Analysis Of Serotonin Research Articles

Electrocatalytic Activity Enhancement Using Graphene-Metal Oxide Nanocomposites for the Ultra Low Level Detection of Biomolecules

Metal oxide/reduced graphene oxide (MO/RGO, MO = NiO, Co3O4, and SnO2) nanocomposites were synthesized by a cost-effective hydrothermal method. The structural, thermal, and morphological characteristics of composites were investigated using PXRD, FT-IR, TGA, Raman, SEM, and HR-TEM. Modified carbon paste electrochemical sensors based on NiO/RGO, Co3O4/RGO, and SnO2/RGO were developed and compared for the effective detection of Epinephrine (EPN), Serotonin (SER), and Tyrosine (TYR). The performance of the NiO/RGO/CPE sensor was superior to other composites modified electrodes. The electrochemical measurements were studied by cyclic voltammetry, differential pulse voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. The modified electrodes showed excellent electrocatalytic activity towards EPN, SER, and TYR arising from the synergistic effect of reduced graphene oxide and metal oxide. The excellent electrical conductivity imparted by direct interphase of RGO to semiconductive metal oxide, increased surface area, and the increased number of active sites favor the sensitive determination of biomolecules. The NiO/RGO/CPE facilitated the analysis of EPN, SER, and TYR with a lower detection limit of 158 pM, 165 pM, and 519 pM respectively. The peaks for the three biomolecules are well separated from each other and the electrodes were effectively used for real samples.

Analysis of 5-hydroxytryptamine and its related indoles in cerebrospinal fluid of leukemic children by gas chromatography-mass spectrometry

Abstract Background It is meaningful to quantify some neurotransmitters in cerebrospinal fluid (CSF) for pathology and clinical diagnosis. The objective of this study was to develop a rapid and reliable method for detecting 5-hydroxyindole ethanol (5-HTOL), 5-hydroxyindole acetic acid (5-HIAA), 5-hydroxytryptophan (5-HTP) and 5-hydroxytryptamine (5-HT) in CSF by gas chromatography-mass spectrometry (GC-MS), and explore the clinical significance of the levels of these neurotransmitters in CSF from acute lymphoblastic leukemia (ALL). Methods The levels of 5-HTOL, 5-HIAA, 5-HTP and 5-HT in CSF from children with ALL and a control (CON) group were examined by the proposed GC-MS method. Results The GC-MS method showed good sensitivity and accuracy. 5-HT and 5-HIAA contents in the ALL group were significantly lower than those in the CON group (p < 0.01), while there was no significant difference in 5-HTP and 5-HTOL contents between the two groups (p > 0.05). Conclusions This sensitive and reliable method could be used in studies focusing on clinical pathogenesis of ALL.

Receptor “Families” for 5-Hydroxytryptamine

Significant advances in the analysis of 5-hydroxytryptamine (5-HT) receptor subtypes occurred in the 1980s. Although the current status of 5-HT receptor pharmacology may appear confusing to many investigators, the evolving data suggest that 5-HT receptor subtypes can be categorized into three major "families." Each "family" consists of multiple receptor subtypes that share similarities in their molecular, biological, pharmacological, biochemical, and/or physiological properties. These receptor subtypes are present throughout the nervous system as well as in the periphery. A simple framework for the classification of 5-HT receptor subtypes is provided in the present review.

Transmitter expression and morphological development of embryonic medullary and mesencephalic raphé neurones after transplantation to the adult rat central nervous system

