Catecholamine Neurotransmitters Research Articles

Changes of Dopamine and Tyrosine Hydroxylase Levels in the Brain of Germ-free Mice.

Dopamine (DA) is one of the most important catecholamine neurotransmitters in the central nervous system. The degeneration and deletion of dopaminergic neurons are closely linked to Parkinson's disease (PD) and other psychiatric or neurological diseases. Several studies have been suggesting that intestinal microorganisms are associated with the occurrence of central nervous diseases, including diseases that are closely related to dopaminergic neurons. However, the intestinal microorganism's regulation of dopaminergic neurons in the brain is largely unknown. This study aimed to investigate the hypothetical differences of DA and its synthase tyrosine hydroxylase (TH) expression in different parts of the brain of germ free (GF) mice. Several studies in recent years have shown that commensal intestinal microbiota promotes changes in DA receptor expression, DA levels, and affects this monoamine turnover. Germ free (GF) and specific pathogen free (SPF) C57b/L male mice were used to analyze TH mRNA and expression levels, and DA levels in the frontal cortex, hippocampus, striatum, and cerebellum, using real time PCR, western blotting, and ELISA tools. Compared with SPF mice, the TH mRNA levels were decreased in the cerebellum of GF mice, while the TH protein expression was tended to increase in the hippocampus, and conversely showed significant decrease in the striatum. The average optical density (AOD) of TH immunoreactive nerve fibers and the number of axons in striatum of mice in GF group were significantly lower than that in SPF group. Compared with SPF mice, the DA concentration in the hippocampus, striatum and frontal cortex of GF mice was decreased in GF mice. The changes of DA and its synthase TH in the brain of GF mice showed that the absence of conventional intestinal microbiota had certain regulatory effects on central dopaminergic nervous system, which is considered helpful for studying the effect of commensal intestinal flora on diseases related to impaired dopaminergic nerve system.

Roles of Pancreatic Islet Catecholamine Neurotransmitters in Glycemic Control and in Antipsychotic Drug-Induced Dysglycemia.

Catecholamine neurotransmitters dopamine (DA) and norepinephrine (NE) are essential for a myriad of functions throughout the central nervous system, including metabolic regulation. These molecules are also present in the pancreas, and their study may shed light on the effects of peripheral neurotransmission on glycemic control. Though sympathetic innervation to islets provides NE that signals at local α-cell and β-cell adrenergic receptors to modify hormone secretion, α-cells and β-cells also synthesize catecholamines locally. We propose a model where α-cells and β-cells take up catecholamine precursors in response to postprandial availability, preferentially synthesizing DA. The newly synthesized DA signals in an autocrine/paracrine manner to regulate insulin and glucagon secretion and maintain glycemic control. This enables islets to couple local catecholamine signaling to changes in nutritional state. We also contend that the DA receptors expressed by α-cells and β-cells are targeted by antipsychotic drugs (APDs)-some of the most widely prescribed medications today. Blockade of local DA signaling contributes significantly to APD-induced dysglycemia, a major contributor to treatment discontinuation and development of diabetes. Thus, elucidating the peripheral actions of catecholamines will provide new insights into the regulation of metabolic pathways and may lead to novel, more effective strategies to tune metabolism and treat diabetes.

Miro1 R272Q disrupts mitochondrial calcium handling and neurotransmitter uptake in dopaminergic neurons.

