Effects of angiotensin II on brain monoamine oxidase activity in non-hypoxic and hypoxic mice.

The effects of angiotensin II (ATII) administered intracerebroventricularly (i.c.v.) at a dose of 0.5 microgram per mouse on the activity of monoamine oxidase A (MAO-A) and monoamine oxidase B (MAO-B) in the forebrain of normoxic and hypoxic mice were studied. The influence of hypoxia (asphyctic and haemic) on MAO-A and MAO-B activity was also investigated. MAO-A activity was increased in haemic hypoxia; MAO-B activity increased in both asphyctic and haemic hypoxia. ATII increased MAO-A activity without affecting MAO-B activity under normoxic conditions. ATII increased MAO-A activity but decreased MAO-B in hypoxic (asphyctic) mice as compared to normoxic controls. The results suggest the role of MAO-A and MAO-B in the ATII-induced increase of susceptibility to acute hypoxia.