Neurochemical Research最新文献

Purinergic signaling plays a major role in aging and neurodegenerative diseases, which are associated with memory decline. Blackcurrant (BC), an anthocyanin-rich berry, is renowned for its antioxidant and neuroprotective activities. However, evidence on the effects of BC on purinergic signaling is lacking. This study investigated the effects of BC and its association with Donepezil (DNPZ) on learning and memory, on the modulation of purinergic signaling, pro-inflammatory responses, and oxidative markers in a mouse model of cognitive impairment chronically induced by scopolamine (SCO). Animals were divided into twelve groups and treated with BC (50 or 100 mg/kg), and/or DNPZ (5 mg/kg), and/or SCO (1 mg/kg). Results showed that SCO decreased spatial learning and memory as assessed by the Morris Water Maze test, and treatment with BC and/or DNPZ restored these effects. Furthermore, BC and/or DNPZ treatments also prevented changes in ecto-nucleoside triphosphate diphosphohydrolase (NTPDase) and adenosine deaminase (ADA) activities and restored the increased density of P2X7 and A2A receptors in synaptosomes of the cerebral cortex of SCO-induced mice. Moreover, the increased Nod-like receptor protein 3 (NLRP3) and interleukin-1β expression, and the oxidative stress markers levels were reduced by BC and/or DNPZ treatments, compared with the SCO group. Overall, BC and/or DNPZ treatments ameliorated SCO-induced cognitive decline, alleviated oxidative stress and pro-inflammatory responses, and improved purinergic signaling. These findings underscore the potential of BC, especially when in combination with DNPZ, as a therapeutic agent for the prevention of memory deficits associated with aging or neurological diseases.

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Trehalose has neuroprotective effects in neurodegenerative diseases. This study aimed to explore the impact of trehalose on traumatic brain injury (TBI) by investigating its role in neuroprotection. The TBI mice model was established utilizing the cortical impact technique followed by trehalose treatment. Traumatic neuronal injury induced by scratch followed by trehalose treatment was performed to mimic TBI in vitro. Memory function was assessed using the Water maze test. Brain damage was evaluated through various methods including brain water content analysis, Nissl staining, Evans blue exudation, and TUNEL staining. Biochemical and morphological changes related to ferroptosis post-TBI were also examined. The results showed that trehalose was found to enhance spatial memory, reduce brain injury, and inhibit ferroptosis in TBI mice, similar to ferroptosis inhibitors. The influence of trehalose on TBI was reversed by the SIRT3 inhibitor. Trehalose upregulated SIRT3 to increase SOD activity in TBI, which could also be counteracted by the SIRT3 inhibitor. Combining trehalose with a ferroptosis inhibitor had a more significant effect on reducing brain injury and inhibiting ferroptosis. Furthermore, in TBI mice treated with trehalose and SIRT3 inhibitors, the effect of trehalose was reversed by SIRT3 inhibitors, but the addition of ferroptosis inhibitors reversed the effect of SIRT3 inhibitors, as shown by decreased ferroptosis and neuronal apoptosis in damaged brain tissue. In summary, this study provides initial evidence that trehalose plays a crucial role in neuroprotection post-TBI through the SIRT3/SOD2 pathway-mediated ferroptosis.

