Sulforaphane protects SK-N-SH cells against antipsychotic-induced oxidative stress

Adverse reactions to antipsychotic drugs (APs) have been attributed to oxidative stress. Sulforaphane (SF) is a potent antioxidant that protects against dopaminergic cell death. We examined the protective properties of SF against AP-induced oxidative stress in dopaminergic neuroblastoma cells. Human neuroblastoma SK-N-SH cells were treated with SF (0.5-5 μM), and 24 h later, haloperidol, risperidone or paliperidone (100 μM) was administered, either alone or in combination with dopamine (100 μM). To determine the antioxidant properties of SF, quinone oxidoreductase (NQO1) activity, glutathione S-transferase activity, and glutathione (GSH) levels were determined. Oxidative stress was measured by the increase in thiobarbituric acid reactive substances (TBARS) and in protein-bound quinones. Cell viability was also assessed. SF treatment increased GSH levels and induced NQO1 activity in SK-N-SH cells. Haloperidol was the only AP that increased TBARS when administered alone. When cells were cocultured with a drug in combination with dopamine, all three APs increased TBARS and protein-bound quinones and also induced neurotoxicity. In all the experimental conditions, 5 μM SF attenuated the accumulation of TBARS and protein-bound quinones and increased cell survival rates. Our results indicate that SF increases GSH levels and induces NQO1 activity and the removal of electrophilic quinones and radical oxygen species. Furthermore, SF could provide protective effects against AP-induced toxicity in dopaminergic cells.

Searching for functional SNPs or rare variants in exonic regions of DRD3 in risperidone-treated patients

Previously one intronic DRD3 SNP, rs167771, was associated with risperidone-induced extrapyramidal side-effects (EPS). The aim of the present study was to search hitherto unidentified common functional variants or rare variants, in DRD3 associated with risperidone-induced EPS. 126 subjects treated with risperidone participated in this study. We sequenced the seven exons of DRD3. After sequencing we localized five dbSNPs and four new rare variants. None of the dSNPs or rare variants seems to be functional after bioinformatics analysis. Our results suggest that, rather than exonic regions, regulatory regions and introns could be related to the associations reported for DRD3 and the incidence of locomotor side-effects.

Xenobiotic metabolizing and transporter genes: gene–gene interactions in schizophrenia and related disorders

Aims: In this study we explored possible epistasis between CYP2D6 (*3, *4, *5, *6 and *1xN), CYP3A5 (*3), CYP1A2 (*1C and *1F) and ABCB1 (G2677T) in schizophrenia and related disorders. Materials & methods: A total of 344 patients diagnosed with schizophrenia and related disorders, and 484 healthy controls participated in the present study. We analyzed gene–gene interactions by multifactor dimensionality reduction. Results: A four-way model including ABCB1 G2677T, CYP3A5*3, CYP1A2*1F and CYP2D6*4 variants had the best overall performances (accuracy: 0.573) and a crossvalidation consistency of 10/10 (permutation testing p < 0.004). Conclusion: Our results suggest a significant involvement of CYPs and transporters in brain metabolism and homeostasis, and provide evidence of gene–gene interactions among xenobiotic metabolizing and transporter genes in the context of schizophrenia.