EFFECT OF CONSTANT LIGHT AND CHEMICAL SYMPATHECTOMY ON DEVELOPMENT OF SEROTONIN N-ACETYLTRANSFERASE AND MONOAMINE-OXIDASE ACTIVITIES IN RAT EPIPHYSES

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  • 1 January 1975
    • journal article
    • research article
    • Vol. 24  (6) , 493-500
Abstract
The daytime activity of N-acetyltransferase per mg epiphysis decreased to 1/10 the newborn level by the age of 13 days, and subsequently remained unchanged. The night activity was equal to the day activity at the age of 3 days, was higher at the age of 6 days and was 20.times. that of the day level at the age of 40 days. Keeping animals in constant light after birth depressed the development of these diurnal differences in N-acetyltransferase activity and slowed down the decrease in enzyme activity after birth. Sympathectomy with 6-hydroxydopamine after birth abolished the development of the diurnal rhythm in N-acetyltransferase in 12-day-old rats in 2 experiments out of 5 and only decreased the night activity without abolishing the rhythm in 3 experiments. Monoamine oxidase activity [MAO] per mg epiphysis, which is the same in newly born and in adult animals, decreased to half the original value for 6 days after birth and then increased again. Constant light after birth did not influence MAO activity, but sympathectomy with 6-hydroxydopamine decreased activity in the epiphysis in 12-day-old animals.

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