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Biomedical subjects

J J Warsh

Publications and source records attributed to J J Warsh.

At least 91 records · Page 5Linked to original sources
PubMed1982

Simultaneous determination of norepinephrine, dopamine and serotonin in rat brain regions by ion-pair liquid chromatography on octyl silane columns and amperometric detection.

A highly sensitive and specific ion-pair liquid chromatography-electrochemical detection method is described for the simultaneous determination of rat brain regional norepinephrine, dopamine and serotonin levels using octylsilane (C8) columns. These amines were first isolated from tissue homogenates by adsorption on Amberlite CG-50 resin followed by separation on RP-8 columns with a mobile phase consisting of 0.05 M NaH2PO4 (pH 3.0) 0.02 mM EDTA, 1 mM heptanesulphonate-methanol (92:8, v/v) at 1.8 ml/min. Using 3,4-dihydroxybenzylamine as the internal standard, tissue recoveries (mean +/- S.D.) for norepinephrine, dopamine and serotonin were 87.5 +/- 2.6%, 61.8 +/- 10.5% and 72.9 +/- 7.5%, respectively. Assay sensitivities were sufficient for reliable quantitation of at least 200 pg of these compounds in a brain sample. The procedure is readily adaptable to determination of brain epinephrine and normetanephrine levels, as well. Finally, the reversed-phase system employed is highly flexible in that the same column and mobile phase conditions may be used for assay of biogenic amine metabolites.

Animals↗
PubMed1981

Controlled exercise elevates plasma but not urinary MHPG and VMA.

The effect of controlled exercise on plasma and urinary 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG) and vanillylmandelic acid (VMA) was investigated in normal subjects. After 3 days of bed rest, six normal volunteers engaged in controlled exercise adjusted to a constant 40% of the individual's maximum oxygen intake. The exercise program consisted of 4 miles of walking and a half-hour each of bicycle ergometry and treadmill walking. Both plasma VMA and MHPG were higher on the exercise day than on the resting day, while urinary VMA and MHPG levels did not differ from rest to exercise. The mean urinary MHPG/VMA ratio (0.46) differed markedly from the mean plasma MHPG/VMA ratio (2.3). Plasma and urinary MHPG apparently represent different indices of norepinephrine metabolism.

Adolescent↗
PubMed1981

Rat brain and plasma norepinephrine glycol metabolites determined by gas chromatography-mass fragmentography.

A gas chromatographic-mass fragmentographic (GC-MF) procedure is described for the simultaneous quantitation of 3,4-dihydroxyphenylethyleneglycol (DHPG) and 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG) in brain tissue and plasma. DHPG and MHPG were assayed as their respective acetyl-trifluoroacyl esters, using [2H2]DHPG and [2H3]MHPG as internal standards. Assay sensitives of at least 1 ng per sample were attainable for the quantitation of free glycols, whereas for determination of total DHPG, assay sensitivity was 2.5 ng. Whole rat brain total (99.2 +/- 4.11 ng/g) and free (13.0 +/- 1.14 ng/g) DHPG concentrations were similar to respective total (86.0 +/- 3.70 ng/g) and free (12.3 +/- 0.41 ng/g) MHPG levels. Total DHPG concentrations exceeded total MHPG levels in hypothalamus (3.0:1), midbrain (1.4:1), pons plus medulla (1.3:1), and hippocampus (1.5:1), whereas in other brain regions the levels of these metabolites were similar. In plasma, however, total DHPG levels were only 20% as high as MHPG concentrations. In mouse brain, DHPG and MHPG occurred almost entirely in free form (greater than 90%), but total DHPG levels were only 50% as high as respective MHPG concentrations. These results emphasize the substantial formation of DHPG compared with MHPG in rat and mouse brain and suggest that DHPG formation and efflux may be of equal or greater importance than MHPG in the metabolic clearance of CNS norepinephrine in some species.

Animals↗
PubMed1981

Postmortem stability of brain 3-methoxy-4-hydroxyphenylethyleneglycol and 3,4-dihydroxyphenylethyleneglycol in the rat and mouse.

To assess the postmortem stability of brain 3-methoxy-4-hydroxy-phenylethyleneglycol (MHPG) and 3,4-dihydroxyphenylethyleneglycol (DHPG) levels, groups of rats and mice were killed by cervical dislocation and left at either 21 degrees or 4 degrees C for intervals of up to 24 h until removal and freezing of whole brain. Whole brain free and total MHPG and DHPG levels were determined simultaneously by gas chromatography-mass fragmentography (GC-MF). By 2 h death, statistically significant decrements occurred in rat brain free DHPG (20%), total MHPG (21%), and total DHPG (11%) at 4 degrees C, but free MHPG increased significantly (50%) compared with controls. At 21 degrees C, rat brain total MHPG increased compared with controls at 2 h (15%) but decreased at 4 h (15%) and 8 h (15%), whereas free MHPG levels were increased at these times. Although brain total and conjugated DHPG levels showed little change, free DHPG levels were reduced at all times. In mouse brain no significant changes occurred in free MHPG and DHPG by 24 h at 4 degrees C. At 21 degrees C, mouse brain DHPG levels decreased whereas MHPG concentrations increased over the 8-h period of study. These findings demonstrate the occurrence of significant postmortem time- and temperature-dependent changes in brain MHPG and DHPG concentrations and indicate caution in the interpretation of changes in these metabolites in studies employing human postmortem brain tissue.

