α-Synuclein induced cell death in mouse hippocampal (HT22) cells is mediated by nitric oxide-dependent activation of caspase-3

AbstractOur previous studies indicated that exogenous α-synuclein (ASN) activates neuronal nitric oxide (NO) synthase (nNOS) in rat brain slices. The present study, carried out on immortalized hippocampal neuronal cells (HT22), was designed to extend the previous results by showing the molecular pathway of NO-mediated cell death induced by exogenous ASN. Extracellular ASN (10μM) was found to stimulate nitric oxide synthase (NOS) and increase caspase-3 activity in HT22 cells, leading to poly(ADP-ribose) polymerase (PARP-1) cleavage. The inhibitor of Ca2+-dependent NOS (N-nitro-l-arginine, 100μM) prevented ASN-evoked caspase-3 activation and PARP-1 degradation. ASN exposure resulted in apoptotic death of HT22 cells and this effect was reversed by inhibition of NO synthesis and caspase-3 activity. Our results demonstrated that extracellular ASN induces neuronal cell death by NO-mediated caspase-3 activation

Potent effects of alkaloid-rich extract from Huperzia selago against sodium nitroprusside-evoked PC12 cells damage via attenuation of oxidative stress and apoptosis

Imbalance between production and scavenging of free radicals and other reactive oxygen species (ROS) is a component of many diseases, but it is especially important in aging-related diseases of the central nervous system. Oxidative stress-induced neuronal dysfunction plays an important role in the pathomechanism of neurodegenerative disorders, including Alzheimer’s and Parkinson’s disease. Experimental data showed that free radical scavengers may protect the brain against oxidative modifications. The need for efficient and safe antioxidants with therapeutic potential stimulated the rise of interest in the medicinal plant products, which are a rich source of phytochemicals possessing biological activity. In our studies we focused on alkaloid fractions (AFs) isolated from club moss, Huperzia selago and Diphasiastrum complanatum, due to their beneficial activity and exclusive chemical structure. Our previous study demonstrated that selected alkaloids from Huperzia selago effectively protect macromolecules from oxidative damage. Therefore, in the present study we investigated the effects and mechanisms of action of AFs isolated from Huperzia selago and Diphasiastrum complanatum against sodium nitroprusside (SNP)-induced oxidative injury in PC12 cells. The results demonstrated that the selected AFs via reduction of nitric oxide (NO) liberation protected cells against oxidative stress, DNA and mitochondrial damage, as well as apoptosis caused by SNP. Selected AF notably decreased SNP-evoked mitochondrial polymerase γ (Polg) up-regulation. Furthermore, AF which contains Lycopodine, Serratidine, Lycoposerramine-G and (probably) Cermizine B completely inhibited the SNP-induced expression of interferon-γ (Ifng) and cyclooxygenase 2 (Ptgs2) as well as significantly down-regulated the expression of 12/15-lipoxygenase (Alox12) and tended to decrease the mRNA level of interleukin-6 gene (Il6). In conclusion, these results suggest that the AFs from Huperzia selago effectively protect PC12 cells against SNP-induced oxidative damage by adjusting the level of reactive nitrogen species, suppression of apoptosis and down-regulation of proinflammatory genes. The compounds present in these AFs could be potential candidates to develop successful drugs preventing oxidative damage and apoptosis in age-related neurodegenerative disorders

Prenatal Exposure to Valproic Acid Affects Microglia and Synaptic Ultrastructure in a Brain-Region-Specific Manner in Young-Adult Male Rats: Relevance to Autism Spectrum Disorders

Autism spectrum disorders (ASD) are a heterogeneous group of neurodevelopmental conditions categorized as synaptopathies. Environmental risk factors contribute to ASD aetiology. In particular, prenatal exposure to the anti-epileptic drug valproic acid (VPA) may increase the risk of autism. In the present study, we investigated the effect of prenatal exposure to VPA on the synaptic morphology and expression of key synaptic proteins in the hippocampus and cerebral cortex of young-adult male offspring. To characterize the VPA-induced autism model, behavioural outcomes, microglia-related neuroinflammation, and oxidative stress were analysed. Our data showed that prenatal exposure to VPA impaired communication in neonatal rats, reduced their exploratory activity, and led to anxiety-like and repetitive behaviours in the young-adult animals. VPA-induced pathological alterations in the ultrastructures of synapses accompanied by deregulation of key pre- and postsynaptic structural and functional proteins. Moreover, VPA exposure altered the redox status and expression of proinflammatory genes in a brain region-specific manner. The disruption of synaptic structure and plasticity may be the primary insult responsible for autism-related behaviour in the offspring. The vulnerability of specific synaptic proteins to the epigenetic effects of VPA may highlight the potential mechanisms by which prenatal VPA exposure generates behavioural changes