Angiotensin II receptor subtypes in the human central nervous system

The distribution of the AT 1 and AT 2 subtypes of angiotensin II receptor was mapped in the adult human central nervous system using quantitative in vitro autoradiography. Binding in all forebrain, midbrain, pontine, medullary and spinal cord sites where angiotensin II receptors have previously been described is of the AT 1 subtype, as is binding in the small and large arteries in the adjacent meninges and in choroid plexus. By contrast, both AT 1 and AT 2 receptors occur in the molecular layer of the cerebellum. Angiotensin II AT 1 receptors in the brain show a moderate degree of conservation across mammalian species studied so far, whereas expression of AT 2 receptors is more variable, and is more restricted in the human CNS than in many other mammals. These differences between the subtype distributions in humans and other animals indicate the need for care when extrapolating the results of animal studies involving the brain angiotensin system.