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Nitric oxide synthases (NOS) are crucial enzymes responsible for the production of nitric oxide (NO), a signaling molecule with essential roles in vascular regulation, immune defense, and neurotransmission. The three NOS isoforms, endothelial NOS (eNOS), neuronal NOS (nNOS), and inducible NOS (iNOS), are tightly regulated by inflammatory mediators and cellular signaling pathways. While physiological NO production is vital for maintaining homeostasis, dysregulated NOS activity contributes to the pathogenesis of numerous diseases, including cardiovascular disorders, neurodegenerative conditions, and cancer. Recent advances in understanding the molecular mechanisms of NOS regulation have unveiled novel therapeutic opportunities, including isoform-specific modulators, upstream pathways, and nanotechnology-enhanced delivery systems. This review highlights these advancements, offering insights into how targeting NOS and its regulatory network can enable precise and effective therapeutic strategies for managing inflammation-driven pathologies. [ABSTRACT FROM AUTHOR]

Background/Objectives: Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta, leading to motor symptoms such as tremor, rigidity, and bradykinesia. The pathological hallmarks of PD include Lewy bodies and mechanisms like oxidative/nitrosative stress, chronic inflammation, and mitochondrial dysfunction. Nitric oxide (NO), produced by nitric oxide synthase (NOS) isoforms, plays a dual role in neuroprotection and neurodegeneration. Excessive NO production exacerbates neuroinflammation and oxidative/nitrosative damage, contributing to dopaminergic cell death. This review explores NO's role in PD pathogenesis and investigates dietary nitrate as a therapeutic strategy to regulate NO levels. Methods: A literature review of studies addressing the role of NO in PD was conducted using major scientific databases, including PubMed, Scopus, and Web of Science, using keywords such as "nitric oxide", "NOSs", "Parkinson's disease", and "nitrate neuroprotection in PD". Studies on nitrate metabolism via the nitrate–nitrite–NO pathway and its effects on PD hallmarks were analyzed. Studies regarding the role of nitrosamine formation in PD, which are mainly formed during the nitrification process of amines (nitrogen-containing compounds), often due to chemical reactions in the presence of nitrite or nitrate, were also examined. In particular, nitrate has been shown to induce oxidative stress, affect the mitochondrial function, and contribute to inflammatory phenomena in the brain, another factor closely related to the pathogenesis of PD. Results: Excessive NO production, particularly from iNOS and nNOS, was strongly associated with neuroinflammation and oxidative/nitrosative stress, amplifying neuronal damage in PD. Dietary nitrate was shown to enhance NO bioavailability through the nitrate–nitrite–NO pathway, mitigating inflammation and oxidative/nitrosative damage. Conclusions: Dysregulated NO production contributes significantly to PD progression via inflammatory and oxidative/nitrosative pathways. Dietary nitrate, by modulating NO levels, offers a promising therapeutic strategy to counteract these pathological mechanisms. Further clinical trials are warranted to establish its efficacy and optimize its use in PD management. [ABSTRACT FROM AUTHOR]

The physiological mechanisms involved in augmented cholinergic agonist-induced sweating in exercise-trained individuals remain unclear. This study hypothesizes that nitric oxide synthase (NOS) contributes to augmented pilocarpine-induced sweating in habitually exercise-trained individuals. Endurance-trained and untrained men (n = 15 each) iontophoretically received 1% L-NAME, a NOS inhibitor, and saline (control) in the forearm and then administered 0.001% and 1% pilocarpine to evaluate sweat rate. L-NAME administration attenuated pilocarpine-induced sweating by 10% in the exercise-trained (P = 0.004) but not in untrained (P = 0.764) groups independent of pilocarpine concentrations. Results indicate that NOS partially contributes to increased cholinergic sweating in exercise-trained men. [ABSTRACT FROM AUTHOR]

Despite advances in neonatal and ophthalmological care, retinopathy of prematurity (ROP) continues to be a leading cause of childhood blindness worldwide. Investigating gene variants associated with vascular responses in ROP may provide valuable insights into its pathogenesis and identify risk or protective factors. Nitric oxide (NO) and endothelin-1 (ET-1) play roles in vascular regulation, influencing processes relevant to ROP development. Functional variants of genes encoding endothelial NO sythetase (NOS3 rs1799983, rs2070744), endothelin-1 (EDN1 rs5370), and endothelin receptor A (EDNRA rs5335) may influence ROP development or progression. The results of our study support the role of the rs2070744 variant in ROP. We identified the protective effect of the rs2070744C allele against the development of ROP requiring treatment, also after adjusting for covariates. Meta-analysis including 298 patients and 397 controls confirmed this protective role. The rs2070744CC homozygous genotype exhibited an odds ratio (OR) of 0.42 (adjusted P = 0.036). Additional meta-analysis results for NOS3 rs1799983 are presented, suggesting potential risk in a recessive model. No associations were found between EDN1, EDNRA variants, and ROP. Exploring genetic predispositions in ROP, including vascular regulation genes, can lead to personalized prevention and treatment approaches. Our results need to be replicated in a larger sample of premature infants. [ABSTRACT FROM AUTHOR]

Diabetic kidney disease (DKD) is a leading cause of chronic kidney disease (CKD) and end-stage renal disease worldwide, affecting approximately 40% of individuals with type 2 diabetes (T2DM) and 30% of those with type 1 diabetes (T1DM). As the prevalence of diabetes continues to rise, the burden of DKD is expected to grow correspondingly. This review explores the roles of key molecular pathways, including the apelinergic system, vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR) axis, and nitric oxide (NO)/nitric oxide synthase (NOS) signaling, in DKD pathogenesis and potential therapeutic applications. The apelinergic system, involving apelin and its receptor (APLNR), influences endothelial function, glucose metabolism, and renal health. Preclinical studies highlight its dual role in renal protection and injury through anti-inflammatory and antioxidant pathways, while other evidence suggests that it may exacerbate DKD through podocyte damage and angiogenesis. Similarly, the VEGF/VEGFR axis demonstrates a complex contribution to DKD, where VEGF-A promotes pathological angiogenesis and glomerular damage, but its inhibition requires careful modulation to prevent adverse effects. The NO/NOS system, integral to vascular and renal homeostasis, also exhibits altered activity in DKD, with reduced bioavailability linked to oxidative stress and inflammation. This review underscores the intricate interplay between these pathways in DKD, revealing both challenges and opportunities in their therapeutic targeting. Further research is essential to refine strategies and develop effective interventions for DKD management. [ABSTRACT FROM AUTHOR]

