(A –B) Brain sections from wild-type (A) or Cav1−/− (B) mice showing Biocytin-TMR leakage 27 h post-t-MCAO. The area of biocytin-TMR leakage and the outline of the brain section are marked with dashed white lines. Note the extensive leakage of tracer into the cortex and putamen. The choroid plexus (A, B; arrows) is intensely labeled due to lack of the barrier. (A′, B′) Higher magnification images for the yellow squares shown in (A, B). (C) Bar graph showing the fraction of biocytin-TMR leakage area in wild-type or Cav1−/− mice. The increased fraction of biocytin-TMR areas in mutant mice is due to tracer in the thalamus. (D) Bar graphs of the biocytin-TMR average pixel intensity ratio between ipsilateral and contralateral areas for cortex, putamen and hippocampus in wild-type (orange bars) or Cav1−/− mice (blue bars). There is no significant difference in biocytin-TMR leakage intensity for matched anatomical regions. Data are represented as mean ± s.e.m, ****p<0.0001, paired t-test. (E–H) Expression of eGFP-Claudin5, Claudin5, Occludin and ZO-1 in Tg eGFP-Claudin5 (E, F) and Tg eGFP-Claudin5 Cav1−/− mice (G, H). TJ proteins are correctly localized in CNS ECs of both strains. (I) Schematic representation of increases in biocytin-TMR (blue), IgG (green) and alb-Alexa594 (red) over time following t-MCAO. There is a non-linear, gradual increase in biocytin-TMR and IgG permeability during stroke progression that becomes significant 24–48 h after t-MCAO, and correlates with the abundance of structural defects in TJs (i.e. junction remodeling). In contrast, alb-Alexa594 uptake increases as early as 6 h post-t-MCAO, suggesting that endocytosis and transcytosis are increased in early phases of ischemic stroke. Upregulation of both Cav1-dependent and -independent endothelial transcytosis, followed by TJ disassembly, contribute to enhanced BBB permeability after t-MCAO. Scale bars = 400 μm (A, B) and 50 μm (E–H). See for analysis of IgG leakage after stroke, the morphology of TJs with TEM and TJ protein levels in wild-type versus Cav1−/− brains.