TrkB-mediated neuroprotection in female hippocampal neurons is autonomous, estrogen receptor alpha-dependent, and eliminated by testosterone: a proposed model for sex differences in neonatal hippocampal neuronal injury.

BACKGROUND: Neonatal hypoxia ischemia (HI) related brain injury is one of the major causes of learning disabilities and memory deficits in children. In both human and animal studies, female neonate brains are less susceptible to HI than male brains. Phosphorylation of the nerve growth factor receptor TrkB has been shown to provide sex-specific neuroprotection following in vivo HI in female mice in an estrogen receptor alpha (ERα)-dependent manner. However, the molecular and cellular mechanisms conferring sex-specific neonatal neuroprotection remain incompletely understood. Here, we test whether female neonatal hippocampal neurons express autonomous neuroprotective properties and assess the ability of testosterone (T) to alter this phenotype. METHODS: We cultured sexed hippocampal neurons from ERα+/+ and ERα-/- mice and subjected them to 4 h oxygen glucose deprivation and 24 h reoxygenation (4-OGD/24-REOX). Sexed hippocampal neurons were treated either with vehicle control (VC) or the TrkB agonist 7,8-dihydroxyflavone (7,8-DHF) following in vitro ischemia. End points at 24 h REOX were TrkB phosphorylation (p-TrkB) and neuronal survival assessed by immunohistochemistry. In addition, in vitro ischemia-mediated ERα gene expression in hippocampal neurons were investigated following testosterone (T) pre-treatment and TrkB antagonist therapy via q-RTPCR. Multifactorial analysis of variance was conducted to test for significant differences between experimental conditions. RESULTS: Under normoxic conditions, administration of 3 µM 7,8-DHF resulted an ERα-dependent increase in p-TrkB immunoexpression that was higher in female, as compared to male neurons. Following 4-OGD/24-REOX, p-TrkB expression increased 20% in both male and female ERα+/+ neurons. However, with 3 µM 7,8-DHF treatment p-TrkB expression increased further in female neurons by 2.81 ± 0.79-fold and was ERα dependent. 4-OGD/24-REOX resulted in a 56% increase in cell death, but only female cells were rescued with 3 µM 7,8-DHF, again in an ERα dependent manner. Following 4-OGD/3-REOX, ERα mRNA increased ~ 3 fold in female neurons. This increase was blocked with either the TrkB antagonist ANA-12 or pre-treatment with T. Pre-treatment with T also blocked the 7,8-DHF- dependent sex-specific neuronal survival in female neurons following 4-OGD/24-REOX. CONCLUSIONS: OGD/REOX results in sex-dependent TrkB phosphorylation in female neurons that increases further with 7,8-DHF treatment. TrkB phosphorylation by 7,8-DHF increased ERα mRNA expression and promoted cell survival preferentially in female hippocampal neurons. The sex-dependent neuroprotective actions of 7,8-DHF were blocked by either ANA-12 or by T pre-treatment. These results are consistent with a model for a female-specific neuroprotective pathway in hippocampal neurons in response to hypoxia. The pathway is activated by 7,8-DHF, mediated by TrkB phosphorylation, dependent on ERα and blocked by pre-exposure to T.

The neuroprotective effect of human primary astrocytes in multiple sclerosis: In vitro model.

Recent studies highlighted the role of astrocytes in neuroinflammatory diseases, particularly multiple sclerosis, interacting closely with other CNS components but also with the immune cells. However, due to the difficulty in obtaining human astrocytes, their role in these pathologies is still unclear. In this study we develop an astrocyte in vitro model to evaluate their role in multiple sclerosis after being treated with CSF isolated from both healthy and MS diagnosed patients. Gene expression and ELISA assays reveal that several pro-inflammatory markers IL-1ß, TNF-α and IL-6, were significantly downregulated in astrocytes treated with MS-CSF. In contrast, neurotrophic survival, and growth factors, and GFAP, BDNF, GDNF and VEGF, were markedly elevated upon the same treatment. In summary, this study supports the notion of the astrocyte involvement in MS. The results reveal the neuroprotective role of astrocyte in MS pathogenicity by suppressing excessive inflammation and increasing the expression of tropic factors.