The mechanistic study of new pharmaceutical compounds is crucial for evaluating their efficacy, identifying potential side effects, and optimising drug formulations. This study aimed to investigate the mechanism of action of trigonelline on the promastigote and amastigote stages of Leishmania major (MRHO/IR/75/ER). An initial in silico study was conducted to examine the pharmacological effects of trigonelline using molecular docking to evaluate the potential binding affinity of trigonelline with nitrate, a crucial molecule in the macrophage immune response against Leishmania. In this experimental study, the inhibitory mechanism of trigonelline on promastigotes was evaluated by measuring metacaspase expression levels. In the amastigote stage of L. major, the expression levels of inducible nitric oxide synthase (iNOS), interleukin 12 (IL‐12), interferon‐gamma (IFN‐γ), tumour necrosis factor alpha (TNF‐α), transforming growth factor‐β (TGF‐β) and interleukin 10 (IL‐10) genes were assessed using Real‐time PCR. Trigonelline demonstrated a high‐binding affinity to the iNOS molecule in computer modelling. In macrophages treated with various concentrations of trigonelline, glucantime and their combination, the expression levels of metacaspase, IL‐12, TNF‐α, IFN‐γ and iNOS genes significantly increased compared to the control group (p < 0.05), whereas IL‐10 and TGF‐β gene expression levels significantly decreased (p < 0.05). Trigonelline exerts its antileishmanial effects through its high antioxidant properties, non‐cytotoxicity to macrophages, and its ability to enhance apoptosis and cell cycle arrest in promastigotes of L. major. [ABSTRACT FROM AUTHOR]

Alzheimer's disease (AD), the most prevalent cause of dementia, is a progressive neurodegenerative condition that commences subtly and inexorably worsens over time. Despite considerable research, a specific drug that can fully cure or effectively halt the progression of AD remains elusive. Nitric oxide (NO), a crucial signaling molecule in the nervous system, is intimately associated with hallmark pathological changes in AD, such as amyloid-beta deposition and tau phosphorylation. Several therapeutic strategies for AD operate through the nitric oxide synthase/NO system. However, the potential neurotoxicity of NO introduces an element of controversy regarding its therapeutic utility in AD. This review focuses on research findings concerning NO's role in experimental AD and its underlying mechanisms. Furthermore, we have proposed directions for future research based on our current comprehension of this critical area. [ABSTRACT FROM AUTHOR]

Endothelial dysfunction, characterized by impaired endothelial function, is critical in developing cardiovascular diseases. Emerging evidence suggests that certain constituents of commonly used spices potentially mitigate endothelial dysfunction. This review summarizes the current literature on the constituents of commonly used spices and their molecular interactions in endothelial system. We first provide an overview of physiological significance as well as dysfunction of endothelium and its role in cardiovascular diseases, including the mechanisms like oxidative stress, inflammation, atherosclerosis, hypertension, thrombosis, and impaired nitric oxide (NO) bioavailability. The physiological significance such as, regulation of thrombosis and fibrinolysis, preventing atherosclerosis and neo-angiogenesis, were discussed. Various spices reported to possess vascular-targeting properties, including curcumin from turmeric, allicin from garlic, gingerol from ginger, piperine from black pepper, quercetin from onion, 2-methoxycinnamaldehyde from cinnamon etc. were discussed. We highlight the molecular interactions of these spice constituents with endothelial cells, including their effects on oxidative stress, inflammation, atherosclerosis, thrombosis, and NO bioavailability. Evidence from in vitro, animal, and human studies reveals that, spice constituents modulate various signaling pathways and enhance NO bioavailability, which collectively contribute to their potential beneficial effects on endothelial function. Furthermore, we discuss the potential mechanisms including reduced expression of ICAM, VCAM, and selectin, inhibition of NF-κB activation and translocation, and decreased ROS and H2O2 levels. In conclusion, the constituents of commonly used spices, such as (allicin, curcumin, quercetin, gingerol etc.) promises a novel approach for modulating endothelial function in vascular disorders. Further research in this area may provide valuable insights into the potential use of these spice constituents as complementary or alternative therapies for cardiovascular diseases. [ABSTRACT FROM AUTHOR]

Eccentric contraction (ECC) has been shown to induce leukocyte invasion into skeletal muscle, resulting in muscle inflammation. This study aimed to investigate whether prior ingestion of L-arginine (ARG), a nitric oxide precursor, inhibits ECC-induced macrophage invasion. Male Wistar rats received ARG in water for 7 days, beginning 3 days prior to ECC. ECCs were induced in the anterior crural muscles for 200 cycles. Three days later, the tibialis anterior and extensor digitorum longus muscles were excised for biochemical analysis and force measurement, respectively. ARG ingestion increased nitrite and nitrate levels in plasma and muscle, inhibiting force depression and reducing CD68 content in muscles subjected to ECC. ARG ingestion also ameliorated an ECC-induced increase in protein nitration, although neither ARG ingestion nor ECC induction affected protein carbonyl levels. The present results suggest that ingestion of ARG or ARG-rich foods may alleviate inflammation by attenuating phagocyte invasion in eccentrically contracted skeletal muscles. [ABSTRACT FROM AUTHOR]

