Multiregional blood-brain barrier permeability abnormalities in a Cwh43 truncating-allele p.(Met533Ter) rat model of normal pressure hydrocephalus

Idiopathic normal pressure hydrocephalus (iNPH) is an aging-associated neurological disorder characterized by ventricular enlargement and disturbances in brain fluid homeostasis, while the contribution of blood-brain barrier (BBB) abnormalities remains incompletely defined. Experimental models linking disease-associated genetic factors to regional BBB phenotypes remain limited. We generated a rat carrying a truncating Cwh43 allele using CRISPR/Cas9 genome editing. Ventricular size and motor performance were assessed, and BBB permeability was examined using intravenously administered tracers of 556 Da, 10 kDa, and 70 kDa. Junctional protein abundance, representative vascular ultrastructural features, vessel-associated VCAM-1 immunoreactivity, glial markers, and ventricular-interface phenotypes were evaluated using immunoblotting, immunofluorescence, and transmission electron microscopy. The mutant allele was defined as Cwh43 NM_001191677.1:c.1597del, predicting NP_001178606.1:p.(Met533Ter), and was associated with reduced Cwh43 transcript abundance. Heterozygous mutant rats developed ventricular enlargement and impaired rotarod performance. Repeated-measures analyses of the three tracer cohorts demonstrated significant overall genotype-associated BBB permeability phenotypes across a multiregional dataset spanning cortical, hippocampal, and cerebellar regions. These permeability-associated phenotypes occurred without a significant reduction in the measured full-length junctional proteins, while representative ultrastructural images showed identifiable vascular junctional contacts. Vessel-associated VCAM-1 immunoreactivity was increased in mutant rats, whereas whole-tissue VCAM-1 and the measured inflammasome-associated proteins did not show consistent genotype-dependent increases. Additional analysis identified reduced apical acetylated α-tubulin-positive coverage and mean fluorescence intensity along the lateral ventricular ependymal surface. In the adjacent periventricular region, normalized tracer values were higher in HZ rats across all three tracer cohorts, but none of the individual genotype comparisons remained significant after correction for the three-tracer family. Cwh43 p.(Met533Ter) rats exhibit reproducible multiregional BBB permeability-associated phenotypes together with associated vascular, glial, and ventricular-interface phenotypes. The present cross-sectional study does not establish their temporal ordering, primary cellular origin, or underlying molecular mechanism, but provides a framework for further investigation of barrier and ventricular-interface abnormalities in CWH43 -related experimental models.