Publication Date



Open access

Embargo Period


Degree Type


Degree Name

Master of Science (MS)


Psychology (Arts and Sciences)

Date of Defense


First Committee Member

Philip M. McCabe

Second Committee Member

Armando J. Mendez

Third Committee Member

Maria M. Llabre


Previous research attests to the relationship between social support and positive health outcomes while linking social isolation or aggression/hostility with negative health outcomes. Several studies examining atherosclerosis with either genetic or behavioral origins, have reported decreased disease severity in socially supportive environments. In order to identify and understand the mechanism responsible for decreased disease, the current study examined physiological differences in New Zealand White rabbits within unstable, stable, and isolated social environments and observed whether functional hormonal changes were apparent over time and as a response to behavior characteristic of these environments. Results indicated that animals within the unstable condition displayed increased agonistic behavior, increased cortisol and epinephrine, decreased body weight, epididymal fat, and retroperitoneal fat, as well as larger spleens. Cortisol values positively correlated with measures of agonistic behavior for all animals, while the reverse relationship was found for affiliative behavior. The novel finding of an increase in oxytocin in animals in the unstable condition within the first ten minutes of pairing that was noticeably distinct from the other two groups suggests that plasma oxytocin levels are related to acute stress. Limitations and interpretations of these findings are discussed. Future work is still needed to help further explain the physiological response to social stress and affiliation and to elucidate the mechanism by which a supportive social environment appears to protect against progression and severity of heart disease.


Behavior; Social Environment; Hormones; Cardiovascular; Catecholamines; Oxytocin; Rabbits