Nitric oxide (NO) is one of the most studied molecules in medical science. The role of NO as an endogenous regulator of inflammation, as an antibacterial agent and as an endogenous gasotransmitter is well established. Even so, despite a plethora of excellent wound healing data, hard-to-heal (chronic) wounds are of epidemic proportions, and still growing in number. However, yet to be established and sorely needed is the identification of a single, continuous NO mechanism of action (MoA), where phase-to-phase variance in the complex sequence of cellular and molecular wound healing may elucidate the potential for placing hard-to-heal wounds on positive healing trajectories. Hence, the objectives of this review were to: identify salient MoAs for NO in each phase of skin wound healing; and to select and validate a single MoA that is both ubiquitous and continuous in NO across acute and hard-to-heal wound sequences, and which potentiates the ability to supplementally motivate and guide the recovery of a hard-to-heal wound onto a positive healing trajectory. The search began by selecting a detailed, multipart wound healing model. Next, as guided by the literature, was the identification of salient NO functionalities for each model segment. These modes of action were then be used to identify and validate a single NO MoA that is continuous across the healing spectrum. Finally, by using the principle of 'super position' of two continuous functions, this acute healing NO MoA solution was compared to a similar solution set describing a hard-to-heal or chronic wound. As both solution sets are continuous in a NO function, the resultant 'overlay' then helped to identify and guide the use of a NO MoA capable of placing any hard-to-heal wound on a positive healing trajectory. [ABSTRACT FROM AUTHOR]

Nitric oxide(NO)is an endothelial-derived relaxing factor produced by endothelial cells and catalyzed by nitric oxide synthase(NOS), which is present in many organs and tissues of the human body. NO is a key gaseous signaling molecule that mediates a variety of physiopathological processes in organisms. NO and NOS have many functions including the regulation of vascular tone, the relaxation of smooth muscle, activation of immune responses and modulation of neuro-transmission. They have been used in the treatment of diseases in a certain field. In recent years, the incidence of ophthalmic diseases has been on the rise, and the quality of life of patients has been reduced. However, treatment for most diseases is limited. It is find that NO and NOS can be detected in various tissue of ocular parts, and they are involved in the occurrence and transformation of many ocular surface and fundus diseases. This article reviews the correlation between them and ocular diseases, analyzes the mechanism and principle of the occurrence and development of diseases, and provides new ideas for the clinical treatment of ophthalmic diseases in the future.

In our efforts to develop inhibitors selective for neuronal nitric oxide synthase (nNOS) over endothelial nitric oxide synthase (eNOS), we found that nNOS can undergo conformational changes in response to inhibitor binding that does not readily occur in eNOS. One change involves movement of a conserved tyrosine, which hydrogen bonds to one of the heme propionates, but in the presence of an inhibitor, changes conformation, enabling part of the inhibitor to hydrogen bond with the heme propionate. This movement does not occur as readily in eNOS and may account for the reason why these inhibitors bind more tightly to nNOS. A second structural change occurs upon the binding of a second inhibitor molecule to nNOS, displacing the pterin cofactor. Binding of this second site inhibitor requires structural changes at the dimer interface, which also occurs more readily in nNOS than in eNOS. Here, we used a combination of crystallography, mutagenesis, and computational methods to better understand the structural basis for these differences in NOS inhibitor binding. Computational results show that a conserved tyrosine near the primary inhibitor binding site is anchored more tightly in eNOS than in nNOS, allowing for less flexibility of this residue. We also find that the inefficiency of eNOS to bind a second inhibitor molecule is likely due to the tighter dimer interface in eNOS compared with nNOS. This study provides a better understanding of how subtle structural differences in NOS isoforms can result in substantial dynamic differences that can be exploited in the development of isoform-selective inhibitors.

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. [ABSTRACT FROM AUTHOR]

Aim. To characterize iNOS expression indicators in the basal magnocellular nucleus of rats during early pathogenetic correction of neurodegeneration induced by intracerebroventricular colchicine administration. Materials and methods. The study was conducted using 50 male Wistar rats aged 10–11 months, which were divided into 5 experimental groups (n = 10). The control animals (group 1) were administered a 0.9 % NaCl solution intracerebroventricularly, while the other experimental group rats (groups 2–5) received a colchicine solution in the same manner. The following day, the animals from groups 3–5 were initiated early pathogenetic correction with citicoline (group 3), thiocetam (group 4), and HSF-1 (group 5) lasting 14 days. All the experimental animals (groups 1–5) were then euthanized with sodium thiopental, and their brains were extracted for histochemical, immunofluorescent, and biochemical examinations. Results. The study has demonstrated that intracerebroventricular administration of colchicine to rats was accompanied by morphological signs of neurodegeneration in the basal magnocellular nucleus and characterized by a significantly smaller area of chromaffin substance in the neurons of this structure by 39 % as compared to the control animals. At the same time, early pathogenetic correction of colchicine-induced neurodegeneration was associated with significantly larger values of Nissl substance area of the basal magnocellular nucleus neurons compared to the corresponding values in animals that did not receive the correction. Additionally, the nitrite level in the brain homogenates of rats administered colchicine without correction (group 2) exceeded the control (group 1) by almost 7 times, while the indicators in experimental groups 3, 4, and 5 exceeded it by 3.5, 2.9, and 3.8 times, respectively. However, no statistical differences were found between the control group and the correction groups in terms of nitrite content. Evaluating the expression of iNOS (the area of immunopositive cells and corrected total cell fluorescence, CTCF) in the basal magnocellular nucleus of the experimental rats it has been shown that the area was most affected in group 5 (HSF-1 correction), exceeding the control parameter by 18.9 %, group 3 (citicoline correction) by 14.7 %, and group 4 (thiocetam correction) by 17.1 %, with no statistical differences compared to group 2 (colchicine administration without correction). Meanwhile, the CTCF of iNOS+-cells in the basal magnocellular nucleus of the experimental animals was the highest in group 2 significantly exceeding the corresponding parameters in the control and correction groups. No significant differences were found between the control and correction groups in this parameter. Additionally, it is noteworthy that intracerebroventricular administration of colchicine to rats, compared to control animals, was associated with a significant double the number of iNOS+ cells in the basal magnocellular nucleus. However, early pathogenetic correction in groups 3-5 did not significantly affect the number of iNOS+ cells in the studied structure, as this parameter did not statistically differ from group 2, although significantly exceeding the corresponding parameter in the control group (group 1). Conclusions. Early pathogenetically substantiated correction with citicoline, thiocetam, and HSF-1 in colchicine-induced neurodegeneration in the basal magnocellular nucleus of experimental rats is accompanied by an increase in the area of chromaffin substance compared to rats that received intracerebroventricular colchicine without correction, as well as a reduction in nitrite levels in brain homogenates to the control level (sham-operated animals). In the basal magnocellular nucleus of experimental rats, under the influence of early pathogenetically substantiated correction of experimental neurodegeneration, iNOS expression indicators (area of immunopositive cells and CTCF) vary depending on the neuroprotectant used. The number of iNOS+ cells in the basal magnocellular nucleus of experimental rats in the correction groups does not change compared to the group that received intracerebroventricular colchicine without correction and is statistically higher than the corresponding indicator in the control rats.