Antipsychotic medications are used to treat a psychological condition called ‘Schizophrenia’. However, its long-term administration causes irregular involuntary motor movements, targeting the orofacial regions. Glycyrrhizic acid (GA) is a naturally occurring triterpene saponin glycoside obtained from the roots of the Glycyrrhiza glabra (liquorice) plant and well known for its antioxidant, antiapoptotic and neuroprotective abilities. The present study investigated the neuroprotective potential of GA against haloperidol (Halo) induced neurotoxicity in SHSY-5Y cells and Wistar rats. Schrodinger software was utilized to estimate the target binding affinity of GA with various targets. To assess cell viability, SHSY-5Y cells were pretreated with GA (25, 50, and 100 µM) 1 h before halo (100 µM) treatment. In an in-vivo study, Wistar rats were divided into five groups: control (saline), halo (1 mg/kg), GA (25 mg/kg), and GA (50 mg/kg). The GA was injected for 21 days, 1 h before halo. All behavior changes were recorded on the 14th and 21st days. Results indicate that pretreatment with GA improves cell viability and reduces ROS formation in halo-treated SHSY-5Y cells, showing its antioxidant ability. Furthermore, GA administration reduced vacuous chewing movements, tongue protrusion, facial jerking, and locomotor abnormalities in halo-treated rats. Moreover, GA treatment improves antioxidant levels, including GSH, and SOD, in halo-injected rats. Additionally, GA treatment upregulates the striatal expression of p-PI3k, p-Akt, and Nrf2 in rats injected with halo. Findings indicate that GA can be a therapeutic agent for tardive dyskinesia and other neurological disorders.

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In mice engineered to express enhanced green fluorescent protein (eGFP) under the control of the entire glutamate transporter 1 (GLT1) gene, eGFP is found in all ‘adult’ cortical astrocytes. However, when 8.3 kilobases of the human GLT1/EAAT2 promoter is used to control expression of tdTomato (tdT), tdT is only found in a subpopulation of these eGFP-expressing astrocytes. The eGFP mice have been used to define mechanisms of transcriptional regulation using astrocytes cultured from cortex of 1–3 day old mice. Using the same cultures, we were never able to induce tdT⁺ expression. We hypothesized that these cells might not have migrated into the cortex by this age. In this study, we characterized the ontogeny of tdT⁺ cells, performed single-cell RNA sequencing (scRNA-seq), and tracked their migration in organotypic slice cultures. At postnatal day (PND) 1, tdT⁺ cells were observed in the subventricular zone and striatum but not in the cortex, and they did not express eGFP. At PND7, tdT⁺ cells begin to appear in the cortex with their numbers increasing with age. At PND1, scRNA-seq demonstrates that the tdT⁺ cells are molecularly heterogeneous, with a subpopulation expressing astrocytic markers, subsequently validated with immunofluorescence. In organotypic slices, tdT⁺ cells migrate into the cortex, and after 7 days they express GLT1, NF1A, and eGFP. An ionotropic glutamate receptor (iGluR) antagonist reduced by 50% the distance tdT⁺ cells migrate from the subventricular zone into the cortex. The pan-glutamate transport inhibitor, TFB-TBOA, increased, by sixfold, the number of tdT⁺ cells in the cortex. In conclusion, although tdT is expressed by non-glial cells at PND1, it is also expressed by glial progenitors that migrate into the cortex postnatally. Using this fluorescent labeling, we provide novel evidence that glutamate signaling contributes to the control of glial precursor migration.

Brain accumulation of the branched-chain α-keto acids α-ketoisocaproic acid (KIC), α-keto-β-methylvaleric acid (KMV), and α-ketoisovaleric acid (KIV) occurs in maple syrup urine disease (MSUD), an inherited intoxicating metabolic disorder caused by defects of the branched-chain α-keto acid dehydrogenase complex. Patients commonly suffer life-threatening acute encephalopathy in the newborn period and develop chronic neurological sequelae of still undefined pathogenesis. Therefore, this work investigated the in vitro influence of pathological concentrations of KIC (5 mM), KMV (1 mM), and KIV (1 mM) on mitochondrial bioenergetics in the cerebral cortex of neonate (one-day-old) rats. KIC, but not KMV and KIV, decreased phosphorylating (stimulated by ADP) and uncoupled (induced by CCCP) mitochondrial respiration supported by pyruvate, malate, and glutamate, indicating metabolic inhibition. These effects were less evident after supplementing the medium with succinate. KIC also mildly increased non-phosphorylating respiration (in the presence of oligomycin) using pyruvate plus malate or glutamate plus malate as substrates, suggesting an uncoupling effect. Moreover, KIC markedly inhibited the activity of α-ketoglutarate dehydrogenase noncompetitively and decreased ATP synthesis. Finally, docking simulations demonstrated that KIC preferentially interacts with E2 and E3 subunits of α-ketoglutarate dehydrogenase at the dihydrolipoamide binding site and into an allosteric site of E1. The present data strongly indicate that KIC compromises mitochondrial bioenergetics in the neonatal rat brain, supporting the hypothesis that disruption of energy homeostasis caused by brain KIC accumulation in the first days of life may be implicated in the neuropathology of MSUD.

