Detailed analysis of paternal knockout Grb10 mice suggests effects on stability of social behavior, rather than social dominance

Abstract

Imprinted genes are highly expressed in monoaminergic regions of the midbrain and their functions in this area are thought to have an impact on mammalian social behaviors. One such imprinted gene is Grb10, of which the paternal allele is currently recognized as mediating social dominance behavior. However, there has been no detailed study of social dominance in Grb10 +/p mice. Moreover, the original study examined tube-test behavior in isolated mice 10 months of age. Isolation testing favors more territorial and aggressive behaviors, and does not address social dominance strategies employed in group housing contexts. Furthermore, isolation stress impacts midbrain function and dominance related behavior, often through alterations in monoaminergic signaling. Thus, we undertook a systematic study of Grb10 +/p social rank and dominance behavior within the cage group, using a number of convergent behavioral tests. We examined both male and female mice to account for sex differences, and tested cohorts aged 2, 6, and 10 months to examine any developments related to age. We found group-housed Grb10 +/p mice do not show evidence of enhanced social dominance, but cages containing Grb10 +/p and wildtype mice lacked the normal correlation between three different measures of social rank. Moreover, a separate study indicated isolation stress induced inconsistent changes in tube test behavior. Taken together, these data suggest future research on Grb10 +/p mice should focus on on the stability of social behaviors, rather than dominance per se.

What it takes to be at the top: The interrelationship between chronic social stress and social dominance

“…We have only used male animals in this study as female mice are not commonly used in assessments of social dominance based on territoriality and vocalizations since females rely more on intrinsic attributes and social feedback to establish a hierarchy rather than prior social experience (Van Den Berg et al., 2015). However, some studies were able to show stable linear hierarchies in female mice, although the effect of estrus stages has to be taken into account (Rienecker et al., 2020).…”

Mice lacking paternal expression of imprintedGrb10are risk-takers

“…Grb10 have altered behavior (Rienecker et al, 2020), including a higher tolerance of delayed 9 rewards in a delay reinforcement task (DRT) (Dent et al, 2018). One suggestion is that 10 these changes reflect a role for Grb10 in regulating risk-taking behavior broadly (Wilkins & 11 Bhattacharya, 2019).…”

What it takes to be at the top: The interrelationship between chronic social stress and social dominance

“…We have only used male animals in this study as female mice are not commonly used in social dominance assessments based on territoriality and vocalizations since they rely more on intrinsic attributes and social feedback to establish a hierarchy rather than prior social experience [31]. However, some studies were able to show stable linear hierarchies in female mice but the effect of oestrus stage has to be taken into account [32]. 6…”