Abstract Ferroptosis is a form of regulated cell death, characterized by excessive iron-dependent lipid peroxidation. Biochemically, ferroptosis can be selectively induced by erastin through glutathione depletion or through inhibition of glutathione peroxidase 4 by RSL3, which leads to accumulation of cytotoxic lipid reactive oxygen species (ROS). Protein disulfide isomerase (PDI) was recently shown to mediate erastin/RSL3-induced ferroptosis and thus also become a new target for protection against chemically-induced ferroptosis. The present study aims to identify endogenous compounds that can protect against erastin/RSL3-induced ferroptotic cell death. We find that 2-hydroxyestrone, 2-hydroxyestradiol, 4-hydroxyestrone and 4-hydroxyestradiol, four major endogenous catechol estrogens, are effective inhibitors of PDI, and can strongly protect against chemically-induced ferroptotic cell death in cultured HT22 mouse hippocampal neuronal cells. The CETSA assay showed that these catechol estrogens can bind to PDI in live cells. PDI knockdown attenuates the protective effect of these catechol estrogens against chemically-induced ferroptosis. Mechanistically, inhibition of PDI’s catalytic activity by catechol estrogens abrogates erastin/RSL3-induced dimerization of nitric oxide synthase, thereby preventing the subsequent accumulation of cellular nitric oxide, ROS and lipid-ROS, and ultimately ferroptotic cell death. In addition, joint treatment of cells with catechol estrogens also abrogates erastin/RSL3-induced upregulation of nitric oxide synthase protein levels, which also contributes to the cytoprotective effect of the catechol estrogens. In conclusion, the present study demonstrates that the catechol estrogens are protectors of HT22 neuronal cells against chemically-induced ferroptosis, and inhibition of PDI’s catalytic activity by these estrogens contributes to a novel, estrogen receptor-independent mechanism of cytoprotection.

Nitric oxide (NO) plays a crucial role as a messenger or effector in the body, yet it presents a dual impact on cardio-cerebrovascular health. Under normal physiological conditions, NO exhibits vasodilatory effects, regulates blood pressure, inhibits platelet aggregation, and offers neuroprotective actions. However, in pathological situations, excessive NO production contributes to or worsens inflammation within the body. Moreover, NO may combine with reactive oxygen species (ROS), generating harmful substances that intensify physical harm. This paper succinctly reviews pertinent literature to clarify the in vivo and in vitro origins of NO, its regulatory function in the cardio-cerebrovascular system, and the advantages and disadvantages associated with NO donor drugs, NO delivery systems, and vascular stent materials for treating cardio-cerebrovascular disease. The findings provide a theoretical foundation for the application of NO in cardio-cerebrovascular diseases. • The article comprehensively reviews NO forms-vascular scaffolds, NO-donor drugs, inhaled NO, and NO-delivery systems and their application in treating cardio-cerebrovascular diseases. • It systematically describes the characteristics of various NOS-catalyzed NO syntheses and their effects on the human body. • It provides a detailed overview of the sources of NO and the mechanisms of its production. [ABSTRACT FROM AUTHOR]

Chikungunya virus (CHIKV) infection is characterized by febrile illness, severe joint pain, myalgia, and cardiovascular complications. Given that CHIKV stimulates reactive oxygen species (ROS) and pro- and anti-inflammatory cytokines, events that disrupt vascular homeostasis, we hypothesized that CHIKV induces arterial dysfunction by directly impacting redox-related mechanisms in vascular cells. Wild-type (WT) and iNOS knockout (iNOS−/−) mice were administered either CHIKV (1.0 × 106 PFU/µL) or Mock vehicle via the intracaudal route. In vivo, CHIKV infection induced vascular dysfunction (assessed by a wire myograph), decreased systolic blood pressure (tail-cuff plethysmography), increased IL-6 and IFN-γ, but not TNF-α levels (determined by ELISA), and increased protein content by Western blot. Marked contractile hyporesponsiveness to phenylephrine was observed 48 h post-infection, which was restored by endothelium removal. L-NAME, 1400W, Tiron, and iNOS gene deletion prevented phenylephrine hyporesponsiveness. CHIKV infection increased vascular nitrite concentration (Griess reaction) and superoxide anion (O2•−) generation (lucigenin chemiluminescence), and decreased hydrogen peroxide (H2O2, by Amplex Red) levels 48 h post-infection, alongside increased TBARS levels. In vitro, CHIKV infected endothelial cells (EA.hy926) and upregulated ICAM-1 and iNOS protein expression (determined by Western blot). These data support the conclusion that CHIKV-induced alterations in vascular ROS/NF-kB/iNOS/NO signaling potentially contribute to cardiovascular events associated with Chikungunya infection. [ABSTRACT FROM AUTHOR]

