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[Relations between urinary 3-methoxytyramine and the peripheral metabolism of dopamine in human adults and children]
Insights
Urinary 3-methoxytyramine (3-MT), a dopamine metabolite, increases significantly in infants. Urinary 3-MT better reflects peripheral dopaminergic activity than dopamine (DA) in young children.
Area of Science:
- Biochemistry
- Pediatrics
- Neuroscience
Background:
- 3-Methoxytyramine (3-MT) is a direct metabolite of dopamine (DA).
- Urinary 3-MT is detectable in human infants at birth.
- Dopaminergic activity is crucial for infant development.
Purpose of the Study:
- To investigate the developmental changes in urinary 3-MT excretion.
- To determine the origin of urinary 3-MT.
- To compare the utility of urinary 3-MT and DA as markers of dopaminergic activity in children.
Main Methods:
- Analysis of urinary 3-methoxytyramine (3-MT) and creatinine levels.
- Comparison of excretion rates in infants and adults.
- Assessment of dietary influences on metabolite excretion.
Main Results:
- Urinary 3-MT excretion increases sharply from birth to 12 months, then slows.
- After age 15, urinary 3-MT levels stabilize.
- Urinary 3-MT appears to originate primarily from peripheral sources.
- 3-MT excretion is less influenced by diet than DA excretion.
Conclusions:
- Urinary 3-MT excretion follows a distinct developmental trajectory.
- Peripheral dopaminergic activity is the likely source of urinary 3-MT.
- Urinary 3-MT is a more reliable indicator of peripheral dopaminergic activity than urinary DA, especially in young children.
Abstract:
3-Methoxytyramine (3-MT), the direct metabolite of dopamine (DA) is present in human urines at birth. The rate of its urinary excretion (microgram/24 h) increases highly from birth to 12 months of age; in the next period of infancy, the increase is slower and parallel to that of creatininury; after 15 years, the urinary amounts of 3-MT remain nearly constant, with advancing age. The analysis of the possible sources of urinary 3-MT, lead us to suggest that this compound has essentially a peripheral origin. On the other hand the comparison between urinary data of 3-MT and DA in normal infants and adult subjects has shown that 3-MT excretion is less affected by dietary input than DA itself, so that it can be concluded that urinary 3-MT is a better indication of peripheral dopaminergic activity than urinary DA, chiefly in the young child.