Triphenyl phosphate disrupts placental tryptophan metabolism by activating MAOA/ROS/NFκB

Triphenyl phosphate (TPhP) is an organophosphate flame retardant widely distributed in the environment. The neurodevelopmental toxicity of TPhP has been observed in animals and humans. Previously, we found that prenatal TPhP exposure disturbed placental tryptophan metabolism, impaired neurodevelopment in male offspring, and induced abnormal neurobehavior; however, the underlying mechanisms are unknown. In this study, using the trophoblast cell line JEG-3, we found that TPhP altered gene and protein expression in the tryptophan metabolism pathway, inhibited the tryptophan-serotonin pathway, and activated the tryptophan-kynurenine pathway. Meanwhile, TPhP induced oxidative stress by activating monoamine oxidase A (MAOA), promoting inflammatory factors including nuclear factor kappa-B (NFκB), interleukin-6, and tumor necrosis factor α. The NFκB inhibitor sulfasalazine could alleviate the effects of TPhP on tryptophan metabolism disturbance. The MAOA inhibitor clorgyline or the antioxidant N-acetylcysteine can mitigate oxidative stress and eliminate TPhP-induced inflammatory factors and tryptophan metabolism disturbances. The data above suggest that TPhP disturbed tryptophan metabolism by activating NFκB through MAOA-mediated oxidative stress. Finally, using the mouse intrauterine exposure model, the results confirmed that TPhP induced oxidative stress, activated inflammatory factors, disturbed tryptophan metabolism, and increased the levels of the tryptophan metabolites serotonin, kynurenine, 3-hydroxykynurenine, and 3-hydroxyanthranilic acid in the placenta during the second trimester of pregnancy. Overall, TPhP can disturb placental tryptophan metabolism by activating the inflammatory factor NFκB, which was induced by MAOA-induced oxidative stress. The results of this study confirm that indirect exposure to xenobiotic compounds at an early life stage can impair offspring development and provide a novel perspective on the neurodevelopmental toxicity of TPhP.

The search for potential hypotensive peptides in the amino acid sequence of human renalase and their identification in proteolytic fragments of this protein

Renalase (RNLS) is a secretory protein discovered in 2005. It plays an important role in the regulation of blood pressure. Studies by two independent laboratories have shown that administration of purified recombinant RNLS reduced blood pressure in experimental animals. However, the mechanisms of the antihypertensive effect of RNLS still remain unclear, especially in the context of the shift in the catalytic paradigm of this protein. In addition, there is growing evidence that endogenous plasma/serum RNLS, detected by enzyme immunoassay, is not an intact protein secreted into the extracellular space, and exogenous recombinant RNLS is effectively cleaved during short-term incubation with human plasma samples. This suggests that the antihypertensive effect of RNLS may be due to peptides formed during proteolytic processing. Based on the results of a bioinformatics analysis of potential RNLS cleavage sites (Fedchenko et al., Medical Hypotheses, 2022; DOI: 10.1016/j.mehy.2022.110895), a number of short peptides have been identified in the RNLS sequence that show similarity to fragments of known peptide inhibitors of angiotensin-converting enzyme. Some of them were found as a part of larger RNLS peptides, formed during RNLS cleavage by chymotrypsin and, and to a lesser extent, by trypsin.

One-pot synthesis of versatile sphere-like nano adsorbent MnAl2O4 (MAO): an optical and magnetic material for efficient fluoride removal and latent finger print detection

Spherically shaped trimetallic MnAl2O4 (MAO) nanoadsorbent was prepared in an one-pot synthesis process for the removal of excess fluoride from water. The adsorbent was characterized by thermogravimetric analysis (TGA), X-ray diffraction study (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), etc. The adsorption property for fluoride on the MAO was analyzed by batch experiments varying the adsorbent dose, pH, contact time, and initial fluoride concentration. The results showed that the fluoride uptake behavior of the samples could precisely be fitted by the Freundlich model, and the maximum adsorption capacity was estimated to be 39.21 mg/g at room temperature. The pseudo-second-order models accurately described the adsorption kinetics data. The regenerated sample showed excellent reusability along with high removal capacity on real water sample also. The underlying fluoride adsorption mechanism via ion-exchange and electrostatic interaction was established from X-ray photoelectron spectroscopy (XPS) and zeta potential studies. The sample showed excellent luminescence with blue emission with a band gap of 2.6 eV. The materials also showed good elastic behavior exhibiting the Poisson's ratio (σ) 0.32 and excellent latent figure print detection capacity distinguishing the clearly the ridge and furrow regions under UV light. The magnetic behavior was also found to be in long range with antiferromagnetic characteristics.