Background: Liqi Tongbian is a traditional Chinese medicine (TCM) preparation that contains herbs that may treat slow transit constipation (STC). Atractylodes macrocephala, Astragalus membranaceus, Fructus aurantii, radish seed, uncooked Polygonum multiflorum, and Agastache rugosa were included in the formula for their unique qualities. The control of water transfer in the colon is greatly influenced by aquaporin 3 (AQP3). Objectives. Based on this, the Liqi Tongbian mixture was used to detect the concentrations of aquaporins (AQPs), 5-HT and nitrix oxide synthase 1 (NOS1) in STC rats, and explore its effect, in order to provide a theoretical basis for the remedy of STC with TCM. Materials and methods: Zhejiang University of Traditional Chinese Medicine provided 32 three-week-old Sprague Dawley rats of SPF-grade. The pairs licensed under SYXK (Zhejiang) 2021-0012 were kept at 20-25°C and humidity of 50-65%. The compound diphenoxylate caused constipation in the control, model, Liqi laxative (LQTB), and mosapride groups. The Liqi laxative rats were administered a mixture of traditional Chinese herbs after modeling, while mosapride was given to the other group. The levels of 5-HT, NOS1 and AQPs were tested in the feces and intestinal tissues. Results: Comparing the condition of rat feces, it was found that the model group had significantly lower overall bulk, score and particles within 24 h compared to the control group. In comparison to mosapride, LQTB performed better. The model group had higher levels of 5-HT and NOS1 in intestinal tissue, while the LQTB and mosapride groups had decreased levels of these AQPs. LQTB had lower levels of AQP1, AQP3 and AQP4 than mosapride, while the model group had higher levels of these AQPs. Conclusions: Liqi Tongbian mixture works better than mosapride in improving constipation symptoms in rats with STC, and its mechanism is related to regulating the level of intestinal AQPs and neurotransmitters. [ABSTRACT FROM AUTHOR]

Glyphosate (GLY) is a pesticide that severely alters nigrostriatal dopaminergic neurotransmission, inducing great increases in dopamine release from rat dorsal striatum. This GLY‐induced striatal dopamine overflow occurs through mechanisms not yet fully understood, hence the interest in evaluating the role of other neurotransmitter systems in such effects. So, the main objective of this mechanistic study was to evaluate the possible mediation of the glutamatergic, cholinergic, and nitrergic systems in the GLY‐induced in vivo dopamine release from rat dorsal striatum. The extracellular dopamine levels were measured by cerebral microdialysis and HPLC with electrochemical detection. Intrastriatal administration of GLY (5 mmol/L) significantly increased the dopamine release (1102%). Pretreatment with MK‐801 (50 or 400 μmol/L), a non‐competitive antagonist of NMDA receptors, significantly decreased the effect of GLY (by 70% and 74%, respectively), whereas AP‐5 (400 μmol/L), a competitive antagonist of NMDA receptors, or CNQX (500 μmol/L), an AMPA/kainate receptor antagonist, had no significant effect. Administration of the nitric oxide synthase inhibitors, L‐nitroarginine (L‐NAME, 100 μmol/L) or 7‐nitroindazole (7‐NI, 100 μmol/L), also did not alter the effect of GLY on dopamine release. Finally, pretreatment of the animals with mecamylamine, an antagonist of nicotinic receptors, decreased the effect of GLY on dopamine release by 49%, whereas atropine, a muscarinic antagonist, had no significant effect. These results indicate that GLY‐induced dopamine release largely depends on the activation of NMDA and nicotinic receptors in rat dorsal striatum. Future research is needed to determine the effects of this pesticide at environmentally relevant concentrations. Glyphosate (GLY) is a pesticide that severely alters nigrostriatal dopaminergic neurotransmission, inducing large increases in striatal dopamine release. In the present study, we confirmed that the intrastriatal administration of GLY increased the in vivo release of dopamine and that local administration of specific antagonists of NMDA and nicotinic receptors significantly decreased the effect of the pesticide. However, this inhibition was only partial, indicating that GLY is a pesticide that alters dopaminergic neurotransmission through several mechanisms. [ABSTRACT FROM AUTHOR]

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Nitric oxide synthases (NOSs), a family of flavo-hemoproteins with relatively rigid domains linked by flexible regions, require optimal FMN domain docking to the heme domain for efficient interdomain electron transfer (IET). To probe the FMN-heme interdomain docking, the magnetic dipole interactions between the FMN semiquinone radical (FMNH•) and the low-spin ferric heme centers in oxygenase/FMN (oxyFMN) constructs of neuronal and inducible NOS (nNOS and iNOS, respectively) were measured using the relaxation-induced dipolar modulation enhancement (RIDME) technique. The FMNH• RIDME data were analyzed using the mesoscale Monte Carlo calculations of conformational distributions of NOS, which were improved to account for the native degrees of freedom of the amino acid residues constituting the flexible interdomain tethers. This combined computational and experimental analysis allowed for the estimation of the stabilization energies and populations of the docking complexes of calmodulin (CaM) and the FMN domain with the heme domain. Moreover, combining the five-pulse and scaled four-pulse RIDME data into a single trace has significantly reduced the uncertainty in the estimated docking probabilities. The obtained FMN—heme domain docking energies for nNOS and iNOS were similar (-3.8 kcal/mol), in agreement with the high degree of conservation of the FMN—heme domain docking interface between the NOS isoforms. In spite of the similar energetics, the FMN—heme domain docking probabilities in nNOS and iNOS oxyFMN were noticeably different (~ 0.19 and 0.23, respectively), likely due to differences in the lengths of the FMN—heme interdomain tethers and the docking interface topographies. The analysis based on the IET theory and RIDME experiments indicates that the variations in conformational dynamics may account for half of the difference in the FMN—heme IET rates between the two NOS isoforms. [ABSTRACT FROM AUTHOR]

