Repeated elevated plus maze trials as a measure for tracking within-subjects behavioral performance in rats (Rattus norvegicus)

Abstract

The elevated plus maze (EPM) is routinely used in neuroscience research to evaluate emotional behavior in rodents by measuring general exploratory performance and avoidance of the aversive open arms of the maze. According to standard practice, behavior on the EPM is evaluated during a single trial to avoid the possibility of habituation to the apparatus that would result in lost sensitivity of key outcome measures. However, this possibility has not been systematically evaluated across repeated trials or across different environmental conditions. In the current study, we assessed within-subject behavior on the EPM in adult male rats over thirteen trials (tested twice weekly) repeated under identical conditions. We also assessed within-subject behavior on the EPM in adult male rats under dim (1 lux in the closed arm) and lit (246 lux in the closed arm) environmental conditions. We found that measures of general performance (basic movements and total distanced travelled throughout the maze) were stable across repeated trials and environmental conditions. We found that measures of open arm avoidance (distance travelled in, time spent in and entries in to the open arm) varied across trials and environmental conditions and were sensitive to the lighting conditions of the initial test. Though measures of open arm avoidance did show a linear trend indicative of habituation across repeated trials, this effect was variable across trials. Notably, preference for the open arm over the closed arm (measured as % of time spent in the open arm) assessed among individual animals occurred rarely and was never observed on the group level across the thirteen repeated trials. Together, these data demonstrate that measures of general performance such as basic movements and total distance traveled are robust to repeated testing and changing environmental lighting conditions. In contrast, measures of open arm avoidance show habituation with repeated testing and are sensitive to changing environmental lighting conditions. Based on these results, we suggest that within-subjects repeated testing on the EPM is valid in well-controlled studies that include an untreated control group to account for inter-trial variability and habituation.

Anxiolytic and antinociceptive-like effects of cinnamic alcohol by possible GABAergic pathway modulation: In vivo and in silico studies

“…Therefore, substances that present anxiolytic activity in the animals tend also to increase both the number of entries and residence time in the open arms of the elevated plus-maze apparatus (PELLOW et al, 1985). Thus, animals treated with diazepam, enter the open arms more often and stay longer (CRAWLEY, 1981;SCHRADER et al, 2018). From our results, CA increased the number of entries and residence times of mice in the open arms of the maze.…”

“…The elevated plus-maze is a widely used model for study of anxiety behavior in rats and mice (LEITE;SIQUEIRA, 2006) (SCHRADER et al, 2018. The test is based on the natural aversion that rodents have for open and elevated areas (WALF;FRYE, 2007).…”

Female rats self-administer heroin by vapor inhalation

“…This may not always be the case, however, since the stability of EPM testing over time has been reported in non-treated rats (Schrader et al, 2018). Nevertheless, we took a cautious approach in the EPM assay by performing testing in ascending order of drug discontinuation time.…”

The Effects of P-Hydroxycinnamic Acid in Ameliorating Spatial Learning and Flexibility Deficits in Rats with Chronic Cerebral Hypoperfusion

“…The anxiolytic effect caused by CCH and pHCA was temporarily in the present study. Open arm avoidance may have been habituated over repeated trials for the Sham-veh rats, which may have caused a lack of differences in the third-week EPM test (Schrader et al 2018).…”