Corticosterone response to the plus-maze: high correlation with risk assessment in rats and mice. Physiol Behav

Ethopharmacology Laboratory, School of Psychology, University of Leeds, UK.
Physiology & Behavior (Impact Factor: 2.98). 12/1999; 68(1-2):47-53. DOI: 10.1016/S0031-9384(99)00140-7
Source: PubMed

ABSTRACT Exposure to the elevated plus-maze induces behavioural and physiological effects in rodents consistent with fear/anxiety. Maze-naive animals display high levels of risk assessment towards the open arms, and explore these areas less extensively than other parts of the maze while, immediately following the test, pain latencies, skin conductance levels, and plasma corticosterone titres (CORT) are significantly elevated. Although previous research has suggested a link between the plasma CORT response and open-arm exploration, significant elevations in CORT have also been found with restricted exposure to the closed arms. The present study employed ethological measures in an attempt to further characterise the relationship between behavioural and CORT responses to this widely used animal model of anxiety. Our results confirm that, relative to home-cage controls, 5-min exposure to the plus-maze significantly increases plasma CORT levels in test-naive male Wistar rats and male Swiss-Webster mice. Furthermore, in both species, the CORT response was found to be highly correlated with measures of risk assessment (mice: rs = +0.87; rats: rs = +0.58), but not with measures of open-arm activity (entries, time), general locomotor activity, rearing, or head dipping. Findings are discussed in relation to the functional significance of risk assessment in potentially dangerous situations and the potential involvement of glucocorticoids in this process. All rights reserved.

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    • "(Rodgers et al., 1999 "
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    ABSTRACT: Abstract Early separation from a family is stressful for young mammals, but might be more stressful for group-living than solitary species. Using juvenile males of three African striped mice Rhabdomys taxa that are either group (R. pumilio) or solitary (R. dilectus dilectus and R. d. chakae) living, we predicted greater separation anxiety in R. pumilio than R. dilectus because group-living could reduce anxiety in R. pumilio. Three brothers from each of 10 litters per taxon were randomly assigned soon after natural weaning (25 days) to one of three treatments for 10 days: 1) remained with the family (philopatric); 2) separated from the family by a wire mesh barrier (separated); and 3) isolated from the family (isolated). Males were individually tested in a four-arm maze to assess their anxiety responses and sampled for corticosterone concentrations 20 mins and 10 days later. Compared to R. dilectus males, R. pumilio males showed a greater treatment response to separation: philopatric males used the light arms of the maze less and had higher corticosterone concentrations compared to isolated males, which spent the most time in the light arms and had the lowest corticosterone concentrations overall; separated males showed an intermediate behavioural response, but had similar corticosterone concentrations to philopatric males. Thus, separation from a family group is more stressful in group-living Rhabdomys and this stress response dissipates with time. Philopatry and group-living may be more important for young R. pumilio, whereas dispersal at weaning is an important life history event for solitary R. dilectus.
    Stress (Amsterdam, Netherlands) 04/2014; 17(3). DOI:10.3109/10253890.2014.910762 · 2.72 Impact Factor
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    • "The stress hormone corticosterone was measured to investigate the response of the HPA axis to valtrate. Research suggests that the exposure of rodents to the standard elevated plus maze activates the HPA axis, leading to an enhancement of plasma corticosterone [32]. In addition, there was a peak in corticosterone secretion which occurs 5 to 10 min after exposure to two different anxiety/fear tests [33]. "
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    Evidence-based Complementary and Alternative Medicine 03/2014; 2014:325948. DOI:10.1155/2014/325948 · 1.88 Impact Factor
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    • "The elevated plus maze (EPM) is a useful tool for testing anxiety. This instrument allows for unconditioned fear/anxiety-like tendencies to be measured and is also sensitive to locomotor activity and decision-making patterns [33], [34]. The EPM was made from dark black acrylic material and consisted of two open arms (50 cm×10 cm) crossed at right angles with two opposed arms of the same size. "
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