Figure 4 - uploaded by Margaret E. Rice
Content may be subject to copyright.
![Enzymatic degradation in termination of H 2 O 2 DA release regulation. (A, B) Exogenous application of the H 2 O 2 metabolizing enzymes glutathione peroxidase (GSHPx) or catalase (Cat) completely prevents the increase in pulse-train evoked striatal [DA] o normally seen with the AMPAR antagonist GYKI-52466 in dorsal striatum. By contrast, heat-inactivated forms of these enzymes (IGSHPx or I-Cat) are without effect. (C) Exogenous catalase also reverses the decrease in DA release usually seen when GSH peroxidase is inhibited with MCS. These data demonstrate the scavenging nature of these antioxidant enzymes in regulating and terminating the DA modulatory effects of endogenous H 2 O 2. Data are means ± SEM (modified from ref 21).](profile/Margaret-Rice-2/publication/233965111/figure/fig4/AS:668286161285120@1536343245061/Enzymatic-degradation-in-termination-of-H-2-O-2-DA-release-regulation-A-B-Exogenous.png)
Enzymatic degradation in termination of H 2 O 2 DA release regulation. (A, B) Exogenous application of the H 2 O 2 metabolizing enzymes glutathione peroxidase (GSHPx) or catalase (Cat) completely prevents the increase in pulse-train evoked striatal [DA] o normally seen with the AMPAR antagonist GYKI-52466 in dorsal striatum. By contrast, heat-inactivated forms of these enzymes (IGSHPx or I-Cat) are without effect. (C) Exogenous catalase also reverses the decrease in DA release usually seen when GSH peroxidase is inhibited with MCS. These data demonstrate the scavenging nature of these antioxidant enzymes in regulating and terminating the DA modulatory effects of endogenous H 2 O 2. Data are means ± SEM (modified from ref 21).
Source publication
Here we review evidence that the reactive oxygen species, hydrogen peroxide (H(2)O(2)), meets the criteria for classification as a neuromodulator through its effects on striatal dopamine (DA) release. This evidence was obtained using fast-scan cyclic voltammetry to detect evoked DA release in striatal slices, along with whole-cell and fluorescence...
Contexts in source publication
Context 1
... already noted, H 2 O 2 is metabolized primarily by the antioxidant enzymes GSH peroxidase and catalase ( Figure 2A); inhibition of GSH peroxidase leading to amplification of endogenous H 2 O 2 levels in cells in which it is generated (e.g., MSNs) ( Figure 2C), with subsequent enhancement of H 2 O 2 -depend- ent suppression of DA release (Figures 1B, 2E). However, our studies have also shown that exogenous application of GSH peroxidase or catalase completely prevents the increase in striatal DA release normally seen with the AMPAR antagonist GYKI-52466 21 ( Figure 4A,B). Moreover, exogenous catalase reverses the decrease in DA release usually seen when GSH peroxidase is inhibited with MCS 21 ( Figure 4C). ...
Context 2
... our studies have also shown that exogenous application of GSH peroxidase or catalase completely prevents the increase in striatal DA release normally seen with the AMPAR antagonist GYKI-52466 21 ( Figure 4A,B). Moreover, exogenous catalase reverses the decrease in DA release usually seen when GSH peroxidase is inhibited with MCS 21 ( Figure 4C). These data not only demonstrate that the actions of endogenous H 2 O 2 on striatal DA release are regulated by enzymatic degradation but they also confirm the role of H 2 O 2 in glutamate-dependent regulation of DA release. ...
Context 3
... NMDARs under the same conditions has no effect on H 2 O 2 generation in MSNs or evoked [DA] o . 21,22 The observations that the effect of GYKI-52466 is absent when the H 2 O 2 scavenging enzymes catalase and GSH peroxidase are present 21 ( Figure 4A,B), when mitochondrial H 2 O 2 generation is prevented, 49 or when H 2 O 2 -sensitive K ATP channels are blocked ( Figure 3A) confirm that glutamatergic AMPAR- modulation of DA release occurs exclusively through mitochondrial H 2 O 2 and K ATP -channel activation. ...
