A Neurotoxic Ménage-à-trois: Glutamate, Calcium, and Zinc in the Excitotoxic Cascade

Molecular events in brain bilirubin toxicity revisited

The mechanisms involved in bilirubin neurotoxicity are still far from being fully elucidated. Several different events concur to damage mainly the neurons among which inflammation and alteration of the redox state play a major role. An imbalance of cellular calcium homeostasis has been recently described to be associated with toxic concentrations of bilirubin, and this disequilibrium may in turn elicit an inflammatory reaction. The different and age-dependent sensitivity to bilirubin damage must also be considered in describing the dramatic clinical picture of bilirubin-induced neurological damage (BIND) formerly known as kernicterus spectrum disorder (KSD). This review aims to critically address what is known and what is not in the molecular events of bilirubin neurotoxicity to provide hints for a better diagnosis and more successful treatments. Part of these concepts have been presented at the 38th Annual Audrey K. Brown Kernicterus Symposium of Pediatric American Society, Washington DC, May 1, 2023.

Graphene Oxide Nanosheets Hamper Glutamate Mediated Excitotoxicity and Protect Neuronal Survival In An In vitro Stroke Model

Small graphene oxide (s-GO) nanosheets reversibly downregulate central nervous system (CNS) excitatory synapses, with potential developments as future therapeutic tools to treat neuro-disorders characterized by altered glutamatergic transmission. Excitotoxicity, namely cell death triggered by exceeding ambient glutamate fueling over-activation of excitatory synapses, is a pathogenic mechanism shared by several neural diseases, from ischemic stroke to neurodegenerative disorders. In this work, CNS cultures were exposed to oxygen-glucose deprivation (OGD) to mimic ischemic stroke in vitro, and it is show that the delivery of s-GO following OGD, during the endogenous build-up of secondary damage and excitotoxicity, improved neuronal survival. In a different paradigm, excitotoxicity cell damage was reproduced through exogenous glutamate application, and s-GO co-treatment protected neuronal integrity, potentially by directly downregulating the synaptic over-activation brought about by exogenous glutamate. This proof-of-concept study suggests that s-GO may find novel applications in therapeutic developments for treating excitotoxicity-driven neural cell death.

Biochemical and Molecular Pathways in Neurodegenerative Diseases: An Integrated View

Neurodegenerative diseases (NDDs) like Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS) are defined by a myriad of complex aetiologies. Understanding the common biochemical molecular pathologies among NDDs gives an opportunity to decipher the overlapping and numerous cross-talk mechanisms of neurodegeneration. Numerous interrelated pathways lead to the progression of neurodegeneration. We present evidence from the past pieces of literature for the most usual global convergent hallmarks like ageing, oxidative stress, excitotoxicity-induced calcium butterfly effect, defective proteostasis including chaperones, autophagy, mitophagy, and proteosome networks, and neuroinflammation. Herein, we applied a holistic approach to identify and represent the shared mechanism across NDDs. Further, we believe that this approach could be helpful in identifying key modulators across NDDs, with a particular focus on AD, PD, and ALS. Moreover, these concepts could be applied to the development and diagnosis of novel strategies for diverse NDDs.

Zn2+ decoration of microtubules arrests axonal transport and displaces tau, doublecortin, and MAP2C

Intracellular Zn2+ concentrations increase via depolarization-mediated influx or intracellular release, but the immediate effects of Zn2+ signals on neuron function are not fully understood. By simultaneous recording of cytosolic Zn2+ and organelle motility, we find that elevated Zn2+ (IC50 ≈ 5-10 nM) reduces both lysosomal and mitochondrial motility in primary rat hippocampal neurons and HeLa cells. Using live-cell confocal microscopy and in vitro single-molecule TIRF imaging, we reveal that Zn2+ inhibits activity of motor proteins (kinesin and dynein) without disrupting their microtubule binding. Instead, Zn2+ directly binds to microtubules and selectively promotes detachment of tau, DCX, and MAP2C, but not MAP1B, MAP4, MAP7, MAP9, or p150glued. Bioinformatic predictions and structural modeling show that the Zn2+ binding sites on microtubules partially overlap with the microtubule binding sites of tau, DCX, dynein, and kinesin. Our results reveal that intraneuronal Zn2+ regulates axonal transport and microtubule-based processes by interacting with microtubules.

A Timm-Nissl multiplane microscopic atlas of rat brain zincergic terminal fields and metal-containing glia

The ability of Timm's sulphide silver method to stain zincergic terminal fields has made it a useful neuromorphological marker. Beyond its roles in zinc-signalling and neuromodulation, zinc is involved in the pathophysiology of ischemic stroke, epilepsy, degenerative diseases and neuropsychiatric conditions. In addition to visualising zincergic terminal fields, the method also labels transition metals in neuronal perikarya and glial cells. To provide a benchmark reference for planning and interpretation of experimental investigations of zinc-related phenomena in rat brains, we have established a comprehensive repository of serial microscopic images from a historical collection of coronally, horizontally and sagittally oriented rat brain sections stained with Timm's method. Adjacent Nissl-stained sections showing cytoarchitecture, and customised atlas overlays from a three-dimensional rat brain reference atlas registered to each section image are included for spatial reference and guiding identification of anatomical boundaries. The Timm-Nissl atlas, available from EBRAINS, enables experimental researchers to navigate normal rat brain material in three planes and investigate the spatial distribution and density of zincergic terminal fields across the entire brain.

