Α7 Nicotinic Research Articles

The protective effect of low-dose nicotine on ischemia stroke by maintaining the integrity of the blood-brain barrier.

Increasing evidence has shown that low-dose nicotine could have preventive and therapeutic effects on ischemic stroke (IS). Nevertheless, direct evidence is still missing, especially key molecules and signal pathways. Mice were randomly assigned to one of three groups: the sham group, the control group, and the nicotine-treated group. In the control group, mice were subjected to middle cerebral artery occlusion/reperfusion (MCAO/R). In the nicotine-treated group, mice were exposed to 12 μg/ml nicotine in their drinking water for 1 month prior to undergoing surgery. For in vitro blood-brain barrier (BBB) model, hCMEC/D3 monolayers were prepared on Transwells and pre-treated with nicotine for 48 hours and then subjected to oxygen-glucose deprivation/reoxygenation (OGD/R). Moreover, RNA-seq was adopted to explore the potential targets and signaling pathways regarding the protective role of nicotine. MCAO/R resulted in significantly compromised BBB integrity and serious brain damage. Notably, pretreatment of mice with 12μg/ml nicotine for one month significantly reduced IS-induced BBB damage and its associated brain injury. In addition, the permeability of hCMEC/D3 monolayer endothelial cells was significantly reduced under OGD/R conditions, which could be ameliorated by nicotine pretreatment. The RNA-seq results showed that TGF-β and Wnt signaling pathways were associated with pathways associated with DEGs between OGD/R and OGD/R plus nicotine treatment. Finally, the activation of Wnt/β-catenin pathways could be antagonized by the α7 nicotine acetylcholine receptor (α7 nAChR) inhibitor α-BTX. These results demonstrate that nicotine treatment could alleviates the IS-compromised integrity of BBB by regulating the Wnt signal pathway through α7 nAChR. The study demonstrates that nicotine at low concentrations exerts neuro-protective effects by supporting the integrity of BBB and subsequent endothelial viability after ischemic stroke. This finding suggests that targeting the BBB, especially endothelial cells, with nicotine treatment is a promising therapeutic strategy for brain injury after ischemic stroke.

Abstract TP369: Alpha7 nicotinic acetylcholine receptor plays a beneficial role in long-term cognitive recovery after stroke.

Introduction: The cholinergic anti-inflammatory pathway regulates immune responses through the alpha7 nicotinic acetylcholine receptor (α7nAChR), found in neurons, macrophages, and monocytes. α7nAChR activation via agonists or Vagus nerve stimulation (VNS) reduces pro-inflammatory cytokines in disease models. In young mice, pharmacological activation or stimulation of the Vagus nerve has been shown to mitigate ischemic stroke injury by reducing brain and peripheral inflammation and oxidative stress. However, the role of α7nAChR in long-term stroke outcomes remains unclear. Methods: Young (8-12 weeks) male wild-type (WT) and α7nAChR knockout (KO) mice underwent middle cerebral artery occlusion (MCAO) for 60 minutes. After 24 hours, brain acetylcholine levels and α7nAChR expression were assessed by mass spectrometry and western blot respectively. Microglia, macrophage counts, and TNF-α expression were evaluated using flow cytometry. Long-term behavioral tests included the Barnes maze (days 7 and 30), novel object recognition (day 10), and object location tests on day 20. A second cohort was euthanized on day 7 for brain-infiltrated immune cell analysis. Results: At 24 hours post-MCAO, brain α7nAChR expression decreased significantly without changes in acetylcholine levels. WT MCAO mice showed reduced microglia, increased microglial TNF-α expression, and fewer α7nAChR-positive microglia compared to shams (p<0.05). In the spleen, no difference in F4/80 positive macrophages was observed, but macrophage TNF-α expression increased, and α7nAChR-positive macrophages decreased in WT MCAO mice (p<0.05). By day 7 post-MCAO, α7nAChR KO mice had more infiltrated myeloid cells and showed poorer performance in novel object and location tests than WT MCAO mice. However, no significant differences were found in the Barnes maze escape latency or incorrect entries between groups on days 7 and 30. Conclusion: α7nAChR plays a beneficial role in maintaining long-term functional outcomes after stroke in young animals.

