Neuronal and behavioral differences between Mus musculus domesticus (C57BL/6JBy) and Mus musculus castaneus (CAST/Ei)

Previous studies have demonstrated that classical inbred strains of laboratory mice do not exhibit large genetic distances when simple sequence repeats (SSRs) are used to test for their polymorphisms whereas mice from wild origin exhibit high polymorphisms (more than 90%) for these sequence when compared with classical inbred strains of laboratory mice. The difference between Mus musculus castaneus and C57BL/6J reaches 98% and F1s male and female are fertile. These two properties pave the way for gene mapping derivating segregating generations between these strains. The phenotypical characteristics of Mus musculus castaneus have not been investigated, unfortunately. The first screening of Mus musculus castaneus and C57BL/6By was carried out for sensorial and motor development, spontaneous behavior in new environment, paw preference, maternal behavior, aggression in two different situations and time to learn escape in a water maze. Morphometry of hippocampus and weight of the male reproductive organs for measures that have been reported to be correlated with several of the examined behavior are also reported. The authors tested also reactivity to one drug (beta-CCM) revealing seizure proneness. The two strains differ for 69% of the reported measures. Comparison to other strains for the same measures obtained in the laboratory for identical tests with mice reared in identical situations provided the mean to compare Mus musculus castaneus with a large set of more or less traditional mice. This strain has the most extreme position for 80% of the comparisons.