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.

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