Injection Of Dopamine Research Articles

Voltammetric Detection of Catechol and Dopamine Based on a Supramolecular Composite Prepared from Multifarene[3,3] and Reduced Graphene Oxide

AbstractA selective and sensitive modified‐electrode for catechol and dopamine was presented with supramolecular recognition accomplished by making use of the macrocyclic host multifarene[3,3] that was used as a composite with reduced graphene oxide. The morphologies and electrochemical nature of the composite were characterized by atomic force microscopy, transmission electron microscopy, cyclic voltammetry and differential pulse anodic voltammetry. The modified electrode, best operated at a potential around 0.16 V vs. Ag/AgCl, displayed a differential pulse voltammetric response in the linear concentration range of 10–100 nM within a detection limit of 0.51 nM (at S/N=3). It was further applied to detect dopamine (at a working potential of 0.18 V vs. Ag/AgCl) in the linear concentration range of 10–100 nM with a detection limit of 0.62 nM. The modified electrode also exhibited satisfactory results to the determination of dopamine injections. The constructed modified electrode for dopamine detection was investigated in the presence of the interfering substances including glucose, urea and ascorbic acid, indicating a good selectivity.

Electrochemical Determination of Dopamine at Pre-Anodized Helical Multi-Walled Carbon Nanotubes Modified Glassy Carbon Electrode

In this article we electrochemically investigated the determination of dopamine (DA) at pre-anodized helical multi-walled carbon nanotubes (H-MWCNTs) modified glassy carbon electrode (GCE) by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The pre-anodized H-MWCNTs/GCE could catalyze DA redox reaction greatly, and the oxidation current of DA from DPV measurement on pre-anodized H-MWCNTs/GCE was about 25 time bigger than on GCE. Furthermore, the pre-anodized H-MWCNTs/GCE could separate the oxidation peak potentials of DA, ascorbic acid (AA) and uric acid (UA) with well-defined peak separation as 164 mV for DA and UA, and 208 mV for DA and AA. The calibration curves of DA were obtained linearly in the range of 1 × 10−7 ∼ 2 × 10−6 M and 6 × 10−5 ∼ 2 × 10−4 M with the limit of detection (LOD, S/N = 3) and the limit of quantification (LOQ, S/N = 10) as 2.1 × 10−8 M and 7.0 × 10−8 M respectively. The sensor had been applied for DA measurement in dopamine injection samples with satisfactory results.

Selective Electrochemical Determination of Dopamine with Molecularly Imprinted Poly(Carbazole‐co‐Aniline) Electrode Decorated with Gold Nanoparticles

AbstractDopamine (DA) is a significant neurotransmitter in the central nervous system, coexisting with uric acid (UA) and ascorbic acid (AA). UA and AA are easily oxidizable compounds having potentials close to that of DA for electrochemical analysis, resulting in overlapping voltammetric response. In this work, a novel molecularly imprinted (MI) electrochemical sensor was proposed for selective determination of DA (in the presence of up to 80‐fold excess of UA and AA), relying on gold nanoparticles (Aunano)‐decorated glassy carbon (GC) electrode coated with poly(carbazole (Cz)‐co‐aniline (ANI)) copolymer film incorporating DA as template (DA imprinted‐GC/P(Cz‐co‐ANI)‐Aunano electrode, DA‐MIP‐Aunano electrode). The DA recognizing sensor electrode showed great electroactivity for analyte oxidation in 0.2 mol L−1 pH 7 phosphate buffer. Square wave voltammetry (SWV) was performed within 10−4–10−5 mol L−1 of DA, of which the oxidation peak potential was observed at 0.16 V. The limit of detection (LOD) and limit of quantification (LOQ) were 2.0×10−6 and 6.7×10−6 mol L−1, respectively. Binary and ternary synthetic mixtures of DA‐UA, DA‐AA and DA‐UA‐AA yielded excellent recoveries for DA. Additionally, DA was quantitatively recovered from a real sample of bovine serum spiked with DA, and determined in concentrated dopamine injection solution. The developed SWV method was statistically validated against a literature potentiodynamic method using a caffeic acid modified‐GC electrode.

