Okadaic acid protects human neuroblastoma SH-SY5Y cells from 1-methyl-4-phenylpyridinium ion-induced apoptosis

1-Methyl-4-phenylpyridinium ion (MPP⁺) has been shown to selectively inhibit mitochondrial function and induce a parkinsonism-like syndrome. MPP⁺ stimulates the production of reactive oxygen species (ROS) and induces cell death in vitro. In this study, we investigated the protective effects of okadaic acid on MPP⁺-induced cell death in SH-SY5Y neuroblastoma cells. We found that MPP⁺-induced apoptosis and -ROS generation were blocked by okadaic acid. MPP⁺-mediated activation of AKT was also inhibited by okadaic acid. Taken together, these results demonstrate that okadaic acid protects against MPP⁺-induced apoptosis by blocking ROS stimulation and ROS-mediated signaling pathways in SH-SY5Y cells. These data indicated that okadaic acid could provide a therapeutic strategy for the treatment of neurodegenerative diseases including Parkinson's disease.     

Effects of overexpression of antioxidants on the release of cytochrome c and apoptosis-inducing factor in the model of ischemia

Apoptosis arises from neuronal damage following an ischemic insult. Apoptosis-inducing factor (AIF) is a protein released from mitochondria in response to pro-apoptotic signals which then translocates to the nucleus and triggers DNA fragmentation. In parallel with this, pro-apoptotic signals cause the release of cytochrome c from mitochondria, activating caspase-dependent apoptosis. During post-ischemic reperfusion, reactive oxygen species (ROS) are formed in excess in mitochondria and can play a role in initiating apoptosis. In cultures, ROS are formed during post oxygen glucose deprivation (OGD) normoxia/normoglycemia that is used as a model for ischemia. In this study, we delivered viral vectors to overexpress antioxidants (GPX, catalase, CuZnSOD, or MnSOD) in mixed cortical cultures, in order to investigate the effects of ROS-reduction on the release of cytochrome c and AIF. Overexpression of MnSOD, CuZnSOD, catalase or GPX all prevented AIF translocation from mitochondria to the nucleus. Potentially, this could reflect broadly non-specific protection due to reducing ROS load. Arguing against this, overexpression of the same antioxidants did not inhibit cytochrome c release. These findings suggest a specific interaction between ROS formation and the caspase-independent route of apoptosis.     

Nanomicellar formulation of coenzyme Q10 (Ubisol-Q10) effectively blocks ongoing neurodegeneration in the mouse 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine model: potential use as an adjuvant treatment in Parkinson's disease

Although the support for the use of antioxidants, such as coenzyme Q₁₀ (CoQ₁₀), to treat Parkinson's disease (PD) comes from the extensive scientific evidence, the results of conducted thus far clinical trials are inconclusive. It is assumed that the efficacy of CoQ₁₀ is hindered by insolubility, poor bioavailability, and lack of brain penetration. We have developed a nanomicellar formulation of CoQ₁₀ (Ubisol-Q₁₀) with improved properties, including the brain penetration, and tested its effectiveness in mouse MPTP (1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine) model with the objectives to assess its potential use as an adjuvant therapy for PD. We used a subchronic MPTP model (5-daily MPTP injections), characterized by 50% loss of dopamine neurons over a period of 28 days. Ubisol-Q₁₀ was delivered in drinking water. Prophylactic application of Ubisol-Q₁₀, started 2 weeks before the MPTP exposure, significantly offset the neurotoxicity (approximately 50% neurons died in MPTP group vs. 17% in MPTP+ Ubisol-Q₁₀ group by day 28). Therapeutic application of Ubisol-Q₁₀, given after the last MPTP injection, was equally effective. At the time of intervention on day 5 nearly 25% of dopamine neurons were already lost, but the treatment saved the remaining 25% of cells, which otherwise would have died by day 28. This was confirmed by cell counts, analyses of striatal dopamine levels, and improved animals' motor skill on a beam walk test. Similar levels of neuroprotection were obtained with 3 different Ubisol-Q₁₀ concentrations tested, that is, 30 mg, 6 mg, or 3 mg CoQ₁₀/kg body weight/day, showing clearly that high doses of CoQ₁₀ were not required to deliver these effects. Furthermore, the Ubisol-Q₁₀ treatments brought about a robust astrocytic activation in the brain parenchyma, indicating that astroglia played an active role in this neuroprotection. Thus, we have shown for the first time that Ubisol-Q₁₀ was capable of halting the neurodegeneration already in progress; however, to maintain it a continuous supplementation of Ubisol-Q₁₀ was required. The pathologic processes initiated by MPTP resumed if supplementation was withdrawn. We suggest that in addition to brain delivery of powerful antioxidants, Ubisol-Q₁₀ might have also supported subcellular oxidoreductase systems allowing them to maintain a favorable cellular redox status, especially in astroglia, facilitating their role in neuroprotection. Based on this data further clinical testing of this formulation in PD patients might be justifiable.