Neurochemical Research最新文献

Ischemia–reperfusion is a complex brain disease involving multiple biological processes, including autophagy, oxidative stress, and mitochondria-associated apoptosis. Chaperone-mediated autophagy (CMA), a selective autophagy, is involved in the development of various neurodegenerative diseases and acute nerve injury, but its role in ischemia–reperfusion is unclear. Here, we used middle cerebral artery occlusion/reperfusion (MCAO/R) and oxygen–glucose deprivation/reoxygenation (OGD/R) models to simulate cerebral ischemic stroke in vivo and in vitro, respectively. LAMP2A (lysosome-associated membrane protein 2A), a key molecule of CMA, was dramatically downregulated in ischemia–reperfusion. Enhancement of CMA activity by LAMP2A overexpression reduced the neurological deficit, brain infarct volume, pathological features, and neuronal apoptosis of the cortex in vivo. Concomitantly, enhanced CMA activity alleviated OGD/R-induced apoptosis and mitochondrial membrane potential decline in vitro. In addition, we found that CMA inhibited the P53(Tumor protein p53) signaling pathway and reduced P53 translocation to mitochondria. The P53 activator, Nutlin-3, not only reversed the inhibitory effect of CMA on apoptosis, but also significantly weakened the protective effect of CMA on OGD/R and MCAO/R. Taken together, these results indicate that inhibition of P53-mediated mitochondria-associated apoptosis is essential for the neuroprotective effect of CMA against ischemia–reperfusion.

Exposure to rotenone results in similar pathophysiological features as Parkinson’s disease. Inflammation and oxidative stress are essential to PD pathogenesis. Maresin-1 has potent anti-inflammatory properties and promotes the regression of inflammation function. The current study aimed to evaluate the protective effects of Maresin-1 (MaR1) in rotenone (ROT)-induced PD and whether this protective role is associated with the initiation of the Janus kinase (JAK)-signal transducers and activator of transcription (STAT) signaling pathway. Thirty male Wister rats were classified into control, ROT-treated, and ROT + MaR1-treated groups. Rats underwent rotarod, open field, grip strength, and stepping tests as part of their motor behavioral evaluation. Serum glial cell-derived neurotrophic factor (GDNF) and striatal dopamine, acetylcholine, malondialdehyde (MDA), reduced glutathione (GSH), TNF-α, IL-6, and IL-1β were evaluated. Expression of JAK1 and STAT3 genes was assessed in striatum. Then, the tissue was subjected to histological and immunohistochemical evaluation for caspase-3, GFAP, and NF-kB. The administrated group with rotenone showed significant motor behavioral impairment. This was accompanied by reduced levels of GDNF and dopamine and increased levels of acetylcholine, as well as augmented oxidative stress and inflammatory biomarkers and reduced antioxidant activity. Inflammatory pathways (JAK1/STAT3, caspase-3, and NF-kB) were upregulated. Histopathological changes and upregulation in GFAP immunopositive reaction were observed. Remarkably, MaR1 treatment effectively alleviated behavior, histopathological changes, and biochemical alterations induced by ROT. MaR1 exerts protective effects against ROT-induced PD by its anti-inflammatory, antiapoptotic, and antioxidant properties. MaR1 mechanisms of action may involve modulation of pathways such as JAK/STAT.

