Effect of PARP inhibitor PJ34 on blood-brain barrier permeability and MMP-9 expression following traumatic brain injury in mice

Abstract

Objective To investigate the role of poly(ADP-ribose) polymerase (PARP) inhibitor PJ34 in regulating blood-brain barrier (BBB) permeability and matrix metalloproteinases-9 (MMP-9) expression in a mouse model of traumatic brain injury (TBI).Methods A total of 136 adult male BALB/c mice were randomly divided into sham-operated group,injured group and PJ34-treated group according to the random number table.Controlled cortical impact in mice was established.At 6 and 24hours postinjury,neurological deficit was evaluated,including motor,sensory,reflex and beam balance tests ; BBB permeability and brain water content were detected using Evans blue test and gravimetric technique; brain contusion volume was measured using HE staining; levels of MMP-9 in cytosolic fractions were detected using Western blotting.Results At 6 and 24 hours postinjury,neurological severity score in PJ34-treated group (8.00 ± 0.26,7.50 ±0.25) were lower than those in injured group (12.50 ±0.39,11.80 ± 0.32) ; brain contusion volume in PJ34-treated group [(11.25 ± 0.91) mm3,(13.55 ±1.06) mm3] was lower than those in injured group [(25.37 ± 1.75) mm3,(28.24 ± 1.51) mm3] ; BBB permeability in PJ34-treated group [(440.08 ± 3.10) μg/mg,(860.46 ± 3.86) μg/mg] was lower than those in injured group [(936.96 ± 4.71) μg/mg,(1 302.23 ± 5.89) μg/mg] (all P ＜ 0.01).Brain water content lowered significantly in PJ34-treated group than in injured group at 6 hours postinjury [(80.77 ± 0.76) ％ vs (82.55 ± 0.73) ％,P ＜ 0.0l],but between-group difference was not significant at 24 hours postinjury.Lower levels in MMP-9 were also observed in PJ34-treated group compared with injured group at 6 and 24 hours postinjury(P ＜ 0.05 or 0.01).Conclusion PARP inhibitor PJ34 can attenuate MMP-9 up-regulation,inhibit BBB injury and hence protect the brain against TBI in mice. Key words: Brain injuries; Blood-brain barrier; Matrix metalloproteinase 9; Poly(ADP-ribose) polymerase