Quantification of plasma phenylethylamine by combined gas chromatography/electron capture negative ion mass spectrometry of the N-acetyl-N-pentafluorobenzoyl derivative

Effects of chronic oral administration of L-deprenyl in the dog

Dogs were administered capsules containing L-deprenyl daily over 3 weeks at dose levels of 0, 0.1, 0.5, and 1.0 mg/kg. Spontaneous behavior was measured using a canine open field test, and was not significantly affected by L-deprenyl. Plasma levels of amphetamine showed a clear dose-dependent elevation 2 h and was not significantly affected by L-deprenyl. Plasma levels of amphetamine showed a clear dose-dependent elevation 2 h following treatment, but were markedly lower after 24 h, and were undetectable 5 days following the last treatment. Plasma levels of phenylethylamine were increased, but were highly variable. Animals sacrificed 1 day following the last treatment showed a dose-dependent inhibition of monoamine oxidase B in the brain, liver, and kidney, whereas monoamine oxidase A was unaffected in these tissues. L-Deprenyl also caused an increase in phenylethylamine in the striatum and hypothalamus, but not in the neocortex. Brain levels of DA, DOPAC, 3-MT, HVA, 5-HT, and 5-HIAA were unaffected. The pharmacological profile for the dog is distinct from that of other species in that long-term treatment did not produce any significant inhibition of MAO-A activity. The absence of an effect on biogenic amines or metabolites suggests that the metabolism of dopamine is mediated at least in part through pathways other than MAO-B in the normal adult dog.

Derivatization with acetic anhydride: applications to the analysis of biogenic amines and psychiatric drugs by gas chromatography and mass spectrometry

Acetylation with acetic anhydride, under both aqueous and anhydrous conditions, has been utilized to derivatize various biogenic amines and psychotropic drugs for subsequent analysis by gas chromatography (GC) or gas chromatography-mass spectrometry (GC-MS). Under basic aqueous conditions, acetic anhydride derivatizes phenols and amines but not alcohols; under anhydrous conditions, all three functions are acetylated. Primary amines, once derivatized with acetic anhydride, can be further derivatized with other reagents; these diderivatives have proven useful for subsequent analysis by GC or GC-MS. Examples of applications of derivatization with acetic anhydride to analysis of biogenic amines, antidepressants, antipsychotics, and some of their metabolites are presented.

The effect of L-deprenyl on behavior, cognitive function, and biogenic amines in the dog

Behavioral and pharmacological effects of oral administration of L-deprenyl in the dog are described. Spontaneous behavior is unaffected at doses below 3 mg/kg while at higher doses there was stereotypical responding. There was evidence of improved cognitive function in animals chronically treated with a 1 mg/kg dose but the effectiveness varied considerably between subjects. Chronic administration produced a dose dependent inhibition in brain, kidney and liver monoamine oxidase B, and had no effect on monoamine oxidase A. There were also dose dependent increases in brain phenylethylamine and in plasma levels of amphetamine. Dog platelets did not have significant levels of MAO-B. Brain dopamine and serotonin metabolism were unaffected by L-deprenyl at doses up to 1 mg/kg. It appears that for the dog, deamination of catecholamines is controlled by MAO-A. Nevertheless, it is suggested that L-deprenyl serves as a dopaminergic agonist, and there is also evidence that it affects adrenergic transmission. These catecholaminergic actions may account for the effects of L-deprenyl on behavior and cognitive function.

The effect of the MAO-A selective inhibitor brofaromine on the plasma and urine concentrations of some biogenic amines and their acidic metabolites in bulimia nervosa

1. Brofaromine or placebo were administered to female bulimia nervosa patients over a period of eight weeks. Plasma and urinary trace amines, their acidic metabolites and the acidic metabolites of the catecholamines and serotonin were assessed prior to treatment and at four and eight weeks after commencement of treatment. 2. The levels of both plasma and urinary homovanillic and vanilmandelic acids declined significantly during the first four weeks of treatment with brofaromine and then partially recovered to pre-drug levels by the eighth week. 5-Hydroxyindoleacetic acid levels were not affected by drug treatment at the times assessments were made. Urinary tryptamine increased significantly during the first four weeks of brofaromine treatment then partially recovered towards pre-drug levels by the eighth week. No effect from placebo treatment was observed.