Citations
... Reactive oxygen species like hydrogen peroxide (H2O2) have been shown to act as a neuromodulator regulating rapid dopamine release in the brain. 90,91 When in excess, H2O2 causes oxidative stress tying it to numerous neurological diseases. 90,91 Discussed previously, several non-electroactive molecules are able to be detected electrochemically with the help of substratespecific enzyme modified electrodes using H2O2 as a reporter molecule for indirect detection. ...
... 90,91 When in excess, H2O2 causes oxidative stress tying it to numerous neurological diseases. 90,91 Discussed previously, several non-electroactive molecules are able to be detected electrochemically with the help of substratespecific enzyme modified electrodes using H2O2 as a reporter molecule for indirect detection. 61,62 Pioneering FSCV detection of H2O2 at CFMEs, 91 the Sombers lab has provided us with a novel approach for sensitive detection in the dorsal striatum 92 and have shown mechanistic studies into the production of hydroxyl radical intermediates and how this modulates dopamine dynamics. ...
Carbon-based sensors have remained critical materials for electrochemical detection of neurochemicals rooted in their inherent biocompatibility and broad potential window. Real-time monitoring, using fast-scan cyclic voltammetry, has resulted in the rise of minimally invasive carbon -fiber microelectrodes as the material of choice for making measurements in tissue, but challenges with carbon fiber’s innate properties have limited its applicability to understudied neurochemicals. Here, we provide a critical review of the state of carbon-based real-time neurochemical detection and offer insight into ways we envision addressing these limitations in the future. We focus on three main hinderances of traditional carbon-fiber based materials: diminished temporal resolution due to geometric properties and adsorption/desorption properties of the material, poor selectivity/specificity to most neurochemicals, and the inability to tune amorphous carbon surfaces for specific interfacial interactions. Routes to addressing these challenges could lie in methods like computational modeling of single-molecule interfacial interactions, expansion to tunable carbon-based materials, and novel approaches to synthesizing these materials. We hope this critical piece does justice to describing the novel carbon-based materials that have preceded this work, and we hope this review provides useful solutions to innovate carbon-based material development in the future for individualized neurochemical structures.
... For instance, H 2 O 2 can modulate neuroplasticity and synaptic transmission in the rodent brain [17,129]. Also, endogenous H 2 O 2 modulates dopamine (DA) release through the activation of potassium ion-sensitive ATP channels in neurons' presence at the substantia nigra and striatal [130,131] [132]. It is also worth mentioning that the superoxide could also convert to peroxynitrite, and thus the H 2 O 2 level might not solely represent the actual level of superoxide ( Figure 1). ...
In this focused review, we examine the influence of reactive oxygen and nitrogen species (ROS/RNS) on physiological processes and the induction of oxidative stress, with particular emphasis on the brain and neuronal systems. We discuss the formation mechanisms of ROS and RNS, their significance in the brain, and various detection methods. The review investigates the latest advancements in nano-engineered electrochemical biosensors designed for in vivo monitoring of ROS and RNS in the brain tissue. We explore the electrochemical measurement of specific species, such as H 2 O 2 , superoxide, NO, and peroxynitrite, while providing a comparative evaluation of sensor designs for ROS and RNS detection in the brain. Finally, we offer an outlook and conclusion on the future of this field.
... Likewise, H 2 O 2 also modulated DA neuron activity and somatodendritic DA release in the substantia nigra pars compacta (SNc). Regulation of the nigrostriatal DA system is critical as the central role this pathway played in the control of movement by the basal ganglia (Patel and Rice, 2012;Rice 2011). Interestingly, H 2 O 2 at effective concentration (80 μM) supported neuronal survival in neuron-astroglia, neuron-microglia and neuron-glia cultures but not in neuron-enriched cultures. ...
