Effects of angiotensin II on brain monoamines in nonhypoxic and hypoxic mice.

The effects of angiotensin II (ATII) administered intracerebroventricularly (ICV, acute) and subcutaneously (SC, acute and chronic) on acute hypoxia (asphyctic and hemic), and on the forebrain concentrations of monoamines dopamine (DA), norepinephrine (NE), and serotonin (5-HT) in male mice were studied. ATII in both routes of administration exerted a decrease of the latency to hypoxia-induced convulsions. ATII slightly reduced the brain levels of DA and NE, and did not change those of 5-HT in hypoxic mice. ATII significantly reduced DA and 5-HT concentrations in nonhypoxic (normoxic) mice. Taken together, the results suggest that ATII-induced increase of susceptibility to hypoxia is accompanied by slight alterations in the brain monoamine metabolism.