NEONATAL AND SENESCENT CHANGES IN L-AROMATIC AMINO ACID DECARBOXYLASE AND MONOAMINE OXIDASE ACTIVITIES IN KIDNEY, LIVER, BRAIN AND HEART OF THE RAT

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Abstract
The activities of AADC and MAO were measured in kidney, liver, brain and heart of the rat at neonatal to senescent stages. Rapid neonatal increase to adult level in the specific activity of AADC was observed in the kidney, liver and brain. The total activity of AADC per organ continued to increase in the brain for 3 weeks after birth and for 20 weeks in the kidney and liver. In the heart, the specific activity of AADC increased up to the 10th day after birth and decreased to the mature level during the next 10 days. Senescent decreases both in specific and total activities of AADC were observed in all organs examined. Neonatal increment to adult level in the specific or total activities of MAO in kidney, liver and brain was observed. Senescent decrement in specific and total MAO activities was demonstrated in the kidney, while significant changes in liver and brain were not observed. The MAO activity in heart continued to increase in linear fashion for 70 weeks after birth. The concentration of 5HT in kidney, liver and brain of the 10 day-old rats was much less than that in the adult. Senescent decrease of 5HT contents was not evident in any organ examined. These findings suggest the age-related change of physiological condition of amine metabolism.