In plants, nitric oxide (NO) has become a versatile signaling molecule essential for mediating a wide range of physiological processes under various biotic and abiotic stress conditions. The fundamental function of NO under various stress scenarios has led to a paradigm shift in which NO is now seen as both a free radical liberated from the toxic product of oxidative metabolism and an agent that aids in plant sustenance. Numerous studies on NO biology have shown that NO is an important signal for germination, leaf senescence, photosynthesis, plant growth, pollen growth, and other processes. It is implicated in defense responses against pathogensas well as adaptation of plants in response to environmental cues like salinity, drought, and temperature extremes which demonstrates its multifaceted role. NO can carry out its biological action in a variety of ways, including interaction with protein kinases, modifying gene expression, and releasing secondary messengers. In addition to these signaling events, NO may also be in charge of the chromatin modifications, nitration, and S-nitrosylation-induced posttranslational modifications (PTM) of target proteins. Deciphering the molecular mechanism behind its essential function is essential to unravel the regulatory networks controlling the responses of plants to various environmental stimuli. Taking into consideration the versatile role of NO, an effort has been made to interpret its mode of action based on the post-translational modifications and to cover shreds of evidence for increased growth parameters along with an altered gene expression. • Nitric oxide(NO) plays a significant role in plant biology, affecting crop improvement and sustainable agriculture. • NO has proven to be a multifaceted molecule that signals plant defense under stress conditions. • NO interacts with other signaling molecules to regulate gene expression and enhance the defense system under stress. • Post-translational modifications (PTMs) of NO affect many cellular activities. [ABSTRACT FROM AUTHOR]

We have previously observed that mice exposed to social defeat stress are more sensitive to cocaine in the conditioned place preference (CPP) paradigm. In this context, it has been suggested that the nitric oxide (NO) pathway plays a role in the effects of stress. The present study evaluates the role of a neuronal NO synthase (nNOS) inhibitor (7-nitroindazole, 7-NI) in the short- and long-term behavioural effects of intermittent social defeat (ISD). Four groups of mice were employed for the study: a control group and three stressed groups, one treated with vehicle and two treated with 7-NI (7.25 or 12.5 mg/kg). After the last episode of defeat, mice were tested in the elevated plus maze (EPM), social interaction, object recognition and tail suspension tests. Three weeks later, mice were conditioned with cocaine (1 mg/kg). Stressed mice, irrespective of the treatment received, showed anxiety in the EPM, presented a deficit of social interaction and spent less time immobile in the tail suspension test. However, only stressed mice treated with vehicle developed CPP. Thus, although 7-NI did not modify the short-term behavioural effects of ISD, it prevented ISD-induced potentiation of the rewarding properties of cocaine in adulthood. These results support a specific role of nNOS in the effects of social stress on drug reward. [ABSTRACT FROM AUTHOR]

BACKGROUND: Folate intake during pregnancy is essential for fetal development and maternal health. However, the specific effects of folic acid (FA) and 5-methyl-(6S)-tetrahydrofolate (5-MTHF) on the prevention and treatment of hypertensive disorders of pregnancy remain unclear. We investigated whether FA and 5-MTHF have different effects on endothelial cell tetrahydrobiopterin (BH4) metabolism in pregnancy and the possible consequences for endothelial NO generation, maternal blood pressure, and fetal growth. METHODS: We analyzed the maternal blood pressure in pregnant wild-type (Gch1fl/fl) and Gch1fl/fl Tie2cre mice treated with either FA or 5-MTHF starting before pregnancy, mid-pregnancy or late pregnancy. BH4, superoxide, and NO bioavailability were determined in mouse and human models of endothelial cell BH4 deficiency by high-performance liquid chromatography. RESULTS: In vitro studies in mouse and human endothelial cells showed that treatment with 5-MTHF, but not FA, elevated BH4 levels, reduced superoxide production, and increased NO synthase activity. In primary endothelial cells isolated from women with hypertensive pregnancies, exposure to 5-MTHF, but not FA, restored the reduction in BH4 levels and NO synthase activity. In vivo studies in mice revealed that oral treatment with 5-MTHF, but not FA, prevented and treated hypertension in pregnancy when administered either before or during pregnancy, respectively, and normalized placental and fetal growth restriction if administered from mid-gestation onward. CONCLUSIONS: Collectively, these studies identify a critical role for 5-MTHF in endothelial cell function in pregnancy, related to endothelial cell BH4 availability and NO synthase activity. Thus, 5-MTHF represents a novel therapeutic agent that may potentially improve endothelial function in hypertensive disorders of pregnancy by targeting endothelial cell BH4. [ABSTRACT FROM AUTHOR]