Daily variation of D2 dopamine receptor transcription in the brain of the Japanese eel Anguilla japonica and its regulation with dopamine and melatonin

Dopamine plays a crucial role in controlling reproduction in eels, and its action is mediated through D2-type dopamine receptors. D2A and D2B receptors in the Japanese eel Anguilla japonica were cloned and characterized in the present study. Attention (daily expression patterns in the brain and endogenous regulation) was paid to D2B receptor because it is considered to play a crucial role in eel reproduction. The cDNAs of D2A and D2B receptors had open reading frames comprising 456 and 454 amino acid residues, respectively, which were phylogenetically clustered with those of other teleost species. Both receptors were highly expressed in the brain. D2B receptor transcript levels exhibited high day/low night variation in the midbrain and pituitary, suggesting that its transcription in these tissues is regulated in a daily manner, possibly under influence of melatonin. Intraperitoneal injection of dopamine downregulated D2B receptor transcription significantly in the midbrain and moderately in the pituitary within 1 h, but upregulated its transcription in the forebrain. Co-injection of dopamine with its antagonist (domperidone) reversed the effect of dopamine in the pituitary and forebrain, but not in the midbrain, suggesting that the effect of dopamine on D2B receptor transcription differs among brain regions. The same treatment with melatonin resulted in decreased D2B receptor transcription in the midbrain. These findings indicate that dopamine and melatonin have key roles in the daily variation in D2B receptor transcription in the brain of Japanese eel, and that they are related to a daily base secretion of hormones in the hypothalamic–pituitary–gonadal axis in this species.

A flexible carbon nanotube-modified poly(styrene-butadiene)-based dopamine sensor

In this work, a multi-walled carbon nanotube-modified flexible poly(styrene-butadiene) fiber membrane material was prepared for the sensitive and selective electrochemical detection of dopamine (DA) in human serum and DA injection. The flexible fiber membrane prepared by electrospinning technology is expected to realize its application in wearable devices. The obtained conductive film-based electrochemical sensor can effectively minimize interference caused by ascorbic acid and uric acid. Under the optimized experimental conditions of differential pulse voltammetry, DA gives a linear response in the range of 1–650 μM (R2 = 0.996). The detection limit of DA (signal-to noise ratio = 3) was determined to be 0.062 μM.

Transcriptome analysis of hemocytes from the white shrimp Litopenaeus vannamei with the injection of dopamine

As a crucial neuroendocrine-immune factor, dopamine (DA) could regulate the immune system of Litopenaeus vannamei. To understand the immune mechanisms and regulatory pathways of DA in L. vannamei, the transcriptome analysis of hemocytes of L. vannamei with injection of DA (10−6 mol/shrimp) at 3 and 12 h were performed in this study. Moreover, quantitative real-time PCR (qPCR) method was applied to validate the accuracy of transcriptome sequencing and analyze the expression pattern of candidate differentially expressed genes (DEGs) at different time points (0, 3, 6, 12, and 24 h) after DA injection. The results showed that a total of 51382 unigenes with a N50 length of 2341 bp were generated. And 1397 and 457 DEGs were obtained by comparative transcriptome at 3 and 12h respectively. Moreover, the results of functional annotation and enriched pathway showed that the DEGs were involved in phagosome (ko04145), lysosome (ko04142), Endocytosis (ko04144), and NOD-like receptor signaling pathway (ko04621). Besides, the Pearson's correlation coefficient (R) between transcriptome sequencing and qPCR was 0.845, which confirmed the reliability of the transcriptome sequencing results and the accuracy of assembly. Furthermore, the expression pattern of 15 candidate DEGs, containing 9 up-regulated and 6 down-regulated DEGs at 3 h, indicated the regulation of DA in physiological functions especially in the immune system. Therefore, these results revealed that DA induced the expressions of membrane receptors or proteins, activated intracellular signaling pathways, regulated cellular and humoral immune systems, controlled antioxidation and apoptosis, and was involved in the regulation of neuroendocrine system. These findings are helpful to promote the understanding on the effects of biogenic amines on physiological functions and regulatory networks of crustacean, and offer a substantial material and foundation for researching the immune response of crustacean.

