Amitriptyline Protects Against Lidocaine-induced Neurotoxicity in SH-SY5Y Cells via Inhibition of BDNF-mediated Autophagy

N6-methyladenosine demethylase FTO regulates synaptic and cognitive impairment by destabilizing PTEN mRNA in hypoxic-ischemic neonatal rats

Hypoxic-ischemic brain damage (HIBD) can result in significant global rates of neonatal death or permanent neurological disability. N6-methyladenosine (m6A) modification of RNA influences fundamental aspects of RNA metabolism, and m6A dysregulation is implicated in various neurological diseases. However, the biological roles and clinical significance of m6A in HIBD remain unclear. We currently evaluated the effect of HIBD on cerebral m6A methylation in RNAs in neonatal rats. The m6A dot blot assay showed a global augmentation in RNA m6A methylation post-HI. Herein, we also report on demethylase FTO, which is markedly downregulated in the hippocampus and is the main factor involved with aberrant m6A modification following HI. By conducting a comprehensive analysis of RNA-seq data and m6A microarray results, we found that transcripts with m6A modifications were more highly expressed overall than transcripts without m6A modifications. The overexpression of FTO resulted in the promotion of Akt/mTOR pathway hyperactivation, while simultaneously inhibiting autophagic function. This is carried out by the demethylation activity of FTO, which selectively demethylates transcripts of phosphatase and tensin homolog (PTEN), thus promoting its degradation and reduced protein expression after HI. Moreover, the synaptic and neurocognitive disorders induced by HI were effectively reversed through the overexpression of FTO in the hippocampus. Cumulatively, these findings demonstrate the functional importance of FTO-dependent hippocampal m6A methylome in cognitive function and provides novel mechanistic insights into the therapeutic potentials of FTO in neonatal HIBD.

Dexmedetomidine Regulates Autophagy via the AMPK/mTOR Pathway to Improve SH-SY5Y-APP Cell Damage Induced by High Glucose

Neurodegenerative diseases and postoperative cognitive dysfunction involve the accumulation of β-amyloid peptide (Aβ). High glucose can inhibit autophagy, which facilitates intracellular Aβ clearance. The α2-adrenoreceptor agonist dexmedetomidine (DEX) can provide neuroprotection against several neurological diseases; however, the mechanism remains unclear. This study investigated whether DEX regulated autophagy via the AMPK/mTOR pathway to improve high glucose-induced neurotoxicity in SH-SY5Y/APP695 cells. SH-SY5Y/APP695 cells were cultured with high glucose with/without DEX. To examine the role of autophagy, the autophagy activator rapamycin (RAPA) and autophagy inhibitor 3-methyladenine (3-MA) were used. The selective AMPK inhibitor compound C was used to investigate the involvement of the AMPK pathway. Cell viability and apoptosis were examined by CCK-8 and annexin V-FITC/PI flow cytometric assays, respectively. Autophagy was analyzed by monodansylcadaverine staining of autophagic vacuoles. Autophagy- and apoptosis-related protein expression and the phosphorylation levels of AMPK/mTOR pathway molecules were quantified by western blotting. DEX pretreatment significantly suppressed high glucose-induced neurotoxicity in SH-SY5Y/APP695 cells, as evidenced by the enhanced viability, restoration of cellular morphology, and reduction in apoptotic cells. Furthermore, RAPA had a protective effect similar to that of DEX, but 3-MA eliminated the protective effect of DEX by promoting mTOR activation. Moreover, the AMPK/mTOR pathway was involved in DEX-mediated autophagy. Compound C significantly suppressed autophagy and reversed the protective effect of DEX against high glucose in SH-SY5Y/APP695 cells. Our findings demonstrated that DEX protected SH-SY5Y/APP695 cells against high glucose-induced neurotoxicity by upregulating autophagy through the AMPK/mTOR pathway, suggesting a role of DEX in treating POCD in diabetic patients.

