Neuronal Nitric Oxide Synthase Research Articles

Characterization of nitric oxide in Octopus maya nervous system and its potential role in sensory perception.

The role of nitric oxide as a neurotransmitter in the olfactory and chemoreception systems of invertebrates has been well documented. This suggests an early and efficient sensory detection system that is evolutionarily preserved in various species, including vertebrates and invertebrates. Additionally, the presence of a nitric oxide neurotransmitter system has been reported in molluscs, particularly in octopus species. In this work, we present evidence for the existence of nitric oxide synthase in neurons and fibers, as well as its anatomical localization in various nuclei involved in chemosensory integration and the motor responses associated with these processes in Octopus maya.

A novel anti-epileptogenesis strategy of temporal lobe epilepsy based on nitric oxide donor.

The molecular mechanism underlying the role of hippocampal hilar interneuron degeneration in temporal lobe epilepsy (TLE) remains unclear. Especially, very few studies have focused on the role of neuronal nitric oxide synthase (nNOS, encoded by Nos1) containing hilar interneurons in TLE. In the present study, Nos1 conditional knockout mice were constructed, and we found that selective deletion of Nos1 in hilar interneurons rather than dentate granular cells (DGCs) triggered epileptogenesis. The level of nNOS was downregulated in patients and mice with TLE. Nos1 deletion led to excessive epilepsy-like excitatory input circuit formation and hyperexcitation of DGCs. Replenishment of hilar nNOS protein blocked epileptogenic development and memory impairment in pilocarpine-induced TLE mice. Moreover, chronic treatment with DETA/NONOate, a slowly released exogenous nitric oxide (NO) donor, prevented aberrant neural circuits of DGCs and the consequent epileptogenesis without acute antiseizure effects. Therefore, we concluded that NO donor therapy may be a novel anti-epileptogenesis strategy, different from existing antiseizure medications (ASMs), for curing TLE.

Targeting acetylated high mobility group box 1 protein (HMGB1) and toll-like receptor (TLR4) interaction to alleviate hypertension and neuroinflammation in fructose-fed rats.

Our previous study reported that fructose intake increased systemic blood pressure and reduced nitric oxide (NO) in the nucleus tractus solitarius (NTS) due to oxidative stress and neuroinflammation. However, it remains unclear how reactive oxygen species (ROS) reduce NO and how this process impacts neuroinflammation in the NTS. This study aimed at investigating the effect of ROS on acetylation of high mobility group box 1 protein (HMGB1) in the NTS of fructose-induced hypertensive rats. Male Wistar-Kyoto (WKY) rats were fed with 10% fructose water to elevate blood pressure. Thereafter, CLI-095 and glycyrrhizic acid (GA) treatments were delivered for up to 2weeks (1mg·12 μL-1·day-1, by intracerebroventricular injection) to reduce the negative effects of toll-like receptor 4 (TLR4) and HMGB1 activation. Two weeks of CLI-095 and GA treatment reduced systemic blood pressure and significantly preserved neuronal and endothelial nitric oxide synthase (nNOS and eNOS) availability against the inflammatory insults of fructose consumption. Both CLI-095 and GA halted the interaction of acetylated HMGB1 and TLR4. Two weeks of CLI-095 and GA treatment markedly reduced NTS inflammation (pro-inflammatory cytokines and microglial activation) and lowered serum norepinephrine levels. Our data reveal novel pharmacological properties for CLI-095 and GA, which improved blood pressure and inflammatory conditions by decreasing the interaction of acetylated HMGB1 with TLR4. These findings challenge the commonly accepted dogma that essential hypertension is specifically mediated by neuroinflammation due to acetylated HMGB1 coupling to TLR4.