Carbonyl stress refers to the excessive accumulation of advanced glycation end products (AGEs) in mammalian tissues. This phenomenon plays a significant role in the pathogenesis of various diseases, including diabetes, chronic renal failure, arteriosclerosis, and central nervous system (CNS) disorders. We have previously demonstrated that an increase in glutathione concentration, dependent on the nuclear factor erythroid 2–related factor 2 (Nrf2) system, provides a potent cytoprotective effect against Methylglyoxal (MGO)-induced carbonyl stress. Meanwhile, dimethyl fumarate (DMF), known for its Nrf2-activating effects, was recently approved as a treatment for multiple sclerosis (MS), a neurodegenerative disease. DMF is a first line therapy for relapsing–remitting MS and may also be effective for other neurodegenerative conditions. However, the detailed mechanisms by which DMF mitigates neurodegenerative pathologies remain unclear. This study investigates the impact of DMF on anticarbonyl activity and its underlying mechanism focusing on the accumulation of carbonyl protein in the cell. MGO, a glucose metabolite, was used to induce carbonylation in the neuronal cell line. MGO is a typical carbonyl compound that readily reacts with arginine and lysine residues to form AGE-modified proteins. Methylglyoxal-derived hydroimidazolone 1 (MG-H1) often forms uncharged, hydrophobic residues on the protein surface, which can affect protein distribution and lead to misfolding. Our findings indicate that DMF increases levels of glutathione (GSH), glutamate cysteine ligase modifier subunit (GCLM), and nuclear Nrf2 in SH-SY5Y cells. Importantly, DMF pretreatment significantly reduced the accumulation of MG-H1-modified proteins. Furthermore, this effect of DMF was diminished when Nrf2 expression was suppressed and when GCL, a rate-limiting enzyme in GSH synthesis, was inhibited. Thus, the increase in GSH levels, leading to the activation of the Nrf2 pathway, a key factor in DMF’s ability to suppress the accumulation of MG-H1-modified proteins. This study is the first to demonstrate that DMF possesses strong anticarbonyl stress activity in neuronal cells. Therefore, future research may extend the application of DMF to other CNS diseases associated with carbonyl stress, such as Alzheimer’s and Parkinson’s disease.

Protein translation is essential for some forms of synaptic plasticity. Here we used fluorescent noncanonical amino acid tagging (FUNCAT) to examine whether dopamine modulates protein translation in cultured nucleus accumbens (NAc) medium spiny neurons (MSN). These neurons were co-cultured with cortical neurons to restore excitatory synapses. We measured translation in MSNs under basal conditions and after disinhibiting excitatory transmission using the GABA_A receptor antagonist bicuculline (2 h). Under basal conditions, translation was not altered by the D1-class receptor (D1R) agonist SKF81297 or the D2-class receptor (D2R) agonist quinpirole. Bicuculline alone robustly increased translation. This was reversed by quinpirole but not SKF81297. It was also reversed by co-incubation with the D1R antagonist SCH23390, but not the D2R antagonist eticlopride, suggesting dopaminergic tone at D1Rs. This was surprising because no dopamine neurons are present. An alternative explanation is that bicuculline activates translation by increasing glutamate tone at NMDA receptors (NMDAR) within D1R/NMDAR heteromers. Supporting this, immunocytochemistry and proximity ligation assays revealed D1R/NMDAR heteromers on NAc cells both in vitro and in vivo, confirming previous results. Furthermore, bicuculline’s effect was reversed to the same extent by SCH23390 alone, the NMDAR antagonist APV alone, or SCH23390 + APV. These results suggest that: (1) excitatory transmission stimulates translation in NAc MSNs, (2) this is opposed when glutamate activates D1R/NMDAR heteromers, even in the absence of dopamine, and (3) antagonist occupation of D1Rs within the heteromers prevents their activation. Our study is the first to suggest a role for D2 receptors and D1R/NMDAR heteromers in regulating protein translation.

Itaconate is produced as endogenous metabolite by decarboxylation of the citric acid cycle intermediate cis-aconitate. As itaconate has anti-microbial and anti-inflammatory properties, this substance is considered as potential therapeutic drug for the treatment of inflammation in various diseases including traumatic brain injury and stroke. To test for potential adverse effects of itaconate on the viability and metabolism of brain cells, we investigated whether itaconate or its membrane permeable derivatives dimethyl itaconate (DI) and 4-octyl itaconate (OI) may affect the basal glucose and glutathione (GSH) metabolism of cultured primary astrocytes. Acute exposure of astrocytes to itaconate, DI or OI in concentrations of up to 300 µM for up to 6 h did not compromise cell viability. Of the tested substances, only OI stimulated aerobic glycolysis as shown by a time- and concentration-dependent increase in glucose-consumption and lactate release. None of the tested itaconates affected the pentose-phosphate pathway-dependent reduction of the water-soluble tetrazolium salt 1 (WST1). In contrast, both DI and OI, but not itaconate, depleted cellular GSH in a time- and concentration-dependent manner. For OI this depletion was accompanied by a matching increase in the extracellular GSH content that was completely prevented in the presence of the multidrug resistance protein 1 (Mrp1)-inhibitor MK571, while in DI-treated cultures GSH was depleted both in cells and medium. These data suggest that OI stimulates Mrp1-mediated astrocytic GSH export, while DI reacts with GSH to a conjugate that is not detectable by the GSH assay applied. The data presented demonstrate that itaconate, DI and OI differ strongly in their effects on the GSH and glucose metabolism of cultured astrocytes. Such results should be considered in the context of the discussed potential use of such compounds as therapeutic agents.