Ivermectin-Induced Apoptotic Cell Death in Human SH-SY5Y Cells Involves the Activation of Oxidative Stress and Mitochondrial Pathway and Akt/mTOR-Pathway-Mediated Autophagy

Ivermectin (IVM) could cause potential neurotoxicity; however, the precise molecular mechanisms remain unclear. This study explores the cytotoxicity of IVM in human neuroblastoma (SH-SY5Y) cells and the underlying molecular mechanisms. The results show that IVM treatment (2.5–15 μM) for 24 h could induce dose-dependent cell death in SH-SY5Y cells. Compared to the control, IVM treatment significantly promoted the production of ROS, mitochondrial dysfunction, and cell apoptosis. IVM treatment also promoted mitophagy and autophagy, which were charactered by the decreased expression of phosphorylation (p)-Akt and p-mTOR proteins, increased expression of LC3II, Beclin1, ATG5, PINK, and Pakin1 proteins and autophagosome formation. N-acetylcysteine treatment significantly inhibited the IVM-induced production of ROS and cell death in SH-SY5Y cells. Autophagy inhibitor (e.g., 3-methyladenine) treatment significantly inhibited IVM-induced autophagy, oxidative stress, and cell apoptosis. Taken together, our results reveal that IVM could induce autophagy and apoptotic cell death in SH-SY5Y cells, which involved the production of ROS, activation of mitochondrial pathway, and inhibition of Akt/mTOR pathway. Autophagy inhibition improved IVM-induced oxidative stress and apoptotic cell death in SH-SY5Y cells. This current study provides new insights into understanding the molecular mechanism of IVM-induced neurotoxicity and facilitates the discovery of potential neuroprotective agents.

Fraxetin suppresses reactive oxygen species-dependent autophagy by the PI3K/Akt pathway to inhibit isoflurane-induced neurotoxicity in hippocampal neuronal cells

Isoflurane, a common volatile anesthetic, has been widely used to provide general anesthesia in operations. However, exposure to isoflurane may cause widespread neurotoxicity in the developing animal brain. Fraxetin, a natural coumarin derivative extracted from the bark of Fraxinus rhynchophylla, possesses versatile pharmacological properties including anti-oxidative, anti-inflammatory, and neuroprotective effects. However, the effect and action mechanism of fraxetin on neurotoxicity induced by isoflurane are unknown. Reactive oxygen species (ROS) generation, cell viability, lactate dehydrogenase (LDH) release, and apoptosis were estimated by 2',7'-dichlorofluorescin-diacetate (DCFH-DA) staining, MTT, LDH release, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling (TUNEL) staining assays, respectively. The protein levels of light chain 3 (LC3)-I, LC3-II, p62, protein kinase B (Akt), and phosphorylated Akt (p-Akt) were detected by western blot analysis. Isoflurane induced ROS, LDH release, apoptosis, and autophagy, but inhibited the viability in HT22 cells, which were overturned by fraxetin or ROS scavenger N-acetyl-L-cysteine. Fraxetin suppressed isoflurane-induced PI3K/Akt inactivation in HT22 cells. PI3K/Akt inactivation by LY294002 resisted the effects of fraxetin on isoflurane-induced autophagy and autophagy-modulated neurotoxicity in HT22 cells. In conclusion, fraxetin suppressed ROS-dependent autophagy by activating the PI3K/Akt pathway to inhibit isoflurane-induced neurotoxicity in hippocampal neuronal cells.

Long Noncoding RNA LINC01347 Modulated Lidocaine-Induced Cytotoxicity in SH-SY5Y Cells by Interacting with hsa-miR-145-5p

Local anesthetics, including lidocaine (Lid), are widely used in clinical settings but new evidence suggested that they may induce strong neurological side-effects in human brains. In this work, we used an in vitro model to examine the functional modulations of a long non-coding RNA (lncRNA), LINC01347 on Lid-induced cytotoxicity in SH-SY5Y cells. SH-SY5Y cells were maintained in vitro and treated with Lid to induce cytotoxicity. Dynamic expression of LINC01347, in response to Lid treatment or lentivirus-mediated overexpression, was examined by quantitative real-time PCR. The effects of LINC01347 overexpression on Lid-induced cell death, LDH, caspase, and autophagy activities were evaluated. A potential downstream target of LINC01347, human microRNA-145-5p (hsa-miR-145-5p), was evaluated in SH-SY5Y cells. Hsa-miR-145-5p was subsequently upregulated to explore its functional correlation with LINC01347 in modulating Lid-induced SH-SY5Y cytotoxicity. Lid caused cell death and downregulated LINC01347 expression in SH-SY5Y cells in vitro. LINC01347 overexpression reduced Lid-induced cell death, LDH and caspase augmentation, and LC3B accumulation. Hsa-miR-145-5p was discovered to be closely affiliated with LINC01347. Its upregulation partially restored Lid-induced cytotoxic effects in LINC01347-overexpressed SH-SY5Y cells. Our study presented strong evidence showing lncRNA LINC01347 modulated lidocaine-induced cytotoxicity in SH-SY5Y cells by interacting with hsa-miR-145-5p.