Neuregulin 1 improved gastric motility and reduced gastric inflammation by activating the α7nAChR through the cholinergic anti-inflammatory pathway in diabetic rats.

Diabetic gastroparesis (DGP), a prevalent complication of diabetes, is characterized by delayed gastric emptying and inflammation. The dorsal motor nucleus of the vagus (DMV) plays a crucial role in modulating gastric function via the vagus nerve. Neuregulin 1 (NRG1), which is present in the DMV and influences the autonomic nervous system, has an unclear role in DGP. This study aimed to investigate the expression of NRG1 in the DMV of Zucker diabetic fatty (ZDF) rats and to evaluate the impact of centrally administered NRG1 on gastric motility and inflammation, as well as the underlying mechanisms. Our findings revealed a decrease in NRG1 and choline acetyltransferase (ChAT) expression in the DMV of ZDF rats, corresponding to weakened gastric motility. Microinjection of AAV-NRG1 (overexpressed NRG1 by means of an adeno-associated viral vector delivery of NRG1) into the DMV enhanced gastric motility and increased vagal nerve discharge frequency. Moreover, AAV-NRG1 upregulated acetylcholine (Ach) and α7 nicotinic acetylcholine receptor (α7nAChR) expression in the gastric body, mitigating gastric inflammation. The beneficial effects of AAV-NRG1 were partially reversed by vagotomy or α7nAChR antagonism. These findings provide novel evidence that NRG1 in the DMV can stimulate Ach release and activate α7nAChRs, thereby reducing inflammation and restoring gastric motility via the vagus nerve. This implicates the NRG1 as a potential therapeutic target for DGP.

Non-conventional toxin WTX and its disulfide-fixed synthetic fragments: Interaction with nicotinic acetylcholine receptors and reduction of blood pressure.

Non-conventional snake venom toxins, such as WTX from the cobra Naja kaouthia, are three-finger proteins containing a fifth disulfide bond in the N-terminal polypeptide loop I and inhibiting α7 and muscle-type nicotinic acetylcholine receptors (nAChRs). Because the central polypeptide loop II of non-conventional toxins plays an important role in their biological activity, we synthesized several WTX loop II fragments with two cysteine residues added at the N- and C-termini and oxidized to form a disulfide bond. The inhibition by peptides of several nAChRs subtypes was investigated using different methods and the effects of peptides on the rat arterial pressure and heart rate were analyzed. The synthetic fragments inhibited α7 and muscle-type nAChRs more potently than WTX. We showed for the first time that WTX and its fragments inhibited α9α10 as well as neuronal α3β2 and α4β2 nAChRs, again the synthetic fragments being more potent than WTX. The loop II fragments reduced blood pressure more potently than WTX in normotensive, awake rats. In connection with this, the WTX cardiovascular effects were analyzed and it was found that toxin very weakly affected parameters of papillary muscle contractions with no influence on aortic ring contractility. The observed effects were not so significant to explain the decrease in BP, the hemodynamic effects of WTX appearing not to result from direct influence on the myocardium and blood vessels. The synthetic fragments of the N- and C-terminal loops I and III were inactive in all tests. Thus, both in inhibition of all analyzed nAChR subtypes and in reduction of blood pressure, fragments of the central loop II were more active than WTX. This appears to be a first indication for three-finger proteins that the fragments of the central loop II are more active than the native toxin.

Cholinergic neurotransmission in the brain of streptozotocin-induced rat model of sporadic Alzheimer's disease: long-term follow up.