Sepsis is a life-threatening disease characterized by a dysregulated immune response to infection, often leading to neuroinflammation. As a known immunomodulator, Maresin-1 (MaR1) may have potential applications in the treatment of sepsis-induced neuroinflammation, but its effects in this context are unknown. We used a mouse cecum ligation and puncture (CLP)-induced sepsis model and an in vitro lipopolysaccharide (LPS)-induced neuroinflammatory model of BV2 microglia. Expression of microglial cell markers (IBA1, CD11B, CD68, CD86 and CD206) and pro-inflammatory markers (iNOS and COX2) was assessed. The role of MaR1 in regulating the P38 MAPK pathway was explored using the P38 MAPK inhibitor SB203580. In the CLP model, an increased proportion of M1-type microglia was observed, and MaR1 was able to reverse it. However, the combination of SB203580 and MaR1 did not enhance the therapeutic effect compared to SB20580 alone. In vitro experiments, MaR1 inhibited LPS-induced P38 MAPK nuclear translocation and decreased the expression of pro-inflammatory markers such as iNOS and COX2. As with the animal results, no stacking effect could be obtained with the co-administration of SB203580 and MaR1. Our findings suggest that MaR1 attenuates sepsis-induced neuroinflammation mainly by inhibiting phosphorylation of P38 MAPK in microglial cells. This suggests that MaR1 may have a potential therapeutic role in the treatment of sepsis neuroinflammation.

Graphical Abstract

Under sepsis, the phosphorylation of P38 MAPK in the brain is increased, which may cause resting microglia in the brain in the transformation to M1-type microglia. At the same time, P38 MAPK in microglia translocates to the nucleus and increases its phosphorylation level, which may promote microglia to trigger neuroinflammation and further induce neuronal degeneration. MaR1 can inhibit the above process. This figure was created by Figdraw

Effects of gamma-aminobutyric acid (GABA) and some selective GABAergic ligands on the quantal acetylcholine (ACh) release in the frog neuromuscular contacts were investigated using combination of microelectrode technique with fluorescent and immunohistochemical assays. Significant attenuation of ACh release was observed in the presence of GABA as well as selective GABA_A and GABA_B receptor agonists. Neither GABA_A nor GABA_B antagonists abolished to full extent this effect of GABA. Fluorescent assay allowed to detect the GABA-induced opening of K⁺ channels, which was inhibited by XE-991, a selective antagonist of K_v7 type. Electrophysiological recordings of endplate potentials in the presence of XE-991 confirmed the contribution of K_v7 type potassium channels to the effects of GABA on ACh release that was not associated with GABA_A and GABA_B receptors activation. Note that XE-991 effectively precluded the action of retigabine, neuronal K_v7 channel opener, on ACh release. Immunohistochemical assay revealed that frog mature skeletal muscle fibers contain a significant amount of GABA, and substantial amount of GABA can be released in the extracellular space at the muscle contractions induced by prolonged high-frequency nerve stimulation. Besides, some binding sites for exogenous GABA were detected on the plasma membranes. It is concluded that GABA, in addition to affecting GABA_A and GABA_B receptors, can directly activate K_v7 channels, thereby negatively modulating the evoked ACh release. Endogenous GABA may serve as a retrograde regulator of neurotransmitter exocytosis.