Traditionally, hydrogen peroxide (H2O2) was formed from cellular oxidative metabolism and often viewed as toxic waste. In fact, H2O2 was a benefit messenger for neuron-glia signaling and synaptic transmission. Thus, H2O2 was a double-edged sword and neuroprotection vs. neurotoxicity produced by H2O2 was difficult to define. Nuclear factor erythroid 2-related factor 2 (Nrf2) has been implicated as an intracellular regulator of neuronal growth. Inactivation of Nrf2 participated in the development of Parkinson's disease (PD). Thus, suitable activation of Nrf2 was essential for the prevention and treatment of PD. This study aimed to explore whether H2O2-conferred neuroprotective effects to support neuronal survival. H2O2 were added into primary neuron-glia, neuron-astroglia and neuron-microglia co-cultures in concentration- and time-dependent manners. H2O2 increased dopamine (DA) neuronal survival in concentration- and time-dependent manners. In addition, glial cells Nrf2 activation involved in H2O2-supported DA neuronal survival with the following phenomenons. First, H2O2 activated Nrf2 signaling pathway. Second, H2O2 generated beneficial neuroprotection in neuron-glia, neuron-astroglia and neuron-microglia co-cultures but not in neuron-enriched cultures. Third, silence of Nrf2 in glial cells abolished H2O2-conferred DA neuronal survival. This study demonstrated that physiological concentration of H2O2-supported DA neuronal survival via activation of Nrf2 signaling in glial cells. Our data permit to re-evaluate the role of H2O2 in the pathogenesis and therapeutic strategies for PD.
Graphic Abstract
... Several studies have shown that H 2 O 2 released by medium spiny neurons in the striatum can activate the K + -ATP channel in dopaminergic terminals. The hyperpolarization resulting from the activity of this channel leads to the decrease of dopamine release [185]. While the authors have argued that this H 2 O 2 is the product of reverse electron transport at complex I of the mitochondrial respiratory chain [186], one must not exclude the possible involvement of vectoral production of O 2 − -• by NOX to the extracellular matrix followed by dismutation to H 2 O 2 by extracellular SOD3 as the source of extracellular H 2 O 2 in the striatum. ...
The small and diffusible free radical nitric oxide (•NO) has fascinated biological and medical scientists since it was promoted from atmospheric air pollutant to biological ubiquitous signaling molecule. Its unique physical chemical properties expand beyond its radical nature to include fast diffusion in aqueous and lipid environments and selective reactivity in a biological setting determined by bioavailability and reaction rate constants with biomolecules. In the brain, •NO is recognized as a key player in numerous physiological processes ranging from neurotransmission/neuromodulation to neurovascular coupling and immune response. Furthermore, changes in its bioactivity are central to the molecular pathways associated with brain aging and neurodegeneration. The understanding of •NO bioactivity in the brain, however, requires the knowledge of its concentration dynamics with high spatial and temporal resolution upon stimulation of its synthesis. Here we revise our current understanding of the role of neuronal-derived •NO in brain physiology, aging and degeneration, focused on changes in the extracellular concentration dynamics of this free radical and the regulation of bioenergetic metabolism and neurovascular coupling.
... Small signaling molecules define and coordinate changes in the brain that mediate experience-dependent neuronal plasticity or underlie neurological disorders. Ample experimental evidence indicates that H 2 O 2 plays a crucial role as a regulatory molecule in the brain in health and disease [1][2][3]. Depending on the intracellular concentration, H 2 O 2 can act as a signaling molecule or can cause oxidative stress followed by adaptation or apoptosis of the affected cell. In the nervous system, H 2 O 2 is thought to act as a neuromodulator and be reported to be involved in signaling, synaptic plasticity, long-term potentiation, and formation of long-term memory [4]. ...