Protective effects of niacin following high fat rich diet: an in-vivo and in-silico study

Niacin had long been understood as an antioxidant. There were reports that high fat diet (HFD) may cause psychological and physical impairments. The present study was aimed to experience the effect of Niacin on % growth rate, cumulative food intake, motor activity and anxiety profile, redox status, 5-HT metabolism and brain histopathology in rats. Rats were administered with Niacin at a dose of 50 mg/ml/kg body weight for 4 weeks following normal diet (ND) and HFD. Behavioral tests were performed after 4 weeks. Animals were sacrificed to collect brain samples. Biochemical, neurochemical and histopathological studies were performed. HFD increased food intake and body weight. The exploratory activity was reduced and anxiety like behavior was observed in HFD treated animals. Activity of antioxidant enzymes was decreased while oxidative stress marker and serotonin metabolism in the brain of rat were increased in HFD treated animals than ND fed rats. Morphology of the brain was also altered by HFD administration. Conversely, Niacin treated animals decreased food intake and % growth rate, increased exploratory activity, produced anxiolytic effects, decreased oxidative stress and increased antioxidant enzyme and 5-HT levels following HFD. Morphology of brain is also normalized by the treatment of Niacin following HFD. In-silico studies showed that Niacin has a potential binding affinity with degradative enzyme of 5-HT i.e. monoamine oxidase (MAO) A and B with an energy of ~ - 4.5 and - 5.0 kcal/mol respectively. In conclusion, the present study showed that Niacin enhanced motor activity, produced anxiolytic effect, and reduced oxidative stress, appetite, growth rate, increased antioxidant enzymes and normalized serotonin system and brain morphology following HFD intake. In-silico studies suggested that increase 5-HT was associated with the binding of MAO with Niacin subsequentially an inhibition of the degradation of monoamine. It is suggested that Niacin has a great antioxidant potential and could be a good therapy for the treatment of HFD induced obesity.

Benzothiazole-Propanamide Linker Pyrrolidine (Morpholine) as Monoamine Oxidase-B and Butyrylcholinesterase Inhibitors

According to the fusion technique create effective multi-target-directed ligands, in this study, we designed and synthesized a series of benzo[d]thiazol-2-yl)-3-(pyrrolidin-1-yl) or 3-(morph- olino-1-yl)propanamide derivatives, and evaluated their inhibitory potency against MAOs, AChE, BuChE by in vitro enzyme effect assays. Based on activity results, we found that derivatives N-(5-methylbenzo[d]thiazol-2-yl)-3-(pyrrolidin-1-yl)propanamide (2 c) and N-(6-bromobenzo[d]thiazol-2-yl)-3-(pyrrolidin-1-yl)propanamide (2 h) showed good inhibitory potency against BuChE with IC50 values of 15.12 μM and 12.33 μM, respectively. Besides, 2 c and 2 h also exhibited selective MAO-B inhibitory effects with inhibition rates of 60.10 % and 66.30 % at 100 μM, respectively. In contrast, all designed derivatives were poor active against AChE and MAO-A at a concentration of 100 μM. The toxicity analysis in vitro by MTT and AO/EB fluorescence staining confirmed that 2 c and 2 h were nontoxic up to 100 μM. Molecular modeling studies showed that 2 c and 2 h could bind to the active site of BuChE. This research paves the way for further study aimed at designing MAO-B and BuChE inhibitors for the treatment of neurodegenerative disorders.

Superiority of the Triple-Acting 5-HT6R/5-HT3R Antagonist and MAO-B Reversible Inhibitor over 5-HT6R Antagonist Intepirdine in Alleviation of Cognitive Deficits in Rats

The multifactorial origin and neurochemistry of Alzheimer's disease (AD) call for the development of multitarget treatment strategies. We report a first-in-class triple acting compound that targets serotonin type 6 and 3 receptors (5-HT-Rs) and monoamine oxidase type B (MAO-B) as an approach for treating AD. The key structural features required for MAO-B inhibition and 5-HT6R antagonism and interaction with 5-HT3R were determined using molecular dynamic simulations and cryo-electron microscopy, respectively. Bioavailable PZ-1922 reversed scopolamine-induced cognitive deficits in the novel object recognition test. Furthermore, it displayed superior pro-cognitive properties compared to intepirdine (a 5-HT6R antagonist) in the AD model, which involved intracerebroventricular injection of an oligomeric solution of amyloid-β peptide (oAβ) in the T-maze test in rats. PZ-1922, but not intepirdine, restored levels of biomarkers characteristic of the debilitating effects of oAβ. These data support the potential of a multitarget approach involving the joint modulation of 5-HT6R/5-HT3R/MAO-B in AD.