High-throughput screening identifies a novel small molecule modulator of Hsp70 that selectively enhances ubiquitination and degradation of misfolded neuronal NO synthase

High-throughput screening identifies a novel small molecule modulator of Hsp70 that selectively enhances ubiquitination and degradation of misfolded neuronal NO synthase

Serine protease inhibitor AEBSF(4-(2-aminoethyl)-benzenesulfonyl fluoride) decreased ischemic brain injury through inhibiting endoplasmic reticulum stress, oxidative stress, and autophagy in rats

4-(2-Aminoethyl)-benzenesulfonyl fluoride (AEBSF) is a serine protease inhibitor that may alleviate endoplasmic reticulum (ER) stress, a significant contributing factor to cerebral ischemia/reperfusion injury. The molecular crosstalk between ER stress, oxidative stress and autophagy represents a vicious cycle that can be pharmacologically targeted to minimize neuronal death after acute injuries to the central nervous system. However, the neuroprotective effects of AEBSF in the context of cerebral ischemia/reperfusion injury remain unknown. In this study,we reported the neuroprotective effect of AEBSF against cerebral ischemia/reperfusion injury and explored the mechanisms involved, particularly its role in reducing ER stress, oxidative stress and autophagy. Rats were pretreated with AEBSF or a vehicle before a 90-minute middle cerebral artery occlusion (MCAO) followed by 24 h of reperfusion. Our results demonstrate that AEBSF treatment reduced infarct volume and improved neurological function compared to vehicle treated rats after 24 h of reperfusion. Furthermore,AEBSF treatment decreased the expression of caspase-3, suggesting a decrease in neuronal apoptosis. Additionally, AEBSF treatment lowered levels of key ER stress biomarkers, including glucose-regulated protein 78 (GRP78), phosphorylated eukaryotic initiation factor 2α (p-eIF2α), and CCAAT-enhancer-binding protein homologous protein (CHOP), while the levels of inositol-requiring enzyme 1α (IRE1α) remained unchanged. AEBSF also decreased the oxidative stress biomarker neuronal nitric oxide synthase (nNOS) and its related molecule pro-MMP-9. Importantly, treatment with AEBSF reversed the trends of autophagy biomarker LC3B II/α-tubulin, Beclin1, and SQSTM1 at 24 h after reperfusion. In conclusion, AEBSF significantly mitigates ischemic brain damage and promotes neurological recovery by inhibiting ER stress, oxidative stress, and autophagy, highlighting its potential as a therapeutic option for ischemic stroke.

Medicinal Chemistry Insights in Neuronal Nitric Oxide Synthase Inhibitors Containing Nitrogen Heterocyclic Compounds: A Mini Review.

Many scientific reports over the last two decades have focused on the discovery and development of novel nNOS inhibitors. The structural identity of isoforms, bioavailability, pharmacokinetic, and safety profile issues remain major obstacles in the discovery of more potent and selective nNOS inhibitors. This review aims to provide an in-depth overview of the molecular interaction patterns between nNOS active site and inhibitors containing structurally diverse nitrogen heterocyclic compounds and highlight the structural properties needed to develop selective nNOS inhibitors. Previously published data allowed the usage of the structure-driven approach in the designing of selective nNOS inhibitors, which relies on the specific structural features required to achieve isoform-selectivity towards nNOS. The incorporation of chiral pyrrolidine ring, two aminopyridine heads, or a specific amino tail group, along with the inhibitor's capacity to adopt the curled conformation in the nNOS environment significantly strengthens the molecular interaction between the inhibitor and nNOS residues by forming specific electrostatic interactions and non-bonded contacts that are vital for isoform selectivity. Additional structure-activity relationship investigations are necessary to elucidate more structural characteristics that will ultimately resolve the exact structural basis required for isoform-selective inhibition of nNOS.

The expression of contextual fear conditioning involves the dorsal hippocampus TRPV1 receptor interacting with the NMDA/NO/cGMP signalling pathway.

