Fig. 5

Injection of CSF tracer via CDP and its temporal and spatial distributions in mice. a Schematic of acute injection of tracers into the CSF system of free-moving mice via CDP and subsequent analysis of the tracers’ dynamic distribution and metabolism by micro-CT imaging and brain sections. b Schematic of mouse brain ventricles. c Representative coronal brain images of micro-CT with contrast agent (shown in red). Numbers in the bottom right corner of each image correspond to the levels of the sections indicated in (b). d Quantification of the contrast agent concentrations in each region. Radiodensity values of the contrast agent were sequentially measured at each time point. n = 3/group. Data are presented as the mean ± SEM. e Relationship between half-life (t1/2) and Tmax values of the contrast agents in each region. Each plot represents the mean of three animals with SEM error bars. p < 0.05, Spearman rank test. Subregions were divided into three groups depending on the metabolic rates of tracers. Group A; regions with rapid distribution and fast clearance of the tracer; Group B; regions with intermediate metabolism of the tracer, Group C; regions with delayed distribution with slow clearance of the tracer. f Representative images of coronal sections of mouse brain after an acute injection of Hoechst solution into the CM (injection site) via CDP. (f, bottom panels) High magnification of the sections corresponding to the dotted outlined area in the top panels. Scale bar, 1,000 μm. g Representative image of the coronal section immunostained with neuronal marker NeuN. High magnifications of the areas corresponding to the dotted outlined area in the right panel are shown in the left three panels. Cortical layers are indicated by Roman numerals in panel 3. Scale bar, 200 μm. CDP chronic dural port, CT computed tomography, DG dentate gyrus, S subiculum, Tmax time to peak concentration