Effects of thrombolysis within 6 hours on acute cerebral infarction in an improved rat embolic middle cerebral artery occlusion model for ischaemic stroke

Recombinant tissue plasminogen activator (rt‐PA) is the first‐line drug for revascularization in acute cerebral infarction (ACI) treatment. In this study, an improved rat embolic middle cerebral artery occlusion model for ischaemic stroke was used and the rats were killed on the first, third and seventh day after model establishment. Increases in infarct volume were significantly less in the thrombolytic group than in the conventional group at every time‐point. The microvascular density (MVD) in the thrombolytic group was significantly higher than that in the conventional group at every time‐point, especially on the seventh day. Increases in the expressions of neuronal nitric‐oxide synthase (NOS) and caspase‐3 in the ischaemic region and in the nitric oxide contents, malondialdehyde contents, and inducible NOS activities in the cortex of infarct side were significantly less in the thrombolytic group than in the conventional group. Furthermore, decreases in the superoxide dismutase activities in the thrombolytic group were significantly less than those in the conventional group. In conclusion, thrombolytic rt‐PA therapy within a broadened therapeutic window (6 hours) could significantly decrease the infarct volume after ACI, possibly by increasing MVD in the ischaemic region, decreasing apoptotic molecule expression, and alleviating the oxidative stress response.