Safety comparisons among monoamine oxidase inhibitors against Parkinson's disease using FDA adverse event reporting system

Monoamine oxidase B (MAO-B) inhibitors are used to control Parkinson's disease (PD). Selegiline, rasagiline, and safinamide are widely used as MAO-B inhibitors worldwide. Although these drugs inhibit MAO-B, there are pharmacological and chemical differences, such as the inhibitory activity, the non-dopaminergic properties in safinamide, and the amphetamine-like structure in selegiline. MAO-B inhibitors may differ in adverse events (AEs). However, differences in actual practical clinics are not fully investigated. A retrospective study was conducted using FAERS, the largest database of spontaneous adverse events. AE signals for MAO-B inhibitors, including selegiline, rasagiline, and safinamide, were detected using the reporting odds ratio method and compared. Hypocomplementemia, hepatic cyst, hepatic function abnormal, liver disorder and cholangitis were detected for selegiline as drug-specific signals. The amphetamine effect was not confirmed for any of the three MAO-B inhibitors. The tyramine reaction was detected as an AE signal only for rasagiline. Moreover, the REM sleep behavior disorder was not detected as an AE signal for safinamide, suggesting that non-dopaminergic effects might be beneficial. Considering the differences in AEs for MAO-B inhibitors will assist with the appropriate PD medication.

The effects of ketamine and methamphetamine on neurotransmitters, glutamate receptors, and conditioned place preference in rat

Combined methamphetamine (MA) and ketamine (KET) abuse is a serious issue. At present, however, few studies have explored the mechanism underlying their combined addiction. We established a rat conditioned place preference (CPP) model. We investigated the role of dopamine (DA), 5-hydroxytryptamine (5-HT), monoamine oxidase (MAO), glutamate receptor 1 (GluR1), and glutamate receptor 2 (GluR2) in combined MA and KET addiction. The expression levels of DA, 5-HT, and MAO were detected by enzyme-linked immunosorbent assay (ELISA), and the expressions levels of GluR1 and GluR2 were detected by western blotting. Our results showed that MA and KET successfully induced CPP in rats respectively, and KET enhanced MA-induced CPP effects, although not significantly, and KET can reduce the MA-induced increase in DA, 5-HT, MAO and promoted the MA-induced increase in GluR1 and GluR2. Therefore, it suggested that DA, 5-HT, MAO, GluR1, and GluR2 expression may be involved in the mechanism underlying MA and KET-induced drug addiction in rats. Moreover, When MA and KET are used in combination, KET appears to play a dual addictive and anti-addictive role in the regulation of MA addiction.

Two dimensional-QSAR and molecular dynamics studies of a selected class of aldoxime- and hydroxy-functionalized chalcones as monoamine oxidase-B inhibitors

Candidates generated from unsaturated ketone (chalcone) demonstrated as strong, reversible and specific monoamine oxidase-B (MAO-B) inhibitory activity. For the research on MAO-B inhibition, our team has synthesized and evaluated a panel of aldoxime-chalcone ethers (ACE) and hydroxylchalcones (HC). The MAO-B inhibitory activity of several candidates is in the micro- to nanomolar range in these series. The purpose of this research was to develop predictive QSAR models and look into the relation between MAO-B inhibition by aldoxime and hydroxyl-functionalized chalcones. It was shown that the molecular descriptors ETA Shape P, MDEO-12, ETA dBetaP, SpMax1 Bhi and ETA EtaP B are significant in the inhibitory action of the MAO-B target. Using the current 2D QSAR models, potential chalcone-based MAO-B inhibitors might be created. The lead molecules were further analyzed by the detailed molecular dynamics study to establish the stability of the ligand-enzyme complex.Communicated by Ramaswamy H. Sarma.