The dorsal hippocampus (dHIP) is pivotal for learning, memory, and defensive responses. Transient receptor potential vanilloid type 1 (TRPV1) receptors in the dHIP modulate contextual fear conditioning by triggering a cascade involving glutamate release, nitric oxide (NO) formation and cyclic guanosine monophosphate (cGMP) production. The present study investigated the involvement of dHIP TRPV1 receptors and their interaction with the glutamate/NO/cGMP signalling pathway in modulating the expression of contextual fear conditioning (CFC). Male Wistar rats were submitted to an aversive contextual conditioning session and, 48 h later, were re-introduced to the same aversive environment where the freezing response and autonomic activity (evidenced by increased arterial pressure and heart rate and a decrease in tail temperature) were measured. The results demonstrated that the TRPV1 antagonist 6-I-CPS in dHIP reduced the expression of CFC, whereas the agonist capsaicin had the opposite effect. Furthermore, dHIP pre-treatment with an NMDA receptor antagonist (AP7), neuronal NO synthase inhibitor (N-propyl-L-arginine), NO scavenger (c-PTIO) or guanylate cyclase inhibitor (ODQ) attenuated capsaicin-induced increases in CFC. Finally, we observed that re-exposure to the aversive chamber increased dHIP NO levels in conditioned animals compared with a non-conditioned group, which was prevented by the administration of the TRPV1 antagonist, 6-I-CPS. Our study revealed that TRPV1 receptors in the dHIP play a crucial role in modulating contextual fear expression by acting through the NMDA receptor/NO/cGMP signalling pathway, providing important insights into the underlying mechanisms and potential therapeutic avenues associated with these pathways.

Application of the Linear Interaction Energy Method to Nitric Oxide Synthase Structure-Based Inhibitor Design.

The overproduction of nitric oxide by neuronal nitric oxide synthase (nNOS) is associated with several neuropathological conditions. As a result, inhibition of nNOS is a desirable therapeutic goal while avoiding the inhibition of endothelial NOS (eNOS) given its essential role in maintaining cardiovascular tone. Designing inhibitors with high specificity for nNOS over eNOS is challenging given the close similarity in the active site structure of all mammalian NOS isoforms. Computational methods like free energy perturbation (FEP) and thermodynamic integration (TI) offer attractive avenues for rational drug design, but application of these methods to NOS is hindered by several challenges, including proper handling of highly charged inhibitors with diverse structures as well as computational expense. To address these issues, we present a simplified approach combining continuum dielectric generalized born (GB) solvent models with linear interaction energy (LIE) calculations. Our method demonstrates excellent agreement with experimental data for charged inhibitors targeting mammalian NOS isoforms (mNOS). Our results highlight the utility of the GB-LIE method as a promising tool for screening NOS inhibitors and potentially other protein targets with charged active sites and diverse inhibitor structures.

Resveratrol relieves myocardial ischemia–reperfusion injury through inhibiting AKT nitration modification

ABSTRACT Objective The aim of this study was to clarify whether Protein kinase B (PKB)/AKT is nitrated in myocardial ischemia and reperfusion injury (MIRI) resveratrol (RSV)’s protective effect during this process. Methods We blocked blood flow of the left coronary artery (LAD) of mice and used H9c2 cells under an oxygen-glucose deprivation (OGD) environment as animal and cell models of MIRI. N-methyl-D-aspartic acid receptor (NMDAR) inhibitor MK801, neuronal nitric oxide synthase (nNOS) inhibitor 7-NI and RSV were used as interventions. Nitration of proteins, infarction area, cardiomyocyte apoptosis and AKT nitration sites were detected during this study. Results During in-vivo study, AKT nitration was induced through the NMDAR/nNOS/peroxynitrite (ONOO–) pathway, leading to decreased phosphorylation of AKT and increased cardiomyocyte apoptosis. AKT nitration was decreased and phosphorylation was elevated when administrated with RSV, MK801 and 7-NI. In in-vitro study, AKT nitration and TUNEL positive cells was elevated when administrated with NO donor H9c2 cells after OGD/R, when administrated with RSV, MK801 and 7-NI, AKT nitration and apoptosis was deceased in H9c2 cells. Mass spectrometry revealed that nitration sites of AKT included 14 Tyrosine residues. Discussion RSV could inhibit AKT nitration and elevated phosphorylation through suppressing NMDAR/nNOS/ONOO– pathway and further reduce the apoptosis of cardiomyocytes in of myocardial I/R.