Brain function requires continuous energy supply. Thus, unraveling brain metabolic regulation is critical not only for our basic understanding of overall brain function, but also for the cellular basis of functional neuroimaging techniques. While it is known that brain energy metabolism is exquisitely compartmentalized between astrocytes and neurons, the metabolic and neuro-energetic basis of brain activity is far from fully understood. ¹H nuclear magnetic resonance (NMR) spectroscopy has been widely used to detect variations in metabolite levels, including glutamate and GABA, while ¹³C NMR spectroscopy has been employed to study metabolic compartmentation and to determine metabolic rates coupled brain activity, focusing mainly on the component corresponding to excitatory glutamatergic neurotransmission. The rates of oxidative metabolism in neurons and astrocytes are both associated with the rate of the glutamate-glutamine cycle between neurons and astrocytes. However, any possible correlation between energy metabolism pathways and the inhibitory GABAergic neurotransmission rate in the living brain remains to be experimentally demonstrated. That is due to low GABA levels, and the consequent challenge of determining GABAergic rates in a non-invasive manner. This brief review surveys the state-of-the-art analyses of energy metabolism in neurons and astrocytes contributing to glutamate and GABA synthesis using ¹³C NMR spectroscopy in vivo, and identifies limitations that need to be overcome in future studies.

Epilepsy (EP) is a neurological disorder characterized by abnormal, sudden neuronal discharges. Seizures increase extracellular glutamate levels, causing excitotoxic damage. Glutamate transporter type 1 (GLT-1) and its human homologue excitatory amino acid transporter-2 (EAAT2) clear 95% of extracellular glutamate. Studies on neurodegenerative diseases suggest that trichostatin A (TSA), a broad-spectrum histone deacetylase (HDAC) inhibitor, can increase GLT-1/EAAT2 transcription. However, the precise mechanism by which TSA modulates GLT-1/EAAT2 levels remains unclear. This research demonstrated that TSA increases GLT-1/EAAT2 expression through histone acetylation, exerting substantial antiepileptic effects. Our results identify a promising therapeutic strategy for EP involving the modulation of glutamate transporters to mitigate seizures. Future research should explore the specific mechanisms underlying the effects of TSA and its potential clinical applications. Acute and chronic EP models were induced using kainic acid (KA) to assess the effects of TSA on the seizure threshold and frequency. Electrophysiological recordings of the hippocampus were used to evaluate the impact of TSA on neuronal excitability. RNA-Seq was used to analyse changes in glutamate transporter-related gene expression. Western blot analysis and qRT‒PCR were used to assess the influence of TSA on HDAC expression. To validate the role of GLT-1/EAAT2 in the antiepileptic effects of TSA, the impact of the GLT-1/EAAT2 inhibitor dihydrokainic acid (DHK) on the effects of TSA was assessed. Glutamate release was measured, and microdialysis was used to determine the glutamate content in the cerebrospinal fluid. Finally, metabolomics analysis was used to explore changes in amino acid levels in the hippocampus following TSA treatment to further confirm the antiepileptic potential of TSA. TSA effectively inhibited seizures in both acute and chronic models. It reduced the amplitude of excitatory postsynaptic currents (PSCs) and the frequency of spontaneous excitatory PSCs in the hippocampus without affecting inhibitory PSCs. Transcriptome analysis was used to identify glutamate transmission-related targets and revealed significant upregulation of the GLT-1 and EAAT2 genes in the hippocampus, which was confirmed by qRT‒PCR and Western blotting. Acetylation-induced upregulation of GLT-1/EAAT2 was observed, and inhibition of these transporters by DHK reduced the seizure-mitigating effects of TSA, underscoring the role of GLT-1/EAAT2 in clearing glutamate and its contribution to the observed antiepileptic effects of TSA. Our findings highlight the crucial role of GLT-1/EAAT2 in mediating the impact of TSA on glutamatergic transmission and seizure activity. These insights pave the way for the development of novel therapeutic approaches for EP involving the modulation of glutamate transporters.