Animals↗
PubMed1980

Serotonin receptors in hippocampus and frontal cortex.

The inhibition by various serotonin agonists and antagonists of the binding of 3 nM 3H-d-LSD, 1.7 nM 3H-serotonin and 0.22 nM 3H-spiperone to homogenates of calf hippocampus and frontal cortex was studied. The 50% inhibitory concentration (IC50) for these drugs versus 3H-d-LSD binding had similar values to and correlated with corresponding IC50 values versus 3H-serotonin binding in the hippocampus, suggesting that 3H-LSD and 3H-serotonin label similar sites in this region. In the calf frontal cortex, serotonin revealed a biphasic inhibition against 3H-d-LSD binding and the tryptamines inhibited over a concentration range of 10 000-fold. The IC25 values of various drugs versus 3H-d-LSD binding correlated with the IC50 values versus 3H-serotonin, but did not correlate with the IC50 values versus 3H-spiperone. These data suggest that 3H-d-LSD bound to more than one serotonin site in the calf frontal cortex and that 3H-spiperone bound to a separate serotonergic site. Scatchard analyses of the binding for these three 3H-ligands indicated that in the calf frontal cortex the density of 3H-d-LSD sites was approximately equal to the sum of the densities for 3H-serotonin (S-1 sites) and 3H-spiperone (S-2 sites). Two weeks after serotonin-depleting radiofrequency heat lesions of the midbrain dorsal and median raphe nuclei in rats, both 3H-serotonin and 3H-LSD showed enhanced binding in the hippocampus. These data support previous suggestions that supersensitivity develops specifically in serotonin receptors following afferent denervation.

Animals↗
PubMed1979

Depression: new evidence in support of biological differentiation.

The authors studied monoamine metabolism in patients with bipolar (manic-depressive) and unipolar depressive illness and in normal control subjects under strict dietary conditions before and during administration of carbidopa, a peripheral decarboxylase inhibitor. They found that unipolar depressed patients excreted higher amounts of 3-methoxy-4-hydroxyphenylglycol (MHPG) and 5-hydroxyindoleacetic acid (5-HIAA) in the drug-free period and while receiving carbidopa and significantly less tryptamine only after carbidopa administration. Plasma tryptophan levels differed in the three groups. The authors state that their research design reveals changes in serotonin and nonrepinephrine metabolism in unipolar depressed subjects that distinguish this group from normal and bipolar depressed subjects, suggesting a reduced CNS uptake of tryptophan in unipolar depression.

Adult↗
PubMed1978

5-Hydroxytryptophol in human cerebrospinal fluid: quantitative determination by gas chromatography-mass spectrometry using a deuterated internal standard.

Procedures for the quantification of 5-hydroxyindole-3-ethanol, or 5-hydroxy-tryptophol (5-HTOL), in human cerebrospinal fluid are described. 5-HTOL was determined as its di-pentafluorpropionyl derivative. Deuterium labelled 5-hydroxyindole-3-ethanol-a,a,b,b-d4 (5-HTOL-d4) was used as internal standard. Mass fragmentography was performed by double ion monitoring each for 5-HTOL and 5-HTOL-d4 and their ratios were determined for specificity. Assay sensitivities of 0.15 ng/ml were achieved using 2.0 ml of cerebrospinal fluid. Free 5-HTOL concentrations in human cerebrospinal fluid were determined to be 0.73 +/- 0.44 ng/ml (mean +/- S.D.) (range 0.33-2.11 ng/ml) from 15 patients with various neurological disorders, and 0.85 +/- 0.30 ng/ml (range 0.48-1.32 ng/ml) from 9 subjects who complained of low back pain but did not show signs of neurological illnesses.

Chromatography, Gas↗
PubMed1978

A radiotracer method for the measurement of central nervous system catecholamines in vivo.

A new strategy for measurement of brain catecholamines was tested in an animal model. [3H]Norepinephrine was infused intravenously in rabbits to label the peripheral norepinephrine pools. The specific activity of urinary 3-methoxy-4-hydroxymandelic acid was consistently higher than that for 3-methoxy-4-hydroxyphenyglycol (MHPG). Central sympathectomy with 6-hydroxydopamine abolished this difference. Using the formula we propose, it is estimated that 30-50% of urinary MHPG originates from the central nervous system.

Animals↗