Sulfate and glucuronide conjugates of 3-methoxy-4-hydroxyphenylglycol (MHPG) in urine of depressed patients: Central and peripheral influences

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Abstract
A number of arguments support the hypothesis that changes in urinary levels of MHPG sulfate and MHPG glucuronide respectively reflect central and peripheral norepinephrine metabolism (NE) in man. In this line, the daily excretion of both conjugates was determined in 36 depressed women comparatively to 23 healthy women in order to assess the extent and the central or peripheral location of their possible NE dysfunction. About 80% of the patients suffering from depression (6 endogenous, 19 neurotic, 11 reactive depressions) exhibited a central NE defect, as evidenced by low MHPG sulfate, and many of them had probably also diminished sympathetic activity, as suggested by low MHPG glucuronide. Clinical symptoms possibly related to the psychic state (mood alteration) or associated to sympathetic changes (anxiety, motor activity) respectively altered sulfate or glucuronide excretion. Sulfate (S) and glucuronide (G) MHPG excretions were significantly correlated in healthy subjects (r = 0.53, p = 0.01), thus supporting the concept of the functional link between central NE activity and sympathetic function. Such a correlation was not found in depressive patients. However the lack of significant changes in the mean ratio S/G in the patient subgroups suggests that as in normal subjects, central and peripheral NE activity As a conclusion, our work shows that urinary MHPG provides in depressed patients an index of the psychobiological state, involving central and peripheral components. Any factor acting on either of both components is able to modify MHGP excretion. The separate assay of sulfate and glucuronide MHPG allows-with some limitations-to define the relative changes of central and peripheral activity. As a whole, our data indicate that in the examined population, 80% had probably a central NE hypoactivity, also associated in a large number to a sympathetic dysfunction. These observations may have valuable physiopathologic and/or therapeutic implications.