What are We Measuring When We Test Strain Differences in Anxiety in Mice?

Abstract

We examined measures of locomotor and anxiety-like behavior in male and female mice of 15 inbred strains on the elevated-plus maze, light/dark transition box and open field. Strain differences were found on all measures of locomotor activity and anxiety. Strain means for measures of locomotor activity on the three apparatus were significantly correlated, but strain means for commonly used measures of anxiety were not correlated. Principal component analysis revealed a common locomotor activity factor, which accounted for 28.6 % of the variance, but no common anxiety factor. Species-typical behaviors (defecations, stretch-attend postures, grooming) accounted for smaller proportions (<11 %) of the variance. These results plus comparisons with previously published data suggest that the elevated-plus maze, light/dark box and open field measure different facets of anxiety, and that the reliability of genetic differences on anxiety is highly dependent on apparatus, procedural variables and laboratory factors. Locomotor activity, however, is a stable trait that differs across strains and is reliably measured in different apparatus and laboratories. We conclude that anxiety traits of inbred mouse strains are best reflected by species-typical behaviors in each apparatus. These results suggest that new ways of measuring trait anxiety are required in order to determine the neural and genetic correlates of anxiety-like behaviour in mice.

Performance of Male and Female C57BL/6J Mice on Motor and Cognitive Tasks Commonly Used in Pre-Clinical Traumatic Brain Injury Research

“…42 However, studies are fundamentally inconsistent. A trend toward or significantly greater OF activity in female C57BL/6 mice is frequently reported, [43][44][45][46][47][48][49] but almost an equal number of other studies find no differences. [50][51][52][53][54][55] Inconsonant observations regarding sex differences could be the result of variations in specific testing conditions, such as lighting level, 56 or subtle aspects of the laboratory environment even when efforts are made to make conditions identical.…”

Neonatal Exposure to the Dipeptidyl Peptidase-IV Inhibitors Diprotin A and Sitagliptin Induces Depression-Like Behavior, Anxiety, and Latent Aggression in Adolescent and Adult Rats

“…The EPM consisted of four arms arranged in the shape of cross: two opposing arms with 2 side walls and an end wall (length × width × height: 43 × 14 × 22 cm) (closed arms) and 2 additional arms without walls To increase the sensitivity of the test, we also estimated the animals' exploration, risk-assessment behavior, and emotional responses using the number and the latency to engage in vertical rearing postures, head dipping over the open arms and grooming episodes, respectively. Although head dipping and grooming may not provide unequivocal measures of anxiety [37], we share the idea that an increased number of head dips is associated with a decrease in anxiety [38], and grooming measures may help to evaluate anxiety-like behaviors [39]. We also used total distance traveled in all of the regions of the EPM as an index of locomotor activity in the test.…”

Delay and trace fear conditioning in C57BL/6 and DBA/2 mice: issues of measurement and performance

“…For mice, this behavior has been linked to changes in emotional state, particularly measures of anxiety and stress (Kalueff and Tuohimaa 2005b;Estanislau et al 2013;O'Leary et al 2013), both of which are related to fear conditioning responses (Ponder et al 2007;Ryoke et al 2014). Thus, grooming behavior could be a pathway for fear learning expression in high grooming strains, such as D2.…”