[Selective study of sulfate and glucuronide conjugates of urinary MHPG in nervous depression. Peripheral and central influences]

Abstract

The determination of urinary MHPG (3-methoxy-4-hydroxyphenyl glycol) has been extensively performed to confirm the noradrenergic hypothesis of some depressions. However, owing to the double origin, central and peripheral, of this norepinephrine metabolite, the validity of total MHPG assay as an index of central noradrenergic activity may be challenged. MHPG exists in human urine in two conjugated forms, at equal amounts: sulfate and glucuronide. A number of arguments suggest that MHPG sulfate and MHPG glucuronide respectively reflect central and peripheral norepinephrine metabolism. In this work, we have selectively estimated both MHPG conjugates in 24 h-urine samples of 36 severely depressed women in view to assess the extent and frequency of central or/and peripheral norepinephrine dysfunction. On the basis of MHPG sulfate and glucuronide values, we conclude that in the examined population (6 endogenous, 19 neurotic, 11 reactive depressions) about 80% of patients exhibited a central NE functional deficit, and many of them had also a diminished sympathetic activity. Clinical symptoms related to psychic factors (melancholia) or associated to sympathetic activity changes (anxiety, retardation) respectively alter sulfate or glucuronide MHPG excretion. These data altogether validate the concept of the independent origin of the two MHPG conjugated and show that their selective assay is able to provide a more satisfactory reflection of the psychobiological state in depressed patients than total MHPG determination.