Simultaneous determination of dopamine and uric acid using a glassy carbon paste electrode modified with copper- para red complex

A simple approach based on cyclic voltammetry (CV) was developed for the simultaneous determination of dopamine (DA) and uric acid (UA) in the presence of ascorbic acid (AA) using a modified glassy carbon paste electrode (GCPE). In the present study, analytical parameters were optimized and electrochemical performance of modified electrode was investigated. The calibration curves were obtained over the range of 15.97-157.98 μmol L-1 dopamine and 15.97-195.35 μmol L-1 uric acid. Detection limits of 12.38 μmol L-1 dopamine and 3 μmol L-1 uric acid were also obtained at pH 7.0. The modified electrode was used for practical application for the detection of dopamine and uric acid in the real samples of uric acid and dopamine injection, human serum and urine samples.

Effects of dopamine on immune signaling pathway factors, phagocytosis and exocytosis in hemocytes of Litopenaeus vannamei

Dopamine (DA) is an important neuroendocrine factor, which can act as neurotransmitter and neurohormone. In this study, we explored the immune defense mechanism in Litopenaeus vannamei with injection of dopamine at 10−7 and 10−6 mol shrimp−1, respectively. The genes expressions of dopamine receptor (DAR), G proteins (Gs, Gi, Gq), phagocytosis and exocytosis-related proteins, as well as intracellular signaling pathway factors, and immune defense parameters were measured. Results showed that mRNA expression levels of dopamine receptor D4 (D4), Gi, nuclear transcription factors and exocytosis-related proteins decreased significantly and reached the minimum at 3 h, while the genes expressions of Gs, Gq and phagocytosis-related proteins reached the highest and lowest levels at 3 h and 6 h, respectively. The second messenger synthetases increased significantly in treatment groups within 3 h. Simultaneously, the second messengers and protein kinases shared a similar trend, which were significantly elevated and reached the peak value at 3 h. Ultimately lead to the total hemocyte count (THC), proPO activity and phagocytic activity decreased significantly, reaching minimum values at 3 h, 3 h and 6 h, respectively. While PO activity showed obvious peak changes, which maximum value reached at 3 h. These results suggested that DA receptor could couple with G protein after DA injection and might regulate immunity through cAMP-PKA, DAG-PKC or CaM pathway.

Molecular characterization of a vitellogenesis-inhibiting hormone (VIH) in the mud crab (Scylla olivacea) and temporal changes in abundances of VIH mRNA transcripts during ovarian maturation and following neurotransmitter administration

The vitellogenesis-inhibiting hormone (VIH), also known as gonad-inhibiting hormone, is a neuropeptide hormone in crustaceans that belongs to the crustacean hyperglycemic hormone (CHH)-family peptide. There is regulation vitellogenesis by VIH during gonad maturation in crustaceans. A full-length Scylla olivacea VIH (Scyol-VIH) was identified through reverse transcription polymerase chain reaction and rapid amplification of cDNA ends. The open reading frame consists of 378 nucleotides, which encodes a 126-amino acid precursor protein, including a 22-residue signal peptide and a 103-amino acid mature peptide in which 6 highly conserved cysteine residues are present. There was expression of the Scyol-VIH gene in immature female Scylla olivacea in the eyestalk, brain and ventral nerve cord. The Scyol-VIH gene expression was localized to the eyestalk X-organ, brain neuronal clusters 6 and 11, and in multiple neuronal clusters of the ventral nerve cord. The relative abundance of Scyol-VIH mRNA transcript in the eyestalk was relatively greater in immature stage females, then decreased as ovarian maturation progressed. Furthermore, eyestalk Scyol-VIH increased after dopamine (5 μg/g BW) injection. The present research provides fundamental information about Scyol-VIH and its potential effect in controlling reproduction.