The Rho GTPase Miro1, located at the mitochondrial outer membrane is known to properly distribute mitochondria to synapses, aid calcium buffering and initiate PINK1-Parkin mediated mitophagy. Several heterozygous RHOT1/Miro1 variants were identified in sporadic Parkinson's disease patients. Miro1 R272Q is located within a calcium binding domain, but the functional outcome of this point mutation and its contribution to the development of disease are unclear. To address this, we introduced a heterozygous RHOT1/Miro1 R272Q point mutation in healthy induced pluripotent stem cells. In dopaminergic neurons, Miro1 R272Q does not affect Miro1 protein levels, CCCP-induced mitophagy, nor mitochondrial movement yet causes the fragmentation of mitochondria with reduction of cristae and ATP5A. Inhibition of the mitochondrial calcium uniporter phenocopied Miro1 R272Q cytosolic calcium response to Thapsigargin in active neurons, a similar effect was observed during the calcium buffering phase in Miro1 knockdown neuroblastoma cells. Altered mitochondrial calcium regulation is associated with reduced mitochondrial respiration and reduced catecholamine neurotransmitter uptake. Synaptic changes are not coupled to dopamine distribution or dopamine transporters but are linked to Miro1 R272Q-related calcium handling via the mitochondria concomitant with defective dopamine regulation at the mitochondrial surface by monoamine oxidase. We conclude that the Miro1 R272Q heterozygous point mutation dampens mitochondrial-calcium regulation and mitochondrial capacity via events at the outer membrane that are sufficient to disrupt dopaminergic function.

Sex-Dimorphic Glucocorticoid Receptor Regulation of Hypothalamic Primary Astrocyte Glycogen Metabolism: Interaction with Norepinephrine.

Astrocyte glycogen is a critical metabolic variable that impacts hypothalamic control of glucostasis. Glucocorticoid hormones regulate peripheral glycogen, but their effects on hypothalamic glycogen are not known. A hypothalamic astrocyte primary culture model was used to investigate the premise that glucocorticoids impose sex-dimorphic independent and interactive control of glycogen metabolic enzyme protein expression and glycogen accumulation. The glucocorticoid receptor (GR) agonist dexamethasone (DEX) down-regulated glycogen synthase (GS), glycogen phosphorylase (GP)-brain type (GPbb), and GP-muscle type (GPmm) proteins in glucose-supplied male astrocytes, but enhanced these profiles in female. The catecholamine neurotransmitter norepinephrine (NE) did not alter these proteins, but amplified DEX inhibition of GS and GPbb in male or abolished GR stimulation of GPmm in female. In both sexes, DEX and NE individually increased glycogen content, but DEX attenuated the magnitude of noradrenergic stimulation. Glucoprivation suppressed GS, GPbb, and GPmm in male, but not female astrocytes, and elevated or diminished glycogen in these sexes, respectively. Glucose-deprived astrocytes exhibit GR-dependent induced glycogen accumulation in both sexes, and corresponding loss (male) or attenuation (female) of noradrenergic-dependent glycogen build-up. Current evidence for GR augmentation of hypothalamic astrocyte glycogen content in each sex, yet divergent effects on glycogen enzyme proteins infers that glucocorticoids may elicit opposite adjustments in glycogen turnover in each sex. Results document GR modulation of NE stimulation of glycogen accumulation in the presence (male and female) or absence (female) of glucose. Outcomes provide novel proof that astrocyte energy status influences the magnitude of GR and NE signal effects on glycogen mass.

CNSC-29. INVESTIGATING THE INFLUENCE OF DOPAMINERGIC ACTIVITY ON THE GLIOBLASTOMA NICHE

Abstract Glioblastoma (GBM) is an incurable disease of adults and children and the deadliest form of central nervous system (CNS) malignancy. Despite major advances in our understanding of GBM biology in recent years, the prognosis for patients who develop this disease has not improved. If we hope to find new treatments for GBM that are safe and effective, we desperately need to reform our thinking. The brain’s chemical milieu is rich with neurotransmitters, and our lab’s screen of 680 neuroactive compounds on patient-derived glioblastoma stem cells (GSCs) in vitro strongly implicates neurotransmitter pathways as critical regulators of the GSC niche. More specifically, disrupting dopamine signaling by inhibiting its receptor D4 on GSCs causes substantial GSC apoptosis in vitro and attenuates GBM growth in vivo (Dolma et al., Cancer Cell, 2016). Dopamine (DA) is a catecholamine neurotransmitter that is essential for reward learning and movement and has numerous roles in cognition. Consequentially, dysregulation of DA signaling is associated with a diversity of brain diseases ranging from drug addiction to schizophrenia to Parkinson’s. Our research aims to determine how DA signaling affects normal neural stem cell (NSC) and tumorigenic GSC populations, as we hypothesize that GSCs arising/residing in DA projection zones exploit dopaminergic (DAergic) activity for GBM growth. Toward these aims, we have developed in vivo model systems and harnessed them to study NSC and GSC niches in the context of either controlled activation or depletion of DAergic neurons. These manipulations of the brain's DAergic neurons are achieved using optogenetic stimulation, genetic depletion, and neurotoxin-mediated ablation in mice. Ultimately, unraveling the dopaminergic influence on GBM may contribute to a redeployment of existing treatments—that modulate DA signaling and are already approved to treat CNS disorders—to patients with this deadly brain cancer.