Rats treated intracerebroventricularly with streptozotocin (STZ-icv) develop pathologic features, which resemble those in Alzheimer's disease and have been proposed as a non-transgenic model for sporadic type of the disease (sAD). We aimed to characterize cholinergic transmission in the rat brain as a function of STZ-icv dose and time after the treatment. Acetylcholinesterase (AChE) activity and expression of muscarinic (M1, M4) and nicotinic (α7) receptors, cholin acetyltransferase (ChAT) and glial fibrillary acidic protein (GFAP) were measured in hippocampus (HPC) and parietotemporal cortex (CTX) of STZ-icv and age-matched control rats one week, and one, three, six and nine months after the icv administration of STZ (0.3, 1 and 3mg/kg), respectively. Cholinergic and astroglial changes were found most pronounced with a highest STZ dose in time-dependent manner. The cortex and hippocampus exhibited specific alterations in cholinergic transmission following STZ-icv administration, with either similar or distinct patterns depending on the parameter observed: increased AChE activity in HPC and invariable in CTX; increased M4 and ChAT levels in both regions; substantial cortical M1 level increment and moderate hippocampal M1 decrement; and decreased α7 levels in both regions, with subsequent increase observed only in HPC. Alterations in cerebral cholinergic neurotransmission in STZ-icv rat model were mostly following a threephasic time pattern: acute response (Phase I), complete/partial compensation (Phase II), and reappearance/progression of changes (Phase III). Staging structure of cholinergic changes in STZ-icv rat model might be speculated to partly correlate with cholinergic pathology in clinical AD stages.

Salivary peptidomic profiling of chronic gingivostomatitis in cats by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry and nanoscale liquid chromatography-tandem mass spectrometry.

Chronic gingivostomatitis in cats (FCGS) is a moderately to severely painful condition, potentially caused by inadequate immune response to oral antigenic stimulation. Salivary peptidome analysis can identify inflammatory protein mediators and pathways involved in oral mucosal immune activation and may indicate potential therapeutic options for FCGS. Evaluate the diversity and abundance of salivary peptides in cats with FCGS using matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) and nanoscale liquid chromatography-tandem mass spectrometry (nano LC-MS/MS). Thirty-two cats with FCGS and 18 healthy controls. Case-control cross-sectional study. We compared the salivary peptide profiles of diseased and healthy cats. The diagnosis of FCGS was confirmed by histopathology. Saliva samples were analyzed for viral infections using polymerase chain reaction (PCR), peptide mass fingerprint (PMF) using MALDI-TOF MS, and peptide identification using nano LC-MS/MS. Distinct clusters of peptide profiles were observed between groups. In FCGS, 26 salivary peptides were altered, including apolipoprotein A1, nuclear receptor subfamily 1 group I member 3, fibrinogen alpha chain, interleukin 2 receptor gamma, interleukin 23 receptor, hemoglobin subunit alpha, and serpin peptidase inhibitor clade A (alpha-1 antiproteinase, antitrypsin) member 12, protein-tyrosine-phosphatase, and cholinergic receptor nicotinic alpha 10 subunit. Protein-anti-inflammatory drug interaction networks were observed. Peptide mass fingerprint and peptide profiles identified distinct clusters between FCGS and healthy cats. The 9 novel salivary peptide markers were associated with the JAK/STAT and PI3K/Akt pathways and immune responses. These potentially noninvasive biomarkers may facilitate understanding of FCGS pathophysiology and guide future therapeutic research.

The synergistic effects of citicoline and silymarin on liver injury and thyroid hormone disturbances in γ-irradiated rats.

Exposure to ionizing radiation is inevitable due to its extensive use in industrial and medical applications. The search for effective and safe natural therapeutic agents as alternatives to chemical drugs is crucial to mitigate their side effects. This study aimed to evaluate the effects of citicoline as a standalone treatment or in combination with the anti-hepatotoxic drug silymarin in protecting against liver injury caused by γ-radiation in rats. The rats were exposed to γ-radiation (7Gy) and treated with citicoline (300mg/kg/day) and/or silymarin (50mg/kg/day). The results showed that citicoline alleviated liver damage in irradiated rats by reducing hepatic malondialdehyde levels, serum aspartate aminotransferase activity, and inflammatory mediators such as tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), and nuclear factor-kappa B (NF-κB). It also increased acetylcholine (ACh) levels and the gene expression of the anti-inflammatory protein α7 nicotinic acetylcholine receptor (α7nAChR). Additionally, citicoline improved serum triiodothyronine (T3) levels, thyroid hormone receptor beta (TRβ) gene expression, and iodothyronine deiodinase type 1 activity in hepatic tissues of irradiated rats. Furthermore, citicoline enhanced the effects of silymarin on thyroxine (T4), TRβ, ACh, and α7nAChR when co-administered in irradiated rats. Histopathological analysis confirmed these findings, demonstrating improved liver tissue structure. Citicoline mitigates γ-radiation-induced liver damage by reducing oxidative stress, activating the cholinergic anti-inflammatory pathway, and modulating thyroid hormone metabolism. These findings support the use of citicoline as a safe standalone treatment or as an adjuvant with silymarin for managing liver damage and thyroid hormone disturbances caused by γ-irradiation.

