Neurochemical Research最新文献

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.

The clinical manifestations of anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis may be closely related to the integrity of the blood–brain barrier (BBB). The P38 mitogen-activated protein kinase (P38MAPK) pathway plays a protective role in neurodegenerative diseases. However, whether the P38MAPK pathway is involved in the underlying mechanism of tight junction (TJ) protein disruption and neuronal damage has not been elucidated. Therefore, in this study, a mouse model of anti-NMDAR encephalitis was established by active immunization with NMDAR NR1_356-385 peptides. The critical pathways of P38MAPK were screened by interaction network and co-enrichment analysis. The role of P38MAPK pathways was investigated by the injection of P38MAPK inhibitor SB203580 (10 mg/kg, i.p.). Compared with the control group, the expression of occludin and zonula occludens (ZO)-1 in NMDAR NR1_356-385 group mice was downregulated, and the structure and function of BBB were damaged. However, after the intervention of SB203580, the activation of the P38MAPK was inhibited, the expression of matrix metalloproteinase 9 (MMP9) was reduced, and the function of BBB was improved. Meanwhile, inhibiting the P38MAPK pathway reversed the degradation of NMDAR NR1, while reducing the expression of the glial fibrillary acidic protein (GFAP) and pro-inflammatory factor tumor necrosis factor (TNF-α). It also relieved the damage of neuron-specific nucleus (NeuN), thus alleviating psychobehavioral symptoms. In conclusion, our results suggested that the P38MAPK pathway is involved in BBB destruction and neurobehavioral change in mice with anti-NMDAR encephalitis. Targeting the P38MAPK pathway may be a promising option for the treatment of anti-NMDAR encephalitis.

Parkinson’s disease (PD) is typically marked by motor dysfunction accompanied by loss of dopaminergic (DA) neurons and aggravated oxidative stress in the substantia nigra pars compacta (SNpc). Atractylenolide-I (ATR-I) is a potent antioxidant sesquiterpene with neuroprotective properties. However, whether ATR-I plays a neuroprotective role against oxidative stress in PD remains unclear. The objective of this study was to explore the mechanism of antioxidant action of ATR-I in PD models both in vivo and in vitro. Here, we show that ATR-I alleviated motor deficits in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mice. Moreover, ATR-I treatment effectively reduced DA neuron loss and increased tyrosine hydroxylase expression in the SNpc of MPTP-induced mice. Additionally, ATR-I inhibited oxidative stress (as manifested by elevated superoxide dismutase and glutathione peroxidase activities, and reduced malondialdehyde content) in MPTP-induced mice and attenuated reactive oxygen species levels in 1-methyl-4-phenylpyridinum (MPP⁺)-treated SH-SY5Y cells. Finally, ATR-I upregulated expressions of silent information regulator 1 (SIRT1), peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), NF-E2-related factor-2 (Nrf2), and heme oxygenase-1 in MPTP-induced mice and MPP⁺-treated SH-SY5Y cells, but had little effect on these factors in the presence of the SIRT1 inhibitor EX527. Taken together, these findings indicated that the important antioxidant role of ATR-I in MPTP/MPP⁺-mediated oxidative stress and the pathogenesis of PD through the SIRT1/PGC-1α/Nrf2 axis, highlighting its potential as a therapeutic option for PD.

