Spectrofluorimetric Estimation of Norepinephrine Using Ethylenediamine Condensation Method

Enhanced sensitivity of dilute aqueous adrenaline solution with an asymmetric hexagonal ring structure in the terahertz frequencies

Quantitative detection of neurotransmitters in aqueous environment is crucial for the early diagnosis of many neurological disorders. Terahertz waves, as a non-contact and non-labeling tool, have demonstrated large potentials in quantitative biosensing. Although the detection of trace-amount analyte has been achieved with terahertz metamaterials in the recent decades, most studies have been focused on dried samples. Here, a hexagonal asymmetric metamaterial sensor was designed and fabricated for aqueous solution sensing with terahertz waves in the reflection geometry. An absorption enhancement of 43 was determined from the simulation. Dilute adrenaline solutions ranging from 30 µM to 0.6 mM were measured on our sensor using a commercial terahertz time-domain spectroscopy system, and the effective absorption was found to be linearly correlated with the concentration (R²= 0.81). Furthermore, we found that as the concentration becomes higher (>0.6 mM), a non-linear relationship starts to take place, which confirmed the previous theory on the extended solvation shell that can be probed on the picosecond scale. Our sensor, without the need of high-power and stable terahertz sources, has enabled the detection of subtle absorption changes induced by the solvation dynamics.

Gill damage and neurotoxicity of ammonia nitrogen on the clam Ruditapes philippinarum

Ammonia nitrogen has been a potential menace to aquatic animals along the coastline of China. Presently, the toxicological effects of ammonia nitrogen were mainly concentrated on fishes, while little attention has been paid to molluscs. In this study, the clam Ruditapes philippinarum was used as the target animal to investigate the toxic effects of ammonia nitrogen. Our results showed that ammonia exposure could significantly reduce the integrity of lysosomes in a dose-dependent manner. Metabolite analysis revealed that exposure doses and duration time of ammonia nitrogen could affect the variation profiles of gill metabolites. In detail, branched chain amino acids, glutamate, choline and phosphocholine were significantly decreased after a one-day exposure. Inosine and phenylalanine were found significantly increased and ATP was decreased after a three-day exposure. The changes of metabolites implied that metabolisms of muscle element, neurotransmission and cell apoptosis of gill tissues would be affected by ammonia exposure. Such inferences were supported by the diminished muscle element, decreased concentrations of catecholamines and increased apoptosis rates, respectively. Therefore, we take advantage of metabolomics integrated with conventional biological assays to find out that ammonia exposure could cause lysosome instability, metabolic disturbance, aberrant gill structures and changes to neurotransmitters, and would result in mollusk gill dysfunction in feeding, respiration and immunity.

Chemical sensing of neurotransmitters

This review focuses on the chemosensors for neurotransmitters published for the last 12 years, covering biogenic amines (dopamine, epinephrine, norepinephrine, serotonin, histamine and acetylcholine), amino acids (glutamate, aspartate, GABA, glycine and tyrosine), and adenosine.

The involvement of PDGF/VEGF related factor in regulation of immune and neuroendocrine in Chinese mitten crab Eriocheir sinensis

Members of the platelet-derived growth factor/vascular endothelial growth factor (PDGF/VEGF) family have been implicated in cell proliferation, cell differentiation, and cell migration, vascular development, angiogenesis and neural development. In the present study, a novel PDGF/VEGF related factor gene was cloned and identified in Chinese mitten crab Eriocheir sinensis (designated as EsPVF1). The full-length cDNA of EsPVF1 was of 1173 bp, consisting a 5' untranslated region (UTR) of 54 bp, a 3' UTR of 1131 bp with a poly (A) tail, and an open reading frame (ORF) of 588 bp encoding 196 amino acid residues. A signal peptide of 20 amino acid residues, a PDGF/VEGF homology growth factor domain of 81 amino acids, and a typical cysteine knot motif (CXCXC) were identified in the deduced amino acid sequence of EsPVF1. By fluorescent quantitative real-time PCR, the EsPVF1 mRNA was detected ubiquitously in the select tissues of hemocytes, gonad, heart, muscle, hepatopancreas and gill, with the high abundance in hemocytes and gonad. The mRNA expression level of EsPVF1 was up-regulated and reached the highest at 24 h after Vibrio anguillarum challenge, while it was induced at 3 h, 6 h, 12 h, 24 h and 48 h compared with the untreated group after Pichia pastoris GS115 challenge. Tissue injury also induced the mRNA expression of EsPVF1 in hemocytes of crabs, and the expression level increased obviously at 8 h. The cDNA fragment encoding mature peptide of EsPVF1 was recombined and expressed in Escherichia coli BL21 (DE3) pLysS. Biogenic amine in hemolymph pre-incubated with recombinant protein of EsPVF1 (rEsPVF1) was detected by fluorimetric method. Norepinephrine and dopamine in hemolymph incubated with rEsPVF1 were higher than that in the blank group. Therefore, EsPVF1 could significantly provoke the release of norepinephrine and dopamine. The results collectively indicated that EsPVF1 was involved in regulation of the immune response and neuroendocrine system in crabs.