S100A8/A9 innate immune signaling as a distinct mechanism driving progression of smoking-related breast cancers.

Smoking plays an underappreciated role in breast cancer progression, increasing recurrence and mortality in patients. Here, we show that S100A8/A9 innate immune signaling is a molecular mechanism that identifies smoking-related breast cancers and underlies their enhanced malignancy. In contrast to acute exposure, chronic nicotine increased tumorigenicity and reprogrammed breast cancer cells to express innate immune response genes. This required the α7 nicotinic acetylcholine receptor, which elicited dynamic changes in cell differentiation, proliferation, and expression of secreted cytokines, such as S100A8 and S100A9, as assessed by unbiased scRNA-seq. Indeed, pharmacologic or genetic inhibition of S100A8/A9-RAGE receptor signaling blocked nicotine's tumor-promoting effects. We also discovered Syntaphilin (SNPH) as an S100A8/A9-dependent gene enriched specifically in estrogen receptor-negative (ER-) cancers from former smokers, linking this response to patient disease. Together, our findings describe a new α7 nAChR-S100A8/A9-Syntaphilin immune signaling module that drives nicotine-induced tumor progression and distinguishes smoking-related patient disease as a distinct subset of aggressive breast cancers.

Nicotinic α7 receptors on cholinergic neurons in the striatum mediate cocaine-reinforcement, but not food reward.

The neurotransmitter acetylcholine has since long been implicated in reward learning and drug addiction. However, the role of specific cholinergic receptor subtypes on different neuronal populations remain elusive. Here, we studied the function of nicotinic acetylcholinergic alpha 7 receptors (α7 nAChRs) in cocaine and food-enforced behaviors. We found that global deletion of α7 nAChRs in mice attenuates cocaine seeking in a Pavlovian conditioned place preference paradigm and decreases operant responding to cocaine in a runway task and in self-administration, without influencing responding to palatable food. This effect can be attributed to alpha 7 receptor signaling in the striatum, as selective deletion of striatal α7 nAChRs using a viral vector approach resulted in a similar decrease in cocaine-preference as that of global deletion. To investigate which type of striatal neurons are responsible for this effect, we selectively targeted Cholinergic (ChAT-expressing) neurons and dopamine D1-receptor (D1R) expressing neurons. Mice with conditional deletion of α7 nAChRs in ChAT-neurons (α7 nAChR-ChATCre) exhibited decreased cocaine place preference and intact place preference for food, while α7 nAChR-D1RCre mice had no changes in reward learning to neither food nor cocaine. Cocaine induction of striatal immediate early gene expression of cFos, FosB, Arc and EGR2 was blocked in α7 nAChR-ChATCre mice, demonstrating the importance of α7 nAChRs on cholinergic neurons for striatal neuronal activity changes. Collectively, our findings show that α7 nAChRs on cholinergic interneurons in the striatum are pivotal for learning processes related to cocaine, but not food reward.

Sulfonium Moieties as Ammonium Bioisosteres: Novel Ligands for the Alpha7 Nicotinic Acetylcholine Receptor.

In the pressing quest of novel treatments for chronic pain, α7 nAChR silent agonists show efficacy as anti-inflammatory modulators and represent a promising strategy. Recent findings reveal that a sulfonium ion can replace the quaternary ammonium nitrogen as an alternative pharmacophore for nAChR silent activation. This study reports the design, synthesis, and electrophysiological evaluation of a new series of sulfonium-based derivatives inspired by the archetypal silent agonist NS6740. Our findings identify NSS-9 as a novel sulfonium α7 silent agonist that effectively alleviates inflammatory pain in a mouse model, highlighting it as a lead compound for further optimization. These results provide insights into the potential of the sulfonium group as a chemotype interacting with the α7 binding site, making it a valuable scaffold for novel α7 silent agonists. Additionally, sulfonium compounds were tested on α9 nAChR, also involved in the cholinergic anti-inflammatory system, identifying one partial agonist and two antagonists.