Liver Cancer Algorithm: A novel bio-inspired optimizer

This paper introduces a new bio-inspired optimization algorithm named the Liver Cancer Algorithm (LCA), which mimics the liver tumor growth and takeover process. It uses an evolutionary search approach that simulates the behavior of liver tumors when taking over the liver organ. The tumor's ability to replicate and spread to other organs inspires the algorithm. LCA algorithm is developed using genetic operators and a Random Opposition-Based Learning (ROBL) strategy to efficiently balance local and global searches and explore the search space. The algorithm's efficiency is tested on the IEEE Congress of Evolutionary Computation in 2020 (CEC'2020) benchmark functions and compared to seven widely used metaheuristic algorithms, including Genetic Algorithm (GA), particle swarm optimization (PSO), Differential Evolution (DE), Adaptive Guided Differential Evolution Algorithm (AGDE), Improved Multi-Operator Differential Evolution (IMODE), Harris Hawks Optimization (HHO), Runge-Kutta Optimization Algorithm (RUN), weIghted meaN oF vectOrs (INFO), and Coronavirus Herd Immunity Optimizer (CHIO). The statistical results of the convergence curve, boxplot, parameter space, and qualitative metrics show that the LCA algorithm performs competitively compared to well-known algorithms. Moreover, the versatility of the LCA algorithm extends beyond mathematical benchmark problems. It was also successfully applied to tackle the feature selection problem and optimize the support vector machine for various biomedical data classifications, resulting in the creation of the LCA-SVM model. The LCA-SVM model was evaluated in a total of twelve datasets, among which the MonoAmine Oxidase (MAO) dataset stood out, showing the highest performance compared to the other datasets. In particular, the LCA-SVM model achieved an impressive accuracy of 98.704% on the MAO dataset. This outstanding result demonstrates the efficacy and potential of the LCA-SVM approach in handling complex datasets and producing highly accurate predictions. The experimental results indicate that the LCA algorithm surpasses other methods to solve mathematical benchmark problems and feature selection.

Impact of Mandibular Angle Osteotomy Using a Geometric Mathematical Design on the Aesthetic Osteotomy Line: A Retrospective Observational Study

BACKGROUND

Mandibular angle osteotomy (MAO) is a frequently described technique in Eastern females. The success hinges on the precise positioning of the osteotomy line. The geometric mathematical method is viable. Therefore, we explored the impact of mandibular angle osteotomy using aesthetic standards and printed digital osteotomy templates (DOTs) on the aesthetic osteotomy line.

METHODS

This retrospective observational study included female patients with prominent mandibular angle (PMA) who underwent MAO at our hospital between January 2020 and March 2021. Thirty-three female patients were included, 22 in the DOTs group using new DOTs, and 11 in the traditional group using traditional free-hand techniques.

RESULTS

Regarding the width of the excised bone, the postoperative deviation from the preoperative plan was not significant in the DOTs group (0.5 ± 0.3 mm, P > 0.05), while the deviation was significant for the traditional group (2.5 ± 1.2 mm, P<0.05). The preparation time was longer in the DOTs group than in the traditional group (82 ± 11 vs. 53±4 min, P < 0.001). The osteotomy time and the operation time were shorter in the DOTs group than in the traditional group (osteotomy: 54 ± 5 vs. 73 ± 6 min; preparation: 124 ± 10 vs. 169 ± 13 min; both P < 0.001). The Likert (4.0 ± 0.5 vs. 1.0 ± 0.6, P = 0.006) and FACE-Q scores (17.5 ± 1.7 vs. 15.6 ± 1.3, P = 0.029) were higher in the DOTs group.

CONCLUSIONS

The new method of positioning the new aesthetic osteotomy line based on geometric analysis might provide a possible osteotomy method that strongly suggests effectiveness, safety, individualization, and accuracy, with a shorter operation and higher patient satisfaction.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

In Silico Neuroprotective Effects of Specific Rheum palmatum Metabolites on Parkinson's Disease Targets

Parkinson's disease (PD) is one of the large-scale health issues detrimental to human quality of life, and current treatments are only focused on neuroprotection and easing symptoms. This study evaluated in silico binding activity and estimated the stability of major metabolites in the roots of R. palmatum (RP) with main protein targets in Parkinson's disease and their ADMET properties. The major metabolites of RP were subjected to molecular docking and QSAR with α-synuclein, monoamine oxidase isoform B, catechol o-methyltransferase, and A2A adenosine receptor. From this, emodin had the greatest binding activity with Parkinson's disease targets. The chemical stability of the selected compounds was estimated using density functional theory analyses. The docked compounds showed good stability for inhibitory action compared to dopamine and levodopa. According to their structure-activity relationship, aloe-emodin, chrysophanol, emodin, and rhein exhibited good inhibitory activity to specific targets. Finally, mediocre pharmacokinetic properties were observed due to unexceptional blood-brain barrier penetration and safety profile. It was revealed that the major metabolites of RP may have good neuroprotective activity as an additional hit for PD drug development. Also, an association between redox-mediating and activities with PD-relevant protein targets was observed, potentially opening discussion on electrochemical mechanisms with biological functions.