Biomarkers of diagnosis, prognosis, pathogenesis, response to therapy: Convergence or divergence? Lessons from Alzheimer's disease and synucleinopathies

Alzheimer's disease (AD) is the most common disorder associated with cognitive impairment. Recent observations emphasize the pathogenic role of multiple factors inside and outside the central nervous system, supporting the notion that AD is a syndrome of many etiologies rather than a "heterogeneous" but ultimately unifying disease entity. Moreover, the defining pathology of amyloid and tau coexists with many others, such as α-synuclein, TDP-43, and others, as a rule, not an exception. Thus, an effort to shift our AD paradigm as an amyloidopathy must be reconsidered. Along with amyloid accumulation in its insoluble state, β-amyloid is becoming depleted in its soluble, normal states, as a result of biological, toxic, and infectious triggers, requiring a shift from convergence to divergence in our approach to neurodegeneration. These aspects are reflected-in vivo-by biomarkers, which have become increasingly strategic in dementia. Similarly, synucleinopathies are primarily characterized by abnormal deposition of misfolded α-synuclein in neurons and glial cells and, in the process, depleting the levels of the normal, soluble α-synuclein that the brain needs for many physiological functions. The soluble to insoluble conversion also affects other normal brain proteins, such as TDP-43 and tau, accumulating in their insoluble states in both AD and dementia with Lewy bodies (DLB). The two diseases have been distinguished by the differential burden and distribution of insoluble proteins, with neocortical phosphorylated tau deposition more typical of AD and neocortical α-synuclein deposition peculiar to DLB. We propose a reappraisal of the diagnostic approach to cognitive impairment from convergence (based on clinicopathologic criteria) to divergence (based on what differs across individuals affected) as a necessary step for the launch of precision medicine.

The interplay of intracellular calcium and zinc ions in response to electric field stimulation in primary rat cortical neurons in vitro

Recent pharmacological studies demonstrate a role for zinc (Zn²⁺) in shaping intracellular calcium (Ca²⁺) dynamics and vice versa in excitable cells including neurons and cardiomyocytes. Herein, we sought to examine the dynamic of intracellular release of Ca²⁺ and Zn²⁺ upon modifying excitability of primary rat cortical neurons using electric field stimulation (EFS) in vitro. We show that exposure to EFS with an intensity of 7.69 V/cm induces transient membrane hyperpolarization together with transient elevations in the cytosolic levels of Ca²⁺ and Zn²⁺ ions. The EFS-induced hyperpolarization was inhibited by prior treatment of cells with the K⁺ channel opener diazoxide. Chemical hyperpolarization had no apparent effect on either Ca²⁺ or Zn²⁺. The source of EFS-induced rise in Ca²⁺ and Zn²⁺ seemed to be intracellular, and that the dynamic inferred of an interplay between Ca²⁺ and Zn²⁺ ions, whereby the removal of extracellular Ca²⁺ augmented the release of intracellular Ca²⁺ and Zn²⁺ and caused a stronger and more sustained hyperpolarization. We demonstrate that Zn²⁺ is released from intracellular vesicles located in the soma, with major co-localizations in the lysosomes and endoplasmic reticulum. These studies further support the use of EFS as a tool to interrogate the kinetics of intracellular ions in response to changing membrane potential in vitro.

Does one plus one always equal two? Structural differences between nesfatin-1, -2, and nesfatin-1/2

Nesfatin-1 and -2 are produced from a reaction in which the N-terminus of human Nucleobindin-2 undergoes proteolytical processing. To date, Nucleobindin-2 and/or nesfatin-1 have only been shown to act as peptide hormones. On the other hand, the purpose of nesfatin-2 remains unknown. Since Nucleobindin-2/nesfatin-1 is thought impact the control of a wide range of physiological processes, including energy homeostasis, neurodegenerative processes and carcinogenesis, its ligands/interactions deserve special studies and attention. However, there are no reports about the molecular properties of the proteolytical products of human Nucleobindin-2 in the literature. Hence, this study aimed to analyze the effect of Zn(II) and Ca(II) on human nesfatin-1, -2, and -1/2 structures. Herein, we report that human nesfatin-1 is a member of the intrinsically disordered protein family, as indicated by circular dichroism and analytical ultracentrifugation experiments. In contrast, we found that the human nesfatin-2 and nesfatin-1/2 structures were globular with intrinsically disordered regions. Under Zn(II) treatment, we observed concentration-dependent structurization and compaction of intrinsically disordered nesfatin-1 and its propensity for oligomerization, as well as destabilization of both nesfatin-2 and nesfatin-1/2. Furthermore, dissociation constants for Zn(II) binding by nesfatin-1, nesfatin-2, and nesfatin-1/2 were also reported. Moreover, structurally distinct nesfatin-1 and -2 seem to be interdependent when linked together, as indicated by the observed molecular properties of nesfatin-1/2, which in turn are not a simple sum of the properties exhibited by the former peptides. Thus, herein, we shed new light on the molecular behavior of human nesfatins, which might help to elucidate the complex function of those peptides. Video abstract.