Docking studies between Natural unsaturated Oleic-acid and a de novo lung cancer peptide of CHRNA3 (Cholinergic Receptor Nicotinic Alpha 3) using Insilico protocols

Abstract Lung cancer, according to current clinical pharmacological studies, is among the most prevalent types of cancer. Polymorphisms in CHRNA3 gene have been associated with an increased risk of smoking initiation and an increased susceptibility to lung cancer. In the current Insilico study, there were two major findings. First, the novel 3D peptide was designed from the genomic sequence of CHRNA3. Next, we observe how Oleic acid interacts with the derived cancer peptide using Insilico tools. The exonic sequence of CHRNA3 was converted into a protein sequence which subject to peptide designing using immuno-medicine protocols. The peptide was modelled using an automated homology modelling server. The binding affinities between the control drug, 5-Fluorouracil and the test compound, Oleic-acid with CHRNA3 can be found using CB Dock, an automated drug docking server. The docking results clearly elucidated that when compared to the existing anti-cancer drug, 5-flourouracil, Oleic acid showed a higher binding affinity with CHRNA3. Hence, Oleic acid can be added as a supplementary drug to existing drugs to enhance their efficiency. Oleic acid, being a natural compound, one can expect lesser side-effects. Our 3D novel peptide structure will be available in PDB-Dev (https://www.modelarchive.org/doi/10.5452/ma-m1plw). Our study clearly revealed that Oleic acid is a potential therapeutic agent for Lung Carcinoma.

Linking altered neuronal and synaptic properties to nicotinic receptor Alpha5 subunit gene dysfunction: a translational investigation in rat mPFC and human cortical layer 6

Genetic variation in the α5 nicotinic acetylcholine receptor (nAChR) subunit of mice results in behavioral deficits linked to the prefrontal cortex (PFC). rs16969968 is the primary Single Nucleotide Polymorphism (SNP) in CHRNA5 strongly associated with nicotine dependence and schizophrenia in humans. We performed single cell-electrophysiology combined with morphological reconstructions on layer 6 (L6) excitatory neurons in the medial PFC (mPFC) of wild type (WT) rats, rats carrying the human coding polymorphism rs16969968 in Chrna5 and α5 knockout (KO) rats. Neuronal and synaptic properties were determined for the three rat genotypes. Compared with neurons in WT rats, L6 regular spiking (RS) neurons in the α5KO group exhibited altered electrophysiological properties, while those in α5SNP rats remained unchanged. L6 RS neurons in mPFC of α5SNP and α5KO rats differed from WT rats in dendritic morphology, spine density and spontaneous synaptic activity. Galantamine was applied to identified L6 neuron populations to specifically boost the nicotinic responses mediated by α5*nAChRs. Remarkably, it restored nicotinic modulation in neurons of α5SNP rats, while no such effect was observed in α5KO rats. Additionally, galantamine functioned as a positive allosteric modulator of α5*nAChRs in RS neurons, both in rat and human cortical L6, but did not affect burst spiking (BS) neurons. Our findings suggest that dysfunction in the α5 subunit gene leads to aberrant neuronal and synaptic properties, shedding light on the underlying mechanisms of cognitive deficits observed in human populations carrying α5SNPs. They highlight a potential pharmacological target for restoring the relevant behavioral output.

Esmolol upregulates the α7 nAChR/STAT3/NF-κB pathway by decreasing the ubiquitin and increasing the ChAT+CD4+ T lymphocyte to alleviate inflammation in septic cardiomyopathy.