PET Evaluation of the Novel F-18 Labeled Reversible Radioligand [18F]GEH200449 for Detection of Monoamine Oxidase-B in the Non-Human Primate Brain

Positron emission tomography (PET) using radioligands for the enzyme monoamine oxidase B (MAO-B) is increasingly applied as a marker for astrogliosis in neurodegenerative disorders. In the present study, a novel reversible fluorine-18 labeled MAO-B compound, [18F]GEH200449, was evaluated as a PET radioligand in non-human primates. PET studies of [18F]GEH200449 at baseline showed brain exposure (maximum concentration: 3.4-5.2 SUV; n = 5) within the range of that for suitable central nervous system radioligands and a regional distribution consistent with the known localization of MAO-B. Based on the quantitative assessment of [18F]GEH200449 data using the metabolite-corrected arterial plasma concentration as input function, the Logan graphical analysis was selected as the preferred method of quantification. The binding of [18F]GEH200449, as calculated based on regional estimates of the total distribution volume, was markedly inhibited (occupancy >80%) by the administration of the selective MAO-B ligands L-deprenyl (0.5 and 1.0 mg/kg) or rasagiline (0.75 mg/kg) prior to radioligand injection. Radioligand binding was displaceable by the administration of L-deprenyl (0.5 mg/kg) at 25 min after radioligand injection, thus supporting reversible binding to MAO-B. These observations support that [18F]GEH200449 is a reversible MAO-B radioligand suitable for applied studies in humans.

Virus infection participates in the occurrence and development of human diseases through monoamine oxidase

Monoamine oxidase (MAO) is a membrane-bound mitochondrial enzyme that maintains the steady state of neurotransmitters and other biogenic amines in biological systems through catalytic oxidation and deamination. MAO dysfunction is closely related to human neurological and psychiatric diseases and cancers. However, little is known about the relationship between MAO and viral infections in humans. This review summarises current research on how viral infections participate in the occurrence and development of human diseases through MAO. The viruses discussed in this review include hepatitis C virus, dengue virus, severe acute respiratory syndrome coronavirus 2, human immunodeficiency virus, Japanese encephalitis virus, Epstein-Barr virus, and human papillomavirus. This review also describes the effects of MAO inhibitors such as phenelzine, clorgyline, selegiline, M-30, and isatin on viral infectious diseases. This information will not only help us to better understand the role of MAO in the pathogenesis of viruses but will also provide new insights into the treatment and diagnosis of these viral diseases.

Hypothalamic GABRA5-positive neurons control obesity via astrocytic GABA

The lateral hypothalamic area (LHA) regulates food intake and energy balance. Although LHA neurons innervate adipose tissues, the identity of neurons that regulate fat is undefined. Here we show that GABRA5-positive neurons in LHA (GABRA5LHA) polysynaptically project to brown and white adipose tissues in the periphery. GABRA5LHA are a distinct subpopulation of GABAergic neurons and show decreased pacemaker firing in diet-induced obesity mouse models in males. Chemogenetic inhibition of GABRA5LHA suppresses fat thermogenesis and increases weight gain, whereas gene silencing of GABRA5 in LHA decreases weight gain. In the diet-induced obesity mouse model, GABRA5LHA are tonically inhibited by nearby reactive astrocytes releasing GABA, which is synthesized by monoamine oxidase B (Maob). Gene silencing of astrocytic Maob in LHA facilitates fat thermogenesis and reduces weight gain significantly without affecting food intake, which is recapitulated by administration of a Maob inhibitor, KDS2010. We propose that firing of GABRA5LHA suppresses fat accumulation and selective inhibition of astrocytic GABA is a molecular target for treating obesity.