Roles of estrogen and progesterone in modulating renal nerve function in the rat kidney

The maintenance of extracellular Na⁺ and Cl^- concentrations in mammals depends, at least in part, on renal function. It has been shown that neural and endocrine mechanisms regulate extracellular fluid volume and transport of electrolytes along nephrons. Studies of sex hormones and renal nerves suggested that sex hormones modulate renal function, although this relationship is not well understood in the kidney. To better understand the role of these hormones on the effects that renal nerves have on Na⁺ and Cl^- reabsorption, we studied the effects of renal denervation and oophorectomy in female rats. Oophorectomized (OVX) rats received 17β-estradiol benzoate (OVE, 2.0 mg·kg^-1·day^-1, sc) and progesterone (OVP, 1.7 mg·kg^-1·day^-1, sc). We assessed Na⁺ and Cl^- fractional excretion (FE_Na⁺ and FE_Cl^-, respectively) and renal and plasma catecholamine release concentrations. FE_Na⁺, FE_Cl^-, water intake, urinary flow, and renal and plasma catecholamine release levels increased in OVX vs control rats. These effects were reversed by 17β-estradiol benzoate but not by progesterone. Renal denervation did not alter FE_Na⁺, FE_Cl^-, water intake, or urinary flow values vs controls. However, the renal catecholamine release level was decreased in the OVP (236.6±36.1 ng/g) and denervated rat groups (D: 102.1±15.7; ODE: 108.7±23.2; ODP: 101.1±22.1 ng/g). Furthermore, combining OVX + D (OD: 111.9±25.4) decreased renal catecholamine release levels compared to either treatment alone. OVE normalized and OVP reduced renal catecholamine release levels, and the effects on plasma catecholamine release levels were reversed by ODE and ODP replacement in OD. These data suggest that progesterone may influence catecholamine release levels by renal innervation and that there are complex interactions among renal nerves, estrogen, and progesterone in the modulation of renal function.

The suppressor of cytokine signaling 2 (SOCS2) modulating the neurotransmitters release in Eriocheir sinensis

The SOCS proteins appear to define an important mechanism for the negative regulation of the cytokine-JAK-STAT pathway. In the present study, the mRNA expression profiles of a SOCS2 from Chinese mitten crab Eriocheir sinensis (EsSOCS2) after pentachlorophenol (PCP) treatment or RNA interference (RNAi) were analyzed to understand its possible regulatory roles in modulating the neurotransmitter release. The EsSOCS2 expression level in the PCP treated group was significantly higher than that of blank at 1.5, 3, 12 and 24 h after exposure, suggesting that EsSOCS2 might be involved in controlling and reducing neuronal cell damage resulted from PCP treatment. After the expression of EsSOCS2 gene was silenced by RNAi, the concentrations of catecholamines and nitric oxide (NO) were examined to evaluate the modulation of EsSOCS2 on the release of neurotransmitters. At 48 h after the treatment with sequence-specific dsRNA targeting EsSOCS2, the expression of EsSOCS2 was reduced to half compared to the original level, and the concentrations of norepinephrine and NO increased, while dopamine decreased significantly in haemolymph. The preliminary results indicated that EsSOCS2 regulated catecholaminergic neuroendocrine system to release catecholamines into haemolymph and might be an important feedback inhibitor of tyrosine kinase signaling pathways in crab, which subsequently regulated NO synthesis and prevented excessive NO release. This information is helpful to further understand the modulation of EsSOCS2 on neurotransmitter release in crab.

Determination of dopamine in pharmaceutical formulation using enhanced luminescence from europium complex

Biologically important compound dopamine plays an important role in the central and peripheral nervous systems. Insufficient dopamine level due to the loss of dopamine producing cells may lead to disease called Schizophrenia and Parkinson's disease. Hence, a simple and fast detection of dopamine is necessary to study in the fields of neurophysiology and clinical medicine. An enhanced fluorimetric determination of dopamine in the presence of ascorbic acid is achieved using photoluminescence of europium complex, Eu(III)-dipicolinic acid. In order to obtain better responses, several operational parameters have been investigated. Under the optimum conditions, the method showed good stability and reproducibility. The application of this method for the determination of dopamine neurotransmitters was satisfactory. Linear response was found down to 3.0 × 10(-7)M with limit of detection 1.0 × 10(-8)M. The relative standard deviation was found to be 3.33% from 20 independent measurements for 1.0 × 10(-5)M of dopamine.