Theabrownin from Pu-erh tea together with swinging exercise synergistically ameliorates obesity and insulin resistance in rats

Theabrownin (TB)-containing Pu-erh tea has been shown to be hypolipidemic in rats fed a high-fat diet. Physical exercise such as swinging is also known to reduce obesity. We hypothesized that TB in combination with swinging can synergistically ameliorate obesity and insulin resistance in rats with metabolic syndrome. TB, rosiglitazone, or lovastatin (controls) was administered by gavage to rats fed a diet high in fat, sugar, and salt. A subgroup of the rats was subjected to a 30-min daily swinging exercise regimen, whereas the other rats did not exercise. Theabrownin in combination with swinging was found to significantly improve serum lipid status and prevent development of obesity and insulin resistance in rats. Liver transcriptomics data suggested that theabrownin activated circadian rhythm, protein kinase A, the adenosine monophosphate-activated protein kinase, and insulin signaling pathways by enhancing cyclic adenosine monophosphate levels and, hence, accelerating nutrient metabolism and the consumption of sugar and fat. The serum dopamine levels in rats increased significantly after exercise. In parallel work, intraperitoneal dopamine injections were shown to significantly reduce weight gain and prevent the elevation in triglyceride levels that would otherwise be induced by the high fat-sugar-salt diet. Theabrownin prevented obesity and insulin resistance mainly by affecting the circadian rhythm, while swinging exercise stimulated the overproduction of dopamine to accelerate metabolism of glucose and lipid. Theabrownin and exercise synergistically ameliorated metabolic syndrome in rats and effectively prevented obesity.

Synthesis and characterization of tetra-ganciclovir cobalt (II) phthalocyanine for electroanalytical applications of AA/DA/UA

Cobalt (II) phthalocyanine embedded with ganciclovir units has been synthesized by a novel method using tetracarboxylic phthalocyanine reported for the first time. The synthesized dark green colored complexes were characterized by electronic spectroscopy, elemental analysis, FT-IR, MASS and XRD. Thermal stability study reveals that the newly synthesized complex was stable up to 300 °C and XRD patterns showed amorphous nature of the complex. In the present work, the synthesized complex was characterized by cyclic voltammetry and shows the redox behavior corresponding to central metal (Co+II/Co+I) of the complex. Three biomolecules are well-separated by their oxidation peaks in simultaneous determination predicting the potentials for (-128, 335, and 723 mV) with highly increasing current. The low detection limit of AA, DA, and UA were 0.33, 0.03 and 0.10 μmol by CV method and good responses of amperometric and DPV technique. The modified tetra substituted CoTGPc/GCE exhibit an excellent electrocatalytic activity, stability, high sensitivity, good linearity, and selectivity without losing its catalytic activity and proves to be a versatile chemical sensor for commercial pharmaceutical samples, vitamin C tablets, and dopamine injections.

Aframomum melegueta prevents the ejaculatory complications of propylthiouracil-induced hypothyroidism in sexually experienced male rats: Evidence from intravaginal and fictive ejaculations