Inhibition of Enzymes Involved in Neurodegenerative Disorders and Aβ1-40 Aggregation by Citrus limon Peel Polyphenol Extract

Alzheimer's (AD) and Parkinson's diseases (PD) are multifactorial neurogenerative disorders of the Central Nervous System causing severe cognitive and motor deficits in elderly people. Because treatment of AD and PD by synthetic drugs alleviates the symptoms often inducing side effects, many studies have aimed to find neuroprotective properties of diet polyphenols, compounds known to act on different cell signaling pathways. In this article, we analyzed the effect of polyphenols obtained from the agro-food industry waste of Citrus limon peel (LPE) on key enzymes of cholinergic and aminergic neurotransmission, such as butyryl cholinesterase (BuChE) and monoamine oxidases (MAO)-A/B, on Aβ1-40 aggregation and on superoxide dismutase (SOD) 1/2 that affect oxidative stress. In our in vitro assays, LPE acts as an enzyme inhibitor on BuChE (IC50 ~ 73 µM), MAO-A/B (IC50 ~ 80 µM), SOD 1/2 (IC50 ~ 10-20 µM) and interferes with Aβ1-40 peptide aggregation (IC50 ~ 170 µM). These results demonstrate that LPE behaves as a multitargeting agent against key factors of AD and PD by inhibiting to various extents BuChE, MAOs, and SODs and reducing Aβ-fibril aggregation. Therefore, LPE is a promising candidate for the prevention and management of AD and PD symptoms in combination with pharmacological therapies.

From Monoamine Oxidase Inhibition to Antiproliferative Activity: New Biological Perspectives for Polyamine Analogs

Monoamine oxidases (MAOs) are well-known pharmacological targets in neurological and neurodegenerative diseases. However, recent studies have revealed a new role for MAOs in certain types of cancer such as glioblastoma and prostate cancer, in which they have been found overexpressed. This finding is opening new frontiers for MAO inhibitors as potential antiproliferative agents. In light of our previous studies demonstrating how a polyamine scaffold can act as MAO inhibitor, our aim was to search for novel analogs with greater inhibitory potency for human MAOs and possibly with antiproliferative activity. A small in-house library of polyamine analogs (2-7) was selected to investigate the effect of constrained linkers between the inner amine functions of a polyamine backbone on the inhibitory potency. Compounds 4 and 5, characterized by a dianiline (4) or dianilide (5) moiety, emerged as the most potent, reversible, and mainly competitive MAO inhibitors (Ki < 1 μM). Additionally, they exhibited a high antiproliferative activity in the LN-229 human glioblastoma cell line (GI50 < 1 μM). The scaffold of compound 5 could represent a potential starting point for future development of anticancer agents endowed with MAO inhibitory activity.

Striking Neurochemical and Behavioral Differences in the Mode of Action of Selegiline and Rasagiline

Selegiline and rasagiline are two selective monoamine oxidase B (MAO-B) inhibitors used in the treatment of Parkinson's disease. In their clinical application, however, differences in L-dopa-sparing potencies have been observed. The aim of this study was to find neurochemical and behavioral explanations for the antiparkinsonian effects of these drugs. We found that selegiline possesses a dopaminergic enhancer effect: it stimulated the electrically induced [3H]dopamine release without influencing the resting [3H]dopamine release from rat striatal slices in 10-10-10-9 mol/L concentrations. Rasagiline added in 10-13 to 10-5 mol/L concentrations did not alter the resting or electrically stimulated [3H]dopamine release. Rasagiline (10-9 mol/L), however, suspended the stimulatory effect of selegiline on the electrically induced [3H]dopamine release. The trace amine-associated receptor 1 (TAAR1) antagonist EPPTB (10-8-10-7 mol/L) also inhibited the stimulatory effect of selegiline on [3H]dopamine release. The effect of selegiline in its enhancer dose (5.33 nmol/kg) against tetrabenazine-induced learning deficit measured in a shuttle box apparatus was abolished by a 5.84 nmol/kg dose of rasagiline. The selegiline metabolite (-)methamphetamine (10-9 mol/L) also exhibited enhancer activity on [3H]dopamine release. We have concluded that selegiline acts as an MAO-B inhibitor and a dopaminergic enhancer drug, and the latter relates to an agonist effect on TAAR1. In contrast, rasagiline is devoid of enhancer activity but may act as an antagonist on TAAR1.