Venous stroke–a stroke subtype that should not be ignored

Based on the etiology, stroke can be classified into ischemic or hemorrhagic subtypes, which ranks second among the leading causes of death. Stroke is caused not only by arterial thrombosis but also by cerebral venous thrombosis. Arterial stroke is currently the main subtype of stroke, and research on this type has gradually improved. Venous thrombosis, the particular type, accounts for 0.5–1% of all strokes. Due to the lack of a full understanding of venous thrombosis, as well as its diverse clinical manifestations and neuroimaging features, there are often delays in admission for it, and it is easy to misdiagnose. The purpose of this study was to review the pathophysiology mechanisms and clinical features of arterial and venous thrombosis and to provide guidance for further research on the pathophysiological mechanism, clinical diagnosis, and treatment of venous thrombosis. This review summarizes the pathophysiological mechanisms, etiology, epidemiology, symptomatology, diagnosis, and treatment heterogeneity of venous thrombosis and compares it with arterial stroke. The aim is to provide a reference for a comprehensive understanding of venous thrombosis and a scientific understanding of various pathophysiological mechanisms and clinical features related to venous thrombosis, which will contribute to understanding the pathogenesis of intravenous stroke and provide insight into diagnosis, treatment, and prevention.

Migraine Pharmacological Treatment and Cognitive Impairment: Risks and Benefits

Migraine is a common neurological disorder impairing the quality of life of patients. The condition requires, as an acute or prophylactic line of intervention, the frequent use of drugs acting on the central nervous system (CNS). The long-term impact of these medications on cognition and neurodegeneration has never been consistently assessed. The paper reviews pharmacological migraine treatments and discusses their biological and clinical effects on the CNS. The different anti-migraine drugs show distinct profiles concerning neurodegeneration and the risk of cognitive deficits. These features should be carefully evaluated when prescribing a pharmacological treatment as many migraineurs are of scholar or working age and their performances may be affected by drug misuse. Thus, a reconsideration of therapy guidelines is warranted. Furthermore, since conflicting results have emerged in the relationship between migraine and dementia, future studies must consider present and past pharmacological regimens as potential confounding factors.

Adenosine A2A Receptor Antagonist Improves Cognitive Impairment by Inhibiting Neuroinflammation and Excitatory Neurotoxicity in Chronic Periodontitis Mice

The adenosine A_2A receptor antagonist SCH58261 has been reported to have anti-inflammatory effects. However, its role in chronic periodontitis (CP)-induced cognitive impairment, which is associated with Porphyromonas gingivalis lipopolysaccharide (P. gingivalis LPS), remains unclear. This study investigated the role of SCH58261 in mice with CP-induced cognitive impairment. C57BL/6J mice were used to develop CP model by injecting 0.5 mg/kg P. gingivalis LPS into the palatal gingival sulcus of maxillary first molars twice a week for four weeks. The mice were divided into control, P. gingivalis LPS (P-LPS), P-LPS + SCH58261, and SCH58261 groups. The passive avoidance test (PAT) and Morris water maze (MWM) were used to assess cognition in mice. Furthermore, CD73/adenosine, neuroinflammation, glutamate transporters, and glutamate were assessed. Compared with the P-LPS group, 0.1 and 0.5 mg/kg SCH58261 increased latency and decreased error times in PAT, but increased platform crossing number in MWM. SCH58261 inhibited microglial activation, and decreased pro-inflammatory cytokines and glutamate levels, but increased GLT-1 and PSD95 expression in the hippocampus. This was the first report of SCH58261 treatment for CP-induced cognitive impairment, which may be related to its anti-inflammatory activities and anti-glutamate excitatory neurotoxicity. This suggests that SCH58261 can be used as a novel agent to treat cognitive impairment.

Zinc Supplementation Partially Decreases the Harmful Effects of a Cafeteria Diet in Rats but Does Not Prevent Intestinal Dysbiosis

Zinc (Zn) plays an important role in metabolic homeostasis and may modulate neurological impairment related to obesity. The present study aimed to evaluate the effect of Zn supplementation on the intestinal microbiota, fatty acid profile, and neurofunctional parameters in obese male Wistar rats. Rats were fed a cafeteria diet (CAF), composed of ultra-processed and highly caloric and palatable foods, for 20 weeks to induce obesity. From week 16, Zn supplementation was started (10 mg/kg/day). At the end of the experiment, we evaluated the colon morphology, composition of gut microbiota, intestinal fatty acids, integrity of the intestinal barrier and blood-brain barrier (BBB), and neuroplasticity markers in the cerebral cortex and hippocampus. Obese rats showed dysbiosis, morphological changes, short-chain fatty acid (SCFA) reduction, and increased saturated fatty acids in the colon. BBB may also be compromised in CAF-fed animals, as claudin-5 expression is reduced in the cerebral cortex. In addition, synaptophysin was decreased in the hippocampus, which may affect synaptic function. Our findings showed that Zn could not protect obese animals from intestinal dysbiosis. However, an increase in acetate levels was observed, which suggests a partial beneficial effect of Zn. Thus, Zn supplementation may not be sufficient to protect from obesity-related dysfunctions.