Esmolol has been demonstrated to mitigate inflammation damage and T lymphocyte apoptosis in septic cardiomyopathy. It has been established that the activation of α7 nicotinic acetylcholine receptor (nAChR) by cluster of differentiation 4(CD4) + T lymphocytes expressing choline acetyltransferase (ChAT) can prevent excessive inflammation and reduce splenocyte apoptosis in septic cardiomyopathy. Given the similar anti-inflammatory effects, we hypothesized that esmolol might be associated with α7 nAChR and thereby exert its cardioprotective functions. In the cecal ligation puncture (CLP)-induced rat septic cardiomyopathy model, esmolol was found to attenuate myocardial injury as evidenced by Hematoxylin and Eosin (HE) staining, terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) assay, and the reduced concentration of interleukin (IL)-1, IL-6, and Tumor Necrosis Factor (TNF)-α detected by enzyme-linked immunosorbent assay (ELISA). Western blotting (WB) revealed that esmolol enhanced the expression of α7 nAChR, elevated the level of Phosphorylated-Signal transducer and activator of transcription 3 (P-STAT3)/STAT3, and decreased the level of Nuclear factor-κB (NF-κB), which led to the reduction of plasma IL-1, IL-6, and TNF-α. Methyl lycaconitine Citrate (MLA, an α7 nAChR inhibitor) suppressed the level of P-STAT3/STAT3, while stattic (a STAT3 inhibitor) inhibited the level of P-STAT3/STAT3 and up-regulated the expression of NF-κB. Real-time quantitative PCR (RT-qPCR) results indicated no significant difference in the mRNA level of α7 nAChR, but immunofluorescence and WB results verified the upregulation of α7 nAChR by esmolol and the reduction of ubiquitin induced by esmolol. In the spleen, esmolol decreased splenocyte apoptosis and increased the expression of α7 nAChR as shown by immunofluorescence. In isolated CD4+ T cells obtained through magnetic cell separation, esmolol enhanced the expression of ChAT mRNA. In conclusion, esmolol upregulates α7 nAChR by decreasing ubiquitin and increasing ChAT+CD4+ T lymphocytes and then increases the P-STAT3/STAT3 which inhibits NF-κB thus alleviating inflammation in septic cardiomyopathy.

Competitive Antagonism of Xylazine on α7 Nicotinic Acetylcholine Receptors and Reversal by Curcuminoids.

Co-use of xylazine with opioids is a major health threat in the United States. However, a critical knowledge gap exists in the understanding of xylazine-induced pharmacological and pathological impact. Xylazine is mostly known as an agonist of α2-adrenergic receptors (α2-ARs), but its deleterious effects on humans cannot be fully reversed by the α2-AR antagonists, suggesting the possibility that xylazine targets receptors other than α2-ARs. Here, we report the discovery of α7 nicotinic acetylcholine receptors (α7 nAChRs) as targets of xylazine. In Xenopus oocytes expressing α7 nAChRs, xylazine competitively antagonizes channel currents elicited by the agonist acetylcholine. In PC12 cells, xylazine suppresses choline-stimulated intracellular calcium ([Ca2+]in) transients that are mediated by endogenously expressed α7 nAChRs. Furthermore, we find that curcuminoids, ivermectin, and the α7-specific positive allosteric modulator PNU120596 can effectively offset the xylazine inhibition of α7 nAChRs. Considering the prominent role of α7 nAChRs in the cholinergic anti-inflammatory pathway and wide expression in the human body, our findings present a potential new strategy to reverse xylazine-caused damage using curcuminoids or repurposing ivermectin. This α7 nAChR-focused strategy may offer an immediate deployment that is likely effective in improving xylazine-related treatment outcomes.

Chronic stress induces behavioural changes through increased kynurenic acid by downregulation of kynurenine-3-monooxygenase with microglial decline.