Suspensions of cells taken from the mesencephalic or medullary raphé regions of the 13-14 day old embryonic rat brain were injected into the hippocampus of adult rats which had previously been denervated of its serotoninergic input by 5,7-dihydroxytryptamine. At periods of up to 14 months after implantation, the brains were taken for immunohistochemical analysis of 5-hydroxytryptamine (5HT)-, substance P (SP)- and thyrotropin releasing hormone (TRH)-like immunoreactivity. Surviving grafts were found in all animals. The implants derived from mesencephalic raphé contained neurones immunoreactive to 5HT, SP or both substances together. On average 19% of the potential number of mesencephalic 5HT neurones were found in the grafts. Outgrowth of 5HT-immunoreactive fibres was extensive, and displayed the typical pattern of 5HT innervation in the normal hippocampus-the densest plexuses were found in the dentate gyrus, with sparser networks in the CA1 and CA2 regions. SP-positive processes were principally found only in the graft itself. Transplants of medullary raphé cells contained 5HT-immunoreactive neurones, some of which also contained SP-and/or TRH-like immunoreactivity, thereby mirroring the situation found in the caudal raphé complex in situ. An average of 18% of the total available medullary serotoninergic neurones were found at each graft site. A rich outgrowth of 5HT-immunoreactive varicose processes was evident, with the same pattern as the 5HT innervation by the mesencephalic raphé grafts, and as in the normal hippocampus. SP- and TRH-positive fibres were essentially detectable only in the graft, but not in the host hippocampus. The present studies indicate that the milieu of the hippocampus does not preferentially attenuate the survival of the serotoninergic cells which do not normally project to it. Nor is the fibre outgrowth of these medullary raphé 5HT neurones significantly different from that of the mesencephalic raphé. However, the hippocampal environment may be responsible for the appearance of SP-LI in the otherwise apparently solely 5HT-containing mesencephalic raphé neurones, and for repressing the outgrowth of fibres containing TRH-, or SP-like immunoreactivity, regardless of their origin.

Increased total activity in the rat after L‐tryptophan plus the monoamine oxidase‐A inhibitor amiflamine but not after L‐tryptophan plus clorgyline

The effect of pretreatment with either saline or the monoamine oxidase-A inhibitors clorgyline and amiflamine upon the total activity, locomotion and rearing behaviour of the rat induced by various doses of the monoamine precursor L-tryptophan was studied by use of automated activity boxes. Amiflamine (2.5 and 5.0 mg kg-1, i.p.) increased in a dose-dependent manner total activity and to a lesser extent, locomotion when given 60 min before L-tryptophan (100 mg kg-1, i.p.). The increased activity was seen after amiflamine plus either 25 or 75 mg kg-1 L-tryptophan. Rearing behaviour was not affected. Analysis of 5-hydroxytryptamine (5-HT) and its deaminated metabolite 5-hydroxyindoleacetic acid (5-HIAA) by high performance liquid chromatography with electrochemical detection indicated that in both frontal cortex and hypothalamus, amiflamine (at both doses) increased 5-HT and reduced 5-HIAA concentrations. Combination of amiflamine with L-tryptophan (100 mg kg-1, i.p.) resulted in a higher 5-HT concentration being found than after amiflamine alone. L-Tryptophan treatment alone did not change 5-HT concentrations but increased 5-HIAA concentrations. Clorgyline, at a dose of either 1 or 5 mg kg-1 i.p. plus L-tryptophan (25 or 100 mg kg-1, i.p.) did not increase total activity, locomotion or behaviour. A number of possible explanations for the differences in the behavioural effects of clorgyline and amiflamine when given with L-tryptophan are discussed. It is concluded that in addition to monoamine oxidase-A inhibition, other pharmacological effects of the drugs, such as 5-HT release (amiflamine) and inhibition of tryptophan hydroxylation (clorgyline) may be of importance in determining the magnitude of the increase in activity when the compounds are given together with L-tryptophan.

Immunohistochemical and quantitative analysis of 5-hydroxytryptamine in the retina of some vertebrates

5-Hydroxytryptamine immunoreactive neurons were found in retinae from chicken, pigeon, frog and goldfish. They were localized among the amacrine cells with a distribution of cell bodies and nerve fibres that varied with the species. In chicken and pigeon, bipolar-like cell bodies were also found in the middle of the inner nuclear layer, sending processes inwards to the inner plexiform layer and outwards to the horizontal cells. The signalling direction of these cells is doubtful. No 5-hydroxytryptamine immunoreactivity was found in retinae from cow, pig, cat, rabbit, guinea-pig, rat or mouse. Quantitative analyses were performed with HPLC on extracts from chicken, pigeon, frog and goldfish retinae. High concentrations were found in goldfish and frog whereas less, about 100 ng/g, was observed in chicken and pigeon. The results suggest that 5-hydroxytryptamine is the transmitter of a set of amacrine cells in cold-blooded vertebrates and perhaps also in birds. The transmitter of the indoleamine accumulating neurons of mammals remains to be further elucidated.