Aim. To characterize iNOS expression indicators in the basal magnocellular nucleus of rats during early pathogenetic correction of neurodegeneration induced by intracerebroventricular colchicine administration. Materials and methods. The study was conducted using 50 male Wistar rats aged 10-11 months, which were divided into 5 experimental groups (n = 10). The control animals (group 1) were administered a 0.9 % NaCl solution intracerebroventricularly, while the other experimental group rats (groups 2-5) received a colchicine solution in the same manner. The following day, the animals from groups 3-5 were initiated early pathogenetic correction with citicoline (group 3), thiocetam (group 4), and HSF-1 (group 5) lasting 14 days. All the experimental animals (groups 1-5) were then euthanized with sodium thiopental, and their brains were extracted for histochemical, immunofluorescent, and biochemical examinations. Results. The study has demonstrated that intracerebroventricular administration of colchicine to rats was accompanied by morphological signs of neurodegeneration in the basal magnocellular nucleus and characterized by a significantly smaller area of chromaffin substance in the neurons of this structure by 39 % as compared to the control animals. At the same time, early pathogenetic correction of colchicine-induced neurodegeneration was associated with significantly larger values of Nissl substance area of the basal magnocellular nucleus neurons compared to the corresponding values in animals that did not receive the correction. Additionally, the nitrite level in the brain homogenates of rats administered colchicine without correction (group 2) exceeded the control (group 1) by almost 7 times, while the indicators in experimental groups 3, 4, and 5 exceeded it by 3.5, 2.9, and 3.8 times, respectively. However, no statistical differences were found between the control group and the correction groups in terms of nitrite content. Evaluating the expression of iNOS (the area of immunopositive cells and corrected total cell fluorescence, CTCF) in the basal magnocellular nucleus of the experimental rats it has been shown that the area was most affected in group 5 (HSF-1 correction), exceeding the control parameter by 18.9 %, group 3 (citicoline correction) by 14.7 %, and group 4 (thiocetam correction) by 17.1 %, with no statistical differences compared to group 2 (colchicine administration without correction). Meanwhile, the CTCF of iNOS+-cells in the basal magnocellular nucleus of the experimental animals was the highest in group 2 significantly exceeding the corresponding parameters in the control and correction groups. No significant differences were found between the control and correction groups in this parameter. Additionally, it is noteworthy that intracerebroventricular administration of colchicine to rats, compared to control animals, was associated with a significant double the number of iNOS+ cells in the basal magnocellular nucleus. However, early pathogenetic correction in groups 3-5 did not significantly affect the number of iNOS+ cells in the studied structure, as this parameter did not statistically differ from group 2, although significantly exceeding the corresponding parameter in the control group (group 1). Conclusions. Early pathogenetically substantiated correction with citicoline, thiocetam, and HSF-1 in colchicine-induced neurodegeneration in the basal magnocellular nucleus of experimental rats is accompanied by an increase in the area of chromaffin substance compared to rats that received intracerebroventricular colchicine without correction, as well as a reduction in nitrite levels in brain homogenates to the control level (sham-operated animals). In the basal magnocellular nucleus of experimental rats, under the influence of early pathogenetically substantiated correction of experimental neurodegeneration, iNOS expression indicators (area of immunopositive cells and CTCF) vary depending on the neuroprotectant used. The number of iNOS+ cells in the basal magnocellular nucleus of experimental rats in the correction groups does not change compared to the group that received intracerebroventricular colchicine without correction and is statistically higher than the corresponding indicator in the control rats. [ABSTRACT FROM AUTHOR]

Background: Periodontitis, a chronic inflammatory disease, has been associated with an elevated risk of cardiovascular disease (CVD). Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase, has emerged as a potential biomarker linking periodontitis, endothelial dysfunction, and CVD. This systematic review aimed to synthesize the existing evidence on the relationship between ADMA, periodontitis, and CVD, and to evaluate ADMA's potential as a biomarker for periodontal disease progression and its correlation with endothelial dysfunction. Methods: A comprehensive literature search was conducted in PubMed, Scopus, and Web of Science databases from their inception to March 2023. Observational and interventional studies assessing ADMA levels in patients with periodontitis and/or CVD were included. The methodological quality of the included studies was evaluated using the NIH Quality Assessment Tools. Due to the heterogeneity of the included studies, a qualitative synthesis was performed. Results: Cross-sectional studies consistently demonstrated significantly elevated ADMA levels in patients with periodontitis and CVD compared to healthy controls. The prospective cohort study indicated that successful periodontal treatment was associated with a significant reduction in ADMA levels and concomitant improvement in endothelial function. The pilot cohort study reported a significant decrease in ADMA levels following periodontal therapy in patients with chronic kidney disease. However, the randomized controlled trials did not demonstrate significant alterations in ADMA levels or endothelial function subsequent to periodontal treatment in patients with periodontitis alone. Conclusions: Periodontal treatment may effectively reduce ADMA levels and improve endothelial function, particularly in patients with comorbidities. These findings suggest that ADMA is a promising biomarker linking periodontitis, endothelial dysfunction, and CVD. However, the limitations of this study include the small number of studies, heterogeneity in the study designs, and a lack of long-term follow-up data. Further high-quality, longitudinal studies are required to confirm its clinical utility and elucidate the underlying mechanisms of these relationships. The integration of periodontal care into CVD prevention and management strategies warrants consideration, as it may contribute to mitigating the cardiovascular risk associated with periodontitis. [ABSTRACT FROM AUTHOR]

BACKGROUND: Enteric neuropathies, which result from abnormalities of the enteric nervous system, are associated with significant morbidity and high health-care costs, but current treatments are unsatisfactory. Cell-based therapy offers an innovative approach to replace the absent or abnormal enteric neurons and thereby restore gut function. METHODS: Enteric neuronal stem cells (ENSCs) were isolated from the gastrointestinal tract of Wnt1-Cre;R26tdTomato mice and generated neurospheres (NS). NS transplants were performed via injection into the mid-colon mesenchyme of nNOS-/- mouse, a model of colonic dysmotility, using either 1 (n = 12) or 3 (n = 12) injections (30 NS per injection) targeted longitudinally 1-2 mm apart. Functional outcomes were assessed up to 6 weeks later using electromyography (EMG), electrical field stimulation (EFS), optogenetics, and by measuring colorectal motility. RESULTS: Transplanted ENSCs formed nitrergic neurons in the nNOS-/- recipient colon. Multiple injections of ENSCs resulted in a significantly larger area of coverage compared to single injection alone and were associated with a marked improvement in colonic function, demonstrated by (1) increased colonic muscle activity by EMG recording, (2) faster rectal bead expulsion, and (3) increased fecal pellet output in vivo. Organ bath studies revealed direct neuromuscular communication by optogenetic stimulation of channelrhodopsin-expressing ENSCs and restoration of smooth muscle relaxation in response to EFS. CONCLUSIONS: These results demonstrate that transplanted ENSCs can form effective neuromuscular connections and improve colonic motor function in a model of colonic dysmotility, and additionally reveal that multiple sites of cell delivery led to an improved response, paving the way for optimized clinical trial design.

