Reciprocal Affiliation Among Adolescent Rats During a Mild Group Stressor Predicts Mammary Tumors and Lifespan

Department of Comparative Human Development, University of Chicago, Chicago, IL 60637, USA.
Psychosomatic Medicine (Impact Factor: 3.47). 11/2008; 70(9):1050-9. DOI: 10.1097/PSY.0b013e31818425fb
Source: PubMed


Although the detrimental physical health effects of social isolation have been known for three decades, the answers to how and why social relationships generally improve health remain elusive. Social relationships are not always beneficial, and we examined a structural dimension that may bring about their salubrious effects: affiliative reciprocity during a stressor.
In a lifespan study, female rats lived with their sisters and were tested for temperament, affiliative reciprocity during an everyday stressor at puberty, corticosterone response to a stressor, mammary tumor development and diagnosis, and death.
Rats that affiliated more reciprocally during a mild group stressor survived longer (p = .0005), having exhibited a lower corticosterone peak in response to an acute novel stressor in late adulthood (p = .0015), and longer time to the development of spontaneous mammary tumors (p = .02). These effects could not be explained solely by the number of affiliative interactions or individual temperament. Indeed, affiliative reciprocity and neophobia were independent and predicted mortality additively (p = .0002).
Affiliative reciprocity during a stressor, a structural quality of social interactions, protected females from early mammary tumor development (the primary pathology in Sprague-Dawley rats) and early all-cause mortality. Conversely, lack of reciprocity (whether disproportionately seeking or receiving attempted affiliation) was as potent a risk factor as neophobia. Thus a social role increased risk additively with individual temperament. Our data indicate that affiliative reciprocity functions as a buffer for everyday stressors and are likely mediated by attenuated reactivity of the hypothalamic-pituitary-adrenal axis.

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Available from: Sonia A Cavigelli
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    • "The effects of social buffering are far reaching, and in humans there is evidence that social relationships aid immune function, cardiovascular health, and other health-related outcomes (reviewed in Berkman and Kawachi, 2000). Stable natural social relationships have even been associated with increased longevity in humans and other species (humans: Holt-Lunstad et al., 2010; baboons: Silk et al., 2010; rats: Yee et al., 2008; dolphins: Stanton and Mann, 2012). The endocrine consequences of social buffering were first described in primates (Coe et al., 1978; Mendoza et al., 1978) and primate studies continue to be important particularly for our understanding of natural social buffering in the context of stress. "
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    • "In social species, social bonds are influential in their moderation of survival, of learning, and of responses to environmental disruptions . Social bonds can facilitate good health and reduce mortality (e.g., Holt-Lunstad et al., 2010; Silk et al., 2010; Yee et al., 2008) and enhance recovery from aversive experiences (e.g., Gilbert and Baker, 2011; Hennessy et al., 2009; Kikusui et al., 2006). One of the means by which recovery from aversive or stressful experiences is gauged is by monitoring hypothalamic–pituitary–adrenal (HPA) hormone release. "
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    ABSTRACT: There is a paucity of studies comparing social buffering in adolescents and adults, despite their marked differences in social behaviour. We investigated whether greater effects of social buffering on plasma corticosterone concentrations and expression of Zif268 in neural regions after an acute stressor would be found in adolescent than adult rats. Samples were obtained before and after one hour of isolation stress and after either one or three hours of recovery back in the colony with either a familiar or unfamiliar cage partner. Adolescent and adult rats did not differ in plasma concentrations of corticosterone at any time point. Corticosterone concentrations were higher after one hour isolation than at baseline (p<0.001), and rats with a familiar partner during the recovery phase had lower corticosterone concentrations than did rats with an unfamiliar partner (p=0.02). Zif268 immunoreactive cell counts were higher in the arcuate nucleus in both age groups after isolation (p=0.007) and in the paraventricular nucleus of adolescents than adults during the recovery phase irrespective of partner familiarity. There was a significant decrease in immunoreactive cell counts after one hour isolation compared to baseline in the basolateral amygdala, central nucleus of the amygdala, and in the pyramidal layer of the hippocampus (all p<0.05). An effect of partner familiarity on Zif268 immunoreactive cell counts was found in the granule layer of the dentate gyrus irrespective of age (higher in those with a familiar partner, p=0.03) and in the medial prefrontal cortex in adolescents (higher with an unfamiliar partner, p=0.02). Overall, the acute stress and partner familiarity produced a similar pattern of results in adolescents and adults, with both age groups sensitive to the social context.
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    • "A number of studies have described an impact of ado - lescent social isolation on the development of an effec - tive and efficient adult stress response system ( Hall , 1998 ; Yee , Cavigelli , Delgado , & McClintock , 2008 ) . "
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