Neuroinflammation-associated oxidative stress in rostral ventrolateral medulla (RVLM), where sympathetic premotor neurons reside, is involved in neurogenic hypertension developed under peripheral inflammation. In this study, we investigated whether this neurogenic hypertension is attributable to mitochondrial biogenesis defect. In normotensive Sprague-Dawley rats, intraperitoneal infusion of a low dose of E. coli lipopolysaccharide (LPS) for 7 days promoted a pressor response, alongside a decrease in mitochondrial DNA (mtDNA) copy number, reductions in protein expression of nuclear DNA-encoded transcription factors for mitochondrial biogenesis, including mitochondrial transcription factor A (TFAM) and nuclear factor erythroid-derived 2-like 2 (Nrf2), and suppression of nuclear translocation of the phosphorylated Nrf2 (p-Nrf2) in RVLM neurons; all of which were abrogated by treatment with intracisternal infusion of an interleukin-1β (IL-1β) blocker, IL-1Ra, or a mitochondrial electron carrier, coenzyme Q10 (CoQ10). Microinjection into RVLM of IL-1β suppressed the expressions of p-Nrf2 and TFAM, and evoked a pressor response; conversely, the Nrf2 inducer, tert-butylhydroquinone, lessened the LPS-induced suppression TFAM expression and pressor response. At cellular level, exposure of N2a cells to IL-1β decreased mtDNA copy number, increased protein interaction of Nrf2 to its negative regulator, kelch-like ECH-associated protein 1 (Keap1), and reduced DNA binding activity of p-Nrf2 to Tfam gene. Together these results indicate that mitochondrial biogenesis defect in RVLM neurons entailing a redox-sensitive and IL-1β-dependent suppression of TFAM because of the increase in the formation of Keap1/Nrf2 complex, reductions in nuclear translocation of the activated Nrf2 and its binding to the Tfam gene promoter may underlie neurogenic hypertension developed under peripheral inflammation.
Physiology 2016 (Dublin, Ireland) (2016) Proc Physiol Soc 37, PCA289
Poster Communications: Mitochondrial biogenesis defect at rostral ventrolateral medulla in neurogenic hypertension under peripheral inflammation
K. Wu1, J. Y. Chan1
1. Institute for Translational Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, Taiwan.
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