Brain angiotensin II: localization and possible functions

The results of biochemical, immunohistochemical and autoradiographic studies have led to the description of the endogenous brain angiotensin II system as a highly localized network of angiotensin II-containing cell bodies and fibers as well as characteristic sites with high angiotensin II receptor density. The specific localization of this system predominantly within limbic, hypothalamic and brain stem structures that are known to be involved in central cardiovascular regulation and the control of volume homeostasis suggests a possible functional role of brain angiotensin II in the control of these homeostatic functions. In particular, brain angiotensin II may function to help maintaining adequate tissue perfusion to vital parts of the body at times, when body fluid and cardiovascular homeostasis are jeopardized. In addition, there is evidence that brain angiotensin II may participate in the control of hormone release from the anterior and posterior pituitary gland, regulation of body temperature and the processing of learning contents. Future research may profitably be directed towards an exact functional characterization of central angiotensinergic pathways as well as an detailed analysis of the mechanisms that underly central angiotensin II-induced responses.