Mitochondrial function influences expression of methamphetamine-induced behavioral sensitization

Repeated methamphetamine use leads to long lasting brain and behavioral changes in humans and laboratory rats. These changes have high energy requirements, implicating a role for mitochondria. We explored whether mitochondrial function underpins behaviors that occur in rats months after stopping methamphetamine self-administration. Accordingly, rats self-administered intravenous methamphetamine for 3 h/day for 14 days. The mitochondrial toxin rotenone was administered as (1 mg/kg/day for 6 days) via an osmotic minipump starting at 0, 14 or 28 days of abstinence abstinence. On abstinence day 61, expression of methamphetamine-induced behavioral sensitization was obtained with an acute methamphetamine challenge in rotenone-free rats. Rotenone impeded the expression of sensitization, with the most robust effects obtained with later abstinence exposure. These findings verified that self-titration of moderate methamphetamine doses results in behavioral (and thus brain) changes that can be revealed months after exposure termination, and that the meth-initiated processes progressed during abstinence so that longer abstinence periods were more susceptible to the consequences of exposure to a mitochondrial toxin.

MitoTox: a comprehensive mitochondrial toxicity database

Background Mitochondria play essential roles in regulating cellular functions. Some drug treatments and molecular interventions have been reported to have off-target effects damaging mitochondria and causing severe side effects. The development of a database for the management of mitochondrial toxicity-related molecules and their targets is important for further analyses. Results To correlate chemical, biological and mechanistic information on clinically relevant mitochondria-related toxicity, a comprehensive mitochondrial toxicity database (MitoTox) was developed. MitoTox is an electronic repository that integrates comprehensive information about mitochondria-related toxins and their targets. Information and data related to mitochondrial toxicity originate from various sources, including scientific journals and other electronic databases. These resources were manually verified and extracted into MitoTox. The database currently contains over 1400 small-molecule compounds, 870 mitochondrial targets, and more than 4100 mitochondrial toxin-target associations. Each MitoTox data record contains over 30 fields, including biochemical properties, therapeutic classification, target proteins, toxicological data, mechanistic information, clinical side effects, and references. Conclusions MitoTox provides a fully searchable database with links to references and other databases. Potential applications of MitoTox include toxicity classification, prediction, reference and education. MitoTox is available online at http://www.mitotox.org.

Pelargonidin as an Attenuator of Neuronal Mitochondrial Dysfunction: An in Vivo Study

Targeting the neuronal mitochondria as a possible intervention to guard against neurodegenerative disorders' progression has been investigated in the current work via the administration of Pelargonidin (PEL) to rats intoxicated by the mitochondrial toxin Reserpine. The main criteria for choosing pelargonidin (PEL) were its reported poly (ADP-ribose) polymerase (PARP)-inhibitor, antioxidant, anti-apoptotic and anti-inflammatory activities. Male rats were randomized into four experimental groups; normal control, reserpinized to induce mitochondrial failure, standard PARP-1-inhibitor 1,5-isoquinolinediol (DIQ)-treated reserpinized, and PEL-treated reserpinized . PEL significantly restored brain glutathione (GSH) with a reduction in nitric oxide contents as compared to reserpine-challenged group. Meanwhile, it improved the neuronal mitochondrial function by the elevation of complex I activity associated with a low ADP/ATP ratio. Likely, through its anti-inflammatory effect, PEL reduced the elevation of serum interlukine-1ß level and inhibited serum lactate dehydrogenase (LDH) activity. These findings were aligned with the reduced expressions of cleaved PARP and cleaved caspase-3 proteins, indicating PEL suppressive effect to the intrinsic apoptotic pathway. Those biochemical findings were confirmed through comparable histopathological tissue examination among the experimental groups. In conclusion, PEL is a promising candidate for the future use in management of mitochondria-associated neuronal complications via controlling the ongoing inflammatory and degeneration cascades.