... NA, not applicable. 1 Determined by alkaline denaturation in 1N NaOH. 2 Relative to mEGFP in PBS buffer (QY is 0.60); quantum yield for the reduced state was estimated according to absorbance and fluorescence changes in response to a 200 µM H 2 O 2 addition to bacterial lysates using the following equation: QY Red = QY Ox × (Abs Ox /Abs Red )/(Fluor Ox /Fluor Red ). 3 pKas for the reduced state were measured in the presence of 14 mM DTT. 4 Impact of a pH change of ±0.5 units to the contrast was calculated using the following equation: 100 × |Fluor Red at pH ± 0.5 -Fluor Red at pH |/|Fluor Ox at pH -Fluor Red at pH |, where Fluor Red at pH ± 0.5 , Fluor Red at pH , and Fluor Ox at pH are the fluorescence intensities of the indicator in the reduced and oxidized states at pH values of pH ± 0.5 and the original pH. Variations of the maximal values of pH impacts for the indicated pH range are shown. ...
Hydrogen peroxide (H2O2) plays an important role in modulating cell signaling and homeostasis in live organisms. The HyPer family of genetically encoded indicators allows the visualization of H2O2 dynamics in live cells within a limited field of view. The visualization of H2O2 within a whole organism with a single cell resolution would benefit from a slowly reducible fluorescent indicator that integrates the H2O2 concentration over desired time scales. This would enable post hoc optical readouts in chemically fixed samples. Herein, we report the development and characterization of NeonOxIrr, a genetically encoded green fluorescent indicator, which rapidly increases fluorescence brightness upon reaction with H2O2, but has a low reduction rate. NeonOxIrr is composed of circularly permutated mNeonGreen fluorescent protein fused to the truncated OxyR transcription factor isolated from E. coli. When compared in vitro to a standard in the field, HyPer3 indicator, NeonOxIrr showed 5.9-fold higher brightness, 15-fold faster oxidation rate, 5.9-fold faster chromophore maturation, similar intensiometric contrast (2.8-fold), 2-fold lower photostability, and significantly higher pH stability both in reduced (pKa of 5.9 vs. ≥7.6) and oxidized states (pKa of 5.9 vs.≥ 7.9). When expressed in the cytosol of HEK293T cells, NeonOxIrr demonstrated a 2.3-fold dynamic range in response to H2O2 and a 44 min reduction half-time, which were 1.4-fold lower and 7.6-fold longer than those for HyPer3. We also demonstrated and characterized the NeonOxIrr response to H2O2 when the sensor was targeted to the matrix and intermembrane space of the mitochondria, nucleus, cell membranes, peroxisomes, Golgi complex, and endoplasmic reticulum of HEK293T cells. NeonOxIrr could reveal endogenous reactive oxygen species (ROS) production in HeLa cells induced with staurosporine but not with thapsigargin or epidermal growth factor. In contrast to HyPer3, NeonOxIrr could visualize optogenetically produced ROS in HEK293T cells. In neuronal cultures, NeonOxIrr preserved its high 3.2-fold dynamic range to H2O2 and slow 198 min reduction half-time. We also demonstrated in HeLa cells that NeonOxIrr preserves a 1.7-fold ex vivo dynamic range to H2O2 upon alkylation with N-ethylmaleimide followed by paraformaldehyde fixation. The same alkylation-fixation procedure in the presence of NP-40 detergent allowed ex vivo detection of H2O2 with 1.5-fold contrast in neuronal cultures and in the cortex of the mouse brain. The slowly reducible H2O2 indicator NeonOxIrr can be used for both the in vivo and ex vivo visualization of ROS. Expanding the family of fixable indicators may be a promising strategy to visualize biological processes at a single cell resolution within an entire organism.
... In our recent study, we show that modeling ALS with increased level of the endogenous aminoacid homocysteine provided exactly the same effect as aging in the present study by enhancing the sensitivity of nerve terminals to the inhibitory action of ROS (Bukharaeva et al., 2015). The stimulatory action of ROS on evoked release in neonates may indicate an activity-dependent contribution of ROS to the maturation of neuromuscular transmission and consistent with the current concept of redox regulation endogenous ROS play important signaling and regulatory roles, and their effect depends on the cellular and extracellular environment (Patel and Rice, 2012). ...
