Effect of a Selective Mas Receptor Agonist in Cerebral Ischemia In Vitro and In Vivo

Abstract

Functional modulation of the non-AT1R arm of the renin-angiotensin system, such as via AT2R activation, is known to improve stroke outcome. However, the relevance of the Mas receptor, which along with the AT2R forms the protective arm of the renin-angiotensin system, as a target in stroke is unclear. Here we tested the efficacy of a selective MasR agonist, AVE0991, in in vitro and in vivo models of ischemic stroke. Primary cortical neurons were cultured from E15-17 mouse embryos for 7–9 d, subjected to glucose deprivation for 24 h alone or with test drugs, and percentage cell death was determined using trypan blue exclusion assay. Additionally, adult male mice were subjected to 1 h middle cerebral artery occlusion and were administered either vehicle or AVE0991 (20 mg/kg i.p.) at the commencement of 23 h reperfusion. Some animals were also treated with the MasR antagonist, A779 (80 mg/kg i.p.) 1 h prior to surgery. Twenty-four h after MCAo, neurological deficits, locomotor activity and motor coordination were assessed in vivo, and infarct and edema volumes estimated from brain sections. Following glucose deprivation, application of AVE0991 (10−8 M to 10−6 M) reduced neuronal cell death by ~60% (P<0.05), an effect prevented by the MasR antagonist. By contrast, AVE0991 administration in vivo had no effect on functional or histological outcomes at 24 h following stroke. These findings indicate that the classical MasR agonist, AVE0991, can directly protect neurons from injury following glucose-deprivation. However, this effect does not translate into an improved outcome in vivo when administered systemically following stroke.

Anti‐atherosclerotic effect of the angiotensin 1–7 mimetic AVE0991 is mediated by inhibition of perivascular and plaque inflammation in early atherosclerosis

“…Our demonstration of the Mas receptor‐dependent inhibition of M1 macrophage differentiation by AVE0991 may extend the potential usefulness of this compound to a number of conditions in which M1 macrophages play a key role (Hammer et al , ). This includes pulmonary remodelling, inflammation and right ventricular hypertrophy in models of allergic asthma (Rodrigues‐Machado et al , ), as well as its protective effects in stroke (Lee et al , ) or liver cirrhosis (Klein et al , ). Mechanisms of the vasoprotective effects of AVE0991 include inhibition of oxidative stress (Ma et al , ), stimulation of eNOS activation and NO production (Pawlik et al , ).…”

“…The peptide Ang‐(1–7) exerts numerous protective effects in the vascular system, including vasodilatory (Ren et al, ), antioxidant (Raffai et al, ) and anti‐inflammatory effects (Lee et al, ). In endothelial cells, it stimulated endothelial NOS (eNOS) and NO production (Sampaio et al, ), as well as inhibiting vascular NADPH oxidase expression and activity (Benter et al, ).…”

Therapeutic potential of the renin angiotensin system in ischaemic stroke

“…Evidence suggests that AT 2 R interacts with other RAS mediators and its effects may be partly mediated by an interaction with the Mas receptor, which is activated by Ang-(1–7) [ 69 ]. Recently, the interaction between ACE2/Ang-(1–7)/MasR in AIS has been studied and shown to be protective in several animal models (Table 3 ) [ 17 , 26 , 70 – 73 ]. Mecca and colleagues were one of the first groups to identify the potential neuroprotective effects of this peptide and its receptor.…”

“…As a result, in order to see an effect following AIS, it has had to be administered centrally, a route of administration which is not clinically feasible. At present, Mas agonist, AVE0991 has been developed, however, following tMCAO in mice, i.p AVE0991 post-treatment failed to induce similar neuroprotective as observed in Ang-(1–7) treated studies [ 73 ].…”

Significance of angiotensin 1–7 coupling with MAS1 receptor and other GPCRs to the renin‐angiotensin system: IUPHAR Review 22

“…Also the MAS1 receptor mediated signalling has been found to be stimulated by several other peptides such as NPFF, alamandine, Ang III, Ang IV, angioprotectin, CGEN‐857 and P61/P33 and CGEN‐856. Some of the peptides have also been found to elicit a response through the MRGPRD receptor, but additional systematic studies are warranted (Dong et al, ; Bikkavilli et al, ; Canals et al, ; Gembardt et al, ; Shemesh et al, ; Savergnini et al, ; Jankowski et al, ; Zhang et al ., ; Savergnini et al, ; Tirupula et al, ; Lee et al, ). In transfected HEK293 cells, the MAS1 receptor was found to activate G q/11 ‐PKC signalling without ligand stimulation (Canals et al, ).…”