Requirement for Rac1-dependent NADPH oxidase in the cardiovascular and dipsogenic actions of angiotensin II in the brain

Matthew C Zimmerman, Ryan P. Dunlay, Eric Lazartigues, Yulong Zhang, Ram V. Sharma, John F. Engelhardt, Robin L. Davisson

Research output: Contribution to journalArticle

142 Citations (Scopus)

Abstract

We have shown that intracellular superoxide (O2.-) production in CNS neurons plays a key role in the pressor, bradycardic, and dipsogenic actions of Ang II in the brain. In this study, we tested the hypothesis that a Rac1-dependent NADPH oxidase is a key source of O 2.- in Ang II-sensitive neurons and is involved in these central Ang II-dependent effects. We performed both in vitro and in vivo studies using adenoviral (Ad)-mediated expression of dominant-negative Rac1 (AdN17Rac1) to inhibit Ang II-stimulated Rac1 activation, an obligatory step in NADPH oxidase activation. Ang II induced a time-dependent increase in Rac1 activation and O2.--production in Neuro-2A cells, and this was abolished by pretreatment with AdN17Rac1 or the NADPH oxidase inhibitors apocynin or diphenylene iodonium. AdN17Rac1 also inhibited Ang II-induced increases in NADPH oxidase activity in primary neurons cultured from central cardiovascular control regions. In contrast, overexpression of wild-type Rac1 (AdwtRac1) caused more robust NADPH oxidase-dependent O2.- production to Ang II. To extend the in vitro studies, the pressor, bradycardic, and drinking responses to intracerebroventricularly (ICV) injected Ang II were measured in mice that had undergone gene transfer of AdN17Rac1 or AdwtRac1 to the brain. AdN17Rac1 abolished the increase in blood pressure, decrease in heart rate, and drinking response induced by ICV injection of Ang II, whereas AdwtRac1 enhanced these physiological effects. The exaggerated physiological responses in AdwtRac1-treated mice were abolished by O2.- scavenging. These results, for the first time, identify a Rac1-dependent NADPH oxidase as the source of central Ang II-induced O2.- production, and implicate this oxidase in cardiovascular diseases associated with dysregulation of brain Ang II signaling, including hypertension.

Original languageEnglish (US)
Pages (from-to)532-539
Number of pages8
JournalCirculation Research
Volume95
Issue number5
DOIs
StatePublished - Sep 3 2004

Fingerprint

NADPH Oxidase
Angiotensin II
Brain
Neurons
Drinking
Superoxides
Oxidoreductases
Cardiovascular Diseases
Heart Rate
Blood Pressure
Hypertension
Injections
Genes

Keywords

  • Blood pressure
  • Dipsogenic response
  • Dominant-negative Rac1
  • Neurons
  • Reactive oxygen species

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine

Cite this

Requirement for Rac1-dependent NADPH oxidase in the cardiovascular and dipsogenic actions of angiotensin II in the brain. / Zimmerman, Matthew C; Dunlay, Ryan P.; Lazartigues, Eric; Zhang, Yulong; Sharma, Ram V.; Engelhardt, John F.; Davisson, Robin L.

In: Circulation Research, Vol. 95, No. 5, 03.09.2004, p. 532-539.

Research output: Contribution to journalArticle

Zimmerman, Matthew C ; Dunlay, Ryan P. ; Lazartigues, Eric ; Zhang, Yulong ; Sharma, Ram V. ; Engelhardt, John F. ; Davisson, Robin L. / Requirement for Rac1-dependent NADPH oxidase in the cardiovascular and dipsogenic actions of angiotensin II in the brain. In: Circulation Research. 2004 ; Vol. 95, No. 5. pp. 532-539.
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AU - Sharma, Ram V.

AU - Engelhardt, John F.

AU - Davisson, Robin L.

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AB - We have shown that intracellular superoxide (O2.-) production in CNS neurons plays a key role in the pressor, bradycardic, and dipsogenic actions of Ang II in the brain. In this study, we tested the hypothesis that a Rac1-dependent NADPH oxidase is a key source of O 2.- in Ang II-sensitive neurons and is involved in these central Ang II-dependent effects. We performed both in vitro and in vivo studies using adenoviral (Ad)-mediated expression of dominant-negative Rac1 (AdN17Rac1) to inhibit Ang II-stimulated Rac1 activation, an obligatory step in NADPH oxidase activation. Ang II induced a time-dependent increase in Rac1 activation and O2.--production in Neuro-2A cells, and this was abolished by pretreatment with AdN17Rac1 or the NADPH oxidase inhibitors apocynin or diphenylene iodonium. AdN17Rac1 also inhibited Ang II-induced increases in NADPH oxidase activity in primary neurons cultured from central cardiovascular control regions. In contrast, overexpression of wild-type Rac1 (AdwtRac1) caused more robust NADPH oxidase-dependent O2.- production to Ang II. To extend the in vitro studies, the pressor, bradycardic, and drinking responses to intracerebroventricularly (ICV) injected Ang II were measured in mice that had undergone gene transfer of AdN17Rac1 or AdwtRac1 to the brain. AdN17Rac1 abolished the increase in blood pressure, decrease in heart rate, and drinking response induced by ICV injection of Ang II, whereas AdwtRac1 enhanced these physiological effects. The exaggerated physiological responses in AdwtRac1-treated mice were abolished by O2.- scavenging. These results, for the first time, identify a Rac1-dependent NADPH oxidase as the source of central Ang II-induced O2.- production, and implicate this oxidase in cardiovascular diseases associated with dysregulation of brain Ang II signaling, including hypertension.

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