when expressed per milligramme of tissue , total protein content was increased to a similar extent in whole brain and in all seven brain regions of the aging rat , whereas mao a activity ( assayed by using 5-hydroxytryptamine as substrate ) was unchanged in whole brain but increased in the cerebellum , and fell in the brainstem , midbrain , hippocampus , and cortex ;
C0006121
brainstem
C0025462
midbrain