Cholesterol oxidation products frequently have a high biological activity. In the present study, we have used microelectrode recording of end plate currents and FM-based optical detection of synaptic vesicle exo-endocytosis to investigate the effects of two structurally similar oxysterols, olesoxime (cholest-4-en-3-one, oxime) and 5ɑ-cholestan-3-one (5ɑCh3), on neurotransmission at the frog neuromuscular junction. Olesoxime is an exogenous, potentially neuroprotective, substance and 5ɑCh3 is an intermediate product in cholesterol metabolism, which is elevated in case of cerebrotendinous xanthomatosis. We found that olesoxime slightly increased evoked neurotransmitter release in response to single stimuli and significantly reduced synaptic depression during high frequency activity. The last effect was due to an increase in both the number of synaptic vesicles involved in exo-endocytosis and the rate of synaptic vesicle recycling. In contrast, 5ɑCh3 reduced evoked neurotransmitter release during the low- and high frequency synaptic activity. The depressant action of 5ɑCh3 was associated with a reduction in the number of synaptic vesicles participating in exo- and endocytosis during high frequency stimulation, without a change in rate of the synaptic vesicle recycling. Of note, olesoxime increased the staining of synaptic membranes with the B-subunit of cholera toxin and the formation of fluorescent ganglioside GM1 clusters, and decreased the fluorescence of 22-NBD-cholesterol, while 5ɑCh3 had the opposite effects, suggesting that the two oxysterols have different effects on lipid raft stability. Taken together, these data show that these two structurally similar oxysterols induce marked different changes in neuromuscular transmission which are related with the alteration in synaptic vesicle cycle.
... In our recent study, we show that modeling ALS with increased level of the endogenous aminoacid homocysteine provided exactly the same effect as aging in the present study by enhancing the sensitivity of nerve terminals to the inhibitory action of ROS (Bukharaeva et al., 2015). The stimulatory action of ROS on evoked release in neonates may indicate an activity-dependent contribution of ROS to the maturation of neuromuscular transmission and consistent with the current concept of redox regulation endogenous ROS play important signaling and regulatory roles, and their effect depends on the cellular and extracellular environment (Patel and Rice, 2012). ...
... In those conditions, MGL sulfenylation might act as an intrinsic neuroprotective mechanism by potentiating 2-AG signaling at CB 1 receptors. Nevertheless, localized foci of heightened H 2 O 2 production (Mishina et al, 2011) might be sufficient to deactivate MGL even under physiological conditions, particularly at synapses that experience high-frequency synaptic activity and use glutamate as a neurotransmitter (Patel and Rice, 2012). In that context, MGL sulfenylation may strengthen endocannabinoid-mediated retrograde transmission by lowering the presynaptic degradation of 2-AG generated in postsynaptic spines. ...
The second messenger hydrogen peroxide transduces changes in the cellular redox state by reversibly oxidizing protein cysteine residues to sulfenic acid. This signaling event regulates many cellular processes but has never been shown to occur in the brain. Here, we report that hydrogen peroxide heightens endocannabinoid signaling in brain neurons through sulfenylation of cysteines C201 and C208 in monoacylglycerol lipase (MGL), a serine hydrolase that deactivates the endocannabinoid 2-arachidonoyl-sn-glycerol (2-AG) in nerve terminals. The results suggest that MGL sulfenylation may provide a presynaptic control point for 2-AG-mediated endocannabinoid signaling.
Copyright © 2015 Elsevier Ltd. All rights reserved.
... As reviewed elsewhere, the absence of AMPARs and GABA A Rs on DAergic axons in dorsal striatum led us to postulate that the cellular sources of glutamate-dependent H 2 O 2 generation were not DAergic axons, but rather other striatal neurons, including the predominant striatal neurons, GABAergic medium spiny neurons (MSNs) (Avshalumov et al. 2007(Avshalumov et al. , 2008Rice et al. 2011;Rice, 2011;Patel & Rice, 2012). We tested this hypothesis using single-cell fluorescence imaging of H 2 O 2 , in which dihydro-dichlorofluorescein diacetate (H 2 DCF-diacetate) is loaded into cells via a patch pipette used for whole-cell recording (Avshalumov et al. , 2008. ...