Microplastic and the Enteric Nervous System: Effect of PET Microparticles on Selected Neurotransmitters and Cytokines in the Porcine Ileum.

Microplastic is an environmental hazard to which both animals and humans are exposed. Current reports show that it can cause inflammation, including in the gastrointestinal tract. To examine the impact on the ileum, 15 eight-week-old gilts (five individuals/group) were exposed to PET microplastics (7.6 µm-416.9 µm) at a dose of 0.1 g/day or 1 g/day for 28 days. The collected ileum fragments were investigated for the cytokine concentrations (IL-1β, IL-6, IL-8, IL-10, and TNF-α; ELISA test), neuron populations (cocaine and amphetamine-regulated transcript, galanin, neuronal nitric oxide synthase, substance P, vesicular acetylcholine transporter, and vasoactive intestinal peptide; immunofluorescence staining), and morphometric parameters (histological analysis). Under the influence of MP-PET, there was a reduction in the populations of CART- and GAL-positive neurons in the submucosal plexuses and of nNOS-, VAChT-, and VIP-positive neurons in all the plexuses. In contrast, there was an increase in GAL-positive neurons in the myenteric plexus and SP-positive neurons in all the plexuses. The concentrations of IL-1β, IL-6, IL-8, IL-10, and TNF-α did not undergo statistically significant changes under the influence of the low or high dose of MP-PET. The changes in the histological structure exclusively concerned the thinning of the mucosa and the muscularis externa. The results support the thesis that MP-PET is not neutral to the ileal cells.

Association of SIRT1 (rs7069102) Gene polymorphism with premature myocardial infarction in young Egyptian patients

Abstract Background Premature myocardial infarction (PMI) is one of the most pressing global issues in modern cardiology. Recently, the incidence of PMI has gradually increased. Researches found that genetics is a major contributor in its development. SIRT1, an extremely conserved class III NAD-dependent deacetylase, has been linked to numerous cardiovascular disorders and engaged in a number of cellular functions. This work investigated the association between SIRT1 SNP rs7069102 in Egyptian patients ≤ 40 years old with premature ST-elevation Myocardial infarction (STEMI). Methods This cross sectional, single-center study included patients younger than 40 with STEMI (PMI group, n = 140) and a control group (n = 140) of healthy subjects of comparable age. In addition to clinical examination and standard tests, all participants underwent echocardiography, coronary angiography, SIRT1 (rs7069102) genotyping, and nitric oxide assay. Results The risk for PMI was increased in CG or CC genotype carriers of SIRT1 gene rs7069102 (OR: 3.93, 95% Cl: 2.25–6.86), as did carriers of the C allele (OR: 2.26, 95% Cl: 1.65–3.86). In the PMI group, endothelial nitric oxide synthase (eNOS) was significantly decreased; whereas, neuronal nitric oxide synthase (nNOS) was significantly increased. Conclusions SIRT1 single-nucleotide polymorphism (rs7069102) may confer an increased risk for PMI in young Egyptian patients with affecting endothelial nitric oxide synthase protein expressions. Traditional cardiovascular risk factors are prevalent in patients with PMI, with dietary behaviors, obesity, diabetes and dyslipidemia serving as independent risk factors for PMI. Clinical trial registration number: NCT05160844.