The Zinc-sensing Receptor (GPR39) Modulates Declarative Memory and Age-related Hippocampal Gene Expression in Male Mice

As a neuromodulator, zinc regulates synaptic plasticity, learning and memory. Synaptic zinc is also a crucial factor in the development of toxic forms of amyloid beta protein and, subsequently, of Alzheimer's dementia (AD). Therefore, efforts to pinpoint mechanisms underlying zinc-dependent cognitive functions might aid AD research, by providing potential novel targets for drugs. One of the most understudied proteins in this regard is a zinc-sensing metabotropic receptor: GPR39. In this study we investigated the impact of GPR39 knock-out (KO) on age-related memory decline in mice of both sexes, by comparing them to age-matched wild-type (WT) littermates. We also tested the effects of a GPR39 agonist (TC-G 1008) on declarative memory of old animals, and its disruption in adult mice. We observed episodic-like memory (ELM) and spatial memory (SM) deficits in male GPR39 KO mice, as well as intact procedural memory in GPR39 KO mice regardless of age and sex. ELM was also absent in old WT male mice, and all female mice regardless of their genotype. Acute application of TC-G 1008 (10 mg/kg) reversed a deficit in two of three ELM components in old WT male mice, and had no promnesic effect on consolidation interference of ELM in adult WT mice. We discuss the possible neurobiological mechanisms and the translational value of these results for potential add-on pharmacotherapy of AD aimed at the zinc-sensing receptor.

Spermatozoan Metabolism as a Non-Traditional Model for the Study of Huntington’s Disease

Huntington’s Disease (HD) is a fatal autosomal dominant neurodegenerative disease manifested through motor dysfunction and cognitive deficits. Decreased fertility is also observed in HD animal models and HD male patients, due to altered spermatogenesis and sperm function, thus resulting in reduced fertilization potential. Although some pharmaceuticals are currently utilized to mitigate HD symptoms, an effective treatment that remedies the pathogenesis of the disease is yet to be approved by the FDA. Identification of genes and relevant diagnostic biomarkers and therapeutic target pathways including glycolysis and mitochondrial complex-I-dependent respiration may be advantageous for early diagnosis, management, and treatment of the disease. This review addresses the HD pathway in neuronal and sperm metabolism, including relevant gene and protein expression in both neurons and spermatozoa, indicated in the pathogenesis of HD. Furthermore, zinc-containing and zinc-interacting proteins regulate and/or are regulated by zinc ion homeostasis in both neurons and spermatozoa. Therefore, this review also aims to explore the comparative role of zinc in both neuronal and sperm function. Ongoing studies aim to characterize the products of genes implicated in HD pathogenesis that are expressed in both neurons and spermatozoa to facilitate studies of future treatment avenues in HD and HD-related male infertility. The emerging link between zinc homeostasis and the HD pathway could lead to new treatments and diagnostic methods linking genetic sperm defects with somatic comorbidities.

ID proteins promote the survival and primed-to-naive transition of human embryonic stem cells through TCF3-mediated transcription

Inhibition of DNA binding proteins 1 and 3 (ID1 and ID3) are important downstream targets of BMP signalling that are necessary for embryonic development. However, their specific roles in regulating the pluripotency of human embryonic stem cells (hESCs) remain unclear. Here, we examined the roles of ID1 and ID3 in primed and naive-like hESCs and showed that ID1 and ID3 knockout lines (IDs KO) exhibited decreased survival in both primed and naive-like state. IDs KO lines in the primed state also tended to undergo pluripotent dissolution and ectodermal differentiation. IDs KO impeded the primed-to-naive transition (PNT) of hESCs, and overexpression of ID1 in primed hESCs promoted PNT. Furthermore, single-cell RNA sequencing demonstrated that ID1 and ID3 regulated the survival and pluripotency of hESCs through the AKT signalling pathway. Finally, we showed that TCF3 mediated transcriptional inhibition of MCL1 promotes AKT phosphorylation, which was confirmed by TCF3 knockdown in KO lines. Our study suggests that IDs/TCF3 acts through AKT signalling to promote survival and maintain pluripotency of both primed and naive-like hESCs.

The Development of Novel Drug Treatments for Stroke Patients: A Review

Acute ischemic stroke is a critical condition that can result in disability and death. The consequences of this medical condition depend on various factors, including the size of the stroke, affected brain region, treatment onset, and the type of treatment. The primary objective of stroke treatment is to restart ischemic penumbra tissue perfusion and reduce infarct volume by sustaining blood flow. Recent research on the condition’s pathological pathways and processes has significantly improved treatment options beyond restoring perfusion. Many studies have concentrated on limiting injury severity via the manipulation of molecular mechanisms of ischemia, particularly in animal research. This article reviews completed and ongoing research on the development of acute ischemic stroke drugs. This study focuses on three main categories of antithrombotic drugs, thrombolytic drugs, and neuroprotective agents. The paper outlines findings from animal and clinical trials and explores the working mechanisms of these drugs.