Recent studies highlight the role of brain metabolites in regulation of neuronal signals and behaviour. To understand the underlying mechanism, brain metabolites and associated signaling molecules were examined in early adolescent rat experienced CRS. Rats were tested for their learning and memory ability, and their metabolite profile was evaluated using Gas chromatography-mass spectrometry (GC-MS). Differences in metabolites were examined by variable importance in projection (VIP) and multivariate analysis. Ingenuity Pathway Analysis (IPA) and KEGG ID were performed for the identified metabolites. We found that CRS altered the metabolites that were involved in biosynthesis of steroid hormone, aminoacyl t-RNA, L-Dopa biosynthesis, and metabolism of tyrosine, fatty acid, and purine. Further analysis showed reduction of 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR, a metabolite involved in purine metabolism) an AMP kinase activator, influenced the hypoxanthine-guanine phosphoribosyltransferase (HPRT), serotonin transporter (SERT), postsynaptic density protein (PSD) -95, its phosphorylation and brain-derived neurotrophic factor (BDNF) in CRS animals, which displayed deficit in memory. The AICAR treated CRS rats showed improved memory and altered metabolites and other molecules (HPRT, SERT, PSD-95 and BDNF) levels were restored. Our analysis revealed that CRS induced changes in metabolites possibly altered synaptic plasticity and memory in which HPRT, SERT-PSD95-BDNF associated pathway involved. Taken together, our observation provides initial insight into how stress differently influences the metabolic pathway, and associated behaviour. Further study will help to develop pharmacological intervention strategies.

Protection against blood-brain barrier (BBB) dysfunction is key to reduce the cerebral ischemia injury as its breakdown causes edema formation and extravasation of blood components and immune cells. The maintenance of BBB integrity requires the GSK-3β/β-catenin pathway activity. Naringenin (NAR), an effective monomer from Chinese herbal medicine, had potent protective effect on brain inflammatory and oxidative injury. However, whether NAR could protect the integrity of BBB during cerebral ischemia injury and the involvement of GSK-3β/β-catenin pathway in the beneficial effect of NAR was unknown. Therefore, mouse middle cerebral artery occlusion/reperfusion (IR) model was employed to answer these questions. NAR was intraperitoneally administrated once daily for 6 days immediately after IR with the dose of 10 mg/kg. BBB damage was evaluated with Evans blue. Protein levels of GSK-3β and β-catenin in vascular endothelial cells at penumbra were assessed with western blotting and immunofluorescence. The experimental data suggested that NAR improved neurological deficits, decreased the percentage of infarct volumes and neuronal apoptosis at 7d after IR. NAR improved BBB damage as evidenced by a lower permeability of Evans blue dye and upregulation of tight junction proteins such as zonula occludens-1(ZO-1), Occludin and Claudin-5. Importantly, GSK-3β/β-catenin pathway activity was related to the improvement of BBB integrity rendered by NAR. Our findings demonstrated that NAR might become a potential therapeutic drug for IR.

L-Proline (l-Pro) is a non-essential amino acid which, in high concentrations, can cause neurological problems including seizures, although the causative mechanism for this is unclear. Here, we studied the impact of physiological levels of proline on brain energy metabolism and investigated the metabolism of l-Pro itself, using the cortical brain tissue slice and stable isotope labelling from [1-¹³ C]glucose and [1,2-¹³ C]acetate detected by NMR spectroscopy and LCMS. l-Pro was actively taken up by the slices and significantly reduced the total metabolic pools of all measured metabolites with glutamine the least affected, while reducing net flux of ¹³C into glycolytic byproducts (lactate and alanine). Conversely, net flux into Krebs cycle intermediates was increased, suggesting that L-Pro at lower concentrations was driving increased mitochondrial activity in both neurons and glia at the expense of glycolysis and metabolic pool sizes. As there was no evidence of metabolism of [1-¹³ C] l-Pro in slices under normo-glycemic conditions, the effect of proline on metabolism was not due to displacement of metabolites by added l-Pro. Comparison of the metabolic fingerprint generated by l-Pro in slices metabolizing [3-¹³ C]pyruvate with that generated by ligands active in the GABAergic system suggested that l-Pro may engender effects similar to that of the inhibitory neurotransmitter and metabolite γ-aminobutyric acid (GABA), in line with previous suggestions that l-Pro may be a GABA mimetic in addition to its role as a modulator of mitochondrial metabolism.