ObjectiveHypothyroidism has been claimed to generate sexual dysfunctions such as ejaculatory disorders. Aframomum melegueta is an aphrodisiac plant with pro-ejaculatory properties. We investigated the protective effects of aqueous extract (AE) and methanolic extract (ME) of A. melegueta on the ejaculatory function of hypothyroid male rats. MethodsForty sexually experienced male rats were partitioned into 8 groups (5 rats per group) and treated for 28 d as follows: Group 1, Control; Group 2, propylthiouracil (PTU, 10 mg/kg) + distilled water (DW, 10 mL/kg); Group 3, PTU + 5% Tween 80 (10 mL/kg); Group 4, PTU + bromocriptine (6 mg/kg); Group 5, PTU + AE (20 mg/kg); Group 6, PTU + AE (100 mg/kg); Group 7, PTU + ME (20 mg/kg), and Group 8, PTU + ME (100 mg/kg). On days 0, 7, 14 and 28 of treatment, each male rat was paired with primed receptive female for measurement of ejaculatory latency time (ELT) and post-ejaculatory interval (PEI) for 1.5 h. On day 29, each male rat was urethane-anesthetized and the spinal cord was transected. Thereafter, following urethral/penile stimulations and intravenous injection of dopamine, contractions of the bulbospongiosus muscles and the intraseminal pressure were registered. After these recordings, blood was collected through the catheterization of abdominal artery and plasma was used for thyroid-stimulating hormone (TSH), prolactin and testosterone assays. ResultsPTU-induced hypothyroidism was characterized by a significant elevation (P < 0.001) of plasmatic TSH and prolactin levels, but a decline (P < 0.001) in plasmatic testosterone, compared to untreated group. ELT, PEI, contractions of the bulbospongiosus muscles and the intraseminal pressure were also altered by PTU treatment. On the contrary, A. melegueta extracts elevated testosterone (AE, 100 mg/kg, P < 0.01; ME, 100 mg/kg, P < 0.05) and decreased prolactin (AE, 100 mg/kg, P < 0.05; ME, 20 mg/kg, P < 0.05) levels, compared to corresponding controls. With regard to DW + PTU group, prolactin concentration was lowered (P < 0.05) in rats administered with bromocriptine. Treatment with A. melegueta extracts significantly prevented the lengthening of ELT (P < 0.05) and PEI (P < 0.001). Hypothyroid state also altered the fictive ejaculation by increasing the latency and decreasing the number and frequency of bulbospongiosus muscle contractions. There was also a decrease in the intraseminal pressure. These alterations were significantly (P < 0.05) alleviated in plant extract-treated groups. ConclusionThis study highlighted the ejaculatory disturbance of hypothyroidism in male rats and its prevention with A. melegueta extracts.

A facile synthesis of Fe3O4-Gr nanocomposite and its effective use as electrochemical sensor for the determination of dopamine and as anode material in lithium ion batteries

The Fe3O4-Graphene (Fe3O4-Gr) nanocomposite has been synthesized by hydrothermal method and demonstrated its application towards electrochemical sensor and anode for high performance lithium ion batteries. The nanocomposite exhibited cubic face centred Fe3O4 structure with an estimated crystallite size of 25 nm. The additional peak at 2θ = 26.4° from XRD spectrum confirmed the inculcation of graphene in the composite. The embedment of Fe3O4 nanoparticles in graphene sheets was further confirmed from TEM analysis. The FESEM analysis revealed that the cubical shaped Fe3O4 particles were strongly anchored with graphene nanosheets with an estimated grain size of 40 nm. The electrochemical properties of Fe3O4-Gr were studied with the help of cyclic voltammetry (CV), Differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS) and chronopotentiometry (CP). The sensor performance was studied by testing the electrochemical activity of dopamine (DA) in presence of phosphate buffer solution (PBS) as an electrolyte at pH 6 using CV and DPV. The Fe3O4-Gr/Glassy carbon electrode (GCE) sensor showed ultimate sensitivity and selectivity in the presence of uric acid (UA) and acetaminophen (AC). It demonstrated utmost low limit of detection of 0.78 μM towards the detection of DA and satisfactory recoveries in dopamine injection formulation. Moreover, as an anode material for Li-ion batteries, the Fe3O4-Gr nanocomposite delivered high discharge capacity of 920 mA h g−1 and retained 96% capacity even after 30 discharge cycles.

Dopamine enhancement of dextrorphan-induced skin antinociception in response to needle pinpricks in rats.