Neurogenic-derived 6-nitrodopamine is the most potent endogenous modulator of the mouse urinary bladder relaxation

6-Nitrodopamine (6-ND) modulates vas deferens, seminal vesicles, and corpus cavernosum contractility; however, its role on the lower urinary tract organs has not been evaluated. Investigations of isolated urinary bladders from wild-type (WT) mice revealed 6-ND release was comparable to that of dopamine and adrenaline, whereas noradrenaline was hardly detected, as assessed by liquid chromatography coupled to tandem mass spectrometry. In vitro, 6-ND induced concentration-dependent relaxations in carbachol pre-contracted bladders with high potency (pEC50: 8.04 ± 0.86), independently of eNOS/sGC activity. Co-incubation of 6-ND (1–10 μM) antagonizes the contractile effects of acetylcholine (p < 0.05). Experiments using nitric oxide synthase (NOS) knockout mice demonstrated that 6-ND release from isolated urinary bladder was significantly reduced by neuronal NOS (nNOS−/−) deletion and abolished by triple NOSs deletion (n/i/eNOS−/−), while no significant changes were observed in endothelial (eNOS−/−) or inducible (iNOS−/−) knockout mice. Incubation with tetrodotoxin resulted in a significant decrease in 6-ND release in bladders obtained from WT, but not in nNOS−/− mice. The bladders from nNOS−/− and n/i/eNOS−/− mice exhibited significantly higher contractile responses to electric field stimulation (EFS), compared to eNOS−/−, iNOS−/−, or WT bladders. The hyperreactivity observed in triple NOS knockouts was reversed by the incubation with bladder mucosal layer obtained from a donor WT mice, but not with the muscular layer. These findings clearly demonstrate 6-ND is the most potent endogenous relaxing agent of urinary bladder, and inhibition of its release is associated with bladder hyperreactivity.

Down regulation of the c-Fos/MAP kinase signaling pathway during learning memory processes coincides with low GnRH levels in aluminum chloride-induced Alzheimer's male rats.

Aluminum chloride (Al) is associated with Alzheimer's disease (AD) and reproductive disorders. But the relationship between gonadotropin-releasing hormone (GnRH) and c-Fos levels, the end product of MAP-kinase signaling, in AD is unknown, so we aimed to investigate this relationship. We exposed rats to Al dissolved in drinking water (10 and 50mg/kg) for two and four weeks. The control group received only drinking water. At the end, the blood sample was collected under deep anesthesia and the brain was dissected on ice, and the testicular tissue was fixed in formalin. Amyloid beta (βA) plaques in brain regions and the number of CA1 neurons were evaluated by Congo red staining and cresyl violet staining. Activation of neuronal nitric oxide synthase (nNOS) was studied using NADPH-diaphorase. The levels of c-Fos and testosterone receptors in the target area were examined immunohistochemically. Brain GnRH levels were determined by blotting, and serum levels of gonadotropins and steroids were measured by enzyme-linked immunosorbent assay (ELISA). All data were analyzed using analysis of variance (ANOVA) at α = 0.05 level. The accumulation of βA plaque was observed along with a decrease in the number of CA1 pyramidal neurons and a significant decrease in the levels of c-Fos and GnRH in the brains of rats receiving Al, which was aligned with a significant decrease in serum levels of testosterone and LH. This study, for the first time, showed a link between dementia and a concomitant decrease in brain GnRH and c-Fos levels.

Raloxifene Prevents Chemically-Induced Ferroptotic Neuronal Death In Vitro and In Vivo.