Affective and psychotic disorders are highly prevalent and severely debilitating mental illnesses that often remain untreated or treatment-resistant. Sulpiride is a common antipsychotic (neuroleptic) drug whose well-established additional (e.g., antidepressant) therapeutic effects call for further studies of a wider spectrum of its CNS effects. Here, we examined effects of acute 20-min exposure to sulpiride (50–200 mg/L) on anxiety- and depression-like behaviors, as well as on brain monoamines, in adult zebrafish (Danio rerio). Overall, sulpiride exerted overt anxiolytic-like effects in the novel tank test and showed tranquilizing-like effects in the zebrafish tail immobilization test, accompanied by lowered whole-brain dopamine and its elevated turnover, without affecting serotonin or norepinephrine levels and their turnover. Taken together, these findings support complex behavioral pharmacology of sulpiride in vivo and reconfirm high sensitivity of zebrafish-based screens to this and, likely, other related clinically active neuroleptics.

Proprotein convertase substilin/kexin type 9 (PCSK9), a pivotal protein regulating lipid metabolism, has been implicated in promoting microthrombotic formation and inflammatory cascades, thereby contributing to cardiovascular ischemia/reperfusion (I/R) injury. However, its involvement in cerebral I/R injury and its potential role in microcirculation protection remain unexplored. In this investigation, we utilized a middle cerebral artery occlusion/reperfusion (MCAO/R) mouse model to simulate ischemic stroke. Different concentrations of evolocumab (1, 5, 10 mg/kg, i.v.), a PCSK9 inhibitor, were administered to assess its impact. Immunofluorescence staining was employed to analyze changes in the expression of occludin, claudin-5, thrombocyte, ICAM-1, VCAM-1, and CD45, providing insights into blood-brain barrier integrity, platelet adhesion, and immune cell infiltration. Moreover, the Morris water maze and elevated plus maze were utilized to evaluate neurological and behavioral functions in MCAO/R mice, shedding light on the effects of PCSK9 inhibition. Our findings revealed a surge in plasma PCSK9 levels post-MCAO/R, peaking at 24 h post-reperfusion. Evolocumab (10 mg/kg) treatment significantly mitigated brain infarction and neurological deficits, evidenced by enhanced locomotor function and reduced post-stroke anxiety. However, it did not ameliorate cognitive impairment following MCAO/R. Additionally, evolocumab administration led to diminished leakage of evans blue solution and upregulated expression of occludin and claudin-5. Thrombocyte, ICAM-1, VCAM-1, and CD45 levels were notably reduced in the penumbral area post-evolocumab treatment. These protective effects are speculated to be mediated through the inhibition of the ERK/NF-κB pathway. The PCSK9 inhibitor evolocumab holds promise as a therapeutic agent during the acute phase of stroke, exerting its beneficial effects by modulating the ERK/NF-κB signaling pathway.

A high cellular concentration of adenosine triphosphate (ATP) is essential to fuel many important functions of brain astrocytes. Although cellular ATP depletion has frequently been reported for astrocytes, little is known on the metabolic pathways that contribute to ATP restoration by ATP-depleted astrocytes. Incubation of cultured primary rat astrocytes in glucose-free buffer for 60 min with the mitochondrial uncoupler BAM15 lowered the cellular ATP content by around 70%, the total amount of adenosine phosphates by around 50% and the adenylate energy charge (AEC) from 0.9 to 0.6. Testing for ATP restoration after removal of the uncoupler revealed that the presence of glucose as exclusive substrate allowed the cells to restore within 6 h around 80% of the initial ATP content, while coapplication of adenosine plus glucose enabled the cells to fully restore their initial ATP content within 60 min. A rapid but incomplete and transient ATP restoration was found for astrocytes that had been exposed to adenosine alone. This restoration was completely prevented by application of the pyruvate uptake inhibitor UK5099, the respiratory chain inhibitor antimycin A or by the continuous presence of BAM15. However, the presence of these compounds strongly accelerated the release of lactate from the cells, suggesting that the ribose moiety of adenosine can serve as substrate to fuel some ATP restoration via mitochondrial metabolism. Finally, the adenosine-accelerated ATP restoration in glucose-fed astrocytes was inhibited by the presence of the adenosine kinase inhibitor ABT-702. These data demonstrate that astrocytes require for a rapid and complete ATP restoration the presence of both glucose as substrate and adenosine as AMP precursor.