Graphical abstract

Antipsychotics are drugs commonly prescribed to treat a variety of psychiatric conditions. They are classified as typical and atypical, depending on their affinity for dopaminergic and serotonergic receptors. Although neurons have been assumed to be the major mediators of the antipsychotic pharmacological effects, glia, particularly astrocytes, have emerged as important cellular targets for these drugs. In the present study, we investigated the effects of acute treatments with the antipsychotics risperidone and haloperidol of hippocampal slices and astrocyte cultures, focusing on neuron-glia communication and how antipsychotics act in astrocytes. For this, we obtained hippocampal slices and primary astrocyte cultures from 30-day-old Wistar rats and incubated them with risperidone or haloperidol (1 and 10 μM) for 30 min and 24 h, respectively. We evaluated metabolic and enzymatic activities, the glutathione level, the release of inflammatory and trophic factors, as well as the gene expression of signaling proteins. Haloperidol increased glucose metabolism; however, neither of the tested antipsychotics altered the glutathione content or glutamine synthetase and Na⁺K⁺-ATPase activities. Haloperidol induced a pro-inflammatory response and risperidone promoted an anti-inflammatory response, while both antipsychotics seemed to decrease trophic support. Haloperidol and risperidone increased Nrf2 and HO-1 gene expression, but only haloperidol upregulated NFκB and AMPK gene expression. Finally, astrocyte cultures confirmed the predominant effect of the tested antipsychotics on glia and their opposite effects on astrocytes. Therefore, antipsychotics cause functional alterations in the hippocampus. This information is important to drive future research for strategies to attenuate antipsychotics-induced neural dysfunction, focusing on glia.

Alpha-synuclein aggregates are strongly associated with Parkinson’s disease (PD), a degenerative neurological disorder characterized by a progressive loss in motor functions. Our study aimed to unravel the potential interaction partners of α-synuclein for exploring the synucleinpathy of PD related to α-synuclein aggregates. α-synuclein was expressed in E.coli and purified by affinity chromatography followed by isolation and identification of its interaction partners using pulldown assay coupled with LC–MS/MS. The impacts of the identified interaction partners on PD were evaluated based on GSE205450 dataset. Consequently, 157 proteins were identified by the criteria of unique peptide = 5. Four proteins including ACO2, ANT1, ATP5F1B and CKB were confirmed using immunostaining coupled with α-synuclein-pulldown assay. Transcriptomics assay showed that the dominant biological processes influenced by α-synuclein interaction partners with differential expression were energy metabolism. Together with GSE205450, Western blot assay showed that α-synuclein interaction partners involved in energy metabolism were down-regulated in PD patients and the MPTP-lesioned mice. ROC curves indicated their clinical implications as diagnostic indices of PD. Using ANT1 as an example, we found that protein aggregates formed by ANT1 and α-synuclein predominantly solely appeared in the cells and mice with PD-like variations. Thereby, low levels of the interaction partners of α-synuclein associated with energy metabolism were associated with PD pathogenesis via forming protein aggregates. This study provides an insight into developing innovative targets on PD based on synucleinpathy.

Modulating role of circRNAs and microRNAs in neurobiological changes induced by drug exposure remains unclear. We examined alterations in some circRNAs and microRNAs in the striatum after morphine dependence and withdrawal and their associations with the changes in spatial working memory performance. Male Wistar rats were used in which 10 days morphine exposure induced dependence. Withdrawal effects were assessed 30 days after stopping morphine exposure. Spatial working memory was assessed using a Y maze test on days 1 and 10 of the drug exposure and 30 days after withdrawal. The gene and protein expression were assessed after dependence and withdrawal. The results revealed that 10 days morphine exposure impaired working memory, which partially reinstated after withdrawal. After 10 days morphine exposure, significant increases in Oprm1 gene and OPRM1 protein levels were detected, which persisted even after withdrawal. The expression of circOprm1 and miR-339-3p decreased in the morphine-dependent group, but they returned to normal levels after withdrawal. The expression of Tlr4 gene and TLR4 protein levels decreased after dependence. While Tlr4 mRNA levels returned to normal after withdrawal, TLR4 protein levels remained lower than the control group. In the morphine-dependent group, both Serpini1 and circSerpini expression significantly increased, but they restored after withdrawal. Expression of miR-181b-3p, miR-181b-5p, miR-181c-3p, and miR-181c-5p decreased after dependence, but they reinstated after withdrawal. It can be concluded that circOprm1 and circSerpini via regulating the OPRM1 and TLR4 expression in the striatum are associated with the neuroadaptation underlying spatial working memory after both morphine dependence and withdrawal.