Dextrorphan with long-acting local anesthetic effects did not cause system toxicity as fast as bupivacaine, while catecholamines (i.e., epinephrine) with the vasoconstrictive characteristics enhanced the effects of local anesthetic drugs. The objective of the experiment was to examine the synergistic effect of local dopamine (a catecholamine) injection on cutaneous antinociception of dextrorphan. The panniculus reflex in response to skin stimulation with a needle was used as the primary endpoint when dextrorphan (1.50, 2.61, 5.46, 10.20 and 20.40 μmol) alone, dopamine (16.20, 32.40, 51.60, 60.00 and 81.60 μmol) alone, or dopamine + dextrorphan (a ratio of ED50vs. ED50) was injected subcutaneously on the rat's back. We used an isobolographic modelling approach to determine whether a synergistic effect would be observed. We showed that dextrorphan, dopamine, or the mixture of dopamine and dextrorphan produced dose-related skin antinociception. The potency (ED50, 50% effective dose) for cutaneous antinociception was dextrorphan [6.02 (5.93-6.14) μmol] greater than dopamine [48.91 (48.80-49.06) μmol] (p < 0.01). The duration of nociceptive inhibition induced by dopamine was longer than that induced by dextrorphan (p < 0.01) based on their equipotent doses (ED25, ED50, and ED75). Enhancement and prolongation of skin antinociception occurred after co-administration of dopamine with dextrorphan. When compared to dopamine, dextrorphan was more potent and had a shorter duration of skin nociceptive block. Dopamine produced a synergistic effect on dextrorphan-mediated antinociception, and prolonged dextrorphan's antinociceptive duration.

Porous tal palm carbon nanosheets: preparation, characterization and application for the simultaneous determination of dopamine and uric acid.

A novel porous tal palm carbon nanosheet (PTPCN) material was synthesized from the leaves of Borassus flabellifer (tal palm) and used for developing an electrochemical sensor through modifying a glassy carbon electrode (GCE) simply by drop-casting on it a solution of the material for the sensitive simultaneous detection of dopamine (DA) and uric acid (UA), even in the presence of interfering species. The drop-casting solution was prepared by simply dispersing the PTPCNs in ethanol without using any other binding materials (e.g. Nafion). The surface morphologies of the PTPCNs were studied through field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and high resolution TEM (HRTEM). Energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction spectroscopy (XPS) studies revealed the chemical composition of the PTPCNs' surface. Their structural properties were studied using X-ray diffraction (XRD) and Raman spectroscopy. Brunauer–Emmett–Teller (BET) analysis confirmed the surface area and pore volume to be 1094.53 m2 g−1 and 0.74 cm3 g−1, respectively, while Barrett–Joyner–Halenda (BJH) pore-size distribution showed the average pore size to be 22 nm. The sufficiently large surface area and pore-size distribution suggested better electrocatalytic properties compared to the average modifying materials. The modified electrode (PTPCNs/GCE) was characterized through impedimetric and CV techniques in standard potassium ferricyanide solution for evaluating their charge-transfer resistance and electrochemical properties. The limits of detection (S/N = 3) were 0.17 μM and 0.078 μM and the sensitivities were 1.2057 μA μM−1 cm−2 and 2.693 μA μM−1 cm−2 for UA and DA, respectively. The possible interactions that took place between the PTPCNs and the analytes that aided in the enhancement of the electroanalytical performance of the PTPCNs/GCE are discussed based on the experimental findings and established theoretical concepts. The PTPCNs/GCE was successfully employed for analyzing real samples, like dopamine injection and urine.

