Angiotensin II immunohistochemistry of the rat brain

Immunoreactive angiotensin II (AII) in rat brain is identified histochemically by the unlabelled antibody-enzyme method. Addition of protease inhibitors, phenylmethyl sulfonyl fluoride (PMSF) and ethylenediamine tetra-acetic acid (EDTA), to subzero (-10 degrees C) fixation with propylene glycol and formaldehyde provides reproducible preservation of immunoreactive AII. Synaptic boutons within the brainstem and cerebellum contain immunoreactive AII. The deep cerebellar nuclei have the richest density of AII positive synapses. Other nonneuronal cells such as pinealocytes, pituicytes, and 3rd ventricular tanycytes contain immunoreactive AII. This dual AII localization suggests that both neurons and blood vessels may be involved in the transport of AII to sensitive sites within the rat brain.