Normative Values of Neuromelanin-Sensitive MRI Signal in Older Adults Obtained Using a Turbo Spin Echo Sequence.

The integrity and function of catecholamine neurotransmitter systems can be assessed using neuromelanin-sensitive MRI (NM-MRI). The relevance of this method to neurodegenerative and psychiatric disorders is becoming increasingly evident, and it has potential as a clinical biomarker. To support future application of NM-MRI as a clinical biomarker by defining the normative range of NM-MRI signal and volume metrics in cognitively normal older adults. Prospective. A total of 152 cognitively normal older adults aged 53-86 years old, including 41 participants who had follow-up NM-MRI data collected 9-16months later. A 3.0 T; NM-MRI turbo spin echo and T1-weighted magnetization-prepared rapid acquisition with gradient echo sequences. NM-MRI images were processed to yield summary measures of volume and signal (contrast-to-noise ratio, CNR) for the substantia nigra (SN) and locus coeruleus (LC) using a recently developed software employing a fully automated algorithm. Change in these metrics over time was also assessed. Mean and standard deviation of NM-MRI metrics were calculated; change over time was tested for significance using 1-sample t-tests. P values < 0.05 were considered statistically significant. At baseline SN signal (CNR) was 10.02% (left) and 10.28% (right) and LC signal was 24.71% (left) and 20.42% (right). Baseline SN volume was 576 mm3 (left) and 540 mm3 (right) and LC volume was 6.31 mm3 (left) and 6.30 mm3 (right). The only NM-MRI metric showing significant change was a decrease in left SN volume (t40 =-2.57, P=0.014). We report normative values for NM-MRI signal and volume in the SN and LC of cognitively normal older adults and explore their change over time. These values may help future efforts to use NM-MRI as a clinical biomarker by facilitating identification of patients with extreme NM-MRI values. 1.

A photoluminescence sensor for in-situ monitoring of the dopamine neurotransmitters released from PC12 cells

Constructing simple, stable, fast, and sensitive neurotransmitter-based sensors is a promising tool to diagnose neurological diseases. Dopamine (DA), “a catecholamine neurotransmitter” is important in transmitting nerve impulses. Therefore, great attention is taken to monitor DA concentrations received. The challenge in developing a DA-based sensor is to enhance its stability and sensitivity. Thus, we have used o-phthalaldehyde (OPA)/2-mercapto ethanol (2ME)/mesoporous silica instated of 2ME in solution. Here we have successfully developed a fluorescence DA neurotransmitters sensor. The sensor was used for detecting a wide range of concentrations of DA (5 nM to 5 µM). Effects of pH (4.3–11.4) and temperatures (25–70 °C) on the sensor efficiency were investigated. The detection limit was 1.35 × 10−11 mol/dm3, which is lower than the normal DA level in the central nervous system. The results indicated that using OPA/2ME/MSNPs has long-time stability over a year of its preparation. Moreover, the developed sensor showed high specificity towards DA in the presence of different interferences such as ascorbic acid or another catecholamine neurotransmitter such as γ-aminobutyric acid. Finally, the fabricated biosensor was used to monitor the DA neurotransmitter released from PC12 cells. Hence, it was successfully developed a simple and stable probe for accurate photoluminescence detection of DA neurotransmitters.