Abstract In this study, we investigated the cerebroprotective effects of fenchone (FEN) against brain ischemia through in silico and in vivo approaches, focusing on the inhibition of nitric oxide synthase (NOS) and the modulation of oxidative stress markers. Molecular docking revealed the potential binding affinity of FEN for the NOS active site, with a binding energy of -6.6 kcal/mol. This was validated through molecular dynamics simulations over a 100 ns time frame, demonstrating stability and favorable interaction profiles. Wistar albino rats underwent bilateral common carotid artery occlusion/reperfusion (BCCAO/R) followed by FEN administration at doses of 100 and 200 mg/kg. Our results indicated a significant reduction in cerebral infarction size and improvements in electroencephalography (EEG) signal magnitude with FEN treatment. Additionally, FEN restored the activity of antioxidant enzymes (catalase and superoxide dismutase) and decreased malondialdehyde (MDA) and nitric oxide (NO) levels and infarct size compared to those in untreated ischemic rats. Histological analysis further corroborated the neuroprotective effects of FEN, demonstrating the structural preservation of neurons in the hippocampal CA1 region. Overall, the results suggest that FEN plays a neuroprotective role in brain ischemia, potentially through the inhibition of NOS, reduction of oxidative stress, and modulation of antioxidants, highlighting the potential of FEN as a therapeutic candidate for ischemic stroke management.

Objective: Many factors regulate the process of angiogenesis under physiological and pathological conditions. However, no reliable marker is currently available that can predict the patient's pro-angiogenic status, which might reliably reflect or predict certain clinical outcomes. This paper targetly reviews the response of certain important vascular effectors to hypoxia and their roles in angiogenesis, trying to introduce a reliable surrogate marker that can reflect the pro-angiogenic status of a patient, based on experimental and clinical published studies. Methods: The adopted approach is a mix of preclinical testing and narration of published examples of individual correlations of the marker components. As tumor-associated angiogenesis is the most prominently and clinically studied, this model constitutes the significant base for the notions of this work. Results: Under hypoxic conditions, a decrease of tissue nostrin, along with increased production of nitric oxide synthase (eNOS), vascular endothelial growth factor (VEGF)-A, sVEGFR1 and endothelin-1 (ET-1) are to be expected. Conclusion: Based on the experimentally proven changes in the selected angiogenesis-related effectors, as well as their experimentally and clinically proven roles and correlations in angiogenesis, the following conclusion can be stated; Low tissue nostrin, high circulating eNOS, high circulating VEGF-A, high circulating ET-1 can indicate a pro-angiogenic status, i.e. hypoxic injury.

A series of potent, selective, and highly permeable human neuronal nitric oxide synthase inhibitors (hnNOS), based on a difluorobenzene ring linked to a 2-aminopyridine scaffold with different functionalities at the 4-position, is reported. In our efforts to develop novel nNOS inhibitors for the treatment of neurodegenerative diseases, we discovered 17, which showed excellent potency toward both rat (Ki 15 nM) and human nNOS (Ki 19 nM), with 1075-fold selectivity over human eNOS and 115-fold selectivity over human iNOS. 17 also showed excellent permeability (Pe = 13.7 × 10-6 cm s-1), a low efflux ratio (ER 0.48), along with good metabolic stability in mouse and human liver microsomes, with half-lives of 29 and >60 min, respectively. X-ray cocrystal structures of inhibitors bound with three NOS enzymes, namely, rat nNOS, human nNOS, and human eNOS, revealed detailed structure-activity relationships for the observed potency, selectivity, and permeability properties of the inhibitors.

Abstract Avascular necrosis (AVN) is a debilitating condition characterized by bone tissue death due to inadequate blood supply, leading to joint dysfunction and collapse. This study investigates the potential association between AVN and COVID-19, focusing on genetic factors such as NOS3 polymorphisms. A total of 180 individuals were included, comprising 120 COVID-19 patients and 60 healthy controls. Clinical, haematological, biochemical, and genetic parameters were assessed. Results revealed significant differences in respiratory and heart rates, haematological counts, and biochemical markers between AVN and control groups. Genetic analysis showed a higher prevalence of the TG genotype and G allele in NOS3 rs1799983 polymorphism among AVN patients. Additionally, NOS3 rs2070744 polymorphism correlated with various clinical parameters, including blood pressure, heart rate, and haematological indices. This study highlights the potential role of genetic factors in predisposing individuals to AVN following COVID-19 infection.

Aim. To characterize the features of iNOS expression in neurons of the basal magnocellular nucleus against the background of nitrosative stress during experimental colchicine-induced neurodegeneration. Materials and methods. The study was conducted on 30 male Wistar rats. At the first stage of the experiment, cognitive impairments were modeled in rats (n = 10) by intracerebroventricular injection of colchicine, and compared with sham-operated and intact animal groups, the validity of the model was demonstrated using an 8-arm radial maze LE760 (PanLab Harvard Apparatus, Spain). Subsequently, the animals were euthanized with sodium thiopental, and the brain was removed for histological, immunofluorescence, and biochemical analyses. Results. It was found that intracerebroventricular injection of colchicine compared to intact and sham-operated animals leads to disruption of histoarchitecture in the basal magnocellular nucleus of rats with a significant decrease in the Nissl substance area in neurons by 47.3 % and 35.9 %, respectively. At the same time, the level of nitrites in the brain homogenates of animals with experimental neurodegeneration exceeded the comparison groups almost 10 times (intact) and 7 times (sham-operated rats). Meanwhile, immunofluorescence investigation of iNOS expression in the basal magnocellular nucleus of rats with intracerebroventricular colchicine administration, compared to intact and sham-operated animals, revealed a significantly higher value of corrected total cell fluorescence by 22.7 % and 45.3 %, respectively. Simultaneously, it was established that experimental colchicine-induced neurodegeneration is accompanied by a significantly greater number of iNOS+ cells in the basal magnocellular nucleus compared to control groups. Conclusions. Intracerebroventricular injection of colchicine to experimental rats is accompanied by morphological signs of neurodestruction in the basal magnocellular nucleus against the background of nitrosative stress. iNOS expression in rats after intracerebroventricular colchicine administration in the cells of the basal magnocellular nucleus is characterized by a higher enzyme content compared to intact and sham-operated animals. The area of immunopositive cells between experimental groups does not change statistically. Intracerebroventricular administration of colchicine to experimental rats is accompanied by an increase in the number of immunopositive cells for iNOS in the basal magnocellular nucleus.