... A key aspect of our hypothesis that H 2 O 2 is a diffusible messenger in the striatum is that K ATP channels are located directly on DAergic axons. Our observation that single-pulse-evoked [DA] o is suppressed by K ATP channel openers supports direct localization, which was confirmed using immunohistochemical methods showing striatal colocalization of a K ATP channel subunit with tyrosine hydroxylase, an enzyme required for DA synthesis Patel & Rice, 2012). Together with our previous work, these data indicate that H 2 O 2 is a diffusible messenger, which is generated in striatal MSNs, but acts at K ATP channels on DA axons. ...
... It should be emphasized at this point that H 2 O 2 -dependent signalling via ion channel activation is fast and transient, with a subsecond to second time scale Patel & Rice, 2012). This was assessed using paired-pulse stimulation to evoke [DA] o with pharmacological blockade of K ATP channels or amplification of H 2 O 2 levels using GSH peroxidase inhibition. ...
Historically, brain neurochemicals have been broadly classified as energetic or informational. However, increasing evidence implicates metabolic substrates and byproducts as signaling agents, which blurs the boundary between energy and information, and suggest introduction of a new category for "translational" substances that convey changes in energy state to information. One intriguing example is hydrogen peroxide (H2 O2 ), which is a small, readily diffusible molecule. Produced during mitochondrial respiration, this reactive oxygen species, can mediate dynamic regulation of neuronal activity and transmitter release by activating inhibitory ATP-sensitive K(+) (KATP ) channels, as well as a class of excitatory non-selective cation channels, TRPM2. Studies using ex vivo guinea pig brain slices have revealed that activity-generated H2 O2 can act via KATP channels to inhibit dopamine release in dorsal striatum and dopamine neuron activity in the substantia nigra pars compacta. In sharp contrast, endogenously generated H2 O2 enhances the excitability of GABAergic projection neurons in the dorsal striatum and substantia nigra pars reticulata by activating TRPM2 channels. These studies suggest that the balance of excitation vs. inhibition produced in a given cell by metabolically generated H2 O2 will be dictated by the relative abundance of H2 O2 -sensitive ion-channel targets that receive this translational signal. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
... ROS, such as the non-radical hydrogen peroxide (H 2 O 2 ) and free superoxide radicals (O 2 − ), are generated as a result of mitochondrial respiration, from the activation of growth factor receptors through NADPH oxidase, the arachidonic acid cascade and others, and play crucial roles as signal transduction molecules and neuroregulators [105,106]. H 2 O 2 may also generate free radicals, including the hydroxyl radical (OH), the most potent oxidizing radical generated by the cell, through routes including ionizing radiation, interactions with O ...
Cancer genome sequence data provide an invaluable resource for inferring the key mechanisms by which mutations arise in cancer cells, favoring their survival, proliferation and invasiveness. Here we examine recent advances in understanding the molecular mechanisms responsible for the predominant type of genetic alteration found in cancer cells, somatic single base substitutions (SBSs). Cytosine methylation, demethylation and deamination, charge transfer reactions in DNA, DNA replication timing, chromatin status and altered DNA proofreading activities are all now known to contribute to the mechanisms leading to base substitution mutagenesis. We review current hypotheses as to the major processes that give rise to SBSs and evaluate their relative relevance in the light of knowledge acquired from cancer genome sequencing projects and the study of base modifications, DNA repair and lesion bypass. Although gene expression data on APOBEC3B enzymes provide support for a role in cancer mutagenesis through U:G mismatch intermediates, the enzyme preference for single-stranded DNA may limit its activity genome-wide. For SBSs at both CG:CG and YC:GR sites, we outline evidence for a prominent role of damage by charge transfer reactions that follow interactions of the DNA with reactive oxygen species (ROS) and other endogenous or exogenous electron-abstracting molecules.
