Abstract:

To explore the effects of isoflurane on autophagy and apoptosis  of rat PC12 cells induced by Aβ25-35,and to elucidate the possible mechanisms.Methods PC12 cells were randomly divided into 4 groups (n=6).Control group:the PC12 cells were administered with normal medium;10   μmol•L-1 Aβ25-35  group(Aβ group):the PC12 cells were administered with 10   μmol•L-1 Aβ25-35;2% isoflurane group(Iso group):the PC12 cells were administered with 2% isoflurane;2% isoflurane and 10   μmol•L-1 Aβ25-35 group(Iso+Aβ group):the PC12 cells were administered with 2% isoflurane +10   μmol•L-1  Aβ25-35.The autophagosomes of PC12 cells in various groups  were examined by transmission electron microscope,and the expressions of autophagy associated protein LC3-Ⅱ,p62 and autophagic signal gene mTOR,Beclin-1 were detected by Western blotting method 6 h after   administration;the  cell viability was determined by MTT assay,and  Western blotting method was performed to observe the expressions of apoptosis associated protein Bcl-2 and caspase-3 24 h after   administration.Results Compared with control group,great amounts of autophagosomes were presented in PC12 cells in Aβ group,the  expressions of LC3-Ⅱ,Beclin-1 and caspase-3 were significantly increased (P<0.05),and the  expressions of p62,p-mTOR and Bcl-2 were significantly decreased as well as  the  survival rate (P<0.05);however,autophagosomes failed to be presented in PC12 cells in Iso group,the  expressions of LC3-Ⅱ,Beclin-1 and Bcl-2 as well as cell survival rate were significantly decreased (P<0.05),and the expression of p62,p-mTOR and caspase-3 were significantly increased(P<0.05).Compared with Aβ group,only a few autophagosomes were found in PC12 cells in Iso+Aβ  group,the  expressions of LC3-Ⅱ and Beclin-1 as well as the  survival rate were significantly decreased (P<0.05),and the expressions of p62,p-mTOR and caspase-3 were significantly increased(P<0.05),but no changes occurred with the expression of Bcl-2 (P>0.05).Conclusion Isoflurane can inhibit autophagy  of rat PC12 cells induced by Aβ25-35 and aggravate the expressions of apoptosis rrelated proteins  through activation of autophagic signal
 gene mTOR and inhibition of Beclin-1.

Key words: isoflurane, Alzheimer&rsquo, s disease, PC12 cells, autophagy, apoptosis, beta-amyloid protein