Colony formation of C57BL/6J mice in visible burrow system: Identification of eusocial behaviors in a background strain for genetic animal models of autism

Abstract

Deficits in social interaction are primary characteristics of autism, which has strong genetic components. Genetically-manipulated mouse models may provide a useful research tool to advance the investigation of genes associated with autism. To identify these genes using mouse models, behavioral assays for social relationships in the background strains must be developed. The present study examined colony formation in groups of one male and three female mice (Experiment 1) and, groups of three male mice (Experiment 2) of the C57BL/6J strain in a seminatural visible burrow system. For adult mixed-sex colonies, four-hour observations during both the dark and light cycles for 15 days demonstrated day-dependent increases in huddling together in the chamber accompanied by decreased frequencies of active social behaviors. Sequential analyses of social interactions indicated that approaches to the back of the approached animal typically elicited flight, while approaches to the front of the approached animal failed to do so. This was seen for female to female, and for female to male approaches, as well as male to female approaches, strongly counter indicating a view that rear approach/flight specifically reflects female responsivirity to unwanted male sexual approach. For adult male colonies, similar protocols found that these social behaviors were similar to those of adult mixed-sex colonies. These findings suggest two potentially useful measures of eusocial behavior in mice, of possible value for genetic mouse models of autism; that is, huddling together and approaches to the front but not the back, of conspecifics.

A new test paradigm for social recognition evidenced by urinary scent marking behavior in C57BL/6J mice

“…Although the scent marking response to the novel context was not as large as that to a novel mouse, this likely reflects the continued presence of rough paper flooring in the novel context [5,20]. C57 mice are used as a common background strain for knockout mice relevant to disorders such as autism that include deficits in social communication, social motivation, and amicable relationships [1,3,[15][16]51]. The present study demonstrated that C57 as well as CD-1 mice display good social recognition as indexed by scent marking behavior.…”

Central oxytocin regulates social familiarity and scent marking behavior that involves amicable odor signals between male mice

“…In nature, individual male mice tend to be solitary, forming their own territories following puberty [3,4]. However, sociality and "amicable" (affiliative) relationships as well as aggression have been documented in male mice in a semi-natural habitat, the visible burrow system (VBS) [5][6][7]. The VBS enclosures provide multiple visible tunnels and burrows in addition to an open "surface" area, to evaluate complicated natural behaviors and social structures among rodents [6,7].…”

“…The VBS enclosures provide multiple visible tunnels and burrows in addition to an open "surface" area, to evaluate complicated natural behaviors and social structures among rodents [6,7]. In the VBS, all-male groups of mice of the C57BL/6J (B6) strain, commonly used as a background for genetic manipulations in mice [8][9][10], displayed active (aggressive) interaction during the first few hours of the colony formation followed by a strong tendency to huddle together in a nest chamber during the inactive (light) period as well as during active (dark) periods [5]. The shift from aggressive interaction to amicable huddling accompanied by decreased active social interaction such as approaches, contacts, flight, and chase between male mice occurs over time, as animals habituate to the colony situation and become familiar with colony mates [5].…”

Temporal dynamics of social hierarchy formation and maintenance in male mice

“…Studies that have examined social dominance in groups of male laboratory mice have limited their scope to the emergence of an alpha male rather than determining finer details regarding the rank order of all individuals (Ely & Henry, 1978;Lewejohann et al, 2009). Moreover, previous studies of social dominance in the laboratory have limitations such as small group sizes, short duration of observations and few replicated groups (Arakawa, Blanchard, & Blanchard, 2007;Ely & Henry, 1978;Lewejohann et al, 2009;So, Franks, Lim, & Curley, 2015).…”