rTMS intervention.Learning and memory functions were evaluated using the Morris water maze test.Amyloid-beta deposition, glymphatic system clearance, and aquaporin-4(AQP4) polarization were assessed using immunofluorescence, and AQP4 expression levels were measured by Western blot.Statistical analysis of the data was conducted using SPSS 25.0 and GraphPad Prism 9.5 softwares.Repeated-measures ANOVA was used for data on escape latency, and one-way ANOVA was used for comparisons between multiple groups for other data.Results:(1)In the novel object recognition test, there were statistically significant differences in recognition indices among the three groups of mice ( F=22.59, P<0.05). Compared with the control group, the mice in the CAA group showed a significant decrease in the new object recognition index ( P<0.05).Compared with the CAA group, the mice in the rTMS group showed a significant increase in the new object recognition index ( P<0.05).(2)In the Y-maze, there were statistical differences in the spontaneous alternation rates among the three groups ( F=5.00, P<0.05). Compared with the control group, the spontaneous alternation rate in the CAA group was significantly lower ( P<0.05).And compared with the CAA group, the spontaneous alternation rate in the rTMS group was significantly higher ( P<0.05).(3)In the Morris water maze test, there were significant interactions in escape latency among the three groups ( F=4.05, P=0.02), significant main effects of time ( F=713.22, P<0.01), and significant main effects of group ( F=421.55, P<0.01). There was no significant statistical difference in swimming speed among the three groups ( F=0.19, P>0.05), while the difference of the number of entries into the inner zone and the proportion of time spent were statistically significant( F=71.67, 294.14, both P<0.05).Compared with the control group, the CAA group mice significantly decreased in the number of entries into the inner zone and the proportion of time spent in the middle zone (both P<0.01).(4)Compared with the CAA group, the rTMS group significantly increased in the number of entries into the inner zone and the proportion of time spent in the middle zone (both P<0.01).The result of immunofluorescence test showed that there was a statistically significant difference in the levels of Aβ in the cerebral vessels among the three groups( F=385.76, P<0.01).The levels of Aβ in the cerebral vessels of the CAA group (62.00±2.65) were significantly higher than those in the control group (9.00±1.00, P<0.01).The levels in the rTMS group (51.33±3.21) were significantly lower than those in the CAA group (62.00±2.65, P<0.01). Using the residual fluorescence tracer levels of the control group as a baseline, there were statistically significant differences in the tracer intensities in the corpus callosum and cerebral cortex( F=258.97, 46.44, both P<0.05), the tracer intensities in the corpus callosum (3.57±0.21) and cerebral cortex (4.96±0.79) of the CAA group mice were significantly higher than those in the rTMS group (1.45±0.14, 1.78±0.47, P<0.01). The polarization of AQP4 in the cerebral cortex of rTMS group (0.51±0.07) was significantly higher than that in the CAA group (0.30±0.02, P<0.01). Conclusion:rTMS can alleviate learning memory and abnormal Aβ deposition in CAA model mice by modulating AQP4 polarisation and promoting transport function of glymphatic system.

Objective:To investigate the effects of repetitive transcranial magnetic stimulation(rTMS) on learning memory and abnormal Aβ deposition in cerebral amyloid angiopathy(CAA) model mice, and further to investigate whether the mechanism involves the transport function of glymphatic system.Methods:Eight-month-old SPF grade Tg-SWDI mice were randomly divided into the CAA group and the rTMS group according to the random number table method with 7 in each group.Seven wild-type mice of the same genetic background and age served as the control group. The mice in rTMS group received two weeks of high-frequency rTMS intervention, and the mice in CAA group and control group were only restrained without rTMS intervention.Learning and memory functions were evaluated using the Morris water maze test.Amyloid-beta deposition, glymphatic system clearance, and aquaporin-4(AQP4) polarization were assessed using immunofluorescence, and AQP4 expression levels were measured by Western blot.Statistical analysis of the data was conducted using SPSS 25.0 and GraphPad Prism 9.5 softwares.Repeated-measures ANOVA was used for data on escape latency, and one-way ANOVA was used for comparisons between multiple groups for other data.Results:(1)In the novel object recognition test, there were statistically significant differences in recognition indices among the three groups of mice ( F=22.59, P<0.05). Compared with the control group, the mice in the CAA group showed a significant decrease in the new object recognition index ( P<0.05).Compared with the CAA group, the mice in the rTMS group showed a significant increase in the new object recognition index ( P<0.05).(2)In the Y-maze, there were statistical differences in the spontaneous alternation rates among the three groups ( F=5.00, P<0.05). Compared with the control group, the spontaneous alternation rate in the CAA group was significantly lower ( P<0.05).And compared with the CAA group, the spontaneous alternation rate in the rTMS group was significantly higher ( P<0.05).(3)In the Morris water maze test, there were significant interactions in escape latency among the three groups ( F=4.05, P=0.02), significant main effects of time ( F=713.22, P<0.01), and significant main effects of group ( F=421.55, P<0.01). There was no significant statistical difference in swimming speed among the three groups ( F=0.19, P>0.05), while the difference of the number of entries into the inner zone and the proportion of time spent were statistically significant( F=71.67, 294.14, both P<0.05).Compared with the control group, the CAA group mice significantly decreased in the number of entries into the inner zone and the proportion of time spent in the middle zone (both P<0.01).(4)Compared with the CAA group, the rTMS group significantly increased in the number of entries into the inner zone and the proportion of time spent in the middle zone (both P<0.01).The result of immunofluorescence test showed that there was a statistically significant difference in the levels of Aβ in the cerebral vessels among the three groups( F=385.76, P<0.01).The levels of Aβ in the cerebral vessels of the CAA group (62.00±2.65) were significantly higher than those in the control group (9.00±1.00, P<0.01).The levels in the rTMS group (51.33±3.21) were significantly lower than those in the CAA group (62.00±2.65, P<0.01). Using the residual fluorescence tracer levels of the control group as a baseline, there were statistically significant differences in the tracer intensities in the corpus callosum and cerebral cortex( F=258.97, 46.44, both P<0.05), the tracer intensities in the corpus callosum (3.57±0.21) and cerebral cortex (4.96±0.79) of the CAA group mice were significantly higher than those in the rTMS group (1.45±0.14, 1.78±0.47, P<0.01). The polarization of AQP4 in the cerebral cortex of rTMS group (0.51±0.07) was significantly higher than that in the CAA group (0.30±0.02, P<0.01). Conclusion:rTMS can alleviate learning memory and abnormal Aβ deposition in CAA model mice by modulating AQP4 polarisation and promoting transport function of glymphatic system.