Gene-corrected Parkinson’s disease neurons show the A30P alpha-synuclein point mutation leads to reduced neuronal branching and function

Parkinson’s disease is characterised by the degeneration of A9 dopaminergic neurons and the pathological accumulation of alpha-synuclein. In a patient-derived stem cell model, we have generated dopaminergic neurons from an individual harbouring the p.A30P SNCA mutation and compared those neurons against gene-corrected isogenic control cell lines. We have used confocal microscopy to assess the neuronal network, specifically segmenting dopaminergic neurons and have identified image-based phenotypes showing axonal impairment and reduced neurite branching. We show using multi-electrode array (MEA) technology that the neurons carrying the endogenous p.A30P alpha-synuclein mutation are functionally impaired and identified mitochondrial dysfunction as a pathogenic cellular phenotype. We report that against gene-corrected isogenic control cell lines the neurons carrying the p.A30P SNCA mutation have a deficit and are susceptible to the mitochondrial toxin and environmental pesticide Rotenone. Our data supports the use of isogenic cell lines in identifying image-based pathological phenotypes that can serve as an entry point for future disease modifying compound screenings and drug discovery strategies.

Astrocytes from cortex and striatum show differential responses to mitochondrial toxin and BDNF: implications for protection of striatal neurons expressing mutant huntingtin

Background Evidence shows significant heterogeneity in astrocyte gene expression and function. We previously demonstrated that brain-derived neurotrophic factor (BDNF) exerts protective effects on whole brain primary cultured rat astrocytes treated with 3-nitropropionic acid (3NP), a mitochondrial toxin widely used as an in vitro model of Huntington’s disease (HD). Therefore, we now investigated 3NP and BDNF effects on astrocytes from two areas involved in HD: the striatum and the entire cortex, and their involvement in neuron survival. Methods We prepared primary cultured rat cortical or striatal astrocytes and treated them with BDNF and/or 3NP for 24 h. In these cells, we assessed expression of astrocyte markers, BDNF receptor, and glutamate transporters, and cytokine release. We prepared astrocyte-conditioned medium (ACM) from cortical and striatal astrocytes and tested its effect on a cellular model of HD. Results BDNF protected astrocytes from 3NP-induced death, increased expression of its own receptor, and activation of ERK in both cortical and striatal astrocytes. However, BDNF modulated glutamate transporter expression differently by increasing GLT1 and GLAST expression in cortical astrocytes but only GLT1 expression in striatal astrocytes. Striatal astrocytes released higher amounts of tumor necrosis factor-α than cortical astrocytes in response to 3NP but BDNF decreased this effect in both populations. 3NP decreased transforming growth factor-β release only in cortical astrocytes, whereas BDNF treatment increased its release only in striatal astrocytes. Finally, we evaluated ACM effect on a cellular model of HD: the rat striatal neuron cell line ST14A expressing mutant human huntingtin (Q120) or in ST14A cells expressing normal human huntingtin (Q15). Neither striatal nor cortical ACM modified the viability of Q15 cells. Only ACM from striatal astrocytes treated with BDNF and ACM from 3NP + BDNF-treated striatal astrocytes protected Q120 cells, whereas ACM from cortical astrocytes did not. Conclusions Data suggest that cortical and striatal astrocytes respond differently to mitochondrial toxin 3NP and BDNF. Moreover, striatal astrocytes secrete soluble neuroprotective factors in response to BDNF that selectively protect neurons expressing mutant huntingtin implicating that BDNF modulation of striatal astrocyte function has therapeutic potential against neurodegeneration. Graphical abstract

Carbamoyl-Phosphate Synthase 1 as a Novel Target of Phomoxanthone A, a Bioactive Fungal Metabolite

Phomoxanthone A, a bioactive xanthone dimer isolated from the endophytic fungus Phomopsis sp., is a mitochondrial toxin weakening cellular respiration and electron transport chain activity by a fast breakup of the mitochondrial assembly. Here, a multi-disciplinary strategy has been developed and applied for identifying phomoxanthone A target(s) to fully address its mechanism of action, based on drug affinity response target stability and targeted limited proteolysis. Both approaches point to the identification of carbamoyl-phosphate synthase 1 as a major phomoxanthone A target in mitochondria cell lysates, giving also detailed insights into the ligand/target interaction sites by molecular docking and assessing an interesting phomoxanthone A stimulating activity on carbamoyl-phosphate synthase 1. Thus, phomoxanthone A can be regarded as an inspiring molecule for the development of new leads in counteracting hyperammonemia states.