Vitamin E inhibits activated chaperone-mediated autophagy in rats with status epilepticus

Abstract

Seizures and status epilepticus induce an excessive production of reactive oxygen species leading to oxidative stress. Vitamin E, a classic antioxidant, has a neuroprotective effect on rats with seizures by regulating reactive oxygen species production. The activity of chaperone-mediated autophagy, a selective pathway for the degradation of cytosolic proteins in lysosomes, is enhanced during oxidative stress. Whether chaperone-mediated autophagy is induced during status epilepticus is not established. To address this problem, we used pilocarpine to elicit status epilepticus in rats. Lysosome-associated membrane protein 2a was used to estimate chaperone-mediated autophagy. We showed that compared to control animals, lysosome-associated membrane protein 2a at lysosomal membranes increased significantly in rats at 8 h, 16 h, and 24 h after induction of status epilepticus, which directly correlated with chaperone-mediated autophagy activity. Since reactive oxygen species are believed to be important in the pathogenesis of status epilepticus and are essential for the process of chaperone-mediated autophagy, we also sought to determine if pretreatment with vitamin E reduced chaperone-mediated autophagy. Pretreatment with vitamin E reduced oxidative stress and partially inhibited chaperone-mediated autophagy in brain at 24 h after status epilepticus versus vehicle. Taken together, these data show that chaperone-mediated autophagy is increased in rats with pilocarpine-induced status epilepticus through upregulation of de novo synthesis of lysosome-associated membrane protein 2a. Antioxidants such as vitamin E may partially inhibit activated chaperone-mediated autophagy.