Angiotensin‐converting enzyme 2: a new target for neurogenic hypertension

Cardiovascular Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
Experimental physiology (Impact Factor: 2.87). 04/2010; 95(5):601 - 606. DOI: 10.1113/expphysiol.2009.047407

ABSTRACT Overactivity of the renin–angiotensin system (RAS) is involved in the pathogenesis of hypertension, and an overactive brain RAS has been highlighted in several genetic and experimental models. Until now, angiotensin II (Ang II) was thought to be the main effector of this system, and the angiotensin-converting enzyme (ACE)–Ang II–Ang II type 1 receptor axis was the main target for antihypertensive therapies. A new member of the RAS, ACE2 (angiotensin-converting enzyme type 2), has been identified in organs and tissues related to cardiovascular function (e.g. heart, kidney and blood vessels) and appears to be part of a counter-regulatory pathway to buffer the excess of Ang II. We recently identified the ACE2 protein in brain regions involved in the central regulation of blood pressure and showed that it regulates, and is regulated by, other components of the RAS. Here, we present evidence for the involvement of brain ACE2 in the central regulation of blood pressure, autonomic and cardiac function. We show that lack of ACE2 is deleterious for the central regulation of blood pressure and that brain ACE2 gene therapy can restore baroreflex and autonomic functions and prevent the development of hypertension. Additionally, and independently of a reduction in Ang II levels, we will highlight some of the mechanisms responsible for the beneficial effects of central ACE2 in cardiovascular function.

  • [Show abstract] [Hide abstract]
    ABSTRACT: We previously demonstrated that mice which overexpress human renin and angiotensinogen (R+A+) show enhanced cerebral damage in both in vivo and in vitro experimental ischemia models. Angiotensin converting enzyme 2 (ACE2) counteracts the effects of angiotensin (Ang-II) by transforming it into Ang-(1-7), thus reducing the ligand for the AT1 receptor and increasing stimulation of the Mas receptor. Triple transgenic mice, SARA, which specifically overexpress ACE2 in neurons of R+A+ mice were used to study the role of ACE2 in ischemic stroke using oxygen and glucose deprivation (OGD) of brain slices as an in vitro model. We examined tissue swelling, the production of reactive oxygen species (ROS), and cell death in cerebral cortex (CX) and the hippocampal CA1 region during OGD. Expression levels of NADPH oxidase isoforms, Nox2 and Nox4 were measured using western blots. Results show that SARA mice and R+A+ mice treated with the Mas receptor agonist Ang-(1-7) had less swelling, cell death, and ROS production in CX and CA1 areas compared to those in R+A+ animals. Treatment of slices from SARA mice with the Mas antagonist A779 eliminated this protection. Finally, western blots revealed less Nox2 and Nox4 expression in SARA mice compared with R+A+ mice both before and after OGD. We suggest that reduced brain swelling and cell death observed in SARA animals exposed to OGD results from diminished ROS production coupled with lower expression of NADPH oxidases. Thus, the ACE2/Ang-(1-7)/Mas receptor pathway plays a protective role in brain ischemic damage by counteracting the detrimental effects of Ang-II-induced ROS production.
    Neuroscience 05/2014; · 3.33 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Nitric oxide (NO) deficiency is involved in the development of hypertension, a condition that can originate early in life. We examined whether NO deficiency contributed to programmed hypertension in offspring from mothers with calorie-restricted diets and whether melatonin therapy prevented this process. We examined 3-month-old male rat offspring from four maternal groups: untreated controls, 50% calorie-restricted (CR) rats, controls treated with melatonin (0.01% in drinking water), and CR rats treated with melatonin (CR + M). The effect of melatonin on nephrogenesis was analyzed using next-generation sequencing. The CR group developed hypertension associated with elevated plasma asymmetric dimethylarginine (ADMA, a nitric oxide synthase inhibitor), decreased L-arginine, decreased L-arginine-to-ADMA ratio (AAR), and decreased renal NO production. Maternal melatonin treatment prevented these effects. Melatonin prevented CR-induced renin and prorenin receptor expression. Renal angiotensin-converting enzyme 2 protein levels in the M and CR + M groups were also significantly increased by melatonin therapy. Maternal melatonin therapy had long-term epigenetic effects on global gene expression in the kidneys of offspring. Conclusively, we attributed these protective effects of melatonin on CR-induced programmed hypertension to the reduction of plasma ADMA, restoration of plasma AAR, increase of renal NO level, alteration of renin-angiotensin system, and epigenetic changes in numerous genes.
    Oxidative medicine and cellular longevity 01/2014; 2014:283180. · 3.36 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Adulthood hypertension can be programmed by corticosteroid exposure in early life. Oxidative stress, epigenetic regulation by histone deacetylases (HDACs), and alterations of renin-angiotensin system (RAS) are involved in the developmental programming of hypertension. We examined whether melatonin prevented neonatal dexamethasone (DEX)-induced programmed hypertension and how melatonin prevented these processes. We also examined whether HDAC inhibition by trichostatin A (TSA, a HDAC inhibitor) had similar effects. Male offspring were assigned to 5 groups (n=6/group): control, DEX, melatonin, DEX+melatonin, and DEX+TSA. Male rat pups were injected i.p. with DEX on day 1 (0.5mg/kg BW), day 2 (0.3mg/kg BW), and day 3 (0.1mg/kg BW) after birth. Melatonin was administered in drinking water at the dose of 0.01% during the lactation period. The DEX+TSA group received DEX and 0.5mg/kg TSA subcutaneous injection once daily for 1 week. All rats were killed at 16 weeks of age. Neonatal DEX exposure induced hypertension in male offspring at 16 weeks of age, which melatonin prevented. Neonatal DEX exposure decreased gene expression related to apoptosis, nephrogenesis, RAS, and sodium transporters. Yet DEX treatment increased protein levels of HDAC-1, -2, and -3 in the kidney. Melatonin therapy preserved the decreases of gene expression and decreased HDACs. Similarly, HDAC inhibition prevented DEX-induced programmed hypertension. In conclusion, melatonin therapy exerts a long-term protection against neonatal DEX-induced programmed hypertension. Its beneficial effects include alterations of RAS components and inhibition of class I HDACs. Given that the similar protective effects of melatonin and TSA, melatonin might inhibit HDACs to epigenetic regulation of hypertension-related genes to prevent programmed hypertension.
    The Journal of Steroid Biochemistry and Molecular Biology 07/2014; · 4.05 Impact Factor


1 Download
Available from
Jan 5, 2015