Immunohistochemical localization of the angiotensin-(1-7) receptor Mas in the murine forebrain.

Apart from the well-known biologically active angiotensin II, other biologically active angiotensins have been discovered, including angiotensin IV and angiotensin-(1-7). Some years ago, we and others discovered that the Mas proto-oncogene encodes a receptor that is essential for angiotensin-(1-7) signaling. Angiotensin-(1-7) is not only expressed in the periphery but also within the brain. Based on that, we examined the distribution of Mas within the murine brain, using an antibody directed against the 3(rd) cytoplasmic loop of the receptor protein. Strongest Mas protein expression was detected in the dentate gyrus of the hippocampus and within the piriform cortex. However, Mas protein expression is not restricted to these areas, since Mas immunopositive neurons were also seen in different parts of the cortex, hippocampus, amygdala, basal ganglia, thalamus and hypothalamus. Based on the expression of Mas protein in the cortex and the limbic system, angiotensin-(1-7) signaling may play a role in synaptic plasticity, learning, memory and emotion, as has been described for angiotensin II and IV.