The diurnal variations of monoamine oxidase activity in discrete nuclei of rat brain

Abstract

The diurnal variations of MAO activities (type A and type B) in the individual hypothalamic nuclei, in addition to some areas of the rat brain, were studied under two different lighting schedules, D-L condition and D-D condition. Type A MAO activities in some nuclei increased significantly in the light period in D-L condition and the change in N. suprachiasmaticus (SCN) and N. supraopticus (SON) was also maintained in D-D condition. Type B MAO activities in some nuclei showed preferably the opposite phase to that of type A MAO activity. These diurnal changes of each MAO type activity may reflect the biological actions of monoamines in relation to a circadian rhythm of the neuroendocrinological system in the brain to some extent.