Squarate-Based Metal-Organic Frameworks for Highly Selective and Sensitive Electrochemical Sensing of Dopamine

Dopamine (DA) is an important catecholamine neurotransmitter associated with learning, depression, addiction, and memory loss with simultaneously coordinating movement and reward-associated behavior. It is very important to design highly effective and sensitive sensors for the detection of DA. However, it remains a challenge for detecting DA to obtain selectively and rapidly sensing materials. In this work, we chose octahedral-coordinated squarate-based MOFs with dense Lewis active centers as electrode materials to investigate the electrochemical performance of dopamine oxidation. The multiple ligand functional groups in squarate-based MOFs enable noncovalent interaction with diols, amines, and phenyl groups of DA molecules through electrostatic, H-bonding, and/or π–π stacking interactions. The modified electrode exhibits a wide linear current response range between 2 μM and 400 μM for DA, and the sensor shows significant selectivity and stability. This work enriches the application library of redox-active squarate compounds and can give us a better comprehension of the design and selection of electrode materials for electrochemical sensing and even more catalysis-related research.

Efficient electrochemical detection of dopamine with carbon nanocoils and copper tetra(p-methoxyphenyl)porphyrin nanocomposite

Dopamine (DA), a critical catecholamine neurotransmitter, is responsible for normal functioning of body. Its dysregulation causes cognitive disturbances. Thus, an efficient real time monitoring of DA in clinical samples is required. Herein we report a novel nanocomposite comprising of carbon nanocoils (CNC) and copper tetra(p-methoxyphenyl)porphyrin (CuTMePP) for efficient electrochemical detection of dopamine that was characterized by FTIR, UV/vis., Raman, XRD, SEM, TEM and energy dispersive X-ray techniques. The electrochemical studies were performed using cyclic voltammetry (CV), electrochemical impedance spectroscopy and differential pulse voltammetry (DPV). CNC/CuTMePP/glassy carbon (GC) has demonstrated two linear trends between current and concentration i.e. 0.1 to 100.0 µM and 100.0 to 800.0 µM. Limit of detection (LoD), limit of quantification (LoQ) and sensitivity of the electrode in the concentration range of 0.1 to 100.0 µM was 50.0 nM, 167.0 nM and 1.76 µAµM-1cm−2, respectively using CV. With DPV, the LoD, LoQ and sensitivity were found to be 64.0 nM, 211.0 nM and 0.75 µAµM-1cm−2, respectively obtained in a concentration range of 0.1 to 100.0 µM. The as prepared sensor exhibited good intra/inter-day stabilities, reproducibility, excellent recovery in the human serum samples, presented significant clinical dopamine detection and showed comparable results with other work in literature.

The Role of Beta-Adrenergic Receptors in Depression and Resilience.

Norepinephrine is a catecholamine neurotransmitter that has been extensively implicated in the neurobiology of major depressive disorder (MDD). An accumulating body of evidence indicates that investigations into the action of norepinephrine at the synaptic/receptor level hold high potential for a better understanding of MDD neuropathology and introduce possibilities for developing novel treatments for depression. In this review article, we discuss recent advances in depression neuropathology and the effects of antidepressant medications based on preclinical and clinical studies related to beta-adrenergic receptor subtypes. We also highlight a beta-3 adrenergic receptor-involved mechanism that promotes stress resilience, through which antidepressant efficacy is achieved in both rodent models for depression and patients with major depression—an alternative therapeutic strategy that is conceptually different from the typical therapeutic approach in which treatment efficacy is achieved by reversing pathological alterations rather than by enhancing a good mechanism such as natural resilience. Altogether, in this review, we systematically describe the role of beta-adrenergic receptors in depression and stress resilience and provide a new avenue for developing a conceptually innovative treatment for depression.