Repeated Methamphetamine Administration Results in Axon Loss Prior to Somatic Loss of Substantia Nigra Pars Compacta and Locus Coeruleus Neurons in Male but Not Female Mice

Methamphetamine (meth) is a neurotoxic psychostimulant that increases monoamine oxidase (MAO)-dependent mitochondrial oxidant stress in axonal but not somatic compartments of substantia nigra pars compacta (SNc) and locus coeruleus (LC) neurons. Chronic meth administration results in the degeneration of SNc and LC neurons in male mice, and MAO inhibition is neuroprotective, suggesting that the deleterious effects of chronic meth begin in axons before advancing to the soma of SNc and LC neurons. To test this hypothesis, mice were administered meth (5 mg/kg) for 14, 21, or 28 days, and SNc and LC axonal lengths and numbers of neurons were quantified. In male mice, the SNc and LC axon lengths decreased with 14, 21, and 28 days of meth, whereas somatic loss was only observed after 28 days of meth; MAO inhibition (phenelzine; 20 mg/kg) prevented axonal and somatic loss of SNc and LC neurons. In contrast, chronic (28-day) meth had no effect on the axon length or numbers of SNc or LC neurons in female mice. The results demonstrate that repeated exposure to meth produces SNc and LC axonal deficits prior to somatic loss in male subjects, consistent with a dying-back pattern of degeneration, whereas female mice are resistant to chronic meth-induced degeneration.

Assembling a Cinnamyl Pharmacophore in the C3-Position of Substituted Isatins via Microwave-Assisted Synthesis: Development of a New Class of Monoamine Oxidase-B Inhibitors for the Treatment of Parkinson's Disease

Monoamine oxidase (MAO, EC 1.4.3.4) is responsible for the oxidative breakdown of both endogenous and exogenous amines and exists in MAO-A and MAO-B isomers. Eighteen indole-based phenylallylidene derivatives were synthesized via nucleophilic addition reactions comprising three sub-series, IHC, IHMC, and IHNC, and were developed and examined for their ability to inhibit MAO. Among them, compound IHC3 showed a strong MAO-B inhibitory effect with an IC50 (half-maximal inhibitory concentration) value of 1.672 μM, followed by IHC2 (IC50 = 16.934 μM). Additionally, IHC3 showed the highest selectivity index (SI) value of >23.92. The effectiveness of IHC3 was lower than the reference pargyline (0.14 μM); however, the SI value was higher than pargyline (17.16). Structurally, the IHC (-H in the B-ring) sub-series exhibited relatively stronger MAO-B inhibition than the others. In the IHC series, IHC3 (-F in the A-ring) exhibited stronger MAO-B suppression than the other substituted derivatives in the order -F > -Br > -Cl > -OCH3, -CH3, and -H at the 2-position in the A-ring. In the reversibility and enzyme kinetics experiments, IHC3 was a reversible inhibitor with a Ki value of 0.51 ± 0.15 μM for MAO-B. Further, it was observed that IHC3 greatly decreased the cell death caused by rotenone in SH-SY5Y neuroblastoma cells. A molecular docking study of the lead molecule was also performed to determine hypothetical interactions in the enzyme-binding cavity. These findings suggest that IHC3 is a strong, specific, and reversible MAO-B inhibitor that can be used to treat neurological diseases.

Structure Characterization and Immunomodulatory Activity of Misgurnus anguillicaudatus Carbohydrates

Misgurnus anguillicaudatus, also known as oriental weather loach, is widely consumed and favored in East Asia due to its superior nutritional values and excellent flavor. In this study, a crude Misgurnus anguillicaudatus carbohydrates (MAC) was isolated from Misgurnus anguillicaudatus. Subsequently, two parts, which were named MAO and MAP, respectively, were separated from MAC, and their primary structures and immunomodulatory activity were investigated. The results showed that MAO had a molecular weight of 2854 Da, and principally consisted of arabinose (77.11%) and rhamnose (21.97%), together with minor levels of fucose (0.92%); MAP, with a molecular weight of 3873 Da, was mainly composed of fucose (87.55%) and a small amount of rhamnose (8.86%) and galactose (3.59%). The in vitro assay showed that MAC could significantly enhance the proliferation of macrophages without cytotoxicity and increase the production of immune substances (TNF-α, IL-6). Together with Western blot results, we speculated that MAC could stimulate RAW264.7 murine macrophage cells to secrete TNF-α and IL-6 through up-regulating TLR4-MAPK-p38 signaling pathways. The results indicated that MAC could be a potential immune agent and might provide meaningful information for further chain conformation and immune mechanism research.