Contrasting grooming phenotypes in C57Bl/6 and 129S1/SvImJ mice

Since C57 and 129 mice are the commonly used background strains, a better knowledge of all their behavioural characteristics is important in neuroscience research. Grooming is a complex and essential ritual in the rodent behavioural repertoire, normally proceeding in a cephalocaudal progression (paws-nose-face-body-legs-tail and genitals). Various stressors as well as genetic manipulations have been reported to alter mouse grooming and its patterning, underlying the importance of analysis of grooming behaviours in detail. Although strain differences between C57BL/6 and 129S1/SvImJ substrains have been assessed in many studies, no ethological analyses of their grooming have been performed. Here we show strain differences between these mice in spontaneous (novelty-induced) and artificial (water-induced) grooming. Overall, 129S1/SvImJ mice demonstrated less grooming activity, more interrupted and incomplete bouts, and more incorrect transitions (contrary to the cephalocaudal rule) between patterns, accompanied by lower vertical activity and higher defecation/urination in both tests. These results are consistent with general hypoactive anxious phenotype in 129S1/SvImJ mice and suggest that ethological analysis of mouse grooming may be used in neurobehavioural stress research, including behavioural phenotyping of both mutant and background mice.