A novel phthalein component ameliorates neuroinflammation and cognitive dysfunction by suppressing the CXCL12/CXCR4 axis in rats with vascular dementia.

ETHNOPHARMACOLOGICAL RELEVANCE: Chuanxiong, a plant of the Umbelliferae family, is a genuine medicinal herb from Sichuan Province. Phthalides are one of its main active components and exhibit good protective effect against cerebrovascular diseases. However, the mechanism by which phthalides exert neuroprotective effects is still largely unclear. AIM OF THE STUDY: In this study, we extracted a phthalein component (named as QBT) from Ligusticum Chuanxiong, and investigated its neuroprotective effects against vascular dementia (VaD) rats and the underlying mechanism, focusing on the chemokine 12 (CXCL12)/chemokine (C-X-C motif) receptor 4 (CXCR4) axis. METHODS: A rat model of VaD was established, and treated with QBT. Cognitive dysfunction in VaD rats was assessed using the Y-maze, new object recognition, and Morris water maze tests. Neuronal damage and inflammatory response in VaD rats were examined through Nissl staining, immunofluorescence, enzyme-linked immunospecific assay, and western blotting analysis. Furthermore, the effects of QBT on CXCL12/CXCR4 axis and its downstream signaling pathways, Janus kinase 2 (JAK2)/signal transducers and activators of transcription 3 (STAT3) and phosphatidylinositol 3 kinase (PI3K)/protein kinase B (AKT)/nuclear factor-κB (NF-κB), were investigated in VaD rats and BV2 microglial cells exposed to oxygen glucose deprivation. RESULTS: QBT significantly alleviated cognitive dysfunction and neuronal damage in VaD rats, along with inhibition of VaD-induced over-activation of microglia and astrocytes and inflammatory response. Moreover, QBT exhibited anti-inflammatory effects by inhibiting the CXCL12/CXCR4 axis and its downstream JAK2/STAT3 and PI3K/AKT/NF-κB pathways, thereby attenuating the neuroinflammatory response both in vivo and in vitro. CONCLUSION: QBT effectively mitigated neuronal damage and cognitive dysfunction in VaD rats, exerting neuroprotective effects by suppressing neuroinflammatory response through inhibition of the CXCL12/CXCR4 axis.

Intercellular communication atlas reveals Oprm1 as a neuroprotective factor for retinal ganglion cells.

Previous studies of neuronal survival have primarily focused on identifying intrinsic mechanisms controlling the process. This study explored how intercellular communication contributes to retinal ganglion cell (RGC) survival following optic nerve crush based on single-cell RNA-seq analysis. We observed transcriptomic changes in retinal cells in response to the injury, with astrocytes and Müller glia having the most interactions with RGCs. By comparing RGC subclasses characterized by distinct resilience to cell death, we found that the high-survival RGCs tend to have more ligand-receptor interactions with neighboring cells. We identified 47 interactions stronger in high-survival RGCs, likely mediating neuroprotective effects. We validated one identified target, the µ-opioid receptor (Oprm1), to be neuroprotective in three retinal injury models. Although the endogenous Oprm1 is preferentially expressed in intrinsically photosensitive RGCs, its neuroprotective effect can be transferred to other subclasses by pan-RGC overexpression of Oprm1. Lastly, manipulating the Oprm1 activity improved visual functions in mice.

Physical and social environmental enrichment alleviate ferroptosis and inflammation with inhibition of TLR4/MyD88/p38MAPK pathway in chronic cerebral hypoperfusion rats.

