Fig. 1

P3C induces a massive pleocytosis and a concomitant accumulation of neutrophils in choroid plexuses of neonatal rats. a CSF leukocyte counts after P3C treatment of P8 rats. Rats were injected i.p. with saline or P3C (either 1 or 5 mg/kg), and CSF leukocytes were counted 14 h later following Türk’s staining. Data from individual animals, and mean ± SEM are shown. * and**: statistically different from saline-treated animals, p < 0.05 and 0.01, respectively, one-way ANOVA followed by Dunnett’s multiple comparisons test. b Immunophenotypic analysis of CSF infiltrating leukocytes in P8 rats treated with 1 mg/kg P3C for 14 h. Neutrophils were identified as MPO⁺, monocytes as CD68⁺, T cells as CD3⁺ and B cells as CD45RA⁺ cells. Data from individual animals, and means ± SEM are shown. c Representative SPIM images of a portion of the ChP of the lateral ventricle from a saline-treated rat (left panel) and P3C-treated rat (right panels). MPO-immunopositive neutrophils in red, endothelial staining with Reca-1 in green. In the bottom right panel, nuclear staining with DAPI in blue allows to visualize the localization of some PMNs on the outer surface of the choroidal epithelium. d Quantification of MPO-immunopositive cells in ChPs of the lateral (LV ChP) and the fourth ventricle (4V ChP) from P3C-treated rats. Cell counts were normalized to the vascular volume of the region of interest. The data are expressed as % of cells counted in ChPs of saline-treated animals. These amounted to 13,009 ± 1884 and 15,092 ± 1347 cells per choroidal tissue volume containing 1 μl of vascular space in LV ChP and 4V ChP, respectively. Data from individual animals and mean ± SEM are shown. ** statistically different from saline-treated animals, p < 0.01, one-tailed Student t-test for unequal variance. e Blood-to-CSF permeability to sucrose in P8 rats following 14 h of treatment with saline or 1 mg/kg P3C. Permeability constants measured in untreated rats for urea (lowly permeable compound) and caffeine (highly permeable compound) are shown for comparison purposes. Data are presented as mean ± SD. * statistically different from saline-treated animals, p < 0.05, one-tailed Student t-test for unequal variance