Effect of administration of neurotransmitters: Serotonin and dopamine on testicular maturation in the freshwater crab Travancoriana schirnerae Bott, 1969 (Crustacea: Gecarcinucidae)

The current investigation aimed at the effect of administration of the neurotransmitters, serotonin and dopamine, on testicular maturation in the freshwater crab Travancoriana schirnerae Bott, 1969 (Crustacea: Gecarcinucidae). Adult males in active, inactive and revival phases of spermatogenesis were injected with serotonin and dopamine in multiple doses and their dissected testes were submitted to histomorphological examinations. Though serotonin treatment during active phase showed increased values for testicular index, acinar diameter and proportion of mature spermatozoa, only the testicular index values differed statistically from that of controls. Serotonin administration during inactive phase caused an increase in testicular index and acinar diameter, reduction in intra and interacinar spaces and pycnosis of germ cells and detection of division stages. A notable increase in the testicular index, acinar diameter and fresh batches of spermatozoa was perceptible in crabs injected with serotonin during revival phase. In contrast, dopamine injection showed a decline in testicular activity irrespective of the phase of spermatogenesis, as evinced from low testicular index, acinar diameter, presence of small, irregularly shaped acini with indistinct acinar boundaries, reduction in the number of mature spermatozoa and absence of division stages. To conclude, the stimulatory neurotransmittant, serotonin can be used to induce testicular maturation in species of aquaculture potential.

Facile synthesis of cellulose microfibers supported palladium nanospindles on graphene oxide for selective detection of dopamine in pharmaceutical and biological samples

The cost-effective synthesis of novel functional nanomaterials has received significant attention in the physical and chemical sciences due to their improved surface area, high catalytic activity along with unique morphological features. This paper reports a facile and eco-friendly synthesis of spindle-like palladium nanostructures (PdSPs) on graphene oxide-cellulose microfiber (GO-CMF) composite for the first time. The GO-CMF/PdSPs composite was synthesized by an electrochemical method without the use of additional surfactants and capping agents. The synthesized materials were characterized and confirmed by using transmission electron microscopy, high-resolution scanning electron microscopy, X-ray diffraction spectroscopy, Raman spectroscopy and Fourier-transform infrared spectroscopy. As-synthesized GO-CMF/PdSPs composite modified electrode was used as a selective electrocatalyst for the oxidation of dopamine (DA). The electrochemical redox behaviors of DA were investigated using cyclic voltammetry (CV). The CV results revealed that the GO-CMF/PdSPs composite modified electrode has 10 folds enhanced oxidation current response to DA than GO, PdSPs and GO-CMF modified GCEs. Under optimized conditions, the GO-CMF/PdSPs composite sensor exhibits a linear response to DA in the concentration range from 0.3 to 196.3 μM with the lower detection limit of 23 nM. The nanocomposite electrode also shows promising features towards the reliable and selective detection of DA, which includes high stability, reproducibility and high selectivity towards the commonly interfering species such as ascorbic acid, uric acid, and dihydroxybenzene isomers. The sensor was successfully tested for the real-time detection of DA in the commercial DA injections and human serum samples.

Effect of microinjections of dopamine into the nucleus accumbens shell on emission of 50 kHz USV: Comparison with effects of d-amphetamine

Systemic pharmacological manipulation of dopamine (DA) signaling has been central to many investigations of 50 kHz ultrasonic vocalizations (USVs) in the rat. In particular, the indirect DA releaser d-amphetamine (AMPH) has been used extensively in many such investigations. The possible unique character of the native transmitter relative to DA-stimulating drugs such as AMPH in inducing and modulating emission of 50 kHz USVs has not been investigated. Adult male Long Evans rats were tested with intracerebral application of DA into the nucleus accumbens shell at several doses (3.75 μg–120 μg) to determine its capacity to induce 50 kHz USV emission. Additionally, the call profile characteristics of intracerebral DA injections were compared with those of intracerebral application of AMPH. Results indicated that local increases in DA signaling within the nucleus accumbens shell are sufficient to increase 50 kHz call rate, reduce latency to call, and increase the degree of frequency modulation of emitted USVs. However, our results found that microinjections of DA were not as efficacious in either inducing 50 kHz USVs or increasing frequency modulation without antagonism of the dopamine reuptake transporter when compared with AMPH. In summary, these results support the notion that the native transmitter DA is driving the increase in frequency modulation seen after administration of DA stimulating drugs. These results also suggest that drugs affecting dopamine may be altering the 50 kHz call profile in a distinct manner from the native transmitter and thus caution should be used in interpreting their effects.