A typical enriched environment (EE), which combines physical activity and social interaction, has been proven to mitigate cognitive impairment caused by chronic cerebral hypoperfusion (CCH). However, it remains unclear how the different components of EE promote cognitive recovery after CCH. This study stripped out the different components of EE into physical environmental enrichment (PE) and social environmental enrichment (SE), and compared the neuroprotective effects of PE, SE and typical EE (PSE) in CCH. The results of novel object recognition and Morris water maze tests showed that PE, SE, and PSE improved cognitive function in CCH rats. Additionally, Nissl and TUNEL staining revealed that three EEs reduced neuronal loss in the hippocampus. PSE exhibited superior neuroprotective and functional improvement effects compared to PE and SE, while there was no significant difference between PE and SE. Furthermore, three EEs reduced lipid peroxidation in the hippocampus with decreasing the levels of MDA and increasing the activities of SOD and GSH. The expression of SLC7A11 and GPX4 was increased, while the level of p53 was reduced in three EEs. This suggested that three EEs inhibited ferroptosis by maintaining the redox homeostasis in the hippocampus. Three EEs reduced the levels of IL-ß, TNF-α, and IL-6, thereby inhibiting neuroinflammation. Additionally, Western blotting and immunofluorescence results indicated that three EEs also inhibited the TLR4/MyD88/p38MAPK signaling pathway. These findings collectively demonstrated that the three EEs alleviated hippocampal ferroptosis and neuroinflammation in CCH rats, thereby reducing neuronal loss, which might be associated with the inhibition of the TLR4/MyD88/p38MAPK signaling pathway. Moreover, the study results supported that it is only through the combination of physical exercise and social interaction that the optimal neuroprotective effects can be achieved. These findings provided valuable insights for the prevention and treatment of vascular cognitive impairment.

The Neuroprotective Effects of BMSC-Derived Exosomes against Glutamate-Induced HT22 Cell Cytotoxicity.

Many central nervous system diseases are closely related to nerve damage caused by dysregulation of the endogenous neurotransmitter glutamate. Exosomes derived from bone marrow mesenchymal stem cells (BMSC-Exos) play an important role in improving injury and regeneration functions. However, its mechanism remains unknown. Therefore, the aim of this study is to investigate whether and how BMSC-Exos improve neurotoxicity caused by glutamate and to fill the gap in the literature. In this study, glutamate-treated HT22 cells were first exposed to mouse-derived BMSC-Exos at different concentrations to observe their effects on HT22 apoptosis. Next, we treated glutamate-treated HT22 cells with mouse-derived BMSC-Exos. We then inhibited the PI3K/Akt/mTOR signaling pathways using the PI3K/Akt inhibitor and the mTOR inhibitor, respectively, and observed the protective effect of mouse-derived BMSC-Exos on HT22 cells treated with glutamate. Our results show that BMSC-Exos reduced apoptosis triggered by glutamate stimulation, increased cell vitality, and decreased the levels of proapoptotic proteins while increasing the levels of anti-apoptotic proteins. The protective effect of BMSC-Exos was weakened when PI3K/Akt inhibitor and mTOR inhibitor were added. To sum up, we draw the following conclusions: BMSC-Exos can reduce neuronal apoptosis and apoptosis-related protein expression after glutamate stimulation by regulating the PI3K/Akt/mTOR signaling pathway.

Ndfip1 protected dopaminergic neurons via regulating mitochondrial function and ferroptosis in Parkinson's disease.

Increasing evidence has shown that mitochondrial dysfunction and iron accumulation contribute to the pathogenesis of Parkinson's disease (PD). Nedd4 family interacting protein 1 (Ndfip1) is an adaptor protein of the Nedd4 E3 ubiquitin ligases. We have previously reported that Ndfip1 showed a neuroprotective effect in cell models of PD. However, whether Ndfip1 could protect dopaminergic neurons in PD animal models in vivo and the possible mechanisms are not known. Here, our results showed that the expression of Ndfip1 decreased in the substantia nigra (SN) of 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-induced PD mouse model. Overexpression of Ndfip1 could improve MPTP-induced motor dysfunction significantly and antagonize the loss of dopaminergic neurons in the SN of MPTP-induced mice. Further study showed that overexpression of Ndfip1 might protect against MPTP-induced neurotoxicity through regulation of voltage-dependent anion-selective channel (VDAC). In addition, we observed the downregulation of Ndfip1 and upregulation of VDAC1/2 in 1-methyl-4-phenylpyridinium ion (MPP+)-induced SH-SY5Y cells. Furthermore, high expression of Ndfip1 in SH-SY5Y cells inhibited MPP+-induced increase of VDAC1/2 and restored MPP+-induced mitochondrial dysfunction. Furthermore, Ndfip1 prevented MPP+-induced increase in the expression of long-chain acyl-CoA synthetase 4 (ACSL4), suggesting the possible role of Ndfip1 in regulating ferroptosis. Our results provide new evidence for the neuroprotective effect of Ndfip1 on dopaminergic neurons in PD animal models and provide promising targets for the treatment of iron-related diseases, including PD.

