Objective  To observe the effect of polyinosinic-polycytidylic acid (Poly-IC) treatment on the expressions of Bcl-2 and Bax after cerebral ischemia-reperfusion （I/R）injury in hyperlipidemia rats, and to detect the cerebral infarction, blood-brain barrier permeability and behavioral injury symptoms, to explore the neuroprotective effect of Poly-IC treatment on cerebral I/R injury in hyperlipidemia rats.    Methods  Hyperlipidemia rats were randomly divided into cerebral I/R group, Poly-IC pretreatment group, Poly-IC post-treatment group and sham operation group, 20 rats in each group. Neurobehavioral performance of rats in each group was recorded according to neurobehavioral score of 0-4 points. Blood-brain barrier permeability of rats in each group was detected by Evans blue staining. TTC staining was used to observe the cerebral infarction in each group. Apoptotic cells in the cerebral cortex of rats in each group was observed by TUNEL staining. The relative expression levels of Bcl-2 and Bax were determined by Western blotting.    Results  Compared with the sham group, the symptoms of neurobehavioral damage in the I/R group were serious and the score increased significantly(P<0.05). The scores of Poly-IC pretreatment and post-treatment groups were significantly lower than that of I/R group(P<0.05). Evans blue staining result  showed that the blood-brain barrier permeability of the I/R group was significantly higher than that of the sham group (P<0.05), and Poly-IC pretreatment or post-treatment could significantly reduce the blood-brain barrier permeability(P<0.05). No infarct was observed in the sham group with uniform red staining, while white infarct was observed in the brain tissue of the I/R group. Compared with the I/R group, the volume of infarct in both Poly-IC pretreatment and post-treatment groups reduced significantly (P<0.05). The apoptosis index in cerebral cortex of rats in I/R group was significantly higher than that in sham group (P<0.05), while the apoptosis index in Poly-IC pretreatment or post-treatment group was significantly lower than that in I/R group(P<0.05). The result  of Western blotting showed that, compared with the sham group, the expression of Bax in the I/R group was significantly increased(P<0.05), the expression of Bcl-2 was significantly decreased(P<0.05). Compared with the I/R group, the expression of Bax in the Poly-IC pretreatment or post-treatment group reduced significantly(P<0.05), the expression of Bcl-2 increased significantly(P<0.05).     Conclusion  Poly-IC pretreatment or post-treatment can improve the symptoms of neurobehavioral injury, reduce the damage of blood-brain barrier, reduce the volume of cerebral infarction, decrease the apoptosis index of nerve cells, play a neuroprotective effect on cerebral ischemia reperfusion injury in rats with hyperlipidemia, and this protective effect may be related to the change of Bcl-2 and Bax expression levels.

Hyperlipidemia, Cerebral ischemia-reperfusion, Polyinosinic-polycytidylic acid, B-cell lymphoma-2, Bcl-2 assaciated X protein, Terminal UTP nickend labeling, Rat