Prevention of self-grooming in rats: Evidence for a rebound effect.

Rodent self-grooming is a stereotyped behavior that can rise due to stressors such as novelty. In the present study, the occurrence of a rebound effect was investigated by means of manipulation of contextual novelty and of the possibility of self-grooming (with an Elizabethan collar which blocked head-body contact). Fourty-six male rats were submitted to an experiment latter replicated with 43 females. Half of the animals were submitted to habituation sessions (30 min) to the test box in three days. The other half was similarly handled but habituated to small cages. On the fourth day, rats from both conditions were assigned to Elizabethan or sham collar groups. Each animal was observed for 15 min with its respective collar and for other 15 min with no collars. Increased locomotion was observed in the rats not habituated to the test box. Such habituation did not affect any grooming parameter. On the other hand, the animals wearing Elizabethan collars during the first half of the test, as compared to those which wore sham collars, showed increased self-grooming during the second half of the test (i.e., with no collars). Females showed pretty similar results. Present results, thus, evidence a rebound effect in self-grooming.

Rat self-grooming and its relationships with anxiety, dearousal and perseveration: Evidence for a self-grooming trait.

Rodent self-grooming is a behavior that, besides its cleaning function, can be led by arousing experiences. A putative trait-like nature of this behavior was studied. With the aim of providing information about how grooming behavior can reflect different behavioral processes, an individual differences approach was adopted. Fifty nine male Wistar-derived rats were submitted to five 30-min long behavioral tests. These tests were selected based on the behavioral processes they entangle. Elevated plus-maze (EPM): anxiety, exploration/habituation, arousal/dearousal; Marble burying (MB): active/passive coping; Operant extinction (EXT): frustration, perseveration; Conditioned fear context (CFC): fearfulness, active/passive coping; Novelty after restraint (NAR): stress induced behavior. Orthogonal (Varimax) factor analyses were performed within each test in order to select the most representative measures. To the selected variables from all tests a Direct Oblimin factor analysis was applied. A three factor solution was found after the application of the Cattell's scree test. This solution accounted for 44.2% of the variance. By looking at the loading variables, some conclusions could be drawn. On Factor 1 loaded time spent grooming in three tests and the measure of extinction resistance. We considered this factor to evidence a trait-like nature of grooming and a relationship between it and perseveration. On Factor 2 loaded freezing in the CFC, SAPs in the EPM and grooming duration in the EXT. We considered this factor to correspond to anxiety. On Factor 3, moderate to high loadings were found for crossings in the NAR test and for grooming duration in this test and in the EPM. A lower loading on this factor was also found for the number of buried marbles. We considered this factor as related to dearousal. The present results suggest important relationships both (1) within grooming measures recorded in different behavioral tests and (2) among grooming and other behaviors observed in the tests. These relationships are in accordance with a trait-like nature for self-grooming and shed some light to how grooming behavior interplays with anxiety, dearousal and perseveration.