Pretreatment with Liposome-Encapsulated Shrimp Shell Extract Attenuated Neuronal Damage and Death in Aß1-42-Induced Memory Deficits in Rats.

The accumulation of amyloid-beta (Aß) peptides is a crucial factor in the neuronal degeneration of Alzheimer's disease (AD). The current study investigated the underlying neuroprotective mechanisms of shrimp shell extract (SSE) and liposome-encapsulated SSE (SSE/L) against Aß1-42-induced neuronal damage and death in rats. Intracerebroventricular infusion of Aß1-42 effectively induced memory decline, as observed in a reduction of the rat's discriminating ability in the novel object recognition and novel object location tasks. Oral pretreatment with 100 mg/kg of SSE demonstrated no preventive effect on the memory decline induced by Aß1-42 infusion. However, treatment with SSE/L 100 mg/kg BW effectively attenuated memory deficits in both behavioral assessments following two and four weeks after Aß1-42 infusion. Moreover, SSE/L exerted neuroprotective effects by reducing lipid peroxidation and increasing Nrf2/HO-1 expression. There was a significant decrease in Iba1 and GFAP (biomarkers of microglia and astrocyte activity, respectively), as well as a decrease in the levels of NF-κB expression and the inflammatory cytokines TNF-α and IL-6 in the cortical and hippocampal tissues. Treatment with SSE/L also reduced the pro-apoptotic proteins Bax and cleaved caspase-3 while raising the anti-apoptotic protein Bcl2. In addition, the beneficial effects of SSE/L were along with the effects of a positive control commercial astaxanthin (AST). The findings of this study indicated that SSE/L provided neuroprotective effects on Aß1-42-induced AD rats by ameliorating oxidative stress, neuroinflammation and apoptotic cell death. Therefore, SSE/L might be employed to prevent and mitigate Aß accumulation-induced neurotoxicity in AD.

The dose-dependent neuroprotective effect of norepinephrine in improving memory retrieval in an experimental model of multiple sclerosis, experimental autoimmune encephalomyelitis.

Multiple sclerosis (MS) is considered an immune-mediated inflammatory disorder that causes cognitive impairments by damaging the hippocampal tissue. Conversely, norepinephrine (NEP) has anti-inflammatory and re-myelinating properties, which improve cognitive impairments. The aim of this study was to assess the neuroprotective effects of NEP on learning and memory disorders in an experimental animal model of MS. Two guide cannulas were bilaterally implanted in the rat hippocampal CA1 regions. After recovery, the animals received 3 µl of 0.01% ethidium bromide (EtB) in each of both hippocampal regions. After three days, the rats were randomly divided into 6 groups (8 rats/group), including control, sham 1, sham 2, and three groups of NEP 0.25, 0.5, and 1 mg/kg by intrahippocampal injection. Behavioral tests (e.g. shuttle box test and open-field test) were then performed. Finally, ROS, MDA, GSH, TNF-α, IL-6, and IL-1ß concentrations in the left CA1 area, as well as using western-blot analysis, p-p38, p-JNK, p-AKT, p-ERK1/2, p-NMDA, p-AMPA, p-CREB, and BDNF proteins in the right CA1 region evaluated. The EtB injection increased ROS, MDA, TNF-α, IL-6, and IL-1ß levels, as well as p-JNK and p-P38, except all other proteins, while decreasing GSH content, as well as step-through latency and locomotor activity in sham groups compared to the control group. Conversely, NEP (0.5 and 1 mg/kg, particularly at the dose of 1 mg/kg) counterbalanced all the alterations mentioned above in comparison to the sham groups. The EtB induced learning and memory impairment; however, NEP dose-dependently restored these impairments to normal levels.

A Capsicum annuum L. seed extract exerts anti-neuroexcitotoxicity in HT22 hippocampal neurons.