Ferroptosis, a regulated form of cell death characterized by excessive iron-dependent lipid peroxidation, can be readily induced in cultured cells by chemicals such as erastin and RSL3. Protein disulfide isomerase (PDI) has been identified as an upstream mediator of chemically induced ferroptosis and also a target for ferroptosis protection. In this study, we discovered that raloxifene (RAL), a selective estrogen receptor modulator known for its neuroprotective actions in humans, can effectively inhibit PDI function and provide robust protection against chemically induced ferroptosis in cultured HT22 neuronal cells. Specifically, RAL can bind directly to PDI both in vitro and in intact neuronal cells and inhibit its catalytic activity. Computational modeling analysis reveals that RAL can tightly bind to PDI through forming a hydrogen bond with its His256 residue, and biochemical analysis further shows that when PDI's His256 is mutated to Ala256, RAL loses its inhibition of PDI's catalytic activity. This inhibition of PDI by RAL significantly reduces the dimerization of both the inducible and neuronal nitric oxide synthases and the accumulation of nitric oxide, both of which have recently been shown to play a crucial role in mediating chemically induced ferroptosis through subsequent induction of ROS and lipid-ROS accumulation. In vivo behavioral analysis shows that mice treated with RAL are strongly protected against kainic acid-induced memory deficits and hippocampal neuronal damage. In conclusion, this study demonstrates that RAL is a potent inhibitor of PDI and can effectively prevent chemically induced ferroptosis in hippocampal neurons both in vitro and in vivo. These findings offer a novel estrogen receptor-independent mechanism for RAL's neuroprotective actions in animal models and humans.

Protective Effect of Protocatechuic Aldehyde on Cerebral Ischemia/Reperfusion Injury in Rats through Blood-Brain Barrier Protection.

Cerebral ischemia can lead to destruction of the blood-brain barrier (BBB), the main cause of cerebral edema and cerebral infarction. BBB damage is also one of the key factors affecting the result of drug therapy. We studied the protective effect of 5-day pretreatment with protocatechuic aldehyde (PAL) at doses of 10 and 20 mg/kg on BBB function and structure after middle cerebral artery occlusion/reperfusion (MCAO/R) in rats. The infarct volume, behavioral neurological deficit score, and Evans blue content in the brain were estimated. We also evaluated the content of nitric oxide (NO) and activities of inducible and neuronal NO synthases. Expression of aquaporin-4 (AQP-4), occludin, claudin-5, and MMP-3 in the brain tissues was estimated by Western blotting. The BBB ultrastructure was analyzed under an electron microscope. We revealed that PAL at both used doses significantly reduced the neurological deficit score, brain infarct volume, and Evans blue extravasation. Electron microscopy showed that PAL significantly improved the ultrastructure of BBB and alleviated its injury. Pretreatment with PAL increased expression of occludin and claudin-5 and reduced expression of AQP-4 and MMP-3. At the same time, the release of NO and activities of NO synthases were notably inhibited. Our results suggest that PAL can be a promising compound to attenuate cerebral ischemia resulting from occlusion/reperfusion injury via BBB protection.

The nitration of SIRT6 aggravates neuronal damage during cerebral ischemia-reperfusion in rat

Ischemic stroke is a major cause of death and disability. The activation of neuronal nitric oxide synthase (nNOS) and the resulting production of nitric oxide (NO) via NMDA receptor-mediated calcium influx play an exacerbating role in cerebral ischemia reperfusion injury. The NO rapidly reacts with superoxide (O2-) to form peroxynitrite (ONOO-), a toxic molecule may modify proteins through tyrosine residue nitration, ultimately worsening neuronal damage. SIRT6 has been proven to be crucial in regulating cell proliferation, death, and aging in various pathological settings. We have previous reported that human SIRT6 tyrosine nitration decreased its intrinsic catalytic activity in vitro. However, the exact role of SIRT6 function in the process of cerebral ischemia reperfusion injury is not yet fully elucidated. Herein, we demonstrated that an increase in the nitration of SIRT6 led to reduce its enzymatic activity and aggravated hippocampal neuronal damage in a rat model of four-artery cerebral ischemia reperfusion. In addition, reducing SIRT6 nitration resulted in increase the activity of SIRT6, alleviating hippocampal neuronal damage. Moreover, SIRT6 nitration affected its downstream molecule activity such as PARP1 and GCN5, promoting the process of neuronal ischemic injury in rat hippocampus. Additionally, treatment with NMDA receptor antagonist MK801, or nNOS inhibitor 7-NI, and resveratrol (an antioxidant) diminished SIRT6 nitration and the catalytic activity of downstream molecules like PARP1 and GCN5, thereby reducing neuronal damage. Finally, in the biochemical regulation of SIRT6 activity, tyrosine 257 was essential for its activity and susceptibility to nitration. Replacing tyrosine 257 with phenylalanine in rat SIRT6 attenuated the death of SH-SY5Y neurocytes under oxygen-glucose deprivation (OGD) conditions. These results may offer further understanding of SIRT6 function in the pathogenesis of cerebral ischemic diseases.

