Some Guidelines for Defining Personality Differences in Rats

Effects of antidepressants on the performance in the forced swim test of two psychogenetically selected lines of rats that differ in coping strategies to aversive conditions

“…It is noteworthy in this context that previous studies have shown that: (a) immobility counts of RLA rats are comparable to those of unselected Wistar rats, and (b) RLA rats are more responsive than unselected rats to the immobility-reducing effect of low doses of antidepressant drugs (our unpublished results). However, those results should be interpreted with caution because it has been shown that even subtle variations in housing conditions and laboratory environment can alter rodent anxiety-and depression-related behavior (Crabbe et al 1999;Driscoll et al 2009;Escorihuela et al 1995b). Therefore, it should be taken into account that, to address this issue, we cannot simply compare the behavior of RHA and RLA rats bred in our laboratory with that of commercially available rats which have been subjected to different pre-and post-natal housing conditions, since these breeding differences may affect the outcome of behavioral experiments.…”

Impulsivity Characterization in the Roman High- and Low-Avoidance Rat Strains: Behavioral and Neurochemical Differences

“…However, the concordant lack of changes in accuracy and the increased response latency in RLA-I rats point to motivational/ emotional factors (rather than impairments in attentional processes) as a possible mechanism underlying strain differences for this parameter. Compared with RHA-I rats, RLA-I rats are characterized by increased anxiety/fear levels, enhanced (hormonal and behavioral) sensitivity to stressful situations, and shows of characteristic passive coping strategies (eg, freezing behavior) when faced with conflict or stressful situations (Carrasco et al, 2008;Driscoll et al, 2009;López-Aumatell et al, 2009a, b;Driscoll, 2003, 2005). In this sense, it appears likely that the demanding (ie, stressful) conditions of the 5-CSRT task could have influenced motivational/emotional aspects in RLA-I rats, possibly leading to their longer response latencies and increased errors of omissions.…”

“…Two phenotypes with different emotional and motivational profiles have been developed through bidirectional selection and breeding of the Roman high-(RHA) and low-avoidance (RLA) rat lines/ strains (outbred or inbred, respectively), selected for rapid (RHA) vs extremely poor (RLA) acquisition of two-way active avoidance in the shuttle-box (Broadhurst and Bignami, 1965;Driscoll and Bättig, 1982) (for reviews, see Driscoll et al, 1990Driscoll et al, , 1998Driscoll et al, , 2009Escorihuela et al, 1995Escorihuela et al, , 1999Fernández-Teruel et al, 1997;Giorgi et al, 2007;Steimer and Driscoll, 2005). These lines/strains show consistent differences in sensation/novelty seeking and in stress/anxiety endocrine and behavioral responses when confronted with novel environments (ie, intended to measure anxiety, emotionality, fearfulness, or novelty seeking), such as the open-field test (Aubry et al, 1995;Carrasco et al, 2008;Escorihuela et al, 1999;Gentsch et al, 1991), elevated plus maze (Escorihuela et al, 1999;Steimer and Driscoll, 2003), elevated zero-maze (López-Aumatell et al, 2009b), blackwhite box test, dark-light open-field test, dark-light hexagonal tunnel maze (Fernández-Teruel et al, 2002b;Steimer and Driscoll, 2005), and hole-board test (Escorihuela et al, 1999;Fernández-Teruel et al, 1992).…”

“…In all of these situations and in fear-conditioning procedures (eg, fear-potentiated startle; López-Aumatell et al, 2009a), RLA rats show increased anxiety or fear, a passive coping style, and increased stress responses by hypothalamus-pituitaryadrenal (HPA) axis activation (Carrasco et al, 2008;Steimer and Driscoll, 2003). RHA rats tend to be novelty/sensation seekers with relatively low HPA axis activation (Driscoll et al, 1998(Driscoll et al, , 2009. Moreover, these differences occur with individual differences in vulnerability to drug addiction, manifested as behavioral and neurochemical responses to different drugs of abuse such as ethanol, morphine, and cocaine (Fattore et al, 2009;Giorgi et al, 2007).…”

Incentive loss and hippocampal gene expression in inbred Roman high- (RHA-I) and Roman low- (RLA-I) avoidance rats

“…The original psychogenetic selection procedure (based on good vs. extremely poor acquisition of the two-way active avoidance response) has led to stable strain divergence related to anxiety/fearfulness and behavioral inhibition/activation traits (i.e. coping style; [29]). Consistent with these results, Roman rats showed significant differences in frustration paradigms such as instrumental and consummatory successive negative contrast effect [30][31][32], extinction [33,34], partial reinforcement extinction effect [35], and partial reinforcement contrast effect [36].…”