title: Fearfulness in a large N/Nih genetically heterogeneous rat stock: differential profiles of timidity and defensive flight in males and females.
abstract: Anxiety-related behaviors were evaluated across various tests in a large sample (n=787, both sexes) of genetically heterogeneous (N/Nih-HS) rats, derived from an eight-way cross of inbred strains. These tests either evoke unlearned (black-white box, BWB-; novel-cage activity, NACT-; elevated "zero" maze, ZM-; baseline acoustic startle response, BAS-) or learned (fear-potentiated startle, FPS-; two-way active-shuttle box-avoidance acquisition, SHAV-) anxious/fearful responses. The results showed that, with the exception of fear-potentiated startle, almost all (unlearned and learned) behaviors assessed fit with a pattern of sex effects characterized by male rats as being more fearful than females. We applied factor analyses (oblique rotation) to each sex, with the final two-factor solution showing: (1) a first factor (labelled as "Timidity") comprising BWB, NACT and ZM variables in both sexes, plus SHAV responding in the case of males, and (2) a second factor (called "Defensive Flight") which grouped BAS, FPS, and SHAV responding in both sexes. An additional regression analysis showed significant influences of (unlearned) risk assessment (i.e. stretch-attendance) behavior on SHAV in males, while FPS was the main variable positively influencing SHAV (in the intermediate and advanced phases of acquisition) in females. This indicates, for the first time, that fear-potentiated startle may have a facilitating role in the rat's active responses (at least in females) to the cue in the intermediate to advanced phases (i.e. when the initial "passive avoidance/active avoidance" begins to fade) of shuttle box avoidance acquisition. The results of this first extensive behavioral evaluation of N/Nih-HS rats are discussed in terms of their potential usefulness for present and future neurobehavioral and genetic studies of fearfulness/anxiety.
authors: Medical Psychology Unit, Department of Psychiatry & Forensic Medicine, Institute of Neurosciences, School of Medicine, Autonomous University of Barcelona, 08193 Bellaterra, Barcelona, Spain.
authors: Regina
authors: R
authors: Lopez-Aumatell
authors: Marc
authors: M
authors: Guitart-Masip
authors: Elia
authors: E
authors: Vicens-Costa
authors: Lydia
authors: L
authors: Gimenez-Llort
authors: William
authors: W
authors: Valdar
authors: Martina
authors: M
authors: Johannesson
authors: Jonathan
authors: J
authors: Flint
authors: Adolf
authors: A
authors: Tobeña
authors: Alberto
authors: A
authors: Fernandez-Teruel
mesh_terms: D000818:Animals; D021461:Animals, Outbred Strains; D001007:Anxiety / Q000235:genetics / Q000503:physiopathology*; D001245:Association Learning / Q000502:physiology; D001362:Avoidance Learning / Q000502:physiology; D003214:Conditioning, Classical / Q000502:physiology; D004924:Escape Reaction / Q000502:physiology*; D005106:Exploratory Behavior; D005163:Factor Analysis, Statistical; D005239:Fear / Q000502:physiology*; D005260:Female; D018740:Genetic Heterogeneity; D008297:Male; D051381:Rats; D013216:Reflex, Startle / Q000502:physiology*; D012641:Selection, Genetic; D012737:Sex Factors; D013045:Species Specificity; D018709:Statistics, Nonparametric