, 2009; McNeal et al., 2014). As the work in prairie voles illustrates, it is important to consider the natural history of species when social manipulations are performed. For example, RG 7204 male Syrian hamsters housed in isolation are more aggressive than those housed in groups (Brain, 1972), but that is not to suggest that isolation

was distressing, or produced an unusual behavioral phenotype, as this species is naturally solitary (Gattermann et al., 2001). Conversely, crowding might be a particularly potent but unnatural stressor for this species, and it has been associated with increased mortality (Germann et al., 1990 and Marchleswska-Koj, 1997). Social species provide good subjects for studying the influence of social interactions on health and related outcomes, and this has been demonstrated both in the laboratory and in the field. In a species of South American burrowing rodent – the colonial tuco–tuco (C. sociabilis) – females may live alone click here or share a burrow with several other adults members and their young ( Lacey et al., 1997). Yearling C. sociabilis that live alone (whether via dispersal in the field or investigator manipulations in the lab), have significantly higher baseline fecal glucocorticoid metabolite levels than do group-living individuals in the same environments ( Woodruff et al., 2013). In a putatively

monogamous species of wild guinea pig (Galea monasteriensis), social separation induces increases in cortisol secretion that are only rectified by return of the social partner ( Adrian et al., 2008). The study of species in the context of their natural behavior allows STK38 us to better understand stress-related outcomes in a variety of rodent species. Some studies employ both crowding and isolation in alternation (for example, 24 h of each for 2 weeks),

as a model for chronic social instability (e.g. Haller et al., 1999 and Herzog et al., 2009). Social instability has particularly been used as a social stressor for female rats, for whom crowding and social defeat are not always effective stressors (Palanza, 2001). In the crowding phase, different social groups consisting of different numbers of males and females are formed. Females exposed to this variable social environment show increased adrenal weight, increased corticosterone secretion, decreased thymus weight, and reduced weight gain relative to females housed in stable male–female pairs (Haller et al., 1999). A second study replicated these findings and demonstrated that social instability also induced dysregulation of the hypothalmic–pituitary–gonadal (HPG) axis (elevated luteinizing hormone, prolactin, and disrupted estrus cycles), and reduced sucrose preference and food intake (Herzog et al., 2009).