The hippocampal memory deficit stands out as a primary symptom in neurodegenerative diseases, including Alzheimer's disease. While numerous therapeutic candidates have been proposed, they primarily serve to delay disease progression. Given the irreversible brain atrophy or injury associated with these conditions, current research efforts are concentrated on preventive medicine strategies. Herein, we investigated whether the extracts of Capsicum annuum L. seeds (CSE) and Capsicum annuum L. pulp (CPE) have preventive properties against glutamate-induced neuroexcitotoxicity (one of the main causes of Alzheimer's disease) in HT22 hippocampal neuronal cells. Pretreatment with CSE demonstrated significant anti-neuroexcitotoxic activity, whereas CPE did not exhibit such effects. Specifically, CSE pretreatment dose-dependently inhibited the elevation of excitotoxic elements (intracellular calcium influx and reactive oxygen species; ROS) and apoptotic elements (p53 and cleaved caspase-3). In addition, the glutamate-induced alterations of neuronal activity indicators (brain-derived neurotrophic factor; BDNF and cAMP response element-binding protein phosphorylation; CREB) were significantly attenuated by CSE treatment. We also found that luteolin is the main bioactive compound corresponding to the anti-neuroexcitotoxic effects of CSE. Our results strongly suggest that Capsicum annuum L. seeds (but not its pulp) could be candidates for neuro-protective resources especially under conditions of neuroexcitotoxicity. Its underlying mechanisms may involve the amelioration of ROS-mediated cell death and BDNF-related neuronal inactivity and luteolin would be an active compound.

Irisin: An unveiled bridge between physical exercise and a healthy brain.

AIMS: Physical exercise has been widely recognized for its positive effects on health and well-being. Recently, the impact of exercise on the nervous system has gained attention, with evidence indicating improvements in attention, memory, neurogenesis, and the release of "happiness hormones." One potential mediator of these benefits is Irisin, a myokine induced by exercise that can cross the blood-brain barrier, reduce neuroinflammation, and counteract neurodegeneration. The objective of this study is to conduct a systematic review of animal trials to summarize the neuroprotective effects of Irisin injection in mitigating neuroinflammation and neurodegeneration. MATERIALS AND METHODS: Two independent reviewers screened three databases (PubMed, Embase, and Google Scholar) in November 2022. Animal studies assessing the neuroprotective effects of Irisin in mitigating neuroinflammation or counteracting neurodegeneration were included. The methodological quality of the included studies was assessed using SYRCLE's Risk of Bias tool. KEY FINDINGS: Twelve studies met the inclusion criteria. Irisin injection in rodents significantly reduced neuroinflammation, cytokine cascades, and neurodegeneration. It also protected neurons from damage and apoptosis, reduced oxidative stress, blood-brain barrier disruption, and neurobehavioral deficits following disease or injury. Various mechanisms were suggested to be responsible for these neuroprotective effects. Most of the included studies presented a low risk of bias based on SYRCLE's Risk of Bias tool. Irisin injection demonstrated the potential to alleviate neuroinflammation and counteract neurodegeneration in rodent models through multiple pathways. However, further research is needed to fully understand its mechanism of action and its potential applications in clinical practice and drug discovery.

Synthesis, biological activity evaluation and mechanism analysis of new ganglioside GM3 derivatives as potential agents for nervous functional recovery.

Neuronal regenerative ability is vital for the treatment of neurodegenerative diseases and neuronal injuries. Recent studies have revealed that Ganglioside GM3 and its derivatives may possess potential neuroprotective and neurite growth-promoting activities. Herein, six GM3 derivatives were synthesized and evaluated their potential neuroprotective effects and neurite outgrowth-promoting activities on a cellular model of Parkinson's disease and primary nerve cells. Amongst these derivatives, derivatives N-14 and 2C-12 demonstrated neuroprotective effects in the MPP + model in SH-SY5Y cells. 2C-12 combined with NGF (nerve growth factor) induced effecially neurite growth in primary nerve cells. Further action mechanism revealed that derivative 2C-12 exerts neuroprotective effects by regulating the Wnt signaling pathway, specifically involving the Wnt7b gene. Overall, this study establishes a foundation for further exploration and development of GM3 derivatives with neurotherapeutic potential.

Role of Transporters and Enzymes in Metabolism and Distribution of 4-Chlorokynurenine (AV-101).

