ABSTRACT
Objective The amyloid β-protein precursor contains a domain highly homologous to Kunitz-type serine protease inhibitors. We have successfully established and characterized the recombinant human rhKD/APP in vitro. The aim of this study is to investigate the potential neuroprotective role of rhKD/APP on cerebral ischemia/reperfusion injury in rats. Methods Rats pretreated with rhKD/APP (4, 8, 16 mg/kg) were subjected to prepare models of cerebral ischemia/reperfusion (I/R) injury and those rats treated with Nimodipine were used as positive control. Comparison of the scores of neurological deficits, TTC-stained infarct volume and cerebral water content between the groups was performed. The activities of SOD, Na+-K+-ATPase and the content of MDA in the cortex tissues were measured and the activities of serum myeloperoxidase ( MPO) enzyme were also compared. The expressions of adhesion molecules ( ICAM-1 and E-selectin) were compared by immunohistochemistry. End-labeling of nuclear DNA fragmentation (TUNEL) and qualification of caspase-3, Bcl-2 and Bax were also employed to evaluate the local apoptosis in cortex tissues. Results By pretreatment with the rhKD/APP at three doses, cerebral infarct volume, water content and neurological deficits were all reduced. The activities of SOD, and Na+-K+-ATPase were increased, the contents of MDA were decreased in the cortex tissues, and the serum MPO activity was reduced. The expressions of adhesion molecules were downregulated and the apoptotic signaling of neurons were inhibited. All the changes induced by rhKD/APP treatment in the ischemia/reperfusion injury models showed statistical significance compared with the control rats. However, no significant difference was shown between the rhKD/APP group and Nimodipine group excepted for the reduced MPO in sera. Conclusions The result of this study suggest that rhKD/APP has neuroprotective effect on the cerebral ischemia/reperfusion injury through inhibiting multiple signaling pathways and is promising to be a potential neuroprotective drug.