Huntington’s disease (HD) is a progressive neurodegenerative disease resulting from a mutation in the huntingtin (HTT) gene and characterized by progressive motor dysfunction, cognitive decline, and psychiatric disturbances. Currently, no disease-modifying treatments are available. Recent research has developed therapeutic agents that may have the potential to directly target the disease pathology, such as gene silencing or clearing the mutant protein. However, these agents are limited by their inability to cross the blood-brain barrier (BBB), preventing optimal therapeutic effects. Although various techniques have been explored to overcome the BBB, focused ultrasound (FUS) has emerged as a promising non-invasive therapeutic modality offering the potential for targeted intervention in neurodegenerative diseases, including HD. Preclinical studies demonstrated the safety and efficacy of FUS in delivering therapeutic agents, such as siRNAs and AAV vector-based gene therapy, resulting in significant reductions in mutant HTT expression and improvements in motor function in HD mouse models. Furthermore, the safety profile of FUS-induced BBB opening has been established in clinical trials on human patients of neurodegenerative diseases other than HD, showing no adverse effects on brain structure or function. This review provides a comprehensive overview of the current state of FUS research in HD and connects existing evidence from neurodegenerative disease studies with its promise in establishing disease-modifying therapies for HD.

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To study the neuronal protective effect and its potential mechanism of C16 against gp120-induced cognitive impairment in vitro and in vivo. The NORT method was used to evaluate the short-term memory abilities of rats, the morphological changes in hippocampus were observed by Nissl staining. Cell viability and damage degree were detected by MTT and LDH. The cell living/apoptosis status of PC12 cells was determined by AO/EB double staining and the relative mRNA expressions of PKR, IRE1α, JNK, GRP78, and CHOP were detected by RT-qPCR. In comparison with the gp120 + Memantine and gp120 + C16 groups, the rats in the gp120 group showed a significantly decreased discrimination index (P < 0.001), with disordered CA1 region cells and reduced neuron numbers. AO/EB double staining revealed morphological changes in the gp120 and NMDA groups, while cells in the gp120 + C16 and NMDA + C16 groups resembled the control group. And C16 can significantly down-regulate the mRNA expression levels of PKR, IRE1α, JNK, GRP78, and CHOP. (P < 0.05). C16 can reduce the cognitive impairment stimulated by gp120 or NMDA, the protective mechanism may be correlated with inhibiting the upregulation of PKR/IRE1α/JNK pathway and suppressing apoptosis induced by downstream proteins GRP78 and CHOP.

Maintaining GABAergic inhibition within physiological limits in the medial prefrontal cortex (mPFC) is critical for working memory. While synaptic GABA_AR typically mediate the primary component of mPFC inhibition, the role of extrasynaptic δ-GABA_AR in working memory remains unclear. To investigate this, we used fiber photometry to examine the effects of δ-GABA_AR in freely moving mice. Our results indicate that the loss of δ-GABA_AR expression leads to learning and memory impairment. Specifically, activation of δ-GABA_AR impaired learning and memory in WT mice but enhanced learning and memory in δ^+/− knockout mice. Furthermore, δ-GABA_AR activation increased calcium activity in the mPFC pyramidal neurons, an effect not observed in δ-Cas9-sgRNA virus-infected mice. Collectively, these findings suggest that δ-GABA_AR deficiency impairs learning and memory by modulating the excitability of pyramidal neurons in the mPFC. These results delineate the functional contribution of δ-GABA_AR to learning and memory, suggesting their role extends beyond the mere maintenance of information.