Morphologically Tunable MnO2 Nanoparticles Fabrication, Modelling and Their Influences on Electrochemical Sensing Performance toward Dopamine

The morphology or shape of nanomaterials plays an important role in functional applications, especially in the electrochemical sensing performance of nanocomposites modified electrodes. Herein, the morphology-dependent electrochemical sensing properties of MnO2-reduced graphene oxide/glass carbon electrode (MnO2-RGO/GCE) toward dopamine detection were investigated. Firstly, various morphologies of nanoscale MnO2, including MnO2 nanowires (MnO2 NWs), MnO2 nanorods (MnO2 NRs), and MnO2 nanotubes (MnO2 NTs), were synthesized under different hydrothermal conditions. Then the corresponding MnO2-RGO/GCEs were fabricated via drop-casting and the subsequent electrochemical reduction method. The oxidation peak currents increase with the electrochemical activity area following the order of MnO2 NWs-RGO/GCE, MnO2 NTs-RGO/GCE, and MnO2 NRs-RGO/GCE. The spatial models for MnO2 NWs, MnO2 NTs, and MnO2 NRs are established and accordingly compared by their specific surface area, explaining well the evident difference in electrochemical responses. Therefore, the MnO2 NWs-RGO/GCE is selected for dopamine detection due to its better electrochemical sensing performance. The response peak current is found to be linear with dopamine concentration in the range of 8.0 × 10−8 mol/L–1.0 × 10−6 mol/L and 1.0 × 10−6 mol/L–8.0 × 10−5 mol/L with a lower detection limit of 1 × 10−9 mol/L (S/N = 3). Finally, MnO2 NWs-RGO/GCE is successfully used for the determination of dopamine injection samples, with a recovery of 99.6–103%. These findings are of great significance for understanding the relationship between unlimited nanoparticle structure manipulation and performance improvement.

Molecular cloning, characterization and effects of catechol-o-methyltransferase (comt) mrna and protein on aggressive behavior in the swimming crab portunus trituberculatus

In the present study, a cDNA that encodes catechol-O-methyltransferase (COMT) was cloned from the muscle of the swimming crab Portunus trituberculatus and named PtCOMT. PtCOMT was proven to be a conserved gene that encodes a protein of 222 amino acid residues with a molecular mass 25.4 kDa that constitutes only the signature motif “SAM_OMT_I.” The RT-PCR results showed that PtCOMT was expressed in all five larval stages (zoea stage I, Z1; zoea stage II, Z2; zoea stage III, Z3; zoea stage IV, Z4; and megalopa, M) of P. trituberculatus. The PtCOMT mRNA levels were higher (P < 0.05) in the Z4 and M stages than in the Z1, Z2, and Z3 stages. In addition, PtCOMT was expressed in the tissues of healthy crabs, namely, ganglion, muscle, and hepatopancreas. On the basis of the RT-PCR and immunohistochemistry analyses, the level of expression in the ganglion and muscle was significantly higher than that in the hepatopancreas (P < 0.05). Aggressiveness of DA injected crabs was tested through a behavioral study where dopamine-treated crabs walked through the “middle” of the pool more frequently than control crabs. When compared with the control group, PtCOMT expression level was significantly upregulated (P < 0.05) at 2 h and significantly downregulated at 4 h in the muscles after dopamine (DA) injection (P < 0.05), whereas it was significantly downregulated (P < 0.05) at 2 h and upregulated after 4 h (P < 0.05) in the ganglia. These results show that DA promotes the release of PtCOMT. Our findings indicate that the expression level of PtCOMT may be directly related to aggressiveness and affect the central nervous system of P. trituberculatus to act on its aggressive behavior. Our results can help further studies on the aggressive behavior mechanism of P. trituberculatus.