The Glutathione Metabolite γ-Glutamyl-Glutamate Partially Activates Glutamate NMDA Receptors in Central Neurons With Higher Efficacy for GluN2B-Containing Receptors

Gamma-L-glutamyl-L-glutamate (γ-Glu-Glu) was synthetized and further characterized for its activity on cultured neurons. We observed that γ-Glu-Glu elicited excitatory effects on neurons likely by activating mainly the N-methyl-D-aspartate (NMDA) receptors. These effects were dependent on the integrity of synaptic transmission as they were blocked by tetrodotoxin (TTX). We next evaluated its activity on NMDA receptors by testing it on cells expressing these receptors. We observed that γ-Glu-Glu partially activated NMDA receptors and exhibited better efficacy for NMDA receptors containing the GluN2B subunit. Moreover, at low concentration, γ-Glu-Glu potentiated the responses of glutamate on NMDA receptors. Finally, the endogenous production of γ-Glu-Glu was measured by LC-MS on the extracellular medium of C6 rat astroglioma cells. We found that extracellular γ-Glu-Glu concentration was, to some extent, directly linked to GSH metabolism as γ-Glu-Glu can be a by-product of glutathione (GSH) breakdown after γ-glutamyl transferase action. Therefore, γ-Glu-Glu could exert excitatory effects by activating neuronal NMDA receptors when GSH production is enhanced.

Reduction of Deuterium Level Supports Resistance of Neurons to Glucose Deprivation and Hypoxia: Study in Cultures of Neurons and on Animals

The effect of a reduced deuterium (D) content in the incubation medium on the survival of cultured neurons in vitro and under glucose deprivation was studied. In addition, we studied the effect of a decrease in the deuterium content in the rat brain on oxidative processes in the nervous tissue, its antioxidant protection, and training of rats in the T-shaped maze test under hypoxic conditions. For experiments with cultures of neurons, 7–8-day cultures of cerebellar neurons were used. Determination of the rate of neuronal death in cultures was carried out using propidium iodide. Acute hypoxia with hypercapnia was simulated in rats by placing them in sealed vessels with a capacity of 1 L. The effect on oxidative processes in brain tissues was assessed by changes in the level of free radical oxidation and malondialdehyde. The effect on the antioxidant system of the brain was assessed by the activity of catalase. The study in the T-maze was carried out in accordance with the generally accepted methodology, the skill of alternating right-sided and left-sided loops on positive reinforcement was developed. This work has shown that a decrease in the deuterium content in the incubation medium to a level of −357‰ has a neuroprotective effect, increasing the survival rate of cultured neurons under glucose deprivation. When exposed to hypoxia, a preliminary decrease in the deuterium content in the rat brain to −261‰ prevents the development of oxidative stress in their nervous tissue and preserves the learning ability of animals in the T-shaped maze test at the level of the control group. A similar protective effect during the modification of the 2H/1H internal environment of the body by the consumption of DDW can potentially be used for the prevention of pathological conditions associated with the development of oxidative stress with damage to the central nervous system.

Organic semiconductors for light-mediated neuromodulation

Organic semiconductors have generated substantial interest in neurotechnology and emerged as a promising approach for wireless neuromodulation in fundamental and applied research. Here, we summarise the range of applications that have been proposed so far, including retinal stimulation, excitation and inhibition of cultured neurons and regulation of biological processes in other non-excitable cells from animal and plant origins. We also discuss the key chemical and physical phenomena at the basis of the interaction between materials and cells. Finally, we provide an overview of future perspectives, exciting research opportunities and the remaining challenges hampering the translation of this blooming technology into the clinic and industry.

Recording of cellular physiological histories along optically readable self-assembling protein chains

Observing cellular physiological histories is key to understanding normal and disease-related processes, but longitudinal imaging is laborious and equipment-intensive. A tantalizing possibility is that cells could record such histories in the form of digital biological information within themselves, for later high-throughput readout. Here we show that this concept can be realized through information storage in the form of growing protein chains made out of multiple self-assembling subunits bearing different labels, each corresponding to a different cellular state or function, so that the physiological history of the cell can be visually read out along the chain of proteins. Conveniently, such protein chains are fully genetically encoded, and easily readable with simple, conventional optical microscopy techniques, compatible with visualization of cellular shape and molecular content. We use such expression recording islands (XRIs) to record gene expression timecourse downstream of pharmacological and physiological stimuli, in cultured neurons and in living mouse brain.

Macroautophagy and normal aging of the nervous system: Lessons from animal models

Aging represents a cumulative form of cellular stress, which is thought to challenge many aspects of proteostasis. The non-dividing, long-lived neurons are particularly vulnerable to stress, and, not sur-prisingly, even normal aging is highly associated with a decline in brain function in humans, as well as in other animals. Macroautophagy is a fundamental arm of the proteostasis network, safeguarding proper protein turnover during different cellular states and against diverse cellular stressors. An intricate interplay between macroautophagy and aging is beginning to unravel, with the emergence of new tools, including those for monitoring autophagy in cultured neurons and in the nervous system of different organisms in vivo. Here, we review recent findings on the impact of aging on neuronal integrity and on neuronal macroautophagy, as they emerge from studies in inverte-brate and mammalian models.

