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At least 1,315 records · Page 73Linked to original sources
PubMed2005

Effects of long-term biogenic amine transporter blockade on receptor/G-protein coupling in rat brain.

This study examines the effect of long-term elevation of brain monoamine levels on receptor/G-protein coupling by chronic administration of a highly potent tropane analog, WF-23 (2beta-propanoyl-3beta-(2-naphthyl) tropane). WF-23 blocks dopamine, serotonin and norepinephrine transporters with high affinity in vitro, and blocks transporters for at least two days following a single in vivo administration. Rats were chronically treated for 15 days with 1mg/kg WF-23, injected i.p. every two days. Receptor activation of G-proteins was determined by [35S]GTPgammaS autoradiography in brain sections for D2, 5-HT1A and alpha2-adrenergic receptors, as well as mu opioid receptors as a non-monoamine receptor control. Chronic treatment with WF-23 produced significant reductions in D2, 5-HT1A, and alpha2-adrenergic receptor-stimulated [35S]GTPgammaS binding in caudate/putamen, hippocampus and amygdala, respectively. There were no effects of WF-23 treatment on mu opioid-stimulated [35S]GTPgammaS binding. Additionally, there was no effect of WF-23 treatment on D2 receptor binding, as determined by [3H]spiperone autoradiography. These data show that chronic blockade of monoamine transporters produces specific uncoupling of receptors and G-proteins in specific brain regions in the absence of receptor downregulation.

Animals↗
PubMed2004

Peripheral P2X receptors and nociception: interactions with biogenic amine systems.

ATP is implicated in peripheral nociception following activation of P2X, and particularly P2X(3) receptors. The present study examined interactions between alphabeta-methylene-ATP (a P2X(3) receptor ligand) and 5-hydroxytryptamine (5-HT), noradrenaline (NA) and histamine, following local administration into the hindpaw, on spontaneous pain behaviors and thermal hyperalgesia in Sprague-Dawley rats. The interaction with NA was further explored using systemic 6-hydroxydopamine (6-OHDA) and locally administered indomethacin. alphabeta-methylene-ATP produced no spontaneous pain behaviors. Coadministration of 5-HT with alphabeta-methylene-ATP mildly augmented flinching behaviors, while histamine had no such effect. Coadministration of NA with alphabeta-methylene-ATP produced a pronounced expression of flinching and biting/licking behaviors. alphabeta-Methylene-ATP, given alone, produced thermal hyperalgesia, and this was markedly augmented by both 5-HT and NA, but not histamine. 6-OHDA (neurotoxin for sympathetic neurons) and indomethacin (cyclooxygenase inhibitor) reduced the augmenting effect of NA on alphabeta-methylene-ATP-induced thermal hyperalgesia, but had no effect on spontaneous pain behaviors produced by the alphabeta-methylene-ATP/NA combination. Effects of alphabeta-methylene-ATP, NA and their combination were also examined in Long Evans and Wistar rats. In both strains, alphabeta-methylene-ATP and NA both individually led to significant intrinsic flinching behaviors, and the effect of their combination was even more pronounced than in Sprague-Dawley rats. These results provide evidence for: (a) a strong enhancement by NA and 5-HT of nociception produced by peripheral P2X receptors in Sprague-Dawley rats, (b) an indirect action of NA, via sympathetic efferents and prostanoids, with thermal hyperalgesia, and (c) a greater expression of spontaneous pain behaviors with alphabeta-methylene-ATP and NA alone, and with their combination, in Wistar and Long Evans rats compared to Sprague-Dawley rats.

Adenosine Triphosphate↗
PubMed2005

Effects of neuropeptide Y on food intake and brain biogenic amines in the rainbow trout (Oncorhynchus mykiss).

Neuropeptide Y (NPY) is one of the most potent stimulants of food intake in mammals, but very little is known about NPY actions in fish. The present study investigated the role of NPY in food intake in the rainbow trout (Oncorhynchus mykiss). Food intake was monitored at different times after intracerebroventricular administration of porcine NPY (4 or 8 microg). Both doses significantly increased food intake at 2 and 3 h, and this effect was dose-dependent. However, 50 h after administration of NPY, food intake was significantly lower than in control fish, and cumulative food intake had returned to levels similar to those seen in the control group. The NPY antagonist (D-Tyr27,36, D-Thr32)-NPY (10 microg) inhibited food intake 2 h after icv administration, but did not block the orexigenic effect of NPY when administered jointly with 4 microg NPY. To identify the NPY receptor subtypes involved in the effects of NPY on food intake, we studied the effects of the Y1 receptor agonist (Leu31, Pro34)-NPY (4 microg), the Y2 receptor agonist NPY(3-36) (4 microg), and the highly specific Y5 receptor agonist (cPP(1-7), NPY19-23, Ala31, Aib32, Gln34)-hPP (4 microg). Short-term (2 h) food intake was moderately stimulated by the Y1 agonist, more strongly stimulated by the Y2 agonist, and unaffected by the Y5 agonist. We found that administration of NPY (8 microg icv) had no effect on aminergic systems in several brain regions 2 and 50 h after NPY administration. These results indicate that NPY stimulates feeding in the rainbow trout, and suggest that this effect is cooperatively mediated by Y2- and Y1-like NPY receptors, not by Y5-like receptors.