Intramolecular hydrogen bond driven specific nucleophilic addition for highly selective detection of NE and its tumor imaging

Pheochromocytoma is an enormous threat to people's health due to its complications. However, it is only known to secrete peripheral catecholamine neurotransmitters (including norepinephrine), but the changes of catecholamine in tumor tissues are unclear. Detection of individual catecholamine neurotransmitters has been a major challenge. However, NE has a unique amino ethanol structure. Here we present a particular mechanism, which was an interesting discovery. In this study, we found that NE can react with pyranium salt in a rapid specific addition reaction. Furthermore, coumarin conjugation can construct a ratiometric fluorescence response. Compared with previous benzothiodiazole sites, the selectivity and reaction rate have been improved, especially the reaction rate has been significantly accelerated. In view of the excellent reactivity, the probe was further used for norepinephrine in pheochromocytoma cell and tumor tissue. Conceptually, we propose a new site to detect norepinephrine, which provides a new idea for the design of norepinephrine fluorescent probe and will enhance the understanding of the physiological and pathological mechanism of norepinephrine.

PSXIII-B-3 Determining Phenylalanine and Tyrosine Amino Acid Requirements in Growing Labrador Retrievers Using the Direct Amino Acid Oxidation Technique

Abstract Phenylalanine and tyrosine are important amino acids for synthesis of proteins, catecholamine neurotransmitters, and melanin in canines. Since phenylalanine (Phe) is converted to tyrosine (Tyr), this experiment used the direct amino acid oxidation (DAAO) technique to determine the phenylalanine requirement and phenylalanine plus tyrosine requirements for growing Labrador Retrievers. The Phe requirement was separated from Phe plus Tyr requirement by supplementing the test diets utilized for Phe requirements with 1.48% crystalline Tyr. A total of twelve dogs were used in two trials to determine the Phe and Phe + Tyr requirements in growing puppies ( &amp;gt;14wk-1yr). Control diet was fed for two days, followed by a testing day where an experimental diet was fed, a tracer amino acid was supplied, and breath samples were collected. On test day, a priming dose of L-[1-13C] phenylalanine (Cambridge Isotope Laboratories, Inc.) based on the dog’s body weight was supplied, followed by enteral feeding of [1-13C]Phe every 30 minutes, spanning a four hour period. Respiration masks were placed on each subject every 30 minutes (Oxymax, Columbus Instruments), 13CO2 collected, and enrichment determined by isotope ratio mass spectrometry (IRMS). Results for IRMS were converted to atom percent excess (APE) and analyzed using a segmented model (JMP® Pro 15). Results showed that Phe mean and population safe requirements were 1.29 +/- 0.26 g/1000 kcal, while the Phe + Tyr requirements were 1.95 +/- 0.65 g/1000 kcal. Knowledge gathered through these studies is invaluable as both the Phe and Phe plus Tyr dietary requirements for growing Labrador Retriever puppies were determined.

Quantification of monoamine biomarkers in cerebrospinal fluid: Comparison of a UHPLC-MS/MS method with a UHPLC coupled to fluorescence detection method.

Inborn errors of monoamine neurotransmitter metabolism are rare genetic diseases classified as catecholamine and serotonin metabolism disorders or neurotransmitter transportopathies. To diagnose these orphan diseases, monoamine metabolites have been identified and validated as cerebrospinal fluid (CSF) biomarkers: 5-hydroxy-tryptophane, 5-hydroxy-indol-acetic acid, 3-ortho-methyl-DOPA, homovanillic acid, and 3-methoxy-4-hydroxyphenylglycol. The present work presents a UHPLC-MS/MS method developed for the quantification of these metabolites in CSF and compares it with a previously described UHPLC with fluorescence detection (UHPLC-FD) method. MS/MS detection was performed in positive electrospray ionization and multiple reaction monitoring mode. The UHPLC-MS/MS and UHPLC-FD methods were validated in terms of accuracy, linearity, precision and matrix effect. The lower limits of quantification (LLOQ) ranged between 0.5and 10nm and between 1 and 5nm for the UHPLC-MS/MS method and the UHPLC-FD one, respectively. We verified the applicability of both methods by analyzing 30 CSF samples. The measured concentrations were comparable with the reference values described in the literature. The two methods allowed pathological samples to be distinguished from healthy ones for clinical diagnosis. UHPLC-MS/MS and UHPLC-FD methods exhibited very close LLOQs. As the UHPLC-MS/MS method is more selective, it allows faster analysis with a run time of 6min per run vs. 10min for the UHPLC-FD method.

