title: Compound 21 is pro-angiogenic in the brain and results in sustained recovery after ischemic stroke.
abstract: BACKGROUND
  Angiotensin II type 2 receptor (AT2R) stimulation is neuroprotective after experimental stroke. However, the therapeutic utility of AT2R stimulation has been hampered by the lack of a specific agonist with favourable bioavailability. Compound 21 (C21) - the first non-peptide AT2R agonist - offers a potential option to enhance stroke recovery. This study aimed to investigate the effect of C21 administration on early and late stroke outcomes, and the molecular mediators involved.
  
  
  METHODS
  Rats were subjected to 3 h or 90 min of middle cerebral artery occlusion (MCAO) and randomized to intraperitoneal C21 (0.03 mg/kg) or saline at reperfusion. Animals were sacrificed at 24 h or 7 days and brains were collected for molecular analysis and immunostaining, respectively. Functional outcome at days 1, 4 and 7 was assessed blindly. C21 angiogenic potential was assessed in vitro.
  
  
  RESULTS
  After 3 h of MCAO, C21 treatment reduced infarct size and improved behavioural outcome at 24 h without affecting blood pressure. Co-administration of the AT2R antagonist (PD123319) blocked these effects. On the molecular level, C21 decreased brain haemoglobin content, down-regulated apoptotic and oxidative markers, and increased pro-survival molecules in the brain. After 90 min of MCAO, C21 treatment resulted in sustained functional improvement at 7 days, together with increased vascular density in the ischemic penumbra. In vitro, C21 showed a pro-angiogenic effect that was blocked with brain-derived neurotrophic factor neutralization.
  
  
  CONCLUSIONS
  These findings demonstrate that a single dose of C21 is neurovascular-protective and improves stroke outcome possibly through increasing neurotrophin activity, mitigating brain inflammation, and promoting antioxidant and pro-angiogenic effects.
authors.affiliation: aCharlie Norwood VA Medical Center, and Center for Pharmacy and Experimental Therapeutics, University of Georgia College of Pharmacy, and Georgia Regents University, Augusta, Georgia, USA bJordan University of Science and Technology, College of Pharmacy, Irbid, Jordan *Both authors contributed equally to this work.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Alhusban
authors.forename: Abdelrahman Y
authors.initials: AY
authors.lastname: Fouda
authors.lastname: Bindu Pillai
authors.forename: Tauheed
authors.initials: T
authors.lastname: Ishrat
authors.forename: Sahar
authors.initials: S
authors.lastname: Soliman
authors.forename: Susan C
authors.initials: SC
authors.lastname: Fagan
mesh_terms: D043925:Angiogenesis Inducing Agents / Q000737:chemistry*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001921:Brain / Q000187:drug effects / Q000503:physiopathology; D002545:Brain Ischemia / Q000188:drug therapy; D019208:Brain-Derived Neurotrophic Factor / Q000737:chemistry; D004195:Disease Models, Animal; D007093:Imidazoles / Q000737:chemistry; D008297:Male; D020768:Middle Cerebral Artery / Q000473:pathology; D018919:Neovascularization, Physiologic; D011725:Pyridines / Q000737:chemistry; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D044139:Receptor, Angiotensin, Type 2 / Q000378:metabolism*; D020521:Stroke / Q000188:drug therapy* / Q000503:physiopathology; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D043925:Angiogenesis Inducing Agents; D019208:Brain-Derived Neurotrophic Factor; D007093:Imidazoles; D011725:Pyridines; D044139:Receptor, Angiotensin, Type 2; C073402:PD 123319