TY - JOUR
T1 - Effects of chronic psychosocial stress on cardiac autonomic responsiveness and myocardial structure in mice
AU - Costoli, Tania
AU - Bartolomucci, Alessandro
AU - Graiani, Gallia
AU - Stilli, Donatella
AU - Laviola, Giovanni
AU - Sgoifo, Andrea
PY - 2004/6
Y1 - 2004/6
N2 - Repeated single exposures to social stressors induce robust shifts of cardiac sympathovagal balance toward sympathetic dominance both during and after each agonistic interaction. However, little evidence is available regarding possible persistent pathophysiological changes due to chronic social challenge. In this study, male CD-1 mice (n = 14) were implanted with a radiotelemetry system for electrocardiographic recordings. We assessed the effects of chronic psychosocial stress (15-day sensory contact with a dominant animal and daily 5-min defeat episodes) on 1) sympathovagal responsiveness to each defeat episode, as measured via time-domain indexes of heart rate variability (R-R interval, standard deviation of R-R interval, and root mean square of successive R-R interval differences), 2) circadian rhythmicity of heart rate across the chronic challenge (night phase, day phase, and rhythm amplitude values), and 3) amount of myocardial structural damage (volume fraction, density, and extension of fibrosis). This study indicated that there was habituation of acute cardiac autonomic responsiveness, i.e., the shift of sympathovagal balance toward sympathetic dominance was significantly reduced across repeated defeat episodes. Moreover, animals exhibited significant changes in heart rate rhythmicity, i.e., increments in day and night values and reductions in the rhythm amplitude, but these were limited to the first 5 days of chronic psychosocial stress. The volume fraction of fibrosis was sixfold larger than in control animals, because of the appearance of many microscopic scarrings. In summary, although mice appeared to adapt to chronic psychosocial stress in terms of acute cardiovascular responsiveness and heart rate rhythmicity, structural alterations occurred at the myocardial level.
AB - Repeated single exposures to social stressors induce robust shifts of cardiac sympathovagal balance toward sympathetic dominance both during and after each agonistic interaction. However, little evidence is available regarding possible persistent pathophysiological changes due to chronic social challenge. In this study, male CD-1 mice (n = 14) were implanted with a radiotelemetry system for electrocardiographic recordings. We assessed the effects of chronic psychosocial stress (15-day sensory contact with a dominant animal and daily 5-min defeat episodes) on 1) sympathovagal responsiveness to each defeat episode, as measured via time-domain indexes of heart rate variability (R-R interval, standard deviation of R-R interval, and root mean square of successive R-R interval differences), 2) circadian rhythmicity of heart rate across the chronic challenge (night phase, day phase, and rhythm amplitude values), and 3) amount of myocardial structural damage (volume fraction, density, and extension of fibrosis). This study indicated that there was habituation of acute cardiac autonomic responsiveness, i.e., the shift of sympathovagal balance toward sympathetic dominance was significantly reduced across repeated defeat episodes. Moreover, animals exhibited significant changes in heart rate rhythmicity, i.e., increments in day and night values and reductions in the rhythm amplitude, but these were limited to the first 5 days of chronic psychosocial stress. The volume fraction of fibrosis was sixfold larger than in control animals, because of the appearance of many microscopic scarrings. In summary, although mice appeared to adapt to chronic psychosocial stress in terms of acute cardiovascular responsiveness and heart rate rhythmicity, structural alterations occurred at the myocardial level.
KW - Cardiac fibrosis
KW - Circadian rhythms
KW - Heart rate variability
KW - Social stress
KW - Sympathovagal balance
UR - http://www.scopus.com/inward/record.url?scp=2542434070&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=2542434070&partnerID=8YFLogxK
U2 - 10.1152/ajpheart.00869.2003
DO - 10.1152/ajpheart.00869.2003
M3 - Article
C2 - 14962836
AN - SCOPUS:2542434070
SN - 0363-6135
VL - 286
SP - H2133-H2140
JO - American Journal of Physiology - Heart and Circulatory Physiology
JF - American Journal of Physiology - Heart and Circulatory Physiology
IS - 6 55-6
ER -