Restoration of Sarco/Endoplasmic Reticulum Ca2+-ATPase Activity Functions as a Pivotal Therapeutic Target of Anti-Glutamate-Induced Excitotoxicity to Attenuate Endoplasmic Reticulum Ca2+ Depletion

Glutamate-induced excitotoxicity is a pathological basis of many acute/chronic neurodegenerative diseases. Sarco/endoplasmic reticulum Ca²⁺-ATPase (SERCA2b) is a membrane-embedded P-type ATPase pump that manages the translocation of calcium ions (Ca²⁺) from cytosol into the lumen of the endoplasmic reticulum (ER) calcium stores. It participates in a wide range of biological functions in the central nervous system (CNS). However, the role of SERCA2b in glutamate-induced excitotoxicity and its mechanism must be elucidated. Herein, we demonstrate that SERCA2b mutants exacerbate the excitotoxicity of hypo-glutamate stimulation on HT22 cells. In this study, SERCA2b mutants accelerated Ca²⁺ depletion through loss-of-function (reduced pumping capacity) or gain-of-function (acquired leakage), resulting in ER stress. In addition, the occurrence of ER Ca²⁺ depletion increased mitochondria-associated membrane formation, which led to mitochondrial Ca²⁺ overload and dysfunction. Moreover, the enhancement of SERCA2b pumping capacity or inhibition of Ca²⁺ leakage attenuated Ca²⁺ depletion and impeded excitotoxicity in response to hypo-glutamate stimulation. In conclusion, SERCA2b mutants exacerbate ER Ca²⁺-depletion-mediated excitotoxicity in glutamate-sensitive HT22 cells. The mechanism of disruption is mainly related to the heterogeneity of SERCA2b mutation sites. Stabilization of SRECA2b function is a critical therapeutic approach against glutamate-induced excitotoxicity. These data will expand understanding of organelle regulatory networks and facilitate the discovery and creation of drugs against excitatory/inhibitory imbalance in the CNS.

Functional coupling of TRPM2 and extrasynaptic NMDARs exacerbates excitotoxicity in ischemic brain injury

Excitotoxicity induced by NMDA receptor (NMDAR) activation is a major cause of neuronal death in ischemic stroke. However, past efforts of directly targeting NMDARs have unfortunately failed in clinical trials. Here, we reveal an unexpected mechanism underlying NMDAR-mediated neurotoxicity, which leads to the identification of a novel target and development of an effective therapeutic peptide for ischemic stroke. We show that NMDAR-induced excitotoxicity is enhanced by physical and functional coupling of NMDAR to an ion channel TRPM2 upon ischemic insults. TRPM2-NMDAR association promotes the surface expression of extrasynaptic NMDARs, leading to enhanced NMDAR activity and increased neuronal death. We identified a specific NMDAR-interacting motif on TRPM2 and designed a membrane-permeable peptide to uncouple the TRPM2-NMDAR interaction. This disrupting peptide protects neurons against ischemic injury in vitro and protects mice against ischemic stroke in vivo. These findings provide an unconventional strategy to mitigate excitotoxic neuronal death without directly targeting NMDARs.

Long-Term Dynamic Changes of NMDA Receptors Following an Excitotoxic Challenge

Excitotoxicity is a form of neuronal death characterized by the sustained activation of N-methyl-D-aspartate receptors (NMDARs) triggered by the excitatory neurotransmitter glutamate. NADPH-diaphorase neurons (also known as nNOS (+) neurons) are a subpopulation of aspiny interneurons, largely spared following excitotoxic challenges. Unlike nNOS (−) cells, nNOS (+) neurons fail to generate reactive oxygen species in response to NMDAR activation, a critical divergent step in the excitotoxic cascade. However, additional mechanisms underlying the reduced vulnerability of nNOS (+) neurons to NMDAR-driven neuronal death have not been explored. Using functional, genetic, and molecular analysis in striatal cultures, we indicate that nNOS (+) neurons possess distinct NMDAR properties. These specific features are primarily driven by the peculiar redox milieu of this subpopulation. In addition, we found that nNOS (+) neurons exposed to a pharmacological maneuver set to mimic chronic excitotoxicity alter their responses to NMDAR-mediated challenges. These findings suggest the presence of mechanisms providing long-term dynamic regulation of NMDARs that can have critical implications in neurotoxic settings.

Long-term exposure to environmental diclofenac concentrations impairs growth and induces molecular changes in Lymnaea stagnalis freshwater snails

As pharmaceutical substances are highly used in human and veterinary medicine and subsequently released in the environment, they represent emerging contaminants in the aquatic compartment. Diclofenac (DCF) is one of the most commonly detected pharmaceuticals in water and little research has been focused on its long-term effects on freshwater invertebrates. In this study, we assessed the chronic impacts of DCF on the freshwater gastropod Lymnaea stagnalis using life history, behavioral and molecular approaches. These organisms were exposed from the embryo to the adult stage to three environmentally relevant DCF concentrations (0.1, 2 and 10 μg/L). The results indicated that DCF impaired shell growth and feeding behavior at the juvenile stage, yet no impacts on hatching, locomotion and response to light stress were noted. The molecular findings (metabolomics and transcriptomic) suggested that DCF may disturb the immune system, energy metabolism, osmoregulation and redox balance. In addition, prostaglandin synthesis could potentially be inhibited by DCF exposure. The molecular findings revealed signs of reproduction impairment but this trend was not confirmed by the physiological tests. Combined omics tools provided complementary information and enabled us to gain further insight into DCF effects in freshwater organisms.

