Sleep
loss in the rat increases blood-brain barrier permeability to
circulating molecules by disrupting interendothelial tight junctions.
Despite the description of the ultrastructure of cerebral microvessels
and the evidence of an apparent pericyte detachment from capillary wall
in sleep restricted rats the effect of sleep loss on pericytes is
unknown. Here we characterized the interactions between pericytes and
brain endothelial cells after sleep loss using male Wistar rats. Animals
were sleep-restricted 20 h daily with 4 h sleep recovery for 10 days.
At the end of the sleep restriction, brain microvessels (MVs) were
isolated from cerebral cortex and hippocampus and processed for Western
blot and immunocytochemistry to evaluate markers of pericyte-endothelial
cell interaction (connexin 43, PDGFR-β), tight junction proteins, and
proinflammatory mediator proteins (MMP9, A2A adenosine
receptor, CD73, NFκB). Sleep restriction reduced PDGFR-β and connexin 43
expression in MVs; in addition, scanning electron microscopy
micrographs showed that pericytes were detached from capillary walls,
but did not undergo apoptosis (as depicted by a reduced active caspase-3
expression). Sleep restriction also decreased tight junction protein
expression in MVs and increased BBB permeability to low- and
high-molecular weight tracers in in vivo permeability assays.
Those alterations seemed to depend on a low-grade inflammatory status as
reflected by the increased expression of phosphorylated NFκB and A2A
adenosine receptor in brain endothelial cells from the sleep-restricted
rats. Our data show that pericyte-brain endothelial cell interaction is
altered by sleep restriction; this evidence is essential to understand
the role of sleep in regulating blood-brain barrier function.
No comments:
Post a Comment