4-Chlorokynurenine (4-Cl-KYN, AV-101) is a prodrug of a NMDA receptor antagonist and is in clinical development for potential CNS indications. We sought to further understand the distribution and metabolism of 4-Cl-KYN, as this information might provide a strategy to enhance the clinical development of this drug. We used excretion studies in rats, in vitro transporter assays, and pharmacogenetic analysis of clinical trial data to determine how 4-Cl-KYN and metabolites are distributed. Our data indicated that a novel acetylated metabolite (N-acetyl-4-Cl-KYN) did not affect the uptake of 4-Cl-KYN across the blood-brain barrier via LAT1. 4-Cl-KYN and its metabolites were found to be renally excreted in rodents. In addition, we found that N-acetyl-4-Cl-KYN inhibited renal and hepatic transporters involved in excretion. Thus, this metabolite has the potential to limit the excretion of a range of compounds. Our pharmacogenetic analysis found that a SNP in N-acetyltransferase 8 (NAT8, rs13538) was linked to levels of N-acetyl-4-Cl-KYN relative to 4-Cl-KYN found in the plasma and that a SNP in SLC7A5 (rs28582913) was associated with the plasma levels of the active metabolite, 7-Cl-KYNA. Thus, we have a pharmacogenetics-based association for plasma drug level that could aid in the drug development of 4-Cl-KYN and have investigated the interaction of a novel metabolite with drug transporters.

Fatsia japonica extract exerts antioxidant and anti-neuroinflammatory effects on neuronal cells and a zebrafish model.

ETHNOPHARMACOLOGICAL RELEVANCE: Fatsia japonica is a traditional medicine used to treat various diseases, including inflammation-related disorders. However, its antineuroinflammatory and neuroprotective effects remain unclear. AIM OF THE STUDY: We aimed to evaluate the anti-neuroinflammatory and neuroprotective effects of F. japonica extract to identify the underlying mechanisms. MATERIALS AND METHODS: The components of F. japonica extract were profiled using ultra-high-performance liquid chromatography-mass spectrometry. The effects of F. japonica extract were investigated in BV2 microglia and HT22 hippocampal cells. Furthermore, in vivo effects of F. japonica extract were assessed using zebrafish models treated with H2O2 and LPS to evaluate the effects of in vivo. RESULTS: We identified 27 compounds in the F. japonica extract. F. japonica extract demonstrated anti-inflammatory properties by suppressing LPS-induced inflammatory responses in both BV2 cells and zebrafish, along with inhibiting the activation of the nuclear factor (NF)-κB (p65) pathway. The protective effects of this extract were also observed on glutamate-treated HT22 cells and in H2O2-induced zebrafish. Furthermore, F. japonica extract upregulated nuclear factor E2-related (Nrf) 2/heme oxygenase (HO)-1 expression in BV2 and HT22 cells. CONCLUSIONS: F. japonica extract exerted anti-neuroinflammatory and neuroprotective effects through Nrf2/HO-1 and the NF-κB pathway.

Secretory Clusterin Inhibits Dopamine Neuron Apoptosis in MPTP Mice by Preserving Autophagy Activity.

Secretory clusterin (sCLU) plays an important role in the research progress of nervous system diseases. However, the physiological function of sCLU in Parkinson's disease (PD) are unclear. The purpose of this study was to examine the effects of sCLU-mediated autophagy on cell survival and apoptosis inhibition in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model of PD. We found that MPTP administration induced prolonged pole-climbing time, shortened traction time and rotarod time, significantly decreased TH protein expression in the SN tissue of mice. In contrast, sCLU -treated mice took less time to climb the pole and had an extended traction time and rotating rod time. Meanwhile, sCLU intervention induced increased expression of the TH protein in the SN of mice. These results indicated that sCLU intervention could reduce the loss of dopamine neurons in the SN area and alleviate dyskinesia in mice. Furthermore, MPTP led to suppressed viability, enhanced apoptosis, an increased Bax/Bcl-2 ratio, and cleaved caspase-3 in the SN of mice, and these effects were abrogated by sCLU intervention. In addition, MPTP increased the levels of P62 protein, decreased Beclin1 protein, decreased the ratio of LC3B-II/LC3B-I, and decreased the numbers of autophagosomes and autophagolysosomes in the SN tissues of mice. These effects were also abrogated by sCLU intervention. Activation of PI3K/AKT/mTOR signaling with MPTP inhibited autophagy in the SN of MPTP mice; however, sCLU treatment activated autophagy in MPTP-induced PD mice by inhibiting PI3K/AKT/mTOR signaling. These data indicated that sCLU treatment had a neuroprotective effect in an MPTP-induced model of PD.