Determination of regional distributions of phenylethylamine and meta- and para-tyramine in rat brain regions and presence in human and dog plasma by an ultra-sensitive negative chemical ion gas chromatography-mass spectrometric (NCI-GC-MS) method

Using a new ultrasensitive method the trace biogenic amines, phenylethylamine, meta-tyramine and para-tyramine have been quantitated in brain regions obtained from a single rat. Phenylethylamine concentrations in ng/g wet tissue (mean +/- std. error) were as follows: caudate 2.71 +/- 0.73, hypothalamus 0.45 +/- 0.15, cerebellum 0.09 +/- 0.02, olfactory bulb 0.35 +/- 0.11, stem 0.13 +/- 0.03, hippocampus 0.20 +/- 0.11, cortex 0.69 +/- 0.13 and the rest (remainder of the brain) 2.81 +/- 0.41. Mean whole brain was 1.23 +/- 0.19 ng/g, in agreement with previous measurements. meta-Tyramine concentrations (ng/g) were: caudate 2.69 +/- 0.19, hypothalamus 0.32 +/- 0.16, cerebellum 0.07 +/- 0.04, olfactory bulb 0.09 +/- 0.04, stem 0.04 +/- 0.01, hippocampus 0.07 +/- 0.02, cortex 0.18 +/- 0.15 and the rest 0.15 +/- 0.06, with a mean whole brain value of 0.26 +/- 0.05 ng/g and para-tyramine concentrations were: caudate 8.99 +/- 1.60, hypothalamus 0.93 +/- 0.13, cerebellum 0.78 +/- 0.27, olfactory bulb 0.70 +/- 0.13, stem 0.90 +/- 0.36, hippocampus 0.40 +/- 0.06, cortex 1.78 +/- 0.28 and the rest 2.38 +/- 0.12 and mean whole brain was 1.90 +/- 0.25 ng/g. In human plasma the concentrations of the three amines were found to be 31.3 +/- 3.4 pg/ml, 5.3 +/- 1.6 pg/ml and 66.0 +/- 9.9 pg/ml respectively and in dog blood 95.3 +/- 4.6 pg/ml, 24.0 +/- 7.6 pg/ml and 486 +/- 43 pg/ml respectively. When monoamine oxidase inhibitors were added to the blood immediately after collection there were no significant increases in the amine levels indicating that MAO-B is not present in plasma in significant quantities.

Determination of amphetamine, methamphetamine and desmethyldeprenyl in human plasma by gas chromatography/negative ion chemical ionization mass spectrometry

A sensitive and specific assay for the quantitative determination of amphetamine, methamphetamine and desmethyldeprenyl in human plasma specimens is described. Electron capture/negative ion chemical ionization gas chromatography/mass spectrometry is used to determine the extracted plasma concentrations of the three target compounds as their N-heptafluorobutyryl derivatives. Quantitation is performed by stable isotope dilution using d6-amphetamine and d6-methamphetamine as internal standards. Selected ion monitoring of the [M-HF]- ions of both the analytes and internal standards results in minimum quantifiable limits of 0.10 ng ml-1 for both amphetamine and methamphetamine and 0.25 ng ml-1 for desmethyldeprenyl. Excellent linearity (r = 0.998) up to at least 5.00 ng ml-1 is demonstrated.

Plasma phenylethylamine in schizophrenic patients

Plasma samples were collected from 41 patients who met DSM-III criteria for schizophrenia and from 34 healthy controls. Phenylethylamine (PE) levels were determined using a gas chromatography-mass spectrometry negative chemical ionization method. PE was significantly higher in the schizophrenic patients compared with controls. There were no differences in PE between paranoid and nonparanoid patients. Plasma PE did not appear to be influenced by the severity of schizophrenic symptoms (rated by BPRS, SANS, and SAPS) or by the amount of dietary phenylalanine ingested within 24 hr of testing. Plasma PE did not correlate with current or past exposure to neuroleptic medication. It was not possible, however, to test individual patients during two periods when they were taking and not taking medication. Thus it is possible that neuroleptic exposure may have confounded the results. This study provides further evidence that PE excess may play a role in the etiology of schizophrenia but does not support previous studies which suggest that such an abnormality is limited to the paranoid subgroup.