title: Modification of the method of thread manufacture improves stroke induction rate and reduces mortality after thread-occlusion of the middle cerebral artery in young or aged rats.
abstract: Improving models of human stroke by the use of aged animals has been advocated; however the commonly used rat middle cerebral artery thread-occlusion model has produced suboptimal stroke induction and excess mortality in aged rats. We report the development of a modified method for silicone-coating the tip of occluding threads which produces a malleable silicone-coated tip which is firmly bonded and of highly consistent diameter, and overcomes problems of thread insertion through the narrowed carotid canal found in aged animals. Comparison of stroke outcomes and mortality were made between these threads and heat-treated poly-L-lysine coated threads. The rate of successful stroke induction in aged rats was significantly improved (from 14% to 86%). Similarly, mortality fell from 21-31% to 3-7% or less in both young and old rats with or without diabetes and hypertension. An occluding thread tip diameter of 0.35-0.38 mm was optimal for induction of mid-sized strokes in both young and old rats. This method of thread manufacture overcomes problems of inconsistency of diameter and bonding of the silicone-coated tip, and these threads produce significant improvements in stroke induction by MCA occlusion, particularly in aged animals and those with co-morbidities.
authors.affiliation: Department of Medicine, University of Melbourne and National Stroke Research Institute, Austin Health, Melbourne, Vic., Australia.
authors.forename: Neil J
authors.initials: NJ
authors.lastname: Spratt
authors.forename: John
authors.initials: J
authors.lastname: Fernandez
authors.forename: Michelle
authors.initials: M
authors.lastname: Chen
authors.forename: Sarah
authors.initials: S
authors.lastname: Rewell
authors.forename: Susan
authors.initials: S
authors.lastname: Cox
authors.forename: Leena
authors.initials: L
authors.lastname: van Raay
authors.forename: Lisa
authors.initials: L
authors.lastname: Hogan
authors.forename: David W
authors.initials: DW
authors.lastname: Howells
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D020520:Brain Infarction / Q000473:pathology; D002560:Cerebrovascular Circulation / Q000502:physiology; D003251:Constriction, Pathologic / Q000150:complications*; D004195:Disease Models, Animal; D020244:Infarction, Middle Cerebral Artery / Q000209:etiology* / Q000401:mortality* / Q000473:pathology / Q000503:physiopathology; D017078:Laser-Doppler Flowmetry / Q000379:methods; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow / Q000502:physiology; D017655:Silicon Compounds / Q000009:adverse effects; D013778:Tetrazolium Salts
chemical_list: D017655:Silicon Compounds; D013778:Tetrazolium Salts; C009591:triphenyltetrazolium