Versatile selective absorption-based optical fiber toward epinephrine detection

A versatile lossy mode resonance (LMR) sensor is developed for Epinephrine monitoring based on the state-of-the-art molecular imprinting technique over an optical fiber. The optical absorption concept of the LMR-based sensor is proven by incorporating an amino silane-functionalized graphene oxide (SiO2-NH2@GO) as an adhesive layer for grafting Epinephrine imprinting polydopamine (Ep-IPDA) as a sensing layer onto the optical fiber curved surface. The accurate structural and morphological characterization confirmed the rough crystalline and spherical particles for Ep-IPDA and SiO2-NH2-GO onto optical fiber curved surface, while spectroscopic analysis confirms the formation of imprinting polymer and desirable absorbance characteristics. The optimized probe exhibits an excellent performance with the maximum sensitivity within two intervals of 0.3–1 µM and 1–90 µM along with the linearity coefficient of R2 = 0.99 possessing a low limit of detection of 0.07 µM. Additionally, this sensor selectively detects Ep in the presence of other species and showed good recovery in human urine and injection samples. This work opens a new avenue for developing bio-inspired LMR-based optical fiber biosensors and could be further extended to detect other catecholamine neurotransmitters.

Electrochemical behavior of intramolecular cyclization reaction of catecholamines at carbon nanotube/carboxymethylcellulose electrode

• Intramolecular cyclization reaction of catecholamines is conducted. • A electron transfer-chemical reaction-electron transfer (ECE) process is addressed. • A carbon nanotube (CNT)/carboxymethylcellulose (CMC) electrode is used. • The electrochemical behavior in the ECE mechanism is justified by DigiElch simulation. • This work contributes to the in-depth understanding of catecholamines. Neurotransmitter catecholamines [dopamine (DA), epinephrine (EP), norepinephrine (NE), and 3,4-dihydroxyphenylalanine (DOPA)] exhibit an electron transfer-chemical reaction-electron transfer (ECE) reaction, wherein two electron transfer reactions are connected by a chemical reaction. The electrochemical behavior of catecholamines depends strongly on the kinetic property of the chemical reaction, that is, the intramolecular cyclization rate. This work provides systematic knowledge of the intramolecular cyclization reactions of catecholamines in the ECE process. We adopt a carbon nanotube (CNT)/carboxymethylcellulose (CMC) electrode because it shows an apparent ECE profile in cyclic voltammetry (CV) results, unlike other electrodes. The analysis of the electrochemical behavior in the ECE mechanism is justified by simulations using the DigiElch simulation program. The cyclization rate of various catecholamines follows a specific order: DA < NE < DOPA < EP. Because the cyclization step involves hydrogen ions, the rate depends on pH—the cyclization rate increases with a decrease in pH. The electrochemical behavior due to cyclization is verified on the basis of the CV results, particularly the change in the intensity of the cathodic peak (Peak Ic) due to the reduction of catecholamine- o -quinone. The intensity of Peak Ic is determined by (i) the type of catecholamines, (ii) pH, and (iii) the time scale of CV. This work contributes to the in-depth understanding of catecholamines and the development of novel strategies for the electrochemical sensing of catecholamines.

Neurochemical Concentration Prediction Using Deep Learning vs Principal Component Regression in Fast Scan Cyclic Voltammetry: A Comparison Study.

