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Introduction: We examined the molecular mechanisms of graphene quantum dot (GQD)- mediated protection of SH-SY5Y human neuroblastoma cells from oxidative/nitrosative stress induced by iron-nitrosyl complex sodium nitroprusside (SNP). Methods: GQD was produced by electrochemical oxidation of graphite and characterized by AFM, UVVIS and FTIR spectroscopy. The antioxidant activity of GQD in cell-free conditions was assessed by DPPH, NBT and EPR analysis. The neuroprotective potential of GQD was determined by cell viability assays MTT, CV. Flow cytometry was used to assess markers of apoptosis and GQD scavenging of intracellular ROS/RNS as well. Cellular internalization of GQD was determined using TEM. Results: GQD prevented SNP-induced apoptosis, caspase activation and mitochondrial depolarization in neuroblastoma cells. Although GQD diminished the NO levels in SNP-treated cells, NO scavengers displayed only a slight protection. GQD significantly protected SH-SY5Y cells from neurotoxicity of lightexhausted SNP, incapable of producing NO, implying that protective mechanism is independent of NO-scavenging. GQD reduced SNP-triggered increase in intracellular levels of ROS, particularly •OH, O2•− in cells and cell-free condition. Nonselective antioxidants, •OH scavengers and iron chelators, mimicked GQD cytoprotection, indicating that GQD protect cells by neutralizing •OH generated in the Fenton reaction. Cellular GQD internalization was required for optimal protection since the removal of extracellular GQD by extensive washing partly diminished their protective effect, suggesting that GQD exerted neuroprotective effect intra- and extracellularly. Conclusion: By demonstrating that GQD protect neuroblastoma cells from SNP-induced apoptosis by •OH/NO scavenging, our results suggest that GQD could be valuable candidates for treatment of neurodegenerative diseases associated with oxidative/nitrosative stress.

We investigated the ability of graphene quantum dot (GQD) nanoparticles to protect SH-SY5Y human neuroblastoma cells from oxidative/nitrosative stress induced by iron-nitrosyl complex sodium nitroprusside (SNP).GQD reduced SNP cytotoxicity by preventing mitochondrial depolarization, caspase-2 activation, and subsequent apoptotic death. Although GQD diminished the levels of nitric oxide (NO) in SNP-exposed cells, NO scavengers displayed only a slight protective effect, suggesting that NO quenching was not the main protective mechanism of GQD. GQD also reduced SNP-triggered increase in the intracellular levels of hydroxyl radical (•OH), superoxide anion (O2•- ), and lipid peroxidation. Nonselective antioxidants, •OH scavenging, and iron chelators, but not superoxide dismutase, mimicked GQD cytoprotective activity, indicating that GQD protect cells by neutralizing •OH generated in the presence of SNP-released iron. Cellular internalization of GQD was required for optimal protection, since a removal of extracellular GQD by extensive washing only partly diminished their protective effect. Moreover, GQD cooperated with SNP to induce autophagy, as confirmed by the inhibition of autophagylimiting Akt/PRAS40/mTOR signaling and increase in autophagy gene transcription, protein levels of proautophagic beclin-1 and LC3-II, formation of autophagic vesicles, and degradation of autophagic target p62. The antioxidant activity of GQD was not involved in autophagy induction, as antioxidants N-acetylcysteine and dimethyl sulfoxide failed to stimulate autophagy in SNP-exposed cells. Pharmacological inhibitors of early (wortmannin, 3-methyladenine) or late stages of autophagy (NH4Cl) efficiently reduced the protective effect of GQD. Therefore, the ability of GQD to prevent the in vitro neurotoxicity of SNP depends on both •OH/NO scavenging and induction of cytoprotective autophagy.