Alterations in tryptophan-kynurenine (TRP-KYN) pathway are implicated in major depressive disorder (MDD). α7 nicotinic acetylcholine (α7nACh) receptor regulates the hypothalamic-pituitary-adrenal (HPA) axis. We have shown that deficiency of kynurenine 3-monooxygenase (KMO) induces depression-like behaviour via kynurenic acid (KYNA; α7nACh antagonist). In this study, we investigated the involvement of the TRP-KYN pathway in stress-induced behavioural changes and the regulation of the HPA axis. Mice were exposed to chronic unpredictable mild stress (CUMS) and subjected to behavioural tests. We measured TRP-KYN metabolites and the expression of their enzymes in the hippocampus. KMO heterozygous mice were used to investigate stress vulnerability. We also evaluated the effect of nicotine (s.c.) on CUMS-induced behavioural changes and an increase in serum corticosterone (CORT) concentration. CUMS decreased social interaction time but increased immobility time under tail suspension associated with increased serum corticosterone concentration. CUMS increased KYNA levels via KMO suppression with microglial decline in the hippocampus. Kmo+/- mice were vulnerable to stress: they exhibited social impairment and increased serum corticosterone concentration even after short-term CUMS. Nicotine attenuated CUMS-induced behavioural changes and increased serum corticosterone concentration by inhibiting the increase in corticotropin-releasing hormone. Methyllycaconitine (α7nACh antagonist) inhibited the attenuating effect of nicotine. CUMS-induced behavioural changes and the HPA axis dysregulation could be induced by the increased levels of KYNA via KMO suppression. KYNA plays an important role in the pathophysiology of MDD as an α7nACh antagonist. Therefore, α7nACh receptor is an attractive therapeutic target for MDD.

Delayed Magnetic Resonance Imaging of Alzheimer's Disease by Using Poly(2-(methacryloyloxy)ethyl phosphorylcholine)-Functionalized Nanoprobes.

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases, commonly affecting the aged, with pathophysiological changes presenting 15 to 20 years before clinical symptoms. Early diagnosis and intervention are crucial in effectively slowing the progression of AD. In the current study, poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC)-functionalized NaGdF4 nanoparticles (NaGdF4-PMPC) were developed as magnetic resonance imaging (MRI) contrast agents for targeting alpha 7 nicotinic acetylcholine receptors (α7 nAChRs) in AD mice. NaGdF4-PMPC showed excellent biocompatibility, targeting ability, and MRI performance, with the longitudinal molar relaxivity (r1) and transverse molar relaxivity (r2) being 1.21-fold and 1.33-fold higher than those of the clinical contrast agent Gd-DTPA, respectively, resulting in higher-sensitive MR angiography. After intravenous injection, 3D dynamic contrast-enhanced (DCE) MR images with high-resolution vasculature of the mouse brain were obtained. In addition, by using NaGdF4-PMPC, susceptibility-weighted imaging (SWI) signals in AD mouse brains were greatly retained compared to those in healthy mice for 24 h, emphasizing the excellent targeting ability of NaGdF4-PMPC. Furthermore, the CD31, α7 nAChRs, and Thioflavin S staining were also utilized to investigate the relationship among vascular inflammation, α7 nAChRs, and amyloid-β (Aβ) deposition in AD mice. This work highlights a promising targeted imaging strategy for the timely diagnosis of AD.

Sinomenine modulates the metabolic reprogramming induced by sepsis via CHRNA7.

Sepsis is a condition capable of causing systemic inflammation and metabolic reprogramming. Previous studies have shown that sinomenine (SIN) can mitigate sepsis by reducing inflammation, while the effect on metabolic reprogramming is unclear. The aim of this study is to investigate the function of SIN in metabolic reprogramming in sepsis. Differential metabolites in lung tissue and serum were analyzed by 1H Nuclear Magnetic Resonance (1H NMR) and metabolomics were used to compare metabolic changes in septic mice. Nicotinic acetylcholine receptors alpha7 subunit (CHRNA7)-Knockdown (KD) mice and other techniques, were used to detect the expression of markers of several metabolic pathways. Metabolomics studies showed that SIN could affect energy metabolism, particularly glucose metabolism, and this effect may be related to the activation of CHRNA7. Further studies showed that SIN could inhibit aerobic glycolysis, promote glutamine anaplerosis, reduce pentose phosphate pathway flux and ultimately mediate metabolic reprogramming. SIN restores glycolysis and glutamine anaplerosis by interacting with CHRNA7, thereby mediating metabolic reprogramming and mitigating sepsis. These findings shed light on the mechanism of SIN in attenuating sepsis from a metabolic perspective.