Zinc Accumulation Aggravates Cerebral Ischemia/Reperfusion Injury Through Inducing Endoplasmic Reticulum Stress

Zinc is highly enriched in the central nervous system. Numerous evidences suggest that high concentration of zinc acts as a critical mediator of neuronal death in the ischemic brain, however, the possible mechanisms of neurotoxicity of zinc during cerebral ischemia/reperfusion (I/R) remain elusive. Endoplasmic reticulum (ER) is a storage location of intracellular zinc. ER stress related genes were up-regulated during zinc-induced neuronal death in vascular-type senile dementia. In the present study, we investigated whether intracellular accumulated zinc aggravates I/R injury through ER stress and ER stress-associated apoptosis. Male Sprague-Dawley rats were subjected to 90 min middle cerebral artery occlusion (MCAO) and received either vehicle or zinc chelator TPEN 15 mg/kg. The expression of ER stress related factors glucose-regulated protein 78 (GRP78) and phosphorylated eukaryotic initiation factor 2α (p-eIF2α), ER stress related apoptotic proteins CCAAT-enhancer-binding protein homologous protein (CHOP) and caspase-12, as well as anti-apoptotic factor B-cell lymphoma-2 (Bcl-2) were assessed 24 h after reperfusion. Our results showed that the levels of GRP78 and p-eIF2α, as well as CHOP and caspase-12, were increased in ischemic brain, indicating that cerebral I/R triggers ER stress. Furthermore, GRP78, CHOP and caspase-12 were all colocalized with the zinc-specific dyes NG, suggesting that there is certain relationship between cytosolic labile zinc and ER stress following cerebral ischemia. Chelating zinc with TPEN reversed the expression of GRP78, p-eIF2α in ischemic rats. Moreover, CHOP and NeuN double staining positive cells, as well as caspase-12 and TUNEL double staining positive cells were also decreased after TPEN treatment, indicating that chelating zinc might inhibit ER stress and decreased ER stress associated neuronal apoptosis. In addition, TPEN treatment reversed the downregulated level of Bcl-2, which localized in the ER membrane and involved in the dysfunction of ER, confirming that the anti-apoptosis effects of chelating zinc following I/R are exerted via inhibition of the ER stress. Taken together, this study demonstrated that excessive zinc activates ER stress and zinc induced neuronal cell death is at least partially due to ER stress specific neuronal apoptosis in ischemic penumbra, which may provide an important mechanism of cerebral I/R injury.

[Dynamics of recovery of cognitive deficit in patients in the early recovery period of ischemic stroke]

OBJECTIVE

Study of the effectiveness of the use of the drug Ampasse in the process of complex rehabilitation in patients in the early recovery period of ischemic stroke at the second (stationary) stage.

MATERIAL AND METHODS

The study included 60 patients, 28 women and 32 men, aged 43 to 76 years (mean - 58.4±9.1 years), in the recovery period after suffering a stroke in the period from 1 to 12 months (on average - 4.7±3.5 months). All patients received complex rehabilitation, patients of the 1st group received additional intravenous injections of the drug Ampasse 25 mg (5.0 ml), 15 injections. Patients of the 2nd group (n 0) did not receive Ampasse. To assess cognitive functions, the following tests were used: the Montreal Cognitive Assessment Scale (MoCA), Stroop's test, subtest 9 of the Wechsler test, Koos cubes (CC), the severity of anxiety and depression was assessed, and motor recovery was assessed by the hand motor activity test (ARAT). The assessment was carried out before the start of treatment and on the 21st day.

RESULTS

There was a statistically significant increase in the score on the MoCA scale, in patients of the 1st group by an average of 2 points, in the 2nd group there was no significant dynamics, a statistically significant difference was found in the proportion of patients who had an increase in the MoCA index after the course of treatment in the 1st group. compared with the 2nd (χ² - 22.528, p<0.001). Decreased the level of rigidity according to the Stroop test in patients of the 1st group compared with the 2nd (χ² - 8.297, p=0.004). The number of patients who showed positive dynamics in the Koos cubes test in the 1st group was statistically significantly higher (χ²- 4.344, p=0.038). A statistically significant decrease in the level of depression was revealed in patients of the 1st group. The number of patients with improved motor function of the hand was greater in the 1st group of MG (χ² - 4.286, p<0.039).

CONCLUSION

In patients in complex therapy receiving intravenous administration of the drug Ampasse at a dose of 25 mg (5.0 ml) 15 administrations, a statistically significant improvement in cognitive functions was revealed according to MoCA tests, Stroop test, Koos Cubes, when compared with the comparison group. The use of Ampasse increased the effectiveness of cognitive and motor rehabilitation in patients with post-stroke disorders.

