[Effects of heat shock protein A5 induced autophagy on cerebral ischemia/reperfusion injury in mice].

Objective: To determine the role of heat shock protein A5 (HSPA5) induced autophagy on cerebral ischemia/reperfusion in-jury in mice.
Methods: Thirty-six BALB/c mice were randomly divided into sham group, ischcmia/reperfusion (I/R) group, vehicle + I/R group, 3-Methyladenine(3-MA) + I/R group, scramble siRNA group and HSPA5 siRNA + I/R group( n =6). In sham group, the operation was only performed, did not insert line switch. Focal cerebral ischemia was performed using the method of middle cerebral artery occlusion (MCAO) for 60 min and 24 h reperfusion. In vehicle + I/R group and 3-MA + I/R group, 2 μ l 0.9% NaCl or 3-MA(30 mg/ml) was admin-istered by intracerebroventricular injection 30 min before MCAO; In scramble siRNA + I/R group and HSPA5 siRNA + I/R group, 5 μ l scram-ble siRNA or HSPA5 siRNA(2 μ g/ μ l) was administered by intracerebroventricular injection 24 h before MCAO. Autophagosome in neuron, the expression of microtubule-associated protein light chain 3 (LC3)-Ⅱ/LC3-I in ischemic cortex, the degree of cerebral ischemic injury and neu-rological function score were detected.
Results: Initial electron microscopy showed that neuronal morphology appeared to be normal in the sham group. At 24 h after I/R, cell shrinkage, loss of cellular organelles and formation of autophagosomes were observed in the ischemic cerebral cortex of I/R group. In addition, autophagosomes were less frequently observed than that in I/R group. The expressions of LC3-Ⅱ/LC3-I and Beclin-1 protein were increased significantly in I/R group compared with that in sham group( P < 0.05). Compare with I/R group, the LC3-Ⅱ/LC3-I protein levels induced by I/R in 3-MA + I/R group or HSPA5 siRNA + I/R group was decreased effectively ( P < 0.05). In addi-tion, the cerebral ischemic injury and neurological symptoms after I/R in 3-MA + I/R group or HSPA5 siRNA + I/R group were exacerbated significantly ( P < 0.05).
Conclusions: These results suggest that HSPA5 induced autophagy may play a protective role in focal I/R damage in mice.