Influence of gender and estrous cycle on plasma and renal catecholamine levels in rats

Several studies have demonstrated that gonadal hormones show significant effects on the brain and signaling pathways of effector organs/cells that respond to neurotransmitters. Since little information is available concerning the impact of male and female gonadal hormones on the renal and peripheral sympathetic system, the objective of this study was to further assess whether and how the renal content and plasma concentration of catecholamines are influenced by gender and the estrous cycle in rats. To achieve this, males Wistar rats were divided into 4 groups: (i) sham (i.e., control), (ii) gonadectomized, (iii) gonadectomized and nandrolone decanoate replacement at physiological levels or (iv) gonadectomized and nandrolone decanoate replacement at high levels. Female Wistar rats were divided into 6 groups: (i) ovariectomized (OVX), (ii) estrogen replacement at physiological levels and (iii) estrogen replacement at at high levels, (iv) progesterone replacement at physiological levels and (v) progesterone replacement at at high levels, and (vi) sham. The sham group was subdivided into four subgroups: (i) proestrus, (ii) estrus, (iii) metaestrus, and (iv) diestrus. Ten days after surgery, the animals were sacrificed and their plasma and renal catecholamine levels measured for intergroup comparisons. Gonadectomy led to an increase in the plasma catecholamine concentration in females, as well as in the renal catecholamine content of both male and female rats. Gonadectomized males also showed a lower level of plasma catecholamine than the controls. The urinary flow, and the fractional excretion of sodium and chloride were significantly increased in gonadectomized males and in the OVX group when compared with their respective sham groups.

The modulation of catecholamines to the immune response against bacteria Vibrio anguillarum challenge in scallop Chlamys farreri

Catecholamines are pivotal signal molecules in the neuroendocrine-immune regulatory network, and implicated in the modulation of immune response. In the present study, the activities of some immune-related enzymes and the concentration of catecholamines were determined in circulating haemolymph of scallops Chlamys farreri after bacteria Vibrio anguillarum challenge. The activities of superoxide dismutase (SOD), catalase (CAT) and lysozyme (LYZ) increased significantly and reached 610 U mg(-1) at 12 h, 37.6 U mg(-1) at 6 h and 261.5 U mg(-1) at 6 h after bacteria challenge, respectively. The concentration of norepinephrine, epinephrine and dopamine also increased significantly and reached 114.9 ng mL(-1) at 12 h, 86.9 ng mL(-1) at 24 h and 480.4 pg mL(-1) at 12 h after bacteria challenge, respectively. Meanwhile, the activities of these immune-related enzymes in haemolymph were monitored in those scallops which were challenged by bacteria V. anguillarum and stimulated simultaneously with norepinephrine, epinephrine and adrenoceptor antagonist. The injection of norepinephrine and epinephrine repressed significantly the induction of bacteria challenge on the activities of immune-related enzymes, and they were reduced to about half of that in the control groups. The blocking of α and β-adrenoceptor by antagonist only repressed the increase of CAT and LYZ activities significantly, while no significant effect was observed on the increase of SOD activities. The collective results indicated that scallop catecholaminergic neuroendocrine system could be activated by bacteria challenge to release catecholamines after the immune response had been triggered, and the immune response against bacteria challenge could been negatively modulated by norepinephrine, epinephrine, and adrenoceptor antagonist. This information is helpful to further understand the immunomodulation of catecholamines in scallops.

Novel fluorimetric assay of trace analysis of epinephrine in human serum

A simple, rapid, and sensitive spectrofluorimetric technique for the microdetermination of epinephrine in human serum is described. The investigation shows that trace amounts of epinephrine, antidepressant of clinical importance, can be determined without the conventional derivatization or use of fluorophores by diazotization. The method is based on the optimization of experimental parameters, such as pH, temperature, careful selection of excitation and emission wavelengths and on the use of anionic surfactant, sodium dodecyl sulfate (SDS), to enhance sensitivity. The measurement was carried out at 360 nm with excitation at 286 nm. Under the optimum conditions, a linear relationship was obtained between the fluorescence intensity and epinephrine concentration in the range of 0.10 and 1.0 microg/mL; the correlation coefficient and detection limit are 0.9953 and 0.05 microg/mL, respectively. Recovery tests indicated an efficiency of 95.5-98.7% by using known amounts of epinephrine spiked with human serum.