ZnT1 is a neuronal Zn2+/Ca2+ exchanger

Zinc transporter 1 (ZnT1; SLC30A1) is present in the neuronal plasma membrane, critically modulating NMDA receptor function and Zn²⁺ neurotoxicity. The mechanism mediating Zn²⁺ transport by ZnT1, however, has remained elusive. Here, we investigated ZnT1-dependent Zn²⁺ transport by measuring intracellular changes of this ion using the fluorescent indicator FluoZin-3. In primary mouse cortical neurons, which express ZnT1, transient addition of extracellular Zn²⁺ triggered a rise in cytosolic Zn²⁺, followed by its removal. Knockdown of ZnT1 by adeno associated viral (AAV)-short hairpin RNA (shZnT1) markedly increased rates of Zn²⁺ rise, and decreased rates of its removal, suggesting that ZnT1 is a primary route for Zn²⁺ efflux in neurons. Although Zn²⁺ transport by other members of the SLC30A family is dependent on pH gradients across cellular membranes, altered H⁺ gradients were not coupled to ZnT1-dependent transport. Removal of cytoplasmic Zn²⁺, against a large inward gradient during the initial loading phase, suggests that Zn²⁺ efflux requires a large driving force. We therefore asked if Ca²⁺ gradients across the membrane can facilitate Zn²⁺ efflux. Elimination of extracellular Ca²⁺ abolished Zn²⁺ efflux, while increased extracellular Ca²⁺ levels enhanced Zn²⁺ efflux. Intracellular Ca²⁺ rises, measured in GCaMP6 expressing neurons, closely paralleled cytoplasmic Zn²⁺ removal. Taken together, these results strongly suggest that ZnT1 functions as a Zn²⁺/Ca²⁺ exchanger, thereby regulating the transport of two ions of fundamental importance in neuronal signaling.

Evolutionary rate covariation identifies SLC30A9 (ZnT9) as a mitochondrial zinc transporter

Recent advances in genome sequencing have led to the identification of new ion and metabolite transporters, many of which have not been characterized. Due to the variety of subcellular localizations, cargo and transport mechanisms, such characterization is a daunting task, and predictive approaches focused on the functional context of transporters are very much needed. Here we present a case for identifying a transporter localization using evolutionary rate covariation (ERC), a computational approach based on pairwise correlations of amino acid sequence evolutionary rates across the mammalian phylogeny. As a case study, we find that poorly characterized transporter SLC30A9 (ZnT9) coevolves with several components of the mitochondrial oxidative phosphorylation chain, suggesting mitochondrial localization. We confirmed this computational finding experimentally using recombinant human SLC30A9. SLC30A9 loss caused zinc mishandling in the mitochondria, suggesting that under normal conditions it acts as a zinc exporter. We therefore propose that ERC can be used to predict the functional context of novel transporters and other poorly characterized proteins.

Presynaptic AMPA Receptors in Health and Disease

AMPA receptors (AMPARs) are ionotropic glutamate receptors that play a major role in excitatory neurotransmission. AMPARs are located at both presynaptic and postsynaptic plasma membranes. A huge number of studies investigated the role of postsynaptic AMPARs in the normal and abnormal functioning of the mammalian central nervous system (CNS). These studies highlighted that changes in the functional properties or abundance of postsynaptic AMPARs are major mechanisms underlying synaptic plasticity phenomena, providing molecular explanations for the processes of learning and memory. Conversely, the role of AMPARs at presynaptic terminals is as yet poorly clarified. Accruing evidence demonstrates that presynaptic AMPARs can modulate the release of various neurotransmitters. Recent studies also suggest that presynaptic AMPARs may possess double ionotropic-metabotropic features and that they are involved in the local regulation of actin dynamics in both dendritic and axonal compartments. In addition, evidence suggests a key role of presynaptic AMPARs in axonal pathology, in regulation of pain transmission and in the physiology of the auditory system. Thus, it appears that presynaptic AMPARs play an important modulatory role in nerve terminal activity, making them attractive as novel pharmacological targets for a variety of pathological conditions.

Fluoroquinolones-Associated Disability: It Is Not All in Your Head

Fluoroquinolones (FQs) are a broad class of antibiotics typically prescribed for bacterial infections, including infections for which their use is discouraged. The FDA has proposed the existence of a permanent disability (Fluoroquinolone Associated Disability; FQAD), which is yet to be formally recognized. Previous studies suggest that FQs act as selective GABAA receptor inhibitors, preventing the binding of GABA in the central nervous system. GABA is a key regulator of the vagus nerve, involved in the control of gastrointestinal (GI) function. Indeed, GABA is released from the Nucleus of the Tractus Solitarius (NTS) to the Dorsal Motor Nucleus of the vagus (DMV) to tonically regulate vagal activity. The purpose of this review is to summarize the current knowledge on FQs in the context of the vagus nerve and examine how these drugs could lead to dysregulated signaling to the GI tract. Since there is sufficient evidence to suggest that GABA transmission is hindered by FQs, it is reasonable to postulate that the vagal circuit could be compromised at the NTS-DMV synapse after FQ use, possibly leading to the development of permanent GI disorders in FQAD.