Quantitative Analysts of 5-Hydroxytryptamtne in Biological Material by High Perfornance Liquid Chromatography and Electrochmical Detection

Abstract A quantitative method for the analysis of 5-hydroxytryptamine in biological material is described. The method is based on high performance liquid chromatography (HPLC) with electrochemical detection. A simple purification on a weakly acidic ion exchange resin prior to the analysis gives quite clean samples and permits concentration of diluted samples. The chromatographic separation is performed on a reverse phase column with organic modifier added to an aqueous eluent. With this analytical system 25 pg of 5-hydroxytryptamine can be detected.

Analysis of 5-hydroxytryptamine- 14C uptake and metabolism in intestinal smooth muscle

The distribution and metabolism of 5-hydroxytryptamine- 14C (5-HT- 14C) in both guinea pig ileal longitudinal smooth muscle and taenia coli preparations were measured. The uptake of 5-HT- 14C increased rapidly over 2 hr to tissue space values of f11.58 ± 0.57 (ileum) and 44.77 ± 0.59 (taenia) times the extracellular 5-HT- 14C concentration. Incubation with 13.3 μM β-phenylisopropylhydrazine (PIH) reduced 5-HT- 14C uptake by about half. Chemical separation of 14C-labeled compounds in the tissue indicated that 87–91% of the radioactivity present was 5-hydroxy-3-indoleacetic acid (5-HIAA) and 7–10% was 5-HT. In both paired ileum and taenia, PIH reduced 5-HIAA levels by 71–72% and doublet 5-HT levels. Addition of 2.67 mM non-radioactive 5-HT to incubation solutions reduced 5-HIAA- 14C levels and either did not increase 5-HT- 14C levels (taenia) or reduced them (ileum). Efflux studies showed that most of the 14C labeled material was lost at a slow rate; this rate was not altered by addition of 2.67 mM non-radioactive 5-HT or 5-HIAA during the washout. Uptake of 5-HIAA- 14C did not exceed an amount which would occupy only the extracellular space. Negligible amounts of 5-HIAA- 14C were formed when muscles were exposed to the 5-HT precursors tryptophan- 14C or 5-hydroxytryptophan- 14C. Thus, uptake of 5-HT- 14C into intestinal muscles occurs rapidly and most of the 5-HT- 14C is then metabolized to 5-HIAA- 14C which cannot readily cross cellular membranes. Synthesis of 5-HT does not occur in significant amounts in these smooth muscle tissues; they are systems in which changes in 5-HT uptake and metabolism can be measured with precision.

Conformational analysis of 5-hydroxytryptamine and its cation: ?, ?-energy contour diagram by the INDO molecular orbital method

Complete conformational energy contour diagrams of 5-hydroxytryptamine and its cationic form have been obtained by the semi-empirical LCAO-MO-SCF method of the INDO level of approximation. The most stable conformation of the neutral form is when Γ is approximately 90 ° (or 270 °) and Φ is near 60 ° (l-gauche) and 300 ° (r-gauche). The higher stability of the gauche conformations over the trans form probably results from protic hydrogen-π-base interaction. The calculated stabilization energy is approximately 1 Kcal/mole. The quantum mechanical calculation of the Γ, Φ energy diagram is in qualitative agreement with the Γ, Φ interatomic distance diagram in the evaluation of the range of conformational degrees of freedom. Calculations on the 5-hydroxytryptamine cation show that the stabilization energy due to proton-π-interaction appears to be exaggerated because the counter-anion is neglected in the calculation. In the neutral species the hydrogen-π-base interaction does not seem to be charge-transfer type, while there is a strong indication that in the cationic form the charge-transfer type of interaction is significant.

An improved fluorometric method for the determination of tryptophan in urine using sephadex G-10 extraction.

Substances interfering with the fluorometric determination of tryptophan (Try) were removed from the urine by a Sephadex G-10 column. Try was eluted with 0.1 N HCI and H2O and determined by the plasma method of Denckla & Dewey instead of their more laborious extraction method used for urine analyses. There was a fairly good correspondence between the urine method of Denckla & Dewey as modified by Lehmann, and the Sephadex method. Recoveries were within the limits ± 10 per cent for 50–500 nanomols Try added to urines and the reproducibility was good. The method was especially useful when combined with the analysis of 5-hydroxytryptamine and 5-hydroxyindole acetic acid eluted from the same columns.