Neurotransmitters, such as dopamine and serotonin, are responsible for mediating a wide array of neurologic functions, from memory to motivation. From measurements using fast scan cyclic voltammetry (FSCV), one of the main tools used to detect synaptic efflux of neurochemicals in vivo, principal component regression (PCR), has been commonly used to predict the identity and concentrations of neurotransmitters. However, the sensitivity and discrimination performance of PCR have room for improvement, especially for analyzing mixtures of similar oxidizable neurochemicals. Deep learning may be able to address these challenges. To date, there have been a few studies to apply machine learning to FSCV, but no attempt to apply deep learning to neurotransmitter mixture discrimination and no comparative study have been performed between PCR and deep learning methods to demonstrate which is more accurate for FSCV analysis so far. In this study, we compared the neurochemical identification and concentration estimation performance of PCR and deep learning in an analysis of FSCV recordings of catecholamine and indolamine neurotransmitters. Both analysis methods were tested on in vitro FSCV data with a single or mixture of neurotransmitters at the desired concentration. In addition, the estimation performance of PCR and deep learning was compared in incorporation with in vivo experiments to evaluate the practical usage. Pharmacological tests were also conducted to see whether deep learning would track the increased amount of catecholamine levels in the brain. Using conventional FSCV, we used five electrodes and recorded in vitro background-subtracted cyclic voltammograms from four neurotransmitters, dopamine, epinephrine, norepinephrine, and serotonin, with five concentrations of each substance, as well as various mixtures of the four analytes. The results showed that the identification accuracy errors were reduced 5-20% by using deep learning compared to using PCR for mixture analysis, and the two methods were comparable for single analyte analysis. The applied deep-learning-based method demonstrated not only higher identification accuracy but also better discrimination performance than PCR for mixtures of neurochemicals and even for in vivo testing. Therefore, we suggest that deep learning should be chosen as a more reliable tool to analyze FSCV data compared to conventional PCR methods although further work is still needed on developing complete validation procedures prior to widespread use.

Self-assembled cyclodextrins-based nanostructures on indium-tin-oxide for a detection of catecholamine neurotransmitters

Host-guest supramolecular systems are the leading technology to mimic biological systems. The current rapid development of non-enzymatic electrochemical sensors of neurotransmitters urges a focus towards the host-guest system on electrode that enables to selectively bind these analytes with an electrochemical response. In this study, novel method to deposit β- and γ-cyclodextrin-based self-assembled nanostructures with the sub-nanometer scale size cavities on the indium-tin-oxide glass surface was developed. The surfaces were characterized using the electrochemical, vibrational spectroscopy, and atomic force microscopy methods. We have demonstrated that these nanostructures can be easily prepared and regenerated. Our performed theoretical computations demonstrated that neutral and protonated forms of the neurotransmitters can be assembled into the cavities and reduce the ionization potential of the analytes. The electrodes with these nanostructures showed the electrochemical response to dopamine and adrenaline as the catecholamine neurotransmitters. These electrodes provide the low limit of detections in nM level, display good selectivity for these catecholamines over co-existing interferential compounds in living cells. The key advantages of the presented electrochemical systems are their simple and cheap preparation, and the ability to achieve the low levels of catecholamine concentration detections.

Behavioral disturbances induced by cyanobacterial oligopeptides microginin-FR1, anabaenopeptin-A and microcystin-LR are associated with neuromotoric and cytotoxic changes in Brachionus calyciflorus

