Relationship between aquaporin-4 expression and blood-brain barrier damage after acute experimental intracerebral hemorrhage

Objective To investigate the relationship between Aquaporin-4(AQP-4) expression and blood-brain barrier damage experimentally after acute intracerebral hemorrhage.Methods The intracerebral hemorrhage(ICH) was established by infusing autoblood into rat caudate nucleus.Brain water content and Evan blue were used to confirm edema,BBB damage.RT-PCR and Western blot were respectively used to evaluate AQP-4 mRNA and protein expression and to observe the correlation between AQP-4 and tight junction protein ZO-1,occludin.Electron microscope was used to explore the level of BBB tight junction damage and astrocyte foot process swelling.Results Electron microscope showed astrocyte foot process swollen without BBB tight junction damage at the 6th hour after hemorrhage. As compared with the sham group,there appeared a significant increase in AQP4 mRNA and protein expression following ICH(P0.05): expression of AQP-4 mRNA appeared increased at the 3rd hour(1.05±0.13) and protein appeared increased(0.62±0.05) at the 6th hour following the hemorrhage.Expression of AQP-4 mRNA and protein reached its maximum at the 72th hour(1.46±0.02).Evan blue and electron microscope revealed BBB tight junction began to damage at the 12th hour following the hemorrhage.At the same time,expression of ZO-1、occludin(0.71±0.05 and 0.72±0.04,respectively)was decreased and shown a negative correlation with expression of AQP-4.Conclusions BBB damage might have negative correlation with expression of AQP-4 following hemorrhage.Increased espression of AQP-4 and astrocyte foot process swollen might be one of the early cause of BBB damage.