Angiotensin II-Induced Expression of Brain-Derived Neurotrophic Factor in Human and Rat Adrenocortical Cells

Angiotensin II (Ang II) is a major regulator of steroidogenesis in adrenocortical cells, and is also an effective inducer of cytokine and growth factor synthesis in several cell types. In microarray analysis of H295R human adrenocortical cells, the mRNA of brain-derived neurotrophic factor (BDNF), a neurotrophin widely expressed in the nervous system, was one of the most up-regulated genes by Ang II. The aim of the present study was the analysis of the Ang II-induced BDNF expression and BDNF-induced effects in adrenocortical cells. Real-time PCR studies have shown that BDNF is expressed in H295R and rat adrenal glomerulosa cells. In H295R cells, the kinetics of Ang II-induced BDNF expression was faster than that of aldosterone synthase (CYP11B2). Inhibition of calmodulin kinase by KN93 did not significantly affect the Ang II-induced stimulation of BDNF expression, suggesting that it occurs by a different mechanism from the CYP11B2-response. Ang II also caused candesartan-sensitive, type-1 Ang II receptor-mediated stimulation of BDNF gene expression in primary rat glomerulosa cells. In rat adrenal cortex, BDNF protein was localized to the subcapsular region. Ang II increased BDNF protein levels both in human and rat cells, and BDNF secretion of H295R cells. Ang II also increased type-1 Ang II receptor-mediated BDNF expression in vivo in furosemide-treated rats. In rat glomerulosa cells, BDNF induced tropomyosin-related kinase B receptor-mediated stimulation of EGR1 and TrkB expression. These data demonstrate that Ang II stimulates BDNF expression in human and rat adrenocortical cells, and BDNF may have a local regulatory function in adrenal glomerulosa cells. Angiotensin II stimulates brain-derived neurotrophic factor expression and secretion in adrenal glomerulosa cells, which may activate TrkB receptor-mediated local regulatory mechanisms in this tissue.