Aquatic animals are exposed to various cyanobacterial products released concomitantly to the environment by decaying blooms. Although there exist results on the toxicity of cyanobacterial extracts little is known on the influence of pure oligopeptides or their mixtures and elucidated mechanisms of behavioral toxicity in zooplanktonic organisms. Therefore, the aim of the present study was to assess the effects of single and mixed pure cyanobacterial oligopeptides: microginin FR-1 (MG-FR1), anabaenopeptin-A (ANA-A) and microcystin-LR (MC-LR) at various concentrations on the swimming behavior and catecholamine neurotransmitter activity, muscular F-actin structure, DNA nuclear content and cell viability of a model rotifer Brachionus calyciflorus. Swimming behavior was analyzed with the use of video digital analysis. Fluorescent microscopy imaging was used to analyze neuromotoric biomarkers in the whole organisms: neuromediator release (by staining with EC517 probe), muscle F-actin filaments (by staining with blue phalloidin dye). DNA content and cytotoxicity was also determined by Hoechst 34580 and propidium iodide double staining, respectively. The results showed that single oligopeptides inhibited all the tested endpoints. The binary mixtures induced synergistic interaction on swimming speed except for MG-FR1 +MC-LR which was nearly additive. Both binary and ternary mixtures also synergistically degraded F-actin and triggered cytotoxic effects visible in the whole organisms. Antagonistic inhibitory effects of all the binary mixtures were found on catecholamine neurotransmitter activity, however the ternary mixture induced additive toxicity. Antagonistic effects of both binary and ternary mixtures were also noted on nuclear DNA content. The results of the study suggest that both depression of neurotransmission and impairment of muscle F-actin structure in muscles may contribute to mechanisms of Brachionus swimming speed inhibition by the tested single cyanobacterial oligopeptides and their mixtures. The study also showed that natural exposure of rotifers to mixtures of these cyanobacterial metabolites may result in different level of interactive toxicity with antagonistic, additive synergistic effects depending on the variants and concentrations present in the environment.

Non-enzymatic electrochemical sensing of dopamine from COVID-19 quarantine person

The worldwide outbreak of COVID-19 pandemic, is not only a great threat to the victim life but it is leaving invisible devastating negative affect on mental health of quarantined individual because of isolation, depression, bereavement, and loss of income. Therefore, the precise monitoring catecholamine neurotransmitters specifically of dopamine (DA) is of great importance to assess the mental health. Thus, herein we have synthesized Co-based zeolitic imidazolate framework (ZIF-67) through solvothermal method for precise monitoring of DA. To facilitate the fast transportation of ions, highly conductive polymer, poly(3,4-ethylenedioxythiophene; PEDOT) has been integrated on the surface of ZIF-67 which not only provides the smooth pathway for ions/electrons transportation but also saves the electrode from pulverization. The fabricated ZIF-67/PEDOT electrode shows a significant sensing performance towards DA detection in terms of short diffusion pathways by expositing more active sites, over good linear range (15–240 μM) and a low detection limit of (0.04 μM) even in the coexistence of the potentially interfering molecules. The developed ZIF-67/PEDOT sensor was successfully employed for sensitive and selective monitoring of DA from COVID-19 quarantined person blood, thus suggesting reliability of the developed electrode.

Analysis of neurotransmitter catecholamines and related amines in human urine and serum by chromatography and capillary electrophoresis with 1, 3, 5, 7-tetramethyl-8-(N-hydroxysuccinimidyl propionic ester)-difluoro-boradiaza-s-indacene

Abstract Two sensitive and effective methods were developed for the detection of catecholamines and related biogenic amines (dopamine, epinephrine, norepinephrine, serotonin, levodopa and tyramine) using high performance liquid chromatography with fluorescence detection and capillary electrophoresis with laser-induced fluorescence detection. A BODIPY fluorescent dye, 1, 3, 5, 7-tetramethyl-8-(N-hydroxysuccinimidyl propionic ester)-difluoroboradiaza- s-indacene was used as pre-column derivatization reagent. The separation and derivatization conditions were optimized in detail. In high performance liquid chromatography with fluorescence detection method, the derivatization reaction was completed at 35 °C for 20 min. At the wavelength of λ ex/λ em = 493 nm/513 nm, dopamine, epinephrine, norepinephrine, and levodopa derivatives achieved baseline separation within 15 min. The limits of detection (S/N = 3) were 1.0, 2.0, 5.0, and 0.5 nmol/L, respectively. In capillary electrophoresis with laser-induced fluorescence detection method, the derivatization reaction was completed at 25 °C for 20 min. Serotonin, tyramine and dopamine derivatives reached baseline separation within 10 min at the wavelength of λ ex = 473 nm. The limits of detection (S/N = 3) for serotonin, tyramine, and dopamine were 0.3, 0.02, and 0.2 nmol/L, respectively. The amino compounds in human serum and urine samples were detected successfully, and the recoveries were 93.3%–106.7% and 91.0%–103.1%, respectively.