Artemisinin protects dopaminergic neurons against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced neurotoxicity in a mouse model of Parkinson's disease.

Artemisinin is an antimalarial drug that has been used for almost half a century. However, the anti-Parkinson's disease (PD) effects of artemisinin with respect to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced oxidative stress have not yet been investigated while focusing on NF-E2-related factor 2 (Nrf2) signaling. Thus, we sought to assess the behavioral and oxidative mechanistic effects of artemisinin on MPTP-induced toxicity via the Nrf2 signaling pathway. We explored this through immunohistochemical assays, ELISA, in differentiated PC12 cells treated with siRNA, and with a PD mouse model. Artemisinin increased Nrf2 DNA-binding activity and HO-1 and NQO1 expression. Artemisinin treatment protected cells against MPP+ -induced neuronal death signaling, including NADH dehydrogenase activity, reactive oxygen species, mitochondrial membrane potential, and cleaved caspase-3. Moreover, it protected cells against MPTP-induced behavioral impairments and significantly reduced dopaminergic neuronal loss. Additionally, Nrf2 pre-inhibition using ML385 neutralized the inhibitory effects of artemisinin on dopaminergic neuronal damage and behavioral impairments induced by MPTP. Our results suggest that artemisinin inhibits MPTP-induced behavioral and neurotoxic effects in mice. This provides a foundation for further research to evaluate artemisinin as a potential therapeutic agent for PD.

TMT-based quantitative proteomics analysis of neuroprotective effects of Forsythoside A on the MPTP-induced Parkinson's disease mouse model.

Parkinson's disease (PD) is a prevalent neurodegenerative disorder characteristized by the presence of dyskinesia and the progressive loss of dopaminergic neurons. Although certain drugs can mitigate the symptoms of PD, they are unable to delay the disease progression, and their prolonged use may result in complications. Therefore, there exists an urgent necessity to identify potential agents that can effectively delay PD progression with fewer side effects. Recent research has unveiled that several traditional Chinese medicines (TCM) exhibit neuroprotective properties in various models pertinent to PD. Forsythoside A (FSA), the primary bioactive compound derived from TCM Lianqiao, has undergone extensive research in animal models of Alzheimer's disease and cerebral ischemia. However, the investigation into the impact of FSA on PD is limited in existing research. In this study, we aimed to evaluate the neuroprotective effects of FSA on MPTP-induced PD mouse model. FSA demonstrated significant improvements in the behavioral and neuropathological changes triggered by MPTP in mice. Furthermore, it exerted a suppressive effect on the activations of astrocyte and microglia. Meanwhile, Tandem mass tag (TMT)-based quantitative proteomics of striatal tissue and bioinformatics analysis were performed to elucidate the underlying mechanisms of FSA on PD mouse model. Proteomics demonstrated a total of 68 differentially expressed proteins (DEPs) were identified between HFSA and MPTP groups including 26 upregulated and 42 downregulated. Systematic bioinformatics analysis of the 68 DEPs illustrated that they were predominantly related to estrogen signaling pathway and calcium signaling pathway. The related DEPs (PLCß4, Grm2, HPAC and Cox4i1) expression levels were verified by Western blot. FSA effectively restored the altered expression of the four DEPs induced by MPTP. Summarily, FSA exerted remarkable neuroprotective effects in MPTP-induced mice. Further, our research may provide proteomics insights that contribute to the further exploration of FSA as a potential treatment for PD.

Knockdown of Smox protects the integrity of the blood-brain barrier through antioxidant effect and Nrf2 pathway activation in stroke.

