Characterization of Signal Transduction Pathway in Neurotropic Action of Angiotensin II in Brain Neurons

Interaction of angiotensin II with the neuronal angiotensin type 1 receptor stimulates the PI3K signaling pathway. Our objective in this study was to investigate the hypothesis that the PI3K cascade regulates the neurotropic actions of angiotensin II in rat brain neurons. We followed growth associated protein-43 expression and neurite extension as markers of neurotropic activity. Angiotensin II, through its interaction with the angiotensin type 1 receptor, increased growth associated protein-43 expression and neurite extension. These effects were abolished by pretreatment of neurons with wortmannin and rapamycin, but not by PD 98059. Antisense oligonucleotides specific for p70S6 kinase also inhibited angiotensin II-stimulated neurotropic activity. These data confirm the involvement of PI3K and p70S6 kinase in angiotensin II-mediated neurotropic action. Further support for this was provided by the observation that angiotensin II caused a time-dependent stimulation of p70S6 kinase by an angiotensin type 1 r...