Acute Phase Expression Pattern of ZnTs, LC3, and Beclin-1 in Rat Hippocampus and Its Regulation by 3-Methyladenine Following Recurrent Neonatal Seizures

Abstract

It has been reported that autophagy and zinc transporters (ZnTs) both play the key roles in excitotoxicity, which is associated with cognitive deficits following developmental seizures. However, the influence of autophagy on acute phase ZnTs expression has never been studied. The present study sought to investigate the contribution of an autophagy inhibitor (3-methyladenine, 3-MA) on the regulation of ZnTs, microtubule-associated protein 1A/1B light chain 3 (LC3), and beclin-1 expression in rat hippocampus following recurrent neonatal seizures. We examined the expression of ZnT1~ZnT3, LC3, and beclin-1 at 1.5, 3, 6, and 24 h after the last seizures using real-time RT-PCR and Western blot methods, respectively. The results showed that there were upregulated expressions of ZnT-1, ZnT-2, LC3, and beclin-1 of RS group. Pretreatment with 3-MA remarkably attenuated seizure-induced ZnT-1, ZnT-2, LC3, and beclin-1 increase. Additionally, linear correlations could be observed between LC3-Beclin1, LC3-ZnT-2, Beclin1-ZnT2, Beclin1-ZnT3, and among ZnT1~ZnT3 in control group, while the linear correlations could be observed between LC3-Beclin1, Beclin1-ZnT2, and Beclin1-ZnT3 in RS group. These results demonstrate, for the first time, that there exists an interaction of Zn(2+) with autophagic signals that are immediately activated in hippocampus after recurrent neonatal seizures, which might play a key role in neonatal seizure-induced excitotoxicity.

Retracted: MicroRNA‐421 suppresses the apoptosis and autophagy of hippocampal neurons in epilepsy mice model by inhibition of the TLR/MYD88 pathway

“…LC3, a mammalian homologue of yeast Apg8p, has been regarded as a cellular marker for the formation of autophagosomes in mammalian cells which has been found localized in autophagosome membranes (Kabeya et al, ). In the line with our study, a previous study found that both of LC3 and Beclin‐1mRNA and protein expression were evidently increased after seizures, indicating the autophagy activation by recurrent neonatal seizures, which might be associated with the acute phase excitotoxicity (Ni, Feng, Gong, Tao, & Wu, ).…”

Long-term Effects of Recurrent Neonatal Seizures on Neurobehavioral Function and Related Gene Expression and Its Intervention by Inhibitor of Cathepsin B

“…This is consistent with our previously reported findings in acute toxicity studies with flurothyl-induced recurrent neonatal seizures which revealed up-regulated expressions of ZnT-1, ZnT-2, LC3 and beclin-1 of RS group. Pre-treatment with 3-MA remarkably attenuated seizure-induced ZnT-1, ZnT-2, LC3 and beclin-1 increase [5]. Additionally, linear correlations Fig.…”

“…Statistical comparisons were carried out by nonparametric Kruskal-Wallis test. **P \ 0.01 versus control and CBI groups; *P \ 0.05 versus control and CBI groups; D P \ 0.05 versus control could be observed between LC3-Beclin1, LC3-ZnT-2, Beclin1-ZnT2, Beclin1-ZnT3 and among ZnT1-ZnT3 in control group, while the linear correlations could be observed between LC3-Beclin1, Beclin1-ZnT2 and Beclin1-ZnT3 in RS group [5]. These data, combined with our present findings that anti-apoptotic protein bcl-2 downregulated, strongly suggest that autophagic/apoptotic pathways may have been impacted at the protein level at the acute phase time point, which might be associated with the acute phase excitotoxicity and the long-term cognitive deficit.…”

“…Increased autophagy has been reported in experimental models of excitotoxicity such as stroke, and in patients with Alzheimer's disease and critical illness [6]. For example, we have previously demonstrated in rat models that autophagic pathway is activated immediately after seizure, ischemia, neurodegenerative and traumatic brain injury [4,5,7,8]. Besides, a lysosomal-apoptosis axis theory of cell death has also been proposed [9].…”

“…Morphological and biochemical approaches have shown the presence of both apoptotic and autophygic neuron death in striatum and hippocampus after kainic acid or flurothyl-induced seizure injury [4,5] As few anti-apoptotic therapies have proven to be useful in inhibiting seizure injury, therefore, autophagy-mediated apoptosis has been intensively studied in recent years and may be a potential target for developing a novel therapy for seizure damage.…”