A method for the preparation and separation of 3-methoxy-4-hydroxyphenethyleneglycol conjugates

Dexamethasone suppression test and urinary MHPG X SO4 determination in depressive disorders

The Dexamethasone Suppression Test (DST) was performed in 64 depressed inpatients, in 48 schizophrenics, and in 20 normal controls. Thirty-four percent of depressive inpatients were found to escape from dexamethasone suppression significantly higher than either schizophrenics (13%) or normal subjects (5%). Among subgroups, bipolar and unipolar endogenous depression patients had much higher abnormal rates for the DST (59% and 48%, respectively) than nonendogenous cases (8%). DST results were also found to be positively correlated with patients' Hamilton scores. These findings suggested that DST could be helpful in diagnosis, discrimination of subtypes, and in assessment of severity of symptoms. In 32 of the 64 depressed inpatients, urinary MHPG X SO4 excretion was determined and compared with 21 normal controls. Bipolar patients (n = 7) had less MHPG X SO4 excretion than unipolar endogenous patients (n = 16). Excretion was positively correlated with cortisol level at 17 hr after dexamethasone administration in 32 depressive inpatients, especially in the unipolar subgroup. A trend toward negative correlation, though not statistically significant, was found in bipolar depression between cortisol levels at 17 hr after dexamethasone administration and urinary MHPG X SO4 excretion. This may indicate that some differences in norepinephrine (NE) metabolism may exist between unipolar and bipolar depression, leading to differing correlations between deviation of central NE function and hypothalamus-pituitary-adrenal (HPA) axis in different subgroups of depression.

Effect of ventral noradrenergic bundle transection and locus coeruleus lesions on urinary 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG) excretion in the rat

Urinary 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG) excretion was determined in rats after central noradrenergic pathway interruption by ventral bundle transection or by locus coeruleus (LC) lesions. The transection prevented an increase in urinary MHPG that occurred in sham-operated animals, an effect that was presumed to be due to loss of cerebrospinal fluid (CSF). Electrolytic lesioning of the LC, which was not attended by loss of CSF, had no effect on baseline MHPG excretion but diminished the response to subsequent administration of the alpha-adrenergic blocking agent, phenoxybenzamine (PBZ). Since the contribution of brain MHPG to total urinary MHPG is small, the observed effects of these procedures are most likely due to disrupted central regulation of peripheral sympathetic nerve activity.

Methodological issues in the measurement of urinary MHPG

Reported mean values for urinary 3-methoxy-4-hydroxyphenylglycol (MHPG) for both depressed patients and controls vary substantially between laboratories. The present study describes methodological sources of variance affecting urinary MHPG values. Although intra-assay variance is small (coefficient of variation (CV) = 4.6%), the interassay variance is high (CV = 14.3%) and suggests caution in the interpretation of small group differences. The gas chromatographic (GC) method in this laboratory produces values highly correlated (r = 0.98) with those obtained by a reference gas chromatographic-mass spectrometric (GC-MS) method. The absolute values obtained by GC are 20% higher than those by GC-MS--a problem that may be shared to a varying extent by all GC assays.

IN CONCLUSION

methodological differences do contribute to some of the variation in reported values of urinary MHPG.

The effect of electric acupuncture treatment on urinary MHPG-sulphate excretion in unmedicated schizophrenics

The daily urinary excretion of 3-methoxy-4-hydroxyphenylglycol sulphate (MHPG-SO4) was determined before and during the course of electric acupuncture treatment (EAT) in eight unmedicated schizophrenic patients. The mean excretion of MHPG-SO4 before treatment was 1439 +/- 74 micrograms/24 hr. EAT was administered once daily and continued for two weeks. The urinary MHPG-SO4 excretion steadily increased during the course of EAT. The mean values obtained during the first and second weeks of treatment were 1712 +/- 108 micrograms/24 hr and 1920 +/- 81 micrograms/24 hr respectively, each being significantly higher than the mean value obtained before EAT.

Extensive conjugation of dopamine (3,4-dihydroxyphenethylamine) metabolites in cultured human skin fibroblasts and rat hepatoma cells

[G-3H]Dopamine (3,4-dihydroxyphenethylamine) metabolism in human skin fibroblasts and rat hepatoma cells in culture was determined by high-pressure liquid-chromatographic analysis of both cell extract and uptake medium. Conjugated metabolites were selectively hydrolysed by incubation with arylsulphatase or beta-glucuronidase before analysis. The principal metabolites of dopamine in fibroblast cells are 3-methoxytyramine 4-O-sulphate and 3-methoxytyramine. No significant differences, either in the amounts of these metabolites or in the amount of dopamine metabolism, were observed in fibroblasts from both normal and homocystinuric individuals. In rat hepatoma cells, the major metabolite of dopamine was 3-methoxytyramine 4- or 3-O-glucuronide; lower concentrations of dopamine 4- or 3-O-glucuronide, 4-hydroxy-3-methoxyphenylacetic acid, 3,4-dihydroxyphenylacetic acid and two unidentified glucuronide conjugates were also observed. Significant differences in the relative concentrations of these metabolites in cell and uptake medium were observed in both cell systems.

A non-enzymic procdure for the quantitative analysis of (3-methoxy-4-sulphoxyphenyl)ethylene glycol(MHPG sulphate) in human urine using stable isotope dilution and gas chromatography-mass spectrometry

A method is described for the quantitative analysis of (3-methoxy-4-sulphoxyphenyl)-ethylene glycol (MHPG sulphate) in human urine, based on selected ion monitoring gas chromatography--mass spectrometry and using a specifically deuterium-labelled analogue of MHPG sulphate as internal standard. The procedure involves extraction of the urine sample on Amberlite XAD-2, followed by isolation of MHPG sulphate by column chromatography on Sephadex LH-20. Cleavage of the sulphate conjugate and formation of the MHPG tris(trifluoroacetate) derivative are carried out in a one-step reaction, without recourse to enzymic hydrolysis.