Abstract
MAO activity in rat brain mitochondria was 40 to 50 % of the adult level at birth and increased to about 90 % of the adult level at 4 weeks of age. In males the activity increased slightly until 8 weeks after birth whereas in females it decreased 7 to 8 weeks after birth, becoming significantly different from that in males. After gonadectomy, the activity in females increased and that in males decreased. Of the sex hormones tesed, only 17 β-estradiol decreased MAO activity. The sexual difference in the patterns of development of MAO activity in rat brain may be partly due to the effect of 17 β-estradiol.