[Efficacy and safety of treatment with ampasse: the results of a randomized, double-blind, placebo-controlled trial in patients with chronic cerebrovascular disorders]

OBJECTIVE

To assess the efficacy and safety of the drug ampasse in the treatment of patients with chronic cerebrovascular disorders (CCVD).

MATERIALS AND METHODS

A multicenter, randomized, double-blind, placebo-controlled, confirmatory study of the efficacy and safety of ampasse (phase III) was conducted in 124 patients aged 50 to 75 years. The main group (MG) - 62 patients, received the test drug ampasse, solution for intravenous administration, 5 mg/ml, at a dose of 5 ml (25 mg), intravenously bolus slowly, the duration of treatment was 15 days. Control group (CG) - 62 patients, received comparison drug: placebo (0.9% sodium chloride-5 ml).

RESULTS

All 124 patients fully completed the procedures and visits, there were no dropouts from the study. The proportion of patients who reached the primary endpoint (an increase in the score by 2 or more points on the MoCA scale) was 83.87% in MG and 22.58% in CG, that is, the efficacy of therapy in MG was 61.29% higher than in CG (p<0.001), and good tolerability of the drug was proved. The secondary endpoint is an increase in quality of life (QOL) on the SF-36 V2 scale on Day 31. In MG, there was a statistically significant improvement in all indicators of QOL compared to the baseline. When assessing the safety spectrum, the proportion of patients who had adverse events was 14.52% in MG and 8.06% in CG (p=0.395).

CONCLUSION

Ampasse has a positive effect on cognitive functions and QOL, does not increase the frequency of adverse events in patients with CCVD compared to placebo, does not cause significant side effects, and is well tolerated by patients.

The Multifaceted Roles of Zinc in Neuronal Mitochondrial Dysfunction

Zinc is a highly abundant cation in the brain, essential for cellular functions, including transcription, enzymatic activity, and cell signaling. However, zinc can also trigger injurious cascades in neurons, contributing to the pathology of neurodegenerative diseases. Mitochondria, critical for meeting the high energy demands of the central nervous system (CNS), are a principal target of the deleterious actions of zinc. An increasing body of work suggests that intracellular zinc can, under certain circumstances, contribute to neuronal damage by inhibiting mitochondrial energy processes, including dissipation of the mitochondrial membrane potential (MMP), leading to ATP depletion. Additional consequences of zinc-mediated mitochondrial damage include reactive oxygen species (ROS) generation, mitochondrial permeability transition, and excitotoxic calcium deregulation. Zinc can also induce mitochondrial fission, resulting in mitochondrial fragmentation, as well as inhibition of mitochondrial motility. Here, we review the known mechanisms responsible for the deleterious actions of zinc on the organelle, within the context of neuronal injury associated with neurodegenerative processes. Elucidating the critical contributions of zinc-induced mitochondrial defects to neurotoxicity and neurodegeneration may provide insight into novel therapeutic targets in the clinical setting.

Dual Role for Astroglial Copper-Assisted Polyamine Metabolism during Intense Network Activity

Astrocytes serve essential roles in human brain function and diseases. Growing evidence indicates that astrocytes are central players of the feedback modulation of excitatory Glu signalling during epileptiform activity via Glu-GABA exchange. The underlying mechanism results in the increase of tonic inhibition by reverse operation of the astroglial GABA transporter, induced by Glu-Na⁺ symport. GABA, released from astrocytes, is synthesized from the polyamine (PA) putrescine and this process involves copper amino oxidase. Through this pathway, putrescine can be considered as an important source of inhibitory signaling that counterbalances epileptic discharges. Putrescine, however, is also a precursor for spermine that is known to enhance gap junction channel communication and, consequently, supports long-range Ca²⁺ signaling and contributes to spreading of excitatory activity through the astrocytic syncytium. Recently, we presented the possibility of neuron-glia redox coupling through copper (Cu⁺/Cu²⁺) signaling and oxidative putrescine catabolism. In the current work, we explore whether the Cu⁺/Cu²⁺ homeostasis is involved in astrocytic control on neuronal excitability by regulating PA catabolism. We provide supporting experimental data underlying this hypothesis. We show that the blockade of copper transporter (CTR1) by AgNO₃ (3.6 µM) prevents GABA transporter-mediated tonic inhibitory currents, indicating causal relationship between copper (Cu⁺/Cu²⁺) uptake and the catabolism of putrescine to GABA in astrocytes. In addition, we show that MnCl₂ (20 μM), an inhibitor of the divalent metal transporter DMT1, also prevents the astrocytic Glu-GABA exchange. Furthermore, we observed that facilitation of copper uptake by added CuCl₂ (2 µM) boosts tonic inhibitory currents. These findings corroborate the hypothesis that modulation of neuron-glia coupling by copper uptake drives putrescine → GABA transformation, which leads to subsequent Glu-GABA exchange and tonic inhibition. Findings may in turn highlight the potential role of copper signaling in fine-tuning the activity of the tripartite synapse.