565 The role of the α7 nicotinic acetylcholine receptor in fibrotic endothelial to mesenchymal transition

565 The role of the α7 nicotinic acetylcholine receptor in fibrotic endothelial to mesenchymal transition

A Novel 14mer Peptide Inhibits Autophagic Flux via Selective Activation of the mTORC1 Signalling Pathway: Implications for Alzheimer's Disease.

During development, a 14mer peptide, T14, modulates cell growth via the α-7 nicotinic acetylcholine receptor (α7 nAChR). However, this process could become excitotoxic in the context of the adult brain, leading to pathologies such as Alzheimer's disease (AD). Recent work shows that T14 acts selectively via the mammalian target of rapamycin complex 1 (mTORC1). This pathway is essential for normal development but is overactive in AD. The triggering of mTORC1 has also been associated with the suppression of autophagy, commonly observed in ageing and neurodegeneration. We therefore investigated the relationship between T14 and autophagic flux in tissue cultures, mouse brain slices, and human Alzheimer's disease hippocampus. Here, we demonstrate that T14 and p-mTOR s2448 expression significantly increases in AD human hippocampus, which was associated with the gradual decrease in the autophagosome number across Braak stages. During development, the reduction in T14 positively correlated with pTau (Ser202, Thr205) and two selective autophagy receptors: p62 and optineurin. In vitro studies also indicated that T14 increases p-mTOR s2448 expression, resulting in the aggregation of polyubiquinated substances. The effective blockade of T14 via its cyclic variant, NBP14, has been validated in vitro, in vivo, and ex vivo. In this study, NBP14 significantly attenuated p-mTOR s2448 expression and restored normal autophagic flux, as seen with rapamycin. We conclude that T14 acts at the α-7 receptor to selectively activate the mTORC1 pathway and consequently inhibit autophagic flux. Hence, this study describes a further step in the process by which T14 could drive neurodegeneration.

Differential participation of CaMKII/ROCK and NOS pathways in the cholinergic inhibitory drive operated by nicotinic α7 receptors in perisynaptic Schwann cells

Nicotinic α7 receptors (α7 nAChRs) present in perisynaptic Schwann cells (PSCs) control acetylcholine (ACh) spillover from the neuromuscular synapse by transiently increasing intracellular Ca2+, which fosters adenosine release via type 1 equilibrative nucleoside transporters (ENT1) and retrograde activation of presynaptic A1 inhibitory receptors. The putative Ca2+-dependent pathways downstream α7 nAChRs involved in the sensing inhibitory drive operated by PSCs is unknown. Herein, we used phrenic nerve-hemidiaphragm preparations from Wistar rats. Time-lapse video-microscopy was instrumental to assess nerve-evoked (50-Hz bursts) transmitter exocytosis and intracellular NO oscillations in nerve terminals and PSCs loaded with FM4-64 and DAF-FM diacetate fluorescent dyes, respectively. Selective activation of α7 nAChRs with PNU 282987 reduced transmitter exocytosis (FM4-64 dye unloading) during 50-Hz bursts. Inhibition of calmodulin activity (with W-7), Ca2+/calmodulin-dependent protein kinase II (CaMKII; with KN-62) and Rho-kinase (ROCK; with H1152) all prevented the release inhibitory effect of PNU 282987. The α7 nAChR agonist transiently increased NO inside PSCs; the same occurred during phrenic nerve stimulation with 50-Hz bursts in the presence of the cholinesterase inhibitor, neostigmine. The nitric oxide synthase (NOS) inhibitor, L-NOARG, but not with the guanylylcyclase (GC) inhibitor, ODQ, prevented inhibition of transmitter exocytosis by PNU 282987. Inhibition of adenosine kinase with ABT 702 favors the intracellular accumulation and translocation of the nucleoside to the synaptic cleft, thus overcoming prevention of the PNU 282987 effect caused by H1152, but not by L-NOARG. In conclusion, the α7nAChR-mediated cholinergic inhibitory drive operated by PSCs involves two distinct Ca2+-dependent intracellular pathways: a CaMKII/ROCK cascade along with a GC-independent NO pathway with divergent end-effects concerning ADK inhibition.