title: Repeated restraint stress produces acute and chronic changes in hemodynamic parameters in rats.
abstract: Noninvasive hemodynamic measurements in rats require placing animals in restrainers. To minimize restraint stress-induced artifacts several habituation protocols have been proposed, however, the results are inconclusive. Here, we evaluated if a four-week habituation is superior to a shorter habituation, or no habituation. This is the first study comparing different habituation protocols with the use of four-week continuous telemetry measurements. We did the experiments on male, 16-week old, Sprague-Dawley rats. Continuous recordings of mean arterial blood pressure (MABP) and heart rate (HR) were made before and during habituation protocols. Rats were subjected either to control (four weeks of restraint-free recordings, n = 5) or two-week (seven restraints, n = 6) or four-week (14 restraints, n = 6) restraint sessions. The restraint protocols included placement of rats in the middle of the dark phase into plastic restrainers as used for tail-cuff measurements. Restraint lasted for 60 min, and was repeated every second day. Each restraint significantly increased MABP (by 15-25 mmHg) and HR (by 40-120 beats/min). Exposure to the restraint protocols decreased diurnal variation in MABP. There was no hemodynamic adaptation to repeated restraint, and no significant difference in hemodynamic response to restraint among controls, the two-week and the four-week groups. In conclusion, our study indicates that measurements in restrained rats are not likely being made without stress-induced changes in MABP. Moreover, in hemodynamic studies in repeatedly restrained rats longer habituation is not superior to shorter habituation.
authors.affiliation: a Department of Experimental Physiology and Pathophysiology, Laboratory of Center for Preclinical Research , Medical University of Warsaw , Warsaw , Poland.
authors.forename: Mariusz
authors.initials: M
authors.lastname: Sikora
authors.affiliation: a Department of Experimental Physiology and Pathophysiology, Laboratory of Center for Preclinical Research , Medical University of Warsaw , Warsaw , Poland.
authors.forename: Piotr
authors.initials: P
authors.lastname: Konopelski
authors.affiliation: a Department of Experimental Physiology and Pathophysiology, Laboratory of Center for Preclinical Research , Medical University of Warsaw , Warsaw , Poland.
authors.forename: Kinga
authors.initials: K
authors.lastname: Pham
authors.affiliation: b Department of Immunology, Transplantation and Internal Diseases , Medical University of Warsaw , Warsaw , Poland.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Wyczalkowska-Tomasik
authors.affiliation: a Department of Experimental Physiology and Pathophysiology, Laboratory of Center for Preclinical Research , Medical University of Warsaw , Warsaw , Poland.
authors.forename: Marcin
authors.initials: M
authors.lastname: Ufnal
mesh_terms: D000208:Acute Disease; D000222:Adaptation, Physiological; D000818:Animals; D001794:Blood Pressure; D002908:Chronic Disease; D002940:Circadian Rhythm; D006185:Habituation, Psychophysiologic; D006339:Heart Rate; D006439:Hemodynamics; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012149:Restraint, Physical; D013315:Stress, Psychological / Q000503:physiopathology*
keywords: Blood pressure measurement; diurnal rhythm; habituation protocol; restraint stress; telemetry