Shizofrenija je neuropsihijatrijski poremećaj sloţene etiologije, sa globalnom prevalencom oko 1%. U terapiji shizofrenije ĉesto je neophodna dugotrajna primena tipiĉnih i/ili atipiĉnih antipsihotika, koji se razlikuju po efikasnosti i imaju razliĉite neţeljene efekte. Postoji veliki broj hipoteza o poreklu bolesti, ali najveći broj istraţivanja govori u prilog neurorazvojne hipoteze prema kojoj poremećaj tokom razvoja mozga dovodi do narušavanja procesa sinaptogeneze i neurotransmisije, pre svega dopaminergiĉkog i glutamatergiĉkog sistema. Fenciklidin (PCP) je nekompetitivni antagonist glutamatskih N-metil-D-aspartat receptora i njegova perinatalna administracija u pacova uzrokuje patofiziološke promene koje odgovaraju patološkim karakteristikama uoĉenim u shizofreniji. Mitohondrije imaju vaţnu ulogu u neurorazvoju i brojne studije povezuju abnormalnosti u strukturi i funkciji mitohondrija sa razvojem shizofrenije. Disfunkcija mitohondrija moţe rezultirati poremećajem u produkciji energije i aktivacijom procesa ćelijske smrti apoptozom i/ili autofagijom. Poremećaji odvijanja procesa apoptoze i autofagije su dokumentovani kod pacijenata obolelih od shizofrenije. Novije studije ukazuju na tesnu povezanost ova dva procesa. MeĊutim, još uvek ostaje nerazjašnjeno da li su uoĉene promene posledica tretmana antipsihoticima ili karakteristika same bolesti. Cilj: UtvrĊivanje neposrednih i dugotrajnih efekata perinatalne primene fenciklidina, kao i efekata haloperidola (tipiĉnog antipsihotika) i klozapina (atipiĉnog antipsihotika) na aktivnost enzima respiratornog lanca, ekspresiju proteinskih markera apoptotoze i autofagije, zastupljenost pojedinih vrsta ćelija nervnog sistema i ultrastrukturne promene u korteksu i hipokampusu pacova. Materijal i metode: Deset grupa Wistar pacova je subkutano tretirano 2, 6, 9. i 12. postnatalnog dana (PN) fenciklidinom (10 mg/kg) ili fiziološkim rastvorom (0.9% NaCl). Jedna NaCl i jedna PCP grupa su ţrtvovane PN13, dok su druge dve NaCl i, Schizophrenia (SCH) is a neuropsychiatric disorder with complex etiology and global prevalence of 1%. Disease usually requires long-term medication with typical and atypical antipsychotics, that have different effectiveness and side effects. There are a number of hypotheses about the origin of SCH, but most research support neurodevelopmental hypothesis according to which alterations during the brain development lead to disturbances of synaptogenesis and neurotransmission, primarily dopaminergic and glutamatergic systems. Phencyclidine (PCP) acts as a non-competitive antagonist of glutamatergic N-methyl-D-aspartate receptors, and its perinatal administration to rats causes pathophysiological changes that mimic some pathological features of schizophrenia. Mitochondria play a crucial role in the neurodevelopment and numerous data indicate that abnormalities in mitochondrial structure and function could be associated with the development of schizophrenia. Mitochondrial dysfunction may affect energy production and could lead to apoptotic cell death and/or autophagy. Altered apoptosis and autophagy processes have been identified in schizophrenia patients. Also, recent investigations indicate that these two processes are tightly correlated. However, remains unclear whether the observed changes are consequence of medication or disease itself. Aim of this study: Assess immediate and long-term effects of perinatal PCP administration, as well as, the effects of typical (haloperidol) and atypical (clozapine) antipsycotics on mitochondrial function determining the activity of respiratory chain enzymes, expression of apoptosis and autophagy markers, density of nervous system cells and ultrastructural changes in the cortex and hippocampus of the rat brain. Material and methods: Ten groups of Wistar rats were subcutaneously treated on 2nd, 6th, 9th and 12th postnatal days (PN), with either PCP (10 mg/kg) or saline (0.9% NaCl). One NaCl and one PCP group were sacrificed on PN13; ot