Once an ischemic stroke occurs, reactive oxygen species (ROS) and oxidative stress degrade the tight connections between cerebral endothelial cells resulting in their damage. The expression of antioxidant genes may be enhanced, and ROS formation may be reduced following Nrf2 activation, which is associated with protection against ischemic stroke. Overexpression of spermine oxidase (Smox) in the neocortex led to increased H2O2 production. However, how Smox impacts the regulation of the blood-brain barrier (BBB) through antioxidants has not been examined yet. We conducted experiments both in the cell level and in the transient middle cerebral artery occlusion (tMCAO) model to evaluate the effect of Smox siRNA lentivirus (si-Smox) knockdown on BBB protection against ischemic stroke. Mice treated with si-Smox showed remarkably decreased BBB breakdown and reduced endothelial inflammation following stroke. The treatment with si-Smox significantly elevated the Bcl-2 to Bax ratio and decreased the production of cleaved caspase-3 in the tMCAO model. Further investigation revealed that the neuroprotective effect was the result of the antioxidant properties of si-Smox, which reduced oxidative stress and enhanced CD31+ cells in the peri-infarct cortical areas. Of significance, si-Smox activated Nrf2 in both bEnd.3 cells and tMCAO animals, and blocking Nrf2 with brusatol diminished the protective effects of si-Smox. The study findings suggest that si-Smox exerts neuroprotective effects and promotes angiogenesis by activating the Nrf2 pathway, thus decreasing oxidative stress and apoptosis caused by tMCAO. As a result, si-Smox may hold potential as a therapeutic candidate for preserving BBB integrity while treating ischemic stroke.

STAT3 protects dopaminergic neurons against degeneration in animal model of Parkinson's disease.

INTRODUCTION: Parkinson's disease (PD) is the most prevalent disorder of the basal ganglia, propagated by the degeneration of axon terminals within the striatum and subsequent loss of dopaminergic neurons in the substantia nigra (SN). Exposure of environmental neurotoxins and mutations of several mitochondrial and proteasomal genes are primarily responsible. METHODS: To determine whether signal transducer and activator of transcription 3 (STAT3) could protect dopaminergic neurons against degeneration, we first screened it in the in vitro capacity using immortalized rat dopaminergic N27 cells under 6-OHDA neurotoxicity. We then evaluated the effectiveness of constitutively active (ca) STAT3 as a neuroprotective agent on N27 cells in a 6-hydroxydopamine (6-OHDA) induced rat model of PD and compared it to control animals or animals where AAV/caRheb was expressed in SN. Behavioral outcomes were assessed using rotational and cylinder assays and mitochondrial function using reactive oxygen species (ROS) levels. RESULTS: Using flow cytometry, the in vitro analysis determined caSTAT3 significantly decreased dopaminergic neuronal death under 6-OHDA treatment conditions. Importantly, in vivo overexpression of caSTAT3 in SN dopaminergic neurons using AAV-mediated expression demonstrated significant neuroprotection of dopaminergic neurons following 6-OHDA. Both caSTAT3 and caRheb + caSTAT3 co-injection into substantia nigra reduced D-amphetamine-induced rotational behavior and increased ipsilateral forelimb function when compared to control animals. In addition, caSTAT3 decreased mitochondrial ROS production following 6-OHDA induced neurotoxicity. CONCLUSION: caSTAT3 confers resistance against ROS production in mitochondria of susceptible SN dopaminergic neurons potentially offering a new avenue for treatment against PD.

Baicalin exerts neuroprotective actions by regulating the Nrf2-NLRP3 axis in toxin-induced models of Parkinson's disease.

Baicalin, a potent anti-oxidative and anti-inflammatory flavonoid compound derived from Scutellaria baicalensis, has emerged as a neuroprotective agent. However, the mechanisms by which baicalin is neuroprotective in Parkinson's disease (PD) remain unclear. In this research, α-syn/MPP+ and MPTP were used to establish PD models in BV2 cells and C57BL/6 mice, respectively. The effect and mechanism of action of baicalin in PD were investigated by Western blotting, RT-qPCR, ELISA, Immunohistochemistry (IHC) staining, Immunofluorescence (IF) staining, HPLC and methods. Results demonstrate that baicalin mitigates oxidative stress, microglia activation and inflammatory response caused by α-syn/MPP+ and MPTP. It protects against dopaminergic neuron loss and relieves motor deficits. Meanwhile, baicalin not only significantly up-regulates the expression of Nrf2 and its downstream antioxidant enzyme, but also suppresses the activation of NLRP3 inflammasome simultaneously. Notably, the beneficial effects of baicalin in PD treatment are blocked by Nrf2 knockdown. This research reveals that baicalin may exert neuroprotective effects in PD treatment by suppressing the activation of NLRP3 inflammasome and it is dependent on the Nrf2-mediated antioxidative response.