A new eburnamine derivative, RU 24722 (RU), is structurally resemblant to Vincamine and is known as a specific and reversible depletor of noradrenaline (NA) in rat brain (Euvrard and Boissier, 1981). We further investigated the effect of RU on turnover of mouse brain monoamines and on catecholamine levels in rat plasma. NA levels in mouse brain were significantly decreased after 10mg/kg i.p. administration of RU with increasing MHPG, DOPAC and HVA. These changes returned to the control levels within 4 hrs. Levels of dopamine (DA), serotonin 5HIAA and histamine did not change at that dose. Vincamine did not affect those levels with the exception of a slight increase in MHPG levels at higher dose (50mg/kg). Plasma catecholamine levels in unanesthetized and freely-moving rats were 5- to 10-fold increased 10 min after RU (10mg/kg) and decreased to the basal levels within 4 hrs. These results indicate that RU increased turnover of NA and DA through releasing them from neural tissues.
