GISNe - Anatomia, Farmacologia e Medicina Legale

INDIVIDUAL DIFFERENCES IN CARDIAC AUTONOMIC AND SYMPATHETIC-
ADRENOMEDULLARY RESPONSES TO SOCIAL CHALLENGE
Andrea Sgoifo, Francesca Mastorci, M. Angeles Pico’ Alfonso
Stress Physiology Lab, Department of Evolutionary and Functional Biology, University of
Parma, Parco Area delle Scienze 11/A, 43100 Parma, Italy
Social stressors play a significant role in the onset and progression of cardiovascular diseases
such as hypertension, atherosclerosis and cardiac arrhythmias. Human and animal data suggest
that an important determinant of cardiocirculatory stress reactivity and morbidity is the
individual behavioral strategy of coping with environmental challenge. This paper summarizes
the results of a number of studies that we performed in rodents and humans, aimed at shedding
further light on the relationship between individual aggression levels and associated
dominance/subordination status and short- and long-term neuroendocrine and cardiovascular
stress reactivity. Our data suggest that: (i) individuals belonging to the 'aggressive tail' of a
wild-type rat population are characterized by a higher sympathetic-adrenomedullary activation
during both social and non-social stress episodes; (ii) in rats, cardiovascular habituation takes
place when social challenge is an intermittent victory experience, whereas no habituation is
observed across repeated defeat episodes; (iii) when social dominance is challenged, rats
exhibit long-term alterations of heart rate circadian rhythmicity, such changes being
modulated by the individual level of aggression; (iv) in mice, chronic subordination induces
transient alterations of heart rate circadian rhythmicity and permanent myocardial damage, the
latter consisting of scattered foci of fibrosis; (v) in humans, subjects with higher scores of
submissive behavior are prone to larger cardiac accelerations and parasympathetic suppression
during and after a laboratory stressor. Altogether, these data underline how important it is to
carefully consider individual differences in trait and state aggression, as well as the context in
which aggression is expressed, when studying acute and long-term autonomic and
neuroendocrine effects of social interactions.