Biology subjects

Romeo, R. D.

Publications and source records attributed to Romeo, R. D..

3 recordsLinked to original sources

bioRxiv2023

Early life adversity reduces affiliative behavior towards a distressed cagemate and leads to sex-specific alterations in corticosterone responses

Experiencing early life adversity (ELA) alters stress physiology and increases the risk for developing psychiatric disorders. The social environment can influence dynamics of stress responding and buffer and/or transfer stress across individuals. Yet, the impact of ELA on sensitivity to the stress of others and social behavior following stress is unknown. Here, to test the impact of ELA on social and physiological responses to stress, circulating blood corticosterone (CORT) and social behaviors were assessed in adult male and female mice reared under limited bedding and nesting (LBN) or control conditions. To induce stress, one cagemate of a pair-housed cage underwent a footshock paradigm and was then returned to their unshocked partner. CORT was measured in both mice 20 or 90 minutes after stress exposure, and social behaviors were recorded and analyzed. ELA rearing influenced the CORT response to stress in a sex-specific manner. In males, both control and ELA-reared mice exhibited similar stress transfer to unshocked cagemates and similar CORT dynamics. In contrast, ELA females showed a heightened stress transfer to unshocked cagemates, and sustained elevation of CORT relative to controls, indicating enhanced stress contagion and a failure to terminate the stress response. Behaviorally, ELA females displayed decreased allogrooming and increased investigative behaviors, while ELA males showed reduced huddling. Together, these findings demonstrate that ELA influenced HPA axis dynamics, social stress contagion and social behavior. Further research is needed to unravel the underlying mechanisms and long-term consequences of ELA on stress systems and their impact on behavioral outcomes.

neuroscience↗

bioRxiv2022

Social dominance status and social stability in spiny mice (Acomys cahirinus) and its relation to ear-hole regeneration and glucocorticoids

Spiny mice (Acomys cahirinus) are an emerging animal model in studies measuring tissue regeneration, but decades of research on social dominance in other animals indicates the relationships animals form in their home-cage may affect phenotypic plasticity in tissue regeneration and glucocorticoids. Studies in baboons and mice, for example, indicate that subordinate ranked animals heal wounds slower than their dominant group-mates, and have increased levels of basal glucocorticoids. Recent studies in tissue regeneration with salamanders and zebrafish indicate that increased glucocorticoids can delay tissue regeneration, but whether this effect extends to Acomys is unknown, especially regarding their social dominance relationships. Here we report that most adult Acomys had a social dominance status, but many groups had unclear social stability, with more frequent huddling than fighting during their active cycle. We also found no sex differences in social dominance behavior, and that Acomys more frequently fled than froze when chased or approached. After a 4mm ear-pinna biopsy, we found that social stability significantly accounted for variability in time to close the ear-hole but adding age to the statistical model removed the effect of social stability. When investigating glucocorticoid blood levels, there were no significant effects of social dominance status or social stability. A transcriptional enhancer for StAR, Nr5a1 had a significant effect for the interaction of social dominance status and social stability. This effect, however, was not reflected in StAR and unclear groups mostly had unclear social statuses, so this effect should be considered with caution. This is the first study to investigate home-cage social dominance behaviors in Acomys since the 1970s or measure any associations with their ability to regenerate tissue. This provides a platform for further work on their social dominance and glucocorticoids and highlights the need to consider the role of aging in their ability to regenerate tissue.

animal behavior and cognition↗

bioRxiv2019

Social hierarchy position in female mice is associated with plasma corticosterone levels and hypothalamic gene expression

Social hierarchies emerge when animals compete for access to resources such as food, mates or physical space. Wild and laboratory male mice have been shown to develop linear hierarchies, however, less is known regarding whether female mice have sufficient intrasexual competition to establish significant social dominance relationships. In this study, we examined whether groups of outbred CD-1 virgin female mice housed in a large vivaria formed social hierarchies. We show that females use fighting, chasing and mounting behaviors to rapidly establish highly directionally consistent social relationships. Notably, these female hierarchies are less linear, steep and despotic compared to male hierarchies. Female estrus state was not found to have a significant effect on aggressive behavior, though dominant females had elongated estrus cycles (due to increased time in estrus) compared to subordinate females. Plasma estradiol levels were equivalent between dominant and subordinate females. Subordinate females had significantly lower levels of basal corticosterone compared to dominant females. Analyses of gene expression in the ventromedial hypothalamus indicated that subordinate females have elevated ER, ER{beta} and OTR mRNA compared to dominant females. This study provides a methodological framework for the study of the neuroendocrine basis of female social aggression and dominance in laboratory mice.

animal behavior and cognition↗