Animals↗
PubMed1997

Effect of PDGF and TGF-beta on the release of biogenic amines from invertebrate immunocytes and their possible role in the stress response.

PDGF-AB and TGF-beta 1 intervene in molluscan stress response, the former inhibiting and the latter inducing the release of norepinephrine and epinephrine from hemocytes. These amines are down-regulated even when TGF-beta 1 is added to hemolymph pre-incubated with PDGF-AB. The opposite behaviour is observed if the growth factors are reversed. The dopamine response is not affected in either case, even after the addition of CRH or ACTH. After pre-incubation with PDGF-AB or TGF-beta 1 in the presence of CRH or ACTH, norepinephrine and epinephrine release falls. These findings suggest that when the interaction is between growth factors, the order of combination is crucial, while in cases where the interaction is between growth factors and other peptides, such as CRH and ACTH, the order is of no importance.

Adrenocorticotropic Hormone↗
PubMed1983

Mass spectrometry of biogenic catecholamine ion pairs by direct liquid introduction.

The mass spectrometry of ion pairs of dopamine, noradrenaline and 3,4-dihydroxyphenylacetic acid with n-octylsulphonate has been investigated by direct liquid introduction in an acidic buffer currently used for their high-performance liquid chromatographic separation. In order to follow the fate of the ion pairs, they were first studied by desorption/chemical ionization as dichloromethane extracts or in the buffer. The results show that characteristic spectra of the solutes can be obtained by direct liquid introduction provided that the interface between the chromatographic system and the mass spectrometer permits the desolvation of the ion pairs from the cluster of solvent molecules.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1981

Gas chromatographic determination of some biogenic amines as their pentafluorobenzoyl derivatives in the picogram range and its applicability to biological materials.

The catecholamines dopamine and noradrenaline were converted into the stable pentafluorobenzoyl (PFB) derivatives for their specific and quantitative gas chromatographic (GC) assay. This allowed their detection in the picogram range using an electron-capture detector. Acylation was performed with pentafluorbenzoyl chloride in the presence of pyridine and with acetonitrile as solvent. The structures of the PFB-catecholamines were confirmed by GC-mass spectrometry. A good separation was obtained on 5% OV-17 at 265 degrees C. The high adsorption activity of the PFB-catecholamines could be overcome by optimizing the reaction conditions and applying special GC precautions. Linearity of the method was demonstrated for 50- 500 ng of the catecholamines with detection at the picogram level. The application of the method to biological materials is demonstrated.

Animals↗
PubMed1981

High-performance liquid chromatographic determination of biogenic amines. II. Comparison of detection methods.

With acidic aqueous mobile phases on silica, detection by electrochemical oxidation on a carbon paste working electrode was compared with detection by the native fluorescence by excitation at 280 nm of catechols and indoles. Based on evaluations of sensitivity, reproducibility, stability, selectively and simplicity of handling, the fluorescence detector was considered superior to the voltammetric detector. Preliminary results from direct injections of deproteinized serum indicated that at levels of at least 10 microgram/1 the content of some indoles in biological fluids could be determined without further sample purification.

Biogenic Amines↗
PubMed1988

Adsorption chromatography on cellulose. II. Separations of aromatic amino acids, biogenic amines, alkaloids, dyes and phenols and determination of hydrophobic constants.

Separations of amines, phenols, alkaloids, etc., using cellulose papers or thin layers with aqueous ammonium sulphate as eluent are reported. These separations illustrate that excellent analytical separations are possible and provide data for the study of the mechanism of adsorption on cellulose from aqueous solutions.

Alkaloids↗
PubMed1984

Determination of biogenic amines in meat by combined ion-exchange and capillary gas chromatography.

A procedure is described for the determination of putrescine, cadaverine and histamine in meat. Crude perchloric acid extracts were pre-separated on a weakly acidic cation exchanger and the amines quantified by capillary gas chromatography. The diamines were analysed as trifluoroacetyl derivatives and histamine was converted into N alpha-trifluoroacetyl-N tau-ethoxycarbonylhistamine. The accuracy of the determination of diamines was examined by a precipitation pre-separation method and by mass fragmentometric quantification. The proposed procedure allows the sensitive, sufficiently precise and highly specific determination of putrescine and cadaverine in meat.

Animals↗