Interaction between BID and VDAC1 is required for mitochondrial demise and cell death in neurons

Mitochondrial damage is a key feature of regulated cell death in neurons. In particular, mitochondrial outer membrane permeabilization (MOMP) has been proposed as a starting point for mitochondrial demise upon cellular stress. Potential mechanisms for MOMP presented in the literature include membrane pore formation by Bcl2-family proteins such as BID and BAX, oligomerization of voltage-dependent anion channels (VDACs) and hetero-oligomer formation of these proteins. In our study, we demonstrate a direct interaction between the voltage-dependent anion channel VDAC1 and the pro-apoptotic protein BID in dying neurons both in vitro and in vivo. Binding of BID to VDAC1 affects anion conductance through VDAC1 and is associated with glutamate-induced cell death in cultured neurons and ischemic brain injury. In cultured neurons, reducing VDAC1 expression significantly attenuates BID-induced hallmarks of mitochondrial damage such as mitochondrial fission, declined mitochondrial respiration, increased ROS production, and mitochondrial membrane potential breakdown. Our data highlight a critical role for VDAC1 as a mitochondrial receptor for activated BID, thereby serving as a key decision point between life and death in neurons.One Sentence SummaryVDAC1 interacts with BID to mediate mitochondrial membrane permeabilization and neuronal cell death.

Neuroprotective Effects of Deproteinized Calf Serum in Ischemic Stroke

Deproteinized calf serum (DCS) may have neuroprotective effects after ischemic stroke. The aim of this study is to investigate whether and how the DCS inhibits neuronal injury following cerebral ischemia. Rats were subjected to 2 h transient middle cerebral artery occlusion (MCAO). One dose of 0.125 mg/gbw DCS was given immediately after reperfusion. Neurological deficit and infarct volume at 24 h post-MCAO in DCS-treated rats were lower than those in vehicle-treated rats (p < 0.0005). In cultured neurons model, cell viability was decreased, and apoptosis was increased by oxygen-glucose deprivation/reperfusion (OGD/R) (p < 0.0005). These effects of OGD/R were attenuated by 0.4 μg/μl DCS (p < 0.05) that were validated by CCK8 cell viability assay, phycoerythrin–Annexin V Apoptosis Detection assay, and TUNEL assay. Furthermore, the increase of intracellular ROS level in cultured neurons was suppressed by DCS (p < 0.05). Compared with cells subjected to OGD/R, the expression level of Bax protein decreased, and bcl-2 protein increased after DSC treatment (p < 0.05). Overall, the neuroprotective effects of DCS following cerebral ischemia may in part be due to decreased ROS production and inhibition of apoptosis.

The Effect of Valproic Acid on the Transcriptional Activity of Ngf and Bdnf Genes of in Vitro Cultured Neurons Under Oxidative Stress Conditions

Brain-derived neurotrophic factor (BDNF) is a secretory molecule that promotes peripheral neurons synaptic transmission and plasticity by TrkB receptor activation. This is shown in cultured central nervous system (CNS) neurons, including hippocampal and cortical cholinergic, dopaminergic and serotonergic neurons. Hypotheses suggesting that BDNF may play a potential role in the pathophysiology of schizophrenia are based on the key role of BDNF in the synaptic plasticity and, consequently, regulation of cognitive functions. In the schizophrenia treatment valproic acid is used in complex combined therapy regimens. Treatment of schizophrenia patients with valproate increases the BDNF level. Since it is not yet clear whether the BDNF protein levels measured in serum samples and in the brain correlate, we investigated valproate effects on the cultured neurons Bdnf transcription level. The primary neuron-glia culture was obtained from the cerebellum of 8-9-day-old Wistar rats. Valproic acid was added to the neurons (at a concentration of 50 µg/ml), oxidative stress was stimulated by 40 µMof H2O2, and injury was caused by mechanical damage to the neuron culture. It was shown that valproic acid in 3-24 hours increases the transcriptional activity of the Bdnf and Ngf (nerve growth factor) genes 2–2.5-fold (p<0.01) and approximately 1.5-fold (p<0.01), respectively. Mechanical trauma, unlike oxidative stress, activates the transcriptional activity of the Ngf and Bdnf genes (p<0.01). However, under oxidative stress and mechanical damage to neurons, the effect of valproic acid on the Ngf and Bdnf genes expression was insignificant. Fluorescence microscopy analysis using specific antibodies to neurons (anti-Map-2) showed that in the presence of valproic acid, the number of neuronal processes and contacts between them significantly increased. Evidently, valproate addition to antipsychotics can be effective for the overall clinical response. Relatively little research has been done on the signaling pathways in neurons that are activated by the valproic acid. However, we have obtained evidence of activation of the Ngf and Bdnf genes transcription in cultured neurons in vitro. We also found that in the presence of valproic acid, the number of neuronal processes and contacts between them significantly increased. However, we have also found that the oxidative stress accompanying the schizophrenia can significantly reduce the valproic acid effect on the Ngf and Bdnf genes expression. The results of the study may be potentially useful for new schizophrenia therapy strategies development.