Antioxidant strategies for neurodegenerative diseases

Methylglyoxal activates transient receptor potential A1/V1 via reactive oxygen species in the spinal dorsal horn

Methylglyoxal (MGO), a highly reactive dicarbonyl metabolite of glucose primarily formed during the glycolytic pathway, is a precursor of advanced glycation end-products (AGEs). Recently, numerous studies have shown that MGO accumulation can cause pain and hyperalgesia. However, the mechanism through which MGO induces pain in the spinal dorsal horn remains unclear. The present study investigated the effect of MGO on spontaneous excitatory postsynaptic currents (sEPSC) in rat spinal dorsal horn neurons using blind whole-cell patch-clamp recording. Perfusion of MGO increased the frequency and amplitude of sEPSC in spinal horn neurons in a concentration-dependent manner. Additionally, MGO administration increased the number of miniature EPSC (mEPSC) in the presence of tetrodotoxin, a sodium channel blocker. However, 6-cyano-7-nitroqiunocaline-2,3-dione (CNQX), an AMPA/kainate receptor antagonist, blocked the enhancement of sEPSC by MGO. HC-030031, a TRP ankyrin-1 (TRPA1) antagonist, and capsazepine, a TRP vanilloid-1 (TRPV1) antagonist, inhibited the action of MGO. Notably, the effects of MGO were completely inhibited by HC-030031 and capsazepine. MGO generates reactive oxygen species (ROS) via AGEs. ROS also potentially induce pain via TRPA1 and TRPV1 in the spinal dorsal horn. Furthermore, we examined the effect of MGO in the presence of N-tert-butyl-α-phenylnitrone (PBN), a non-selective ROS scavenger, and found that the effect of MGO was completely inhibited. These results suggest that MGO increases spontaneous glutamate release from the presynaptic terminal to spinal dorsal horn neurons through TRPA1, TRPV1, and ROS and could enhance excitatory synaptic transmission.

Nootropic Effects of Filipendula Vulgaris Moench Water Extract Fractions

Nootropic activity of water extract fractions from aerial parts of Filipendula vulgaris Moench was demonstrated on the models of hermetic volume hypoxia, conditioned passive avoidance response, open field test, and forced swimming with a load. The fractions stimulated hypoxic resistance, normalized orientation and exploratory behavior, improved conditioned response reproduction during testing after hypoxic injury, and increased exercise tolerance. Fractionation of the extract led to dissociation of the effect components, which suggests that individual constituents have specific characteristics. Ethylacetate fraction exhibited most pronounced nootropic activity and was superior to plant extract by some characteristics. The detected effects seemed to be caused by modulation of the hippocampus activity the under the effects of phenol and triterpene compounds.

Oxidative stress in the spinal cord is an important contributor in capsaicin-induced mechanical secondary hyperalgesia in mice

Recent studies indicate that reactive oxygen species (ROS) are critically involved in persistent pain primarily through spinal mechanisms, thus suggesting ROS involvement in central sensitization. To investigate ROS involvement in central sensitization, the effects of ROS scavengers and donors on pain behaviors were examined in mice. Capsaicin- induced hyperalgesia was used as a pain model since it has 2 distinctive pain components, primary and secondary hyperalgesia representing peripheral and central sensitization, respectively. Capsaicin (25 microg/5 microl) was injected intradermally into the left hind foot. Foot withdrawal frequencies in response to von Frey filament stimuli were measured and used as an indicator of mechanical hyperalgesia. The production of ROS was examined by using a ROS sensitive dye, MitoSox. Mice developed primary and secondary mechanical hyperalgesia after capsaicin injection. A systemic or intrathecal post-treatment with either phenyl-N-tert-butylnitrone (PBN) or 4-hydroxy-2,2,6,6-tetramethylpiperidine-1 oxyl (TEMPOL), ROS scavengers, significantly reduced secondary hyperalgesia, but not primary hyperalgesia, in a dose-dependent manner. Pretreatment with ROS scavengers also significantly reduced the magnitude and duration of capsaicin-induced secondary hyperalgesia. On the other hand, intrathecal injection of tert-butylhydroperoxide (t-BOOH, 5 microl), a ROS donor, produced a transient hyperalgesia in a dose-dependent manner. The number of MitoSox positive dorsal horn neurons was increased significantly after capsaicin treatment. This study suggests that ROS mediates the development and maintenance of capsaicin-induced hyperalgesia in mice, mainly through central sensitization and that the elevation of spinal ROS is most likely due to increased production of mitochondrial superoxides in the dorsal horn neurons.

Genetic findings in Parkinson's disease and translation into treatment: a leading role for mitochondria?

Parkinson's disease (PD) is a progressive neurodegenerative movement disorder and in most patients its aetiology remains unknown. Molecular genetic studies in familial forms of the disease identified key proteins involved in PD pathogenesis, and support a major role for mitochondrial dysfunction, which is also of significant importance to the common sporadic forms of PD. While current treatments temporarily alleviate symptoms, they do not halt disease progression. Drugs that target the underlying pathways to PD pathogenesis, including mitochondrial dysfunction, therefore hold great promise for neuroprotection in PD. Here we summarize how the proteins identified through genetic research (alpha-synuclein, parkin, PINK1, DJ-1, LRRK2 and HTRA2) fit into and add to our current understanding of the role of mitochondrial dysfunction in PD. We highlight how these genetic findings provided us with suitable animal models and critically review how the gained insights will contribute to better therapies for PD.

On the stability of 2-aminoselenophene-3-carboxylates: potential dual-acting selenium-containing allosteric enhancers of A1 adenosine receptor binding

Ethyl-2-amino-4,5,6,7-tetrahydro-1-benzoselenophene-3-carboxylate (4), has been prepared as a potential dual-acting selenium-containing allosteric enhancer of adenosine A(1)A receptor binding utilising a modified Gewald reaction. While preliminary testing indicated that 4 is a superior enhancer of A(1)AR binding than its thiophene counterpart, its instability under mildly acidic conditions is cause for concern. X-Ray crystallography, together with DFT calculations, provide evidence that the decomposition of 4 involves the ring-opening of selenophenium ion (12b) followed by the loss of elemental selenium through a radical chain process.

Dietary flavonoids as potential neuroprotectants

There is an increasing awareness of the role of certain nutritional components, including dietary flavonoids found in fruit, vegetables and beverages, in the maintenance of health and prevention of chronic diseases. In this regard, recent studies highlight an exciting role with respect to their potential neuroprotective actions, in particular towards deficits commonly observed with aging, such as reduced performance of cognitive, memory and learning tasks. These neurological functions, and possible mechanisms involved in controlling them, can be influenced by supplementation of single dietary flavonoids, or as part of a flavonoid-rich preparation. With this, a renewed emphasis is aimed at further understanding their modes and sites of action. Moreover a common theme among many in vitro studies examining mechanisms of neuroprotection is the failure to include biologically relevant metabolites of the flavonoids known to enter the circulation, and thus most likely to be bioavailable to cells and tissues. This oversight will ultimately influence the mechanisms of action proposed to explain the neuroprotection observed in animals and human studies. As such, emerging findings suggest a variety of potential mechanisms of action of flavonoids and their bioavailable metabolites in cytoprotection against oxidative stress, which may be independent of conventional antioxidant reducing activities. Such mechanisms might involve their interaction with cell signalling cascades, their influence on gene expression and the down regulation of pathways leading to cell death.