title: The gradient of luminosity between open/enclosed arms, and not the absolute level of Lux, predicts the behaviour of rats in the plus maze.
abstract: The effect of the gradient of luminosity between the open and the enclosed arms (O/E(DeltaLux)) of the elevated plus maze (EPM), upon the level of fear/anxiety in rats submitted to the trial 1/trial 2 paradigm was investigated. Male Wistar rats were assigned to freely explore either of three EPM configuration, with the enclosed arm walls constructed with either translucent glass (O/E(DeltaLux)=11), opaque glass (O/E(DeltaLux)=96) or wood (O/E(DeltaLux)=141), for 2 consecutive days (trial 1/trial 2). Independently of the EPM configuration, rats exhibited increased fear during trial 2 relative to trial 1, thus indicating that the level of O/E(DeltaLux), at least in the range used here, is not a determinant variable for the establishment of increased anxiety induced by prior maze experience. The groups tested under 11 and 141 O/E(DeltaLux) were those who exhibited the low and higher level of open arm avoidance, respectively. There was also an increased open arms avoidance over trial 1 in rats tested under 11 and 96 O/E(DeltaLux), only. These results suggest that the enclosed arm preference of rats during trial 1 EPM procedure may be changed by the level of O/E(DeltaLux) of the test. The present results are discussed with respect to the controversy regarding the role of luminosity on EPM performance.
authors.affiliation: Department of Physiological Sciences, Centre of Biological Sciences, Federal University of Santa Catarina, 88.040-900 Florianópolis, SC, Brazil.
authors.forename: Lenir Orlandi
authors.initials: LO
authors.lastname: Pereira
authors.forename: Isabel Cristina
authors.initials: IC
authors.lastname: da Cunha
authors.forename: José Marino
authors.initials: JM
authors.lastname: Neto
authors.forename: Marta Aparecida
authors.initials: MA
authors.lastname: Paschoalini
authors.forename: Moacir Serralvo
authors.initials: MS
authors.lastname: Faria
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001007:Anxiety / Q000503:physiopathology; D001362:Avoidance Learning / Q000502:physiology / Q000528:radiation effects*; D003624:Darkness; D005106:Exploratory Behavior / Q000502:physiology / Q000528:radiation effects*; D005239:Fear / Q000502:physiology / Q000528:radiation effects*; D008027:Light; D008029:Lighting; D008297:Male; D018782:Maze Learning / Q000502:physiology / Q000528:radiation effects*; D051381:Rats; D017208:Rats, Wistar