Cues to the usefulness of grooming behavior in the evaluation of anxiety in the elevated plus-maze.

Abstract

Grooming behavior has been reported to be a response to novelty and other stressors. However, studies that sought to identify anxiety-related measures in the elevated plus-maze have not found grooming as a reliable index. Grooming has been implied with dearousal after a stressful experience. In the present work, a detailed investigation of this behavior was performed in a test with a longer duration (i.e., 10 min) than the usual duration in the elevated plus-maze. The level of anxiety was manipulated prior to the test by confining male rats to environments known to differ in the degree of aversive stimulation, including a familiar cage, a closed arm of the elevated plus-maze, and an open arm (i.e., the most aversive arm) of the elevated plus-maze. Grooming behavior was classified into three constituent elements: rostral grooming, head grooming, and body grooming. The groups were compared with regard to conventional measures of the elevated plus-maze and grooming behavior. Prior confinement to an open arm led to a delayed effect of decreased open-arm exploration undetectable during the first half of the test compared with rats previously confined to a closed arm. Prior confinement to an open arm also increased the total duration of grooming during the second half of the test. These increases were found to be partially attributable to increases in the rostral element of grooming. The percentage of interrupted bouts was also found to discriminate the group previously confined to an open arm. These results indicate that prolongation of the session can reveal effects that are otherwise undetectable and that under such conditions some grooming measures can be useful in the evaluation of anxiety-like behavior.

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

“…Based on the view that grooming takes place during de-arousal after a stressful experience [39], one could propose that the two-month-old diprotin A-and sitagliptin-treated animals exhibited increased emotional tension. Judging by the increase in the number of grooming episodes in the sitagliptin-treated rats and reduced latency to the first episode in the diprotin A-treated rats compared to the controls, the signs of increased emotional tension were maintained in three-month-old animals.…”

“…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.…”

Inhibition of corticotropin releasing factor expression in the central nucleus of the amygdala attenuates stress-induced behavioral and endocrine responses

“…In this experiment, grooming behavior on the EPM was significantly attenuated by loss of CRF in CeA regardless of whether or not animals had been previously exposed to restraint stress. Grooming behavior on the EPM is often used as a corollary measure of anxiety-like behavior (Bolanos et al, 2003; Estanislau, 2012; Tapia-Osorio et al, 2013), however, this is not universally accepted (Bolles, 1960; van Erp et al, 1994). Self-grooming is a behavioral response in rodents to stressful or anxiogenic stimuli (Spruijt et al, 1992).…”

Rats with differential self-grooming expression in the elevated plus-maze do not differ in anxiety-related behaviors

“…This analysis followed the criteria established by Kalueff et al [60][61][62] and termed "Grooming Analysis Algorithm" (GAA). Although the GAA has been previously proposed to take place in an apparatus designed solely for measuring grooming, it has been recently applied to the EPM test [63]. Briefly, the analysis consisted in evaluating the grooming microstructure, particularly the number and percentage of incorrect transitions, number of interruptions, percentage of completed sequences and the regional distribution of grooming.…”