A Skeletal Muscle-Mediated Anticontractile Response on Vascular Tone: Unraveling the Lactate-AMPK-NOS1 Pathway in Femoral Arteries.

The regulation of vascular tone by perivascular tissues is a complex interplay of various paracrine factors. Here, we investigate the anti-contractile effect of skeletal muscle surrounding the femoral and carotid arteries and its underlying mechanisms. Using male and female Wistar rats, we demonstrated that serotonin, phenylephrine, and U-46619 induced a concentration-dependent vasoconstrictor response in femoral artery rings. Interestingly, this response was diminished in the presence of surrounding femoral skeletal muscle, irrespective of sex. No anti-contractile effect was observed when the carotid artery was exposed to its surrounding skeletal muscle. The observed effect in the femoral artery persisted even in the absence of endothelium and when the muscle was detached from the artery. Furthermore, the skeletal muscle surrounding the femoral artery was able to promote an anti-contractile effect in three other vascular beds (basilar, mesenteric, and carotid arteries). Using inhibitors of lactate dehydrogenase and the 1/4 monocarboxylate transporter, we confirmed the involvement of lactate, as both inhibitors were able to abolish the anti-contractile effect. However, lactate did not directly promote vasodilation; rather, it exerted its effect by activating 5' AMP-activated protein kinase (AMPK) and neuronal nitric oxide synthase (NOS1) in the skeletal muscle. Accordingly, Nω-propyl L-arginine, a specific inhibitor of NOS1, prevented the anti-contractile effect, as well as lactate-induced phosphorylation of NOS1 at the stimulatory serine site (1417) in primary skeletal muscle cells. Phosphorylation of NOS1 was reduced in the presence of Bay-3827, a selective AMPK inhibitor. In conclusion, femoral artery-associated skeletal muscle is a potent paracrine and endocrine organ that influences vascular tone in both sexes. Mechanistically, the anti-contractile effect involves muscle fiber type and/or its anatomical location but not the type of artery or its related vascular endothelium. Finally, the femoral artery anti-contractile effect is mediated by the lactate-AMPK-phospho-NOS1Ser1417-NO signaling axis.

PSD-95 Protein: A Promising Therapeutic Target in Chronic Pain.

Chronic pain, as a social public health problem, has a serious impact on the quality of patients' life. Currently, the main drugs used to treat chronic pain are opioids, antipyretic, and nonsteroidal anti-inflammatory drugs (NSAIDs). But the obvious side effects limit their use, so it is urgent to find new therapeutic targets. Postsynaptic density (PSD)-95 protein plays an important role in the occurrence and development of chronic pain. The over-expression of the PSD-95 protein and its interaction with other proteins are closelyrelated to the chronic pain. Besides, the PSD-95-related drugs that inhibit the expression of PSD-95 as well as the interaction with other protein have been proved to treat chronic pain significantly. In conclusion, although more deep studies are needed in the future, these studies indicate that PSD-95 and the related proteins, such as NMDA receptor (NMDAR) subunit 2B (GluN2B), AMPA receptor (AMPAR), calmodulin-dependent protein kinase II (CaMKII), 5-hydroxytryptamine 2A receptor (5-HT2AR), and neuronal nitric oxide synthase (nNOS), are the promising therapeutic targets for chronicpain.

A Bis(Acridino)-Crown Ether for Recognizing Oligoamines in Spermine Biosynthesis.

Oligoamines in cellular metabolism carry extremely diverse biological functions (i.e., regulating Ca2+-influx, neuronal nitric oxide synthase, membrane potential, Na+, K+-ATPase activity in synaptosomes, etc.). Furthermore, they also act as longevity agents and have a determinative role in autophagy, cell growth, proliferation, and death, while oligoamines dysregulation is a key in a variety of cancers. However, many of their mechanisms of actions have just begun to be understood. In addition to the numerous biosensing methods, only a very few simple small molecule-based tests are available for their selective but reversible tracking or fluorescent labeling. Motivated by this, we present herein a new fluorescent bis(acridino)-crown ether as a sensor molecule for biogenic oligoamines. The sensor molecule can selectively distinguish oligoamines from aliphatic mono- and diamino-analogues, while showing a reversible 1:2 (host:guest) complexation with a stepwise binding process accompanied by a turn-on fluorescence response. Both computational simulations on molecular docking and regression methods on titration experiments were carried out to reveal the oligoamine-recognition properties of the sensor molecule. The new fluorescent chemosensor molecule has a high potential for molecular-level functional studies on the oligoamine systems in cell processes (cellular uptake, transport, progression in cancers, etc.).

Polarized benzene rings can promote the interaction between CaM and the CaMBD region of nNOS.

The neuronal nitric oxide synthase (nNOS) subtype of nitric oxide synthase (NOS) is an enzyme required for learning and memory. Overactivation of nNOS can lead to oxidative/nitrite stress, which is complicit in the pathophysiology of various neurological and psychiatric disorders. Previous studies have shown that calmodulin (CaM) forms complexes with Ca2+ and binds to the calmodulin-binding domain (CaMBD) of nNOS, thereby upregulating its catalytic activity in hippocampal neurons. To date, there has been no explanation for the non-covalent interactions in the CaMBD-CaM binding structure model of nNOS. In this study, we aimed to investigate the intrinsic factors involved in the binding of CaM to NOS-CaMBD and designed interfering peptides based on the N0 peptide structure of the original nNOS-CaMBD sequence: N1 (obtained from the L734F mutation), N2 (obtained from the F731Y and F740Y mutations), and N3 (obtained from the F731L, V738L, and F740L mutations). We employed homology modeling to construct six CaM-peptide complex models, aiming to elucidate the roles of key amino acid residues within the N0 peptide in its interaction with CaM by means of molecular dynamics simulations. The effect of the peptides on the activation and release of NO by nNOS in neurons was assessed using murine primary neuronal cells. When measuring neuronal NO content, it was found that adding N2 and N3 to cultivated neurons significantly increased nNOS activity, leading to the increased NO production. We found that interfering peptides could stably bind to CaM. Among them, N2 and CaM exhibited the strongest binding ability, indicating that the polarized benzene ring significantly enhanced the binding between nNOS-CaMBD and CaM. Conversely, the binding ability between N0 and CaM was the weakest, as they exhibited the worst polar contact, weakest hydrogen bonding, and the lowest binding free energy. The simulation results also highlighted several important amino acid residues: The K76 of CaM plays an important role in polar contact and hydrogen bonding formation, the L734 residue suppressed model flexibility to a certain extent and had an adverse effect on the overall binding free energy of the model. These results, compared with the results of cellular NO content, a preliminary verification of the antagonistic competitive mechanism between CaM allosteric activation of nNOS and SUMOylation hyperactivation was performed. In summary, this study explored the ability and mode of action of key residues in nNOS-CaMBD on the binding of interfering peptides to CaM, thereby providing new structural perspectives for the activation of